Method for manufacturing oxide-based materials

Abstract

The present invention provides a method for manufacturing oxide-based materials that can reduce yield deterioration. [Solution] The method for producing an oxide-based material comprises a step of firing a lithium-containing material, the step of firing the material placed on a firing jig in a furnace, the firing jig being made of metal at least in the part that comes into contact with the material. The metal can be mainly composed of at least one of W, Mo, and Ni. The metal composition can be such that the proportions of Si, Al, Cr, and Ti are each less than 1 wt%.

Description

Technical Field

[0001] The present invention relates to a method for manufacturing an oxide-based material including a step of firing a lithium-containing material.

Background Art

[0002] In the technology of manufacturing an oxide-based material by firing a lithium-containing material, a technology using a firing jig made of magnesia is disclosed in Patent Document 1.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] Since the firing jig made of magnesia has a relatively large coefficient of thermal expansion, the firing jig may be damaged by thermal shock during firing, and the material may fall into the furnace, deteriorating the yield of the oxide-based material.

[0005] The present invention has been made to solve this problem, and an object thereof is to provide a method for manufacturing an oxide-based material that can reduce the deterioration of the yield.

Means for Solving the Problems

[0006] A first aspect for achieving this object is a method for manufacturing an oxide-based material including a step of firing a lithium-containing material, the step including an operation of firing the material placed on a firing jig in a furnace, and at least a portion of the firing jig that comes into contact with the material being made of metal.

[0007] A second aspect is that, in the first aspect, the firing jig includes a bottom and a wall provided around the bottom, and the material is placed on the bottom.

[0008] A third embodiment is the second embodiment, wherein at least the inner surface of the wall is made of metal.

[0009] The fourth aspect is that, in any of the first to third aspects, the metal mainly consists of at least one of W, Mo, and Ni.

[0010] The fifth embodiment is one in which, in any of the first to fourth embodiments, the metal components consist of less than 1 wt% each of Si, Al, Cr, and Ti. [Effects of the Invention]

[0011] According to the present invention, since the material is fired using a firing jig in which at least the part that comes into contact with the material is made of metal, the high-temperature strength and thermal shock resistance of the firing jig can be improved compared to a firing jig made of magnesia. Since the number of firing jigs that break during firing can be reduced, the deterioration of the yield of oxide-based materials can be reduced. [Brief explanation of the drawing]

[0012] [Figure 1] This is a schematic diagram of the firing process of the material contained in the firing jig in the first embodiment. [Figure 2] (a) is a cross-sectional view of the firing jig containing the material, and (b) is a cross-sectional view of the firing jig containing the material after primary firing. [Figure 3] This is a schematic diagram showing the crystal structure of a garnet-type crystal. [Figure 4] (a) and (b) are cross-sectional views of the firing jig. [Figure 5] (a) is a perspective view of the firing jig in the second embodiment, and (b) is a perspective view of the firing jig in the third embodiment. [Modes for carrying out the invention]

[0013] Hereinafter, preferred embodiments of the present invention will be described with reference to the accompanying drawings. FIG. 1 is a schematic diagram of the firing of the material 10 (see FIG. 2(a)) accommodated in the firing jig 11 in the first embodiment. The oxide-based material is manufactured through a process of firing the firing jig 11 containing the material 10 containing lithium in the furnace 20.

[0014] FIG. 2(a) is a cross-sectional view of the firing jig 11 containing the material 10. Examples of the oxide-based material manufactured through the process of firing the material 10 include a solid electrolyte having lithium ion conductivity, a positive electrode active material and a negative electrode active material that occlude or release lithium ions. Examples of the solid electrolyte include NASICON-based materials, LISICON-based materials, and oxides having a perovskite structure or a garnet structure.

[0015] Examples of the positive electrode active material and the negative electrode active material include oxides containing a transition metal and Li. Examples of the positive electrode active material include LiCoO2, LiNi (1-x) / 3 , x Co 0.15 Al 0.05 O2, LiMn2O4, LiNiVO4, LiNi 0.5 Mn 1.5 O4, LiNi 1 / 3 Mn 1 / 3 Co 1 / 3 O2, and LiFePO4, and an example of the negative electrode active material is Li4Ti5O 12 is exemplified.

[0016] The NASICON-based material is a material represented by the general formula Li​​​​​​​​​​​​​​​​​​​​​​2 / 3-X Li 3X One example is TiO3 (0 ≤ x ≤ 1). The crystal structure of garnet-type oxides is given by the general formula C3A2B3O 12 It is represented as follows.

[0017] Figure 3 schematically shows a garnet-type crystal structure. In the garnet-type crystal structure, the C site Sc is dodecahedral in coordination with the oxygen atom Oa, the A site Sa is octahedral in coordination with the oxygen atom Oa, and the B site Sb is tetrahedral in coordination with the oxygen atom Oa. In the garnet-type crystal structure, Li can be present in the void V, which is the site where the oxygen atom Oa is octahedral in coordination with the oxygen atom Oa. The void V is, for example, the area between B site Sb1 and B site Sb2. The Li present in void V is octahedral in coordination with the oxygen atom Oa that constitutes an octahedron including the tetrahedron face Fb1 forming B site Sb1 and the tetrahedron face Fb2 forming B site Sb2.

[0018] For example, Li7La3Zr2O 12 In a garnet-type solid electrolyte with this composition, La may occupy the C site Sc, Zr may occupy the A site Sa, and Li may occupy the B site Sb and the void V. Garnet-type solid electrolytes are found in the CSD (Cambridge Structural Database) X-ray diffraction file No. 422259 (Li7La3Zr2O 12 It has an XRD pattern similar to ).

[0019] In garnet-type solid electrolytes, various elements are substituted. For example, Ca, Sr, Ba, etc., are substituted at the C site; Nb, Ta, Sn, Hf, etc., are substituted at the A site; and Al, Ga, etc., are substituted at the B site. Elemental substitution changes the amount of lithium, altering the arrangement, occupancy, and occupancy sites of lithium ions within the crystal structure, thereby changing the ionic conductivity. Elemental substitution may result in differences in diffraction angles and intensity ratios compared to No. 422259.

[0020] Li7La3Zr2O 12The constituent elements may be partially substituted with other elements, or trace amounts of other elements may be added without substituting any constituent elements. Examples of other elements include at least one element selected from the group consisting of Mg, Al, Si, Ca, Ti, V, Ga, Sr, Y, Nb, Sn, Sb, Ba, Hf, Ta, W, Bi, Rb, and lanthanides (excluding La).

[0021] For example, Li6La3Zr 1.5 W 0.5 O 12 ,Li 6.15 La3Zr 1.75 Ta 0.25 Al 0.2 O 12 ,Li 6.15 La3Zr 1.75 Ta 0.25 Ga 0.2 O 12 ,Li 6.25 La3Zr2Ga 0.25 O 12 ,Li 6.4 La3Zr 1.4 Ta 0.6 O 12 ,Li 6.5 La3Zr 1.75 Te 0.25 O 12 ,Li 6.75 La3Zr 1.75 Nb 0.25 O 12 ,Li 6.9 La3Zr 1.675 Ta 0.289 Bi 0.036 O 12 ,Li 6.46 Ga 0.23 La3Zr 1.85 Y 0.15 O 12 ,Li 6.8 La 2.95 Ca 0.05 Zr 1.75 Nb 0.25 O 12 ,Li 7.05 La 3.00 Zr 1.95 Gd 0.05 O 12 ,Li 6.20 Ba 0.30 La2.95 Rb 0.05 Zr2O 12 These are some examples.

[0022] Garnet-type solid electrolytes are preferably those containing Mg and at least one of element A (where A is at least one element selected from the group consisting of Ca, Sr, and Ba), with the molar ratio of each element satisfying all of the following conditions (1) to (3), or those containing both Mg and element A, with the molar ratio of each element satisfying all of the following conditions (4) to (6). Element A is preferably Sr in order to increase the ionic conductivity of powder 19. (1) 1.33 ≤ Li / (La+A) ≤ 3 (2) 0 ≤ Mg / (La+A) ≤ 0.5 (3) 0 ≤ A / (La + A) ≤ 0.67 (4) 2.0 ≤ Li / (La+A) ≤ 2.6 (5) 0.01 ≤ Mg / (La+A) ≤ 0.14 (6) 0.04 ≤ A / (La + A) ≤ 0.17

[0023] Let's return to Figure 2(a) for explanation. Material 10 can be exemplified by powder, or molded bodies formed by applying pressure to the powder or agglomerating the powder. Examples of powders include mixtures of various metal salts such as oxides, hydroxides, and carbonates containing metal elements that constitute oxide-based materials, or powders prepared by solid-phase, liquid-phase, or gas-phase methods. Wet mixing and dry mixing can be used without limitation as means for mixing the various metal salts.

[0024] Material 10 is set so that the proportion of metal elements matches or approximates the stoichiometric composition to the extent that the desired oxide-based material can be obtained. Material 10 may contain certain metal elements, such as lithium, that tend to evaporate and disappear during firing, in excess of the stoichiometric composition.

[0025] The material 10 is fired in a firing jig 11 (refractory container). The firing jig 11 includes a container 12 and a lid 17. The container 12 includes a first bottom 13 and a wall 14 provided around the first bottom 13. The lid 17 rests on the wall 14. The lid 17 is a component that closes the opening of the container 12. By covering the container 12 with the lid 17 during firing, the evaporation of lithium contained in the material 10 and the incorporation of refractory materials and other materials falling from the furnace 20 (see Figure 1) can be reduced.

[0026] Examples of the shape of the first base 13 include polygons such as triangles and squares, and circles such as circles and ellipses. One or more holes penetrating the first base 13 may be provided in the first base 13, as long as the mechanical strength of the first base 13 at the firing temperature is ensured. There are no particular restrictions on the shape or size of the holes, as long as the mechanical strength of the first base 13 is ensured.

[0027] The wall 14 is provided around the entire outer circumference of the first base 13, enclosing the entire first base 13. The wall 14 may be perpendicular to the first base 13, or it may extend beyond the first base 13 such that the width of the wall 14 gradually increases as it moves away from the first base 13. The container 12 may be a single molded product in which the first base 13 and the wall 14 are integrated, or it may be made by bonding the first base 13 and the wall 14 together.

[0028] The second base 15 is placed on top of the first base 13. In order to reduce the distance (gap) between the outer circumference of the second base 15 and the wall 14, the shape of the second base 15 is almost identical to that of the first base 13. Reducing the gap is to decrease the amount of material 10 that gets between the edge of the second base 15 and the wall 14 and comes into contact with the first base 13. If the coefficient of linear expansion of the second base 15 between room temperature and the firing temperature is greater than the coefficient of linear expansion of the first base 13 between room temperature and the firing temperature, the dimensions of the second base 15 are set so that there is a small gap between the second base 15 and the wall 14 at room temperature. This is to prevent the wall 14 from being damaged by the second base 15 which expands relatively due to the heat during firing.

[0029] Multiple holes 16 are provided in the firing jig 11, connecting the inside and outside of the jig. Gas generated from the material 10 inside the firing jig 11 during firing exits the firing jig 11 through the holes 16. Examples of gas include carbon dioxide and water vapor produced by the decomposition of metal salts contained in the material 10. To prevent the material 10 from spilling out of the firing jig 11 through the holes 16, the holes 16 are positioned higher than the volume of the material 10. In this embodiment, the holes 16 are provided in the wall 14.

[0030] The firing jig 11 is made of metal at least in the part that comes into contact with the material 10. This is to improve the high-temperature strength and thermal shock resistance of the firing jig 11. Examples of metal materials include those whose main component is at least one of W, Mo, and Ni. A main component means that the combined mass of W, Mo, and Ni is 50 wt% or more of the mass of the metal material.

[0031] Examples of metallic materials with W as the main component include W, W-Fe alloy, W-ThO2 alloy, W-Mo alloy, W-Zr alloy, W-Ni-Cu alloy, W-Ni-Mo alloy, W-Ni-Fe alloy, W-Ni-Fe-Mo alloy, and W-Ni-Cu-Fe alloy. Examples of metallic materials with Mo as the main component include Mo, Mo-Cu alloy, Mo-Zr-Hf-C alloy, Mo-La2O3 alloy, and Mo-Re alloy. Examples of metallic materials with Ni as the main component include Ni, Ni-Cu alloy, Ni-Mo-Fe alloy, and Ni-Fe alloy.

[0032] It is preferable that the part of the firing jig 11 that comes into contact with the material 10 is made of metal. This is because, at the firing temperature of the material 10, the material 10 does not react easily with metal materials, thus reducing the reaction between the material 10 and the firing jig 11 during firing and reducing the deterioration of the properties of the oxide-based material. Examples of the parts that come into contact with the material 10 are the inner surfaces of the walls 14 and the second bottom 15. The entire walls 14 and the second bottom 15 may be made of metal. The lid 17, which does not come into contact with the material 10, may be made of an inorganic material, but the lid 17 may also be made of metal.

[0033] Figures 4(a) and 4(b) are enlarged partial cross-sectional views of a part of the firing jig 11. Preferably, the metal material used to make the firing jig 11 has a Si, Al, Cr, and Ti content of less than 1 wt% each. The Si, Al, Cr, and Ti contained in the metal material react with gases such as oxygen, nitrogen, and steam in the furnace 20 to produce reaction products 18. If the Si, Al, Cr, and Ti content of the metal material is high, reaction products 18 are more likely to appear on the surface 19 of the firing jig 11, as shown in Figure 4(b). When material 10 comes into contact with the reaction products 18 on the surface 19 of the firing jig 11, material 10 is more likely to adhere to the firing jig 11 via the reaction products 18. If the Si, Al, Cr, and Ti content of the metal material is less than 1 wt% each, the reaction products 18 that appear on the surface 19 of the firing jig 11 can be reduced, as shown in Figure 4(a), thus reducing the adhesion of material 10 to the firing jig 11 via the reaction products 18.

[0034] Let's return to Figure 1 for explanation. Material 10 is generally fired two or more times. The main purpose of the first firing (hereinafter referred to as "primary firing") is the thermal decomposition of material 10. Primary firing is carried out while an atmospheric gas flows through the furnace 20. The arrow G shown in Figure 1 indicates the direction in which the atmospheric gas flows through the furnace 20. Examples of atmospheric gases include inert gases such as argon and helium, neutral gases such as nitrogen and ammonia, and reducing gases such as hydrogen and carbon monoxide.

[0035] In this embodiment, the furnace 20 is a continuous firing furnace in which a firing jig 11 placed on a base plate 21 is transported through a heating zone (not shown) by the movement of the base plate 21. Examples of continuous firing furnaces include roller hearth kilns, pusher kilns, tunnel kilns, walking beam furnaces, and mesh belt furnaces. If the furnace 20 is a mesh belt furnace, the base plate 21 may be omitted, and the firing jig 11 may be transported by placing it directly on the mesh belt.

[0036] The arrow W shown in Figure 1 indicates the direction in which the firing jig 11 moves within the furnace 20. As the material 10 contained within the firing jig 11 moves downstream in the direction of the firing jig 11's movement, phase changes and chemical reactions proceed due to firing. Since the material 10 is fired while covered by the firing jig 11, the evaporation of lithium due to firing can be reduced. Preferably, the furnace 20 is equipped with atmospheric control measures such as increasing the airtightness of the furnace, creating positive pressure inside the furnace, and providing gas exchange chambers at the inlet and outlet of the furnace 20, so that air does not enter at least downstream in the direction of the firing jig 11's movement.

[0037] The furnace 20 transports the firing jigs 11 by arranging them in two rows, with one firing jig 11 placed on top of the lid 17 of the firing jig 11, but this is not the only way. To reduce the effects of temperature variations in the height and width directions inside the furnace 20, it is certainly possible to transport the firing jigs 11 one by one in a single row without stacking them.

[0038] In this embodiment, the walls 14 of the firing jig 11 are rectangular and cylindrical. Multiple holes 16 are provided on each of the four sides of the walls 14 of the firing jig 11. Because the firing jig 11 has multiple holes 16, exchange between the gas generated from the material 10 inside the firing jig 11 and the atmospheric gas is facilitated. This reduces the reaction between the gas generated by firing the material 10 and the oxide-based material produced by firing, thereby reducing the reaction products adsorbed or formed on the surface of the oxide-based material. Since reaction products cause a decrease in the activity of the oxide-based material, reducing reaction products reduces the deterioration of the properties of the oxide-based material.

[0039] The firing jig 11 is positioned inside the furnace 20 such that the holes 16 provided in the firing jig 11 are located upstream and downstream of the atmospheric gas, respectively, along arrow G. This makes it easier for the atmospheric gas to enter the firing jig 11 through the upstream hole 16 and for the gas to exit the firing jig 11 through the downstream hole 16, thus further facilitating the exchange between the gas generated from the material 10 and the atmospheric gas. Consequently, the deterioration of the properties of the oxide material can be further reduced.

[0040] It is preferable to align the conveying direction of the firing jig 11 (direction of arrow W) with the direction of the atmospheric gas flow (direction of arrow G). Since the material 10 is fired while the firing jig 11 is conveyed toward the upstream side of the atmospheric gas, the gases and evaporated elements generated from the material 10 are carried upstream in the conveying direction of the firing jig 11 by the atmospheric gas. Therefore, the concentration of gases and evaporated elements generated from the material 10 is lower upstream in the conveying direction of the firing jig 11 than downstream in the conveying direction of the firing jig 11. Downstream in the conveying direction of the firing jig 11, phase changes and chemical reactions of the material 10 are progressing, so by lowering the concentration of gases and evaporated elements generated from the material 10, contamination of the material 10, where phase changes and chemical reactions are progressing, by gases and the like can be reduced. Therefore, the deterioration of the properties of oxide-based materials can be further reduced.

[0041] The material 10 that has undergone primary firing is more likely to form a crystalline structure of an oxide-based material during the second firing (hereinafter referred to as "secondary firing"). The material 10 after primary firing may already have a crystalline structure of an oxide-based material. Performing primary and secondary firing is just one example, and the number of firings is not limited to two. The number of firings may be more or less than two.

[0042] Figure 2(b) is a cross-sectional view of the firing jig 11 containing the material 10 after primary firing. The material 10 inside the firing jig 11 is partially in contact with the second bottom 15 and partially in contact with the wall 14 during primary firing (see Figure 2(a)). During primary firing, gas is generated from the material 10, and material movement occurs between the particles of the material 10, causing the material 10 to shrink. The force exerted by the weight of the material 10 on the portion of the material 10 in contact with the second bottom 15 is greater than the force exerted by the weight of the material 10 on the portion of the material 10 in contact with the wall 14. The greater this force, the more easily the material 10 adheres during firing; therefore, the material 10 adheres more easily to the second bottom 15 than to the wall 14.

[0043] To reduce the amount of material 10 adhering to the firing jig 11, it is preferable that the second bottom 15, at least on the surface in contact with the material 10, is made of a metallic material mainly composed of at least one of W, Mo, and Ni. This is because the material 10 does not react easily with the metallic material, thus reducing contamination of the material 10 by diffusion of the material on the second bottom 15 and reducing the adhesion of the material 10 to the second bottom 15.

[0044] Since metallic materials generally have better thermal conductivity than inorganic materials, if at least a part of the firing jig 11 is made of metallic material, heat can be more easily transferred to the interior of the material 10, thereby reducing the range of temperature distribution of the material 10 during heating and cooling. This contributes to reducing variations in the properties of oxide-based materials manufactured through the firing process of the material 10.

[0045] The entire second base 15 may be made of metal. The first base 13 and wall 14 may be made of inorganic material. This is because the force exerted by the weight of material 10 against the wall 14 is smaller than the force exerted by the weight of material 10 against the second base 15, so material 10 is less likely to adhere to the wall 14.

[0046] The second bottom 15 may be omitted, and the inner surface of the first bottom 13 and wall 14 of the container 12, or the entire first bottom 13 and wall 14, may be made of metal. Alternatively, the first bottom 13 may be omitted, and the second bottom 15 may be placed inside the cylindrical wall 14, with the inner surface of the second bottom 15 and wall 14, or the entire second bottom 15 and wall 14, being made of metal, or the second bottom 15 may be made of metal and the wall 14 made of inorganic material.

[0047] Because metal materials have high high-temperature strength, thermal shock resistance, and good thermal conductivity, the heating and cooling rates of the furnace 20 can be increased compared to when firing with a firing jig 11 made of inorganic material. Therefore, the time required for heating and cooling the furnace 20 can be shortened. Because the time required for heating and cooling can be shortened, a shorter furnace can be used when using a continuous firing furnace.

[0048] When an inert gas or nitrogen is used as the atmospheric gas, metal materials mainly composed of W, Mo, and Ni do not react well with the atmospheric gas. Furthermore, the oxides that are slightly formed on the metal material by reacting with residual oxygen and water vapor in the furnace 20 sublimate easily, so oxides are less likely to remain on the surface of the firing jig 11. Since deterioration of the metal material is less likely to occur, the adhesion of the material 10 to the firing jig 11 can be reduced.

[0049] The main purpose of secondary calcination is the synthesis of oxide-based materials. When the oxide-based material is a garnet-type solid electrolyte, the primary calcination temperature is typically 850°C to 1150°C. Primary calcination may include steps of calcination at lower temperatures and steps of calcination at higher temperatures within this temperature range. Before proceeding to the next calcination step, the material 10 after each step may be crushed and mixed. It is desirable to crush the material 10 dry at this time. The primary calcination time is typically 10 to 15 hours at the set maximum temperature. The secondary calcination temperature is typically 1100°C to 1250°C. The secondary calcination time is typically 10 to 20 hours at the set maximum temperature.

[0050] Alternatively, the material 10 after secondary firing may be removed from the firing jig 11, pressure may be applied to the removed material 10 to form a molded body, and the molded body may be placed in the firing jig 11 for firing. The firing temperature and time at this time are the same as those for secondary firing. Alternatively, the material 10 after primary firing may be removed from the firing jig 11, pressure may be applied to the removed material 10 to form a molded body, and the molded body may be placed in the firing jig 11 for secondary firing.

[0051] The fabricated oxide-based materials can be used as materials for energy storage devices such as secondary batteries and electrochemical capacitors. Examples of electrochemical capacitors include redox capacitors that utilize redox reactions and hybrid capacitors, which are asymmetric cells combining electric double-layer capacitors and solid electrolytes. Examples of materials for energy storage devices include mixtures of oxide-based material powder and electrolyte, slurries containing oxide-based material powder and dispersion medium, and active materials contained in electrodes.

[0052] The second embodiment will be described with reference to Figure 5(a). In the first embodiment, the case in which a hole 16 is provided in the container 12 of the firing jig 11 was described. In the second embodiment, the case in which a hole 33 is provided between the container 32 and the lid 17 of the firing jig 31 will be described. In the second embodiment, the same reference numerals are used for the same parts as in the first embodiment, and the description of the same parts is omitted.

[0053] Figure 5(a) is a perspective view of the firing jig 31 in the second embodiment. The firing jig 31 containing the material 10 is placed in the furnace 20 in place of the firing jig 11 in the first embodiment.

[0054] The firing jig 31 includes a container 32 and a lid 17. The container 32 includes a bottom and a wall provided around the bottom. In this embodiment, the container 32 has a rectangular cylindrical wall integrally provided with the rectangular bottom. The lid 17 is rectangular and is positioned at a 45° rotation from its normal position that covers the opening of the container 32. This creates four triangular holes 33 between the four corners of the container 32 and the lid 17.

[0055] Similar to the first embodiment, the holes 33 of the firing jig 31 are located on the upstream and downstream sides of the atmospheric gas, respectively. The material 10 is placed inside the container 32. The container 32 is made of a metallic material mainly composed of at least one of W, Mo, and Ni. The firing jig 31 is conveyed toward the upstream side of the atmospheric gas, and the material 10 inside the container 32 is fired. According to the second embodiment, the same effects and advantages as the first embodiment can be achieved.

[0056] A third embodiment will be described with reference to Figure 5(b). In the first and second embodiments, firing jigs 11 and 31 that cover containers 12 and 32 containing the material 10 with a lid 17 were described. In the third embodiment, a firing jig 41 equipped with a cover 43 that covers the material 10 placed on the bottom 42 will be described. In the third embodiment, the same reference numerals are used for the same parts as in the first embodiment, and the description of the same parts is omitted.

[0057] Figure 5(b) is a perspective view of the firing jig 41 in the third embodiment. The firing jig 41 containing the material 10 is placed in the furnace 20 in place of the firing jig 11 in the first embodiment.

[0058] The firing jig 41 includes a base 42 and a cover 43. The base 42 is made in the shape of a plate from a metallic material mainly composed of at least one of W, Mo, and Ni. A block-shaped molded body (material 10), formed by applying pressure to powder, is placed on the base 42.

[0059] The cover 43 includes a cylindrical wall 44 surrounding the material 10 and a roof 45 that closes the upper end of the wall 44, covering the perimeter of the material 10. The cover 43 is made of, for example, an inorganic material. The cover 43 has rectangular notches 46 on the edges of the walls 44 that are opposite each other. Two holes 47 are formed between the two notches 46 in the wall 44 and the bottom 42, connecting the inside and outside of the firing jig 41.

[0060] Similar to the first embodiment, the holes 47 of the firing jig 41 are located on the upstream and downstream sides of the atmospheric gas, respectively. The firing jig 41 is conveyed toward the upstream side of the atmospheric gas, and the material 10 inside the cover 43 is fired. Thus, according to the third embodiment, the same effects and advantages as the first embodiment can be achieved.

[0061] Although the present invention has been described above based on embodiments, it can be easily inferred that the present invention is not limited in any way to the above embodiments, and that various improvements and modifications are possible without departing from the spirit of the present invention.

[0062] In this embodiment, the case of firing the material 10 using a continuous firing furnace has been described, but it is not limited to this. It is of course possible to fire the material 10 contained in firing jigs 11, 31, and 41 using a batch firing furnace. In the case of a batch firing furnace, the gas generated from the material 10 can be exchanged with the atmospheric gas by firing while flowing an atmospheric gas.

[0063] The shapes, sizes, and number of holes 16, 33, and 47 described in the embodiment are just examples. The shapes, sizes, and number of holes 16, 33, and 47 are set appropriately according to the shapes and sizes of the firing jigs 11, 31, and 41.

[0064] In the second embodiment, a case was described in which the lid 17 placed over the container 32 is shifted to create a hole 33 between the container 32 and the lid 17, but the invention is not limited to this. It is of course possible to make multiple holes in the lid 17 and cover the opening of the container 32 with the lid 17. This is because even if the opening of the container 32 is covered with the lid 17, gas can be exchanged between the inside and outside of the container 32 through the holes made in the lid 17. [Explanation of symbols]

[0065] 10 materials 11, 31, 41 Firing jigs 14 Wall 15. The second bottom 20 furnace 42 bottom 44 Wall

Claims

1. A method for producing an oxide-based material, comprising a step of calcining a lithium-containing material, The above process includes the operation of firing the material placed on the firing jig in a furnace, The method for manufacturing an oxide-based material, wherein the firing jig is made of metal at least in the part that comes into contact with the material.

2. The firing jig includes a bottom and a wall provided around the bottom, The method for producing an oxide-based material according to claim 1, wherein the material is placed on the bottom.

3. The method for producing an oxide-based material according to claim 2, wherein at least the inner surface of the wall is made of metal.

4. The method for producing an oxide-based material according to any one of claims 1 to 3, wherein the metal mainly consists of at least one of W, Mo, and Ni.

5. The method for producing an oxide-based material according to claim 4, wherein the metal components consist of less than 1 wt% each of Si, Al, Cr, and Ti.

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