Process for producing halides

Abstract

The method for producing a halide of the present disclosure includes calcining a material including a MO x The mixed material of the MO powder and the NH4X powder is calcined in an inert gas atmosphere or vacuum. M is at least one element selected from rare earth elements, X is at least one element selected from F, Cl, Br, and I, x is 1 or more and 2 or less, and the MO x When the average particle diameter of the MO powder is defined as D1 and the average particle diameter of the NH4X powder is defined as D2, the following necessary conditions (a) or (b) are satisfied. D1 ≤ D2, and D2 - D1 ≤ 0.5 × D2 (a), D2

Description

Technical Field

[0001] This disclosure relates to a method for manufacturing halides. Background Technology

[0002] Non-patent document 1 discloses solid electrolytes such as Li3YCl6 and Li3YBr6. These solid electrolytes are synthesized by sintering using vacuum-sealed tubes.

[0003] Patent document 1 discloses a method for synthesizing halide solid electrolytes by using a mechanochemical grinding reaction of a planetary ball mill.

[0004] Patent document 2 discloses a method for manufacturing halides using oxides as raw materials.

[0005] Existing technical documents

[0006] Patent documents

[0007] Patent Document 1: International Publication No. 2018 / 025582

[0008] Patent Document 2: International Publication No. 2020 / 136956

[0009] Non-patent literature

[0010] Non-patent literature 1: Z. Anorg. Allg. Chem., 623 (1997), 1352-1356. Summary of the Invention

[0011] The problem that the invention aims to solve

[0012] The purpose of this disclosure is to provide a manufacturing method suitable for reducing impurities contained in halides.

[0013] Methods for solving problems

[0014] This disclosure provides a method for manufacturing a halide, which includes taking a product containing MO x Materials containing powder and NH4X powder, i.e., mixtures, are sintered in an inert gas atmosphere or in a vacuum.

[0015] M is at least one element selected from the rare earth elements.

[0016] X is at least one element selected from F, Cl, Br and I.

[0017] x is greater than or equal to 1 and less than or equal to 2.

[0018] In the above MO x When the average particle size of the powder is defined as D1, and the average particle size of the above NH4X powder is defined as D2, the following necessary conditions (a) or (b) must be met.

[0019] D1 ≤ D2 and D2 - D1 ≤ 0.5×D2 (a)

[0020] D2 < D1 and D1 - D2 ≤ 0.5×D1 (b)

[0021] Advantages of the Invention

[0022] According to the present disclosure, a manufacturing method suitable for reducing impurities contained in a halide can be provided. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1A It is a flowchart showing an example of the manufacturing method of the first embodiment.

[0024] Figure 1B It is a flowchart showing another example of the manufacturing method of the first embodiment.

[0025] Figure 1C It is a flowchart showing yet another example of the manufacturing method of the first embodiment.

[0026] Figure 1D It is a flowchart showing yet another example of the manufacturing method of the first embodiment.

[0027] Figure 2A It is a SEM image of NH4Cl raw material powder before the pulverization treatment.

[0028] Figure 2B It is a SEM image of Y2O3 raw material powder.

[0029] Figure 2C It is a SEM image of NH4Cl raw material powder after the pulverization treatment.

[0030] Figure 3 It is a schematic view showing the compression molding die 300 used to evaluate the ionic conductivity of a solid electrolyte.

[0031] Figure 4 It is a graph showing the Cole-Cole plot obtained by impedance measurement of the halide solid electrolyte of Example 3. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0032] (Insight underlying the present disclosure)

[0033] Non-Patent Document 1 discloses halide solid electrolytes such as Li3YCl6 and Li3YBr6. However, this solid electrolyte is synthesized by firing using a vacuum sealed tube. The ionic conductivity of the synthesized solid electrolyte is low, and ionic conductivity has not been confirmed at room temperature. In addition, firing using a vacuum sealed tube is not suitable for mass production.

[0034] Patent Document 1 discloses a method for synthesizing a halide solid electrolyte by a mechanochemical grinding reaction using a planetary ball mill. This method is not suitable for mass production and has a low yield.

[0035] Patent Document 2 discloses a method for synthesizing a halide solid electrolyte using an oxide as a raw material. Although this method can be applied to mass production, in order to allow the raw materials to react sufficiently with each other, raw materials in amounts deviating from the stoichiometric composition are used. Therefore, raw materials tend to remain, and the original ionic conductivity of the halide solid electrolyte cannot be obtained.

[0036] In view of the above circumstances, the inventors of the present invention have studied a manufacturing method suitable for reducing impurities contained in halides.

[0037] Hereinafter, embodiments of the present disclosure will be described while referring to the accompanying drawings. The following embodiments are examples, and the present disclosure is not limited to the following embodiments.

[0038] (First Embodiment)

[0039] Figure 1A It is a flowchart showing an example of the manufacturing method of the first embodiment.

[0040] The manufacturing method of the first embodiment includes a first firing step S10.

[0041] In the first firing step S10, a mixed material as a material containing MO x powder and NH4X powder is fired in an inert gas atmosphere or in a vacuum. Here, M is at least one element selected from rare earth elements. X is at least one element selected from F, Cl, Br, and I. x is 1 or more and 2 or less.

[0042] When the average particle diameter of the MO x powder is defined as D1 and the average particle diameter of the NH4X powder is defined as D2, the following necessary condition (a) or (b) is satisfied.

[0043] D1 ≤ D2, and D2 - D1 ≤ 0.5 × D2 (a)

[0044] D2 < D1, and D1 - D2 ≤ 0.5 × D1 (b)

[0045] According to the above configuration, the average particle diameters are close to each other, so the materials are likely to react with each other, thereby reducing impurities contained in the target halide. In addition, since the manufacturing method of the present disclosure employs a so-called firing method, it is suitable for mass production. However, the firing method can also be used in combination with other synthesis methods such as mechanochemical grinding.

[0046] The mixed material is obtained by mixing MOx It is obtained by mixing raw material powders such as powder and NH4X powder.

[0047] In the first firing process S10, MO x (i.e., rare earth oxides) react with NH4X (i.e., ammonium halide).

[0048] For example, when M is Y and X is Cl, that is, when Y2O3 reacts with NH4Cl, the reaction shown in the following formula (1) is carried out.

[0049] Y2O3+12NH4Cl→2(NH4)3YCl6+6NH3+3H2O (1)

[0050] MO x The average particle size D1 of the powder and the average particle size D2 of the NH4X powder can both be less than 100 μm. Based on this composition, MO x It readily reacts with NH4X. MO x There are no specific lower limits for the average particle size D1 of the powder and the average particle size D2 of the NH4X powder. For example, their respective lower limits are 0.05 μm.

[0051] Hybrid materials may also contain two or more MOs with different M values. x The mixed material may also contain two or more NH4Xs with different X values ​​from each other.

[0052] Mixed materials may also contain MO x Materials other than NH4X. In this case, all materials contained in the mixture can have average particle sizes that are close to each other. For example, the average particle size of the material with the largest average particle size in the mixture is defined as Dmax, and the average particle size of the material with the smallest average particle size in the mixture is defined as Dmin. In this case, the difference in average particle sizes (Dmax-Dmin) can be less than (0.5×Dmax). With such a configuration, the materials contained in the mixture are more likely to react with each other.

[0053] Hybrid materials can also be made from MO x Made from NH4X. "From MO x "Made with NH4X" means that no other ingredients other than unavoidable impurities were intentionally added.

[0054] To further improve the reactivity of the mixed material, the difference in average particle size (Dmax-Dmin) can be less than (0.3×Dmax), less than (0.1×Dmax), or less than (0.05×Dmax).

[0055] All materials contained in the mixture can also have an average particle size of less than 100 μm. With such a composition, the materials contained in the mixture are more likely to react with each other. The lower limit for the average particle size is, for example, 0.05 μm.

[0056] All materials contained in the mixture can also have an average particle size of less than 50 μm. With such a composition, the materials contained in the mixture are more likely to react with each other.

[0057] MO x The average particle size of materials such as NH4X refers to the particle size that accounts for 50% of the total volume in the particle size distribution measured by a laser diffraction / scattering particle size analyzer, i.e., the median particle size (D50).

[0058] The manufacturing method of this embodiment may also include a step of pulverizing the materials contained in the mixture.

[0059] Figure 1B This is a flowchart illustrating another example of the manufacturing method of the first embodiment.

[0060] The manufacturing method of the first embodiment may also include a crushing step S11.

[0061] The materials contained in the mixture are pulverized before the first firing step S10. That is, the pulverization step S11 is performed before the first firing step S10.

[0062] In the pulverizing step S11, at least one of the multiple materials that should be included in the mixture is pulverized. This allows for adjustment of MO. x The average particle size of materials such as NH4X.

[0063] For example, suppose the mixture should contain multiple materials including material 1 and material 2, and the average particle size of material 1 is larger than that of material 2. In this case, material 1 is pre-crushed to make its average particle size close to that of material 2. Then, the crushed material 1 is mixed with material 2 to prepare the mixture. Alternatively, both material 1 and material 2 can be crushed. In one example, material 1 is MO. x In one example, the first material is NH4X, and the second material is MO. x .

[0064] There are no particular limitations on the pulverization method; mechanical pulverization is also acceptable. Pulverization methods may utilize pulverizing devices such as ball mills, pot mills, high-speed milling mills, and jet mills. Pulverization can be achieved using a single method or a combination of multiple methods.

[0065] Materials that are soluble in solvents can also have their average particle size reduced by dissolving and redefining them.

[0066] Figure 1C This is a flowchart illustrating yet another example of the manufacturing method of the first embodiment.

[0067] The manufacturing method of the first embodiment may also include a dissolution step S12 and a removal step S13.

[0068] The process of dissolving the materials contained in the mixture in a solvent to obtain a solution and removing the solvent from the solution are performed before the mixture is fired. That is, the dissolution process S12 and the removal process S13 are performed before the first firing process S10.

[0069] In the dissolution step S12, at least one of the multiple materials that should be included in the mixture is dissolved in the solvent. Then, in the removal step S13, the solvent is removed from the solution. This allows for adjustment of MO. x The average particle size of materials such as NH4X.

[0070] For example, suppose the mixture should contain a first material and a second material, and the average particle size of the first material is larger than the average particle size of the second material. In this case, the first material is dissolved in a solvent to prepare a solution. Then, the solvent is removed from the solution, causing the first material to precipitate again. This brings the average particle size of the first material closer to the average particle size of the second material. Then, the first material and the second material are mixed. Alternatively, the second material can be dissolved and precipitated separately from the first material. Or, all the materials that should be included in the mixture can be mixed before performing the dissolution step S12 and the removal step S13.

[0071] In one example, the first material is NH4X, and the second material is MO. x In another example, the first material is MO. x The second material is NH4X. In particular, NH4X is an ionic compound and therefore can be fully dissolved in various solvents.

[0072] The solvent can be either an inorganic solvent or an organic solvent.

[0073] Alternatively, the pulverizing step S11 can be performed after the dissolving step S12 and the removing step S13. Or, the dissolving step S12 and the removing step S13 can be performed after the pulverizing step S11.

[0074] The materials with adjusted average particle size were precisely weighed in a manner that resulted in a stoichiometric composition based on the chemical reaction formula used to obtain the desired composition, and then mixed.

[0075] To obtain a uniform mixture, the manufacturing method of this embodiment may also include a mixing step. The mixing method is not limited; ball mills, pot mills, V-type mixers, double-cone mixers, automatic mortars, and other mixing devices can be used.

[0076] Rare earth ammonium halide salts are obtained by firing the mixed materials in the first firing process S10.

[0077] The first firing step S10 is carried out in an inert gas atmosphere or in a vacuum. Examples of inert gas atmospheres include helium, argon, nitrogen, or a mixture thereof. When the first firing step S10 is performed in a vacuum, the vacuum level is, for example, 10. -1 Pa~10 -8 Pa.

[0078] In the first firing process S10, the firing temperature (atmosphere temperature) can also be 200℃~250℃.

[0079] In the first firing process S10, the firing time can also be 1 hour to 36 hours.

[0080] The firing temperature and firing time can be appropriately changed according to the materials used and the desired type of rare earth ammonium halide salt.

[0081] Whether the reaction of the mixed materials has ended, i.e., whether the desired composition has been obtained, can be confirmed by identifying the generated phase using an X-ray diffraction apparatus or by measuring the mass change based on the chemical reaction formula. The composition can be identified using methods such as ICP luminescence spectrometry, ICP mass analysis, and fluorescence X-ray spectrometry.

[0082] A halide is obtained by reacting the rare earth ammonium halide salt obtained in the first firing step S10 with lithium halide. The halide is, for example, a halide solid electrolyte.

[0083] For example, when a rare earth ammonium halide salt, namely (NH4)3YCl6, reacts with a lithium halide, namely LiBr, the reaction shown in the following formula (2) is carried out.

[0084] (NH4)3YCl6+3LiBr→Li3YBr3Cl3+3NH4Cl (2)

[0085] The above reaction yields Li3YBr3Cl3, which is a compound formed from lithium, rare earth elements, and halogens.

[0086] When the average particle diameter of the rare earth ammonium halide salt powder is defined as D3 and the average particle diameter of the lithium halide powder is defined as D4, the following necessary condition (c1) or (d1) can also be satisfied. With such a configuration, the reaction of formula (2) can be easily carried out.

[0087] D3 ≤ D4 and D4 - D3 ≤ 0.5 × D4 (c1)

[0088] D4 < D3 and D3 - D4 ≤ 0.5 × D3 (d1)

[0089] In order to further promote the reaction of formula (2), the following necessary condition (c2) or (d2) can also be satisfied.

[0090] D3 ≤ D4 and D4 - D3 ≤ 0.3 × D4 (c2)

[0091] D4 < D3 and D3 - D4 ≤ 0.3 × D3 (d2)

[0092] In order to further promote the reaction of formula (2), the following necessary condition (c3) or (d3) can also be satisfied.

[0093] D3 ≤ D4 and D4 - D3 ≤ 0.1 × D4 (c3)

[0094] D4 < D3 and D3 - D4 ≤ 0.1 × D3 (d3)

[0095] In order to further promote the reaction of formula (2), the following necessary condition (c4) or (d4) can also be satisfied.

[0096] D3 ≤ D4 and D4 - D3 ≤ 0.05 × D4 (c4)

[0097] D4 < D3 and D3 - D4 ≤ 0.05 × D3 (d4)

[0098] The average particle diameter of each of the rare earth ammonium halide salt and the lithium halide can be 100 μm or less, and can also be 50 μm or less. Thereby, the above reaction can be easily carried out. The average particle diameter of each of the rare earth ammonium halide salt and the lithium halide can also be 0.05 μm or more.

[0099] The method for adjusting the average particle diameter of the material, the method for evaluating the average particle diameter, and the method for mixing the materials are as described above.

[0100] The reaction between the rare earth ammonium halide salt and the lithium halide obtained in the first firing step S10 can also be carried out by firing. For example, the reaction carried out using formula (2) can also be carried out by firing.

[0101] Figure 1DThis is a flowchart illustrating yet another example of the manufacturing method of the first embodiment.

[0102] The manufacturing method of the first embodiment may also include a second firing process S20.

[0103] The second firing process S20 is performed before the first firing process S10.

[0104] In the second firing step S20, the material containing halides and LiZ, obtained by firing the mixed material in the first firing step S10, is fired. Here, Z is at least one element selected from F, Cl, Br and I.

[0105] The second firing step S20 can also be carried out in an inert gas atmosphere or in a vacuum. Examples of inert gas atmospheres are helium, argon, nitrogen, or atmospheres containing mixtures thereof. When the first firing step S10 is performed in a vacuum, the vacuum level is, for example, 10. -1 Pa~10 -8 Pa.

[0106] In the second firing process S20, the firing temperature (atmosphere temperature) can also be 400℃~700℃.

[0107] In the second firing process S20, the firing time can also be 1 hour to 36 hours.

[0108] The firing temperature and firing time can be adjusted appropriately according to the materials used and the type of halide desired.

[0109] To confirm whether the firing reaction has ended, the same procedure as in the first firing step can be followed.

[0110] By reacting rare-earth ammonium halide salts with lithium halides, compounds containing lithium, rare-earth elements, and halogens can be obtained. These compounds can be solid electrolytes. More specifically, they can be halide solid electrolytes.

[0111] The average particle size of the halide solid electrolyte can be 100 μm or less, preferably 10 μm or less, and more preferably 1 μm or less. There is no particular limitation on the lower limit of the average particle size of the halide solid electrolyte. For example, the lower limit is 0.05 μm. The grinding method used to achieve such an average particle size is not limited. As a grinding method, methods using grinding devices such as ball mills, pot mills, high-speed milling mills, and jet mills can be employed. Grinding can be performed using a single method or a combination of multiple methods.

[0112] Example

[0113] Hereinafter, this disclosure will be described in more detail with reference to the embodiments and comparative examples. In the following examples, halides produced by the method of this disclosure are manufactured as solid electrolytes and evaluated.

[0114] <Example 1>

[0115] (Preparation of (NH4)3YCl6)

[0116] (NH4)3YCl6 was synthesized as a raw material for halide solid electrolytes.

[0117] First, commercially available Y2O3 and NH4Cl are prepared as raw material powders.

[0118] Figure 2A This is a SEM image of the NH4Cl raw material powder before pulverization. Figure 2B This is a SEM image of Y2O3 raw material powder. (Example) Figure 2A and Figure 2B As shown, the average particle sizes of the NH4Cl raw material powder and the Y2O3 raw material powder are 1 mm and 0.5 μm, respectively.

[0119] In order to bring the average particle size difference to within 50%, that is, to crush the NH4Cl raw material powder using a hammer mill in a manner that satisfies the necessary conditions (a) or (b) described above.

[0120] Figure 2C This is a SEM image of the NH4Cl raw material powder after pulverization. The average particle size of the pulverized NH4Cl raw material powder is 0.8 μm. Therefore, the difference between the average particle size of the NH4Cl raw material powder and the average particle size of the Y2O3 raw material powder is 0.3 μm. This value is within 50% of the average particle size of the NH4Cl raw material powder.

[0121] Y₂O₃ raw material powder and pulverized NH₄Cl raw material powder were weighed at a molar ratio of Y₂O₃:NH₄Cl = 1:12. These raw material powders were dry-mixed using a rotary drum mixer. This process was repeated to obtain a mixed material. The resulting mixed material was placed in an alumina crucible and maintained at 200°C for 15 hours under a nitrogen atmosphere. This process yielded (NH₄)₃YCl₆ of Example 1. The mass reduction rate was calculated by dividing the mass of (NH₄)₃YCl₆ obtained by calcination by the total mass of the mixed material measured before calcination.

[0122] <Example 2>

[0123] (Preparation of (NH4)3YCl6)

[0124] Except for the molar ratio of the raw material powders contained in the mixed material, the same procedure as in Example 1 was followed to obtain (NH4)3YCl6 of Example 2.

[0125] In Example 2, Y₂O₃ raw material powder and pulverized NH₄Cl raw material powder were weighed to a molar ratio of Y₂O₃:NH₄Cl = 1:12.6. These raw material powders were dry-mixed using a drum mixer. This process was repeated to obtain a mixed material. The Y₂O₃:NH₄Cl molar ratio of 1:12.6 represents a 5% excess of NH₄Cl compared to the stoichiometric ratio.

[0126] In Example 2, the same procedure as in Example 1 was followed to calculate the mass reduction rate.

[0127] <Example 3>

[0128] (Preparation of halide solid electrolytes)

[0129] A halide solid electrolyte was synthesized using (NH4)3YCl6 from Example 1.

[0130] In an argon atmosphere with a dew point below -60°C, (NH4)3YCl6 and LiBr of Example 1 were prepared in a molar ratio of (NH4)3YCl6:LiBr = 1:3. These materials were mixed using a rotary drum mixer. The resulting mixture was placed in an alumina crucible. Two crucibles filled with the mixture were prepared and kept in an electric furnace filled with argon atmosphere at 500°C for 1 hour. The two crucibles were respectively located in locations 1 and 2 within the electric furnace.

[0131] To confirm reproducibility, the above firing process was performed four times. In Table 2, the nth firing is recorded as "firing n".

[0132] The resulting calcined material was pulverized in an agate mortar. This process was repeated to obtain the halide solid electrolyte of Example 3.

[0133] The Li content per unit mass of the halide solid electrolyte in Example 3 was determined by atomic absorption spectrometry. The Y content of the halide solid electrolyte in Example 3 was determined by ICP-N spectroscopy. Based on the Li and Y contents obtained from these measurements, the Li:Y molar ratio was calculated. The result was a Li:Y molar ratio of 3:1. This value is consistent with the value calculated from the feed ratio of the raw material powder.

[0134] (Evaluation of ionic conductivity)

[0135] Figure 3 This is a schematic diagram of a pressure forming die 200 used to evaluate the ionic conductivity of a solid electrolyte.

[0136] The pressure forming die 200 includes an upper punch 301, a die frame 302, and a lower punch 303. Both the upper punch 301 and the lower punch 303 are made of electrically conductive stainless steel. The die frame 302 is made of insulating polycarbonate.

[0137] use Figure 3 The pressure forming die 300 shown is used to measure the ionic conductivity of the halide solid electrolyte of Example 3 by the following method.

[0138] In a dry atmosphere with a dew point below -60°C, the powder of the halide solid electrolyte of Example 3 (i.e., Figure 3 Solid electrolyte powder 101 is filled inside the pressure forming die 200. A pressure of 400 MPa is applied to the halide solid electrolyte powder 101 of Example 3 using the upper part 301 and the lower part 303 of the punch.

[0139] Under pressure, the upper part 301 and the lower part 303 of the punch are connected to a potentiostat (Princeton Applied Research, VersaSTAT4) equipped with a frequency response analyzer. The upper part 301 of the punch is connected to the working electrode and the terminal for potential measurement. The lower part 303 of the punch is connected to the counter electrode and the reference electrode. The impedance of the solid electrolyte is determined at room temperature by electrochemical impedance spectroscopy.

[0140] Figure 4 This is a Cole-Cole plot showing the halide solid electrolyte of Example 3 obtained by impedance measurement.

[0141] exist Figure 4 In this study, the real value of the impedance at the measurement point where the absolute value of the phase of the complex impedance is the smallest is considered as the resistance of the halide solid electrolyte for ion conduction. Regarding this real value, refer to... Figure 4 The arrow R shown SE Using this resistance value, the ionic conductivity is calculated based on the following equation (3).

[0142] σ=(R SE ×S / t) -1 (3)

[0143] Here, σ represents the ionic conductivity. S represents the contact area between the solid electrolyte and the upper part 301 of the punch. S and Figure 3 The cross-sectional areas of the hollow portions of the middle mold frame 302 are equal. SE This represents the resistance value of the solid electrolyte in the impedance measurement. t represents the thickness of the solid electrolyte. t in... Figure 3 The thickness of the layer formed by the powder 101 of the solid electrolyte is indicated in the figure.

[0144] <Comparative Example 1>

[0145] (Preparation of (NH4)3YCl6)

[0146] In Comparative Example 1, the NH4Cl raw material powder was not pulverized. Otherwise, the same procedure as in Example 1 was followed to obtain (NH4)3YCl6 of Comparative Example 1.

[0147] In Comparative Example 1, the same procedure as in Example 1 was followed to calculate the mass reduction rate.

[0148] <Comparative Example 2>

[0149] (Preparation of (NH4)3YCl6)

[0150] In Comparative Example 2, the NH4Cl raw material powder was not pulverized. Otherwise, the same procedure as in Example 2 was followed to obtain (NH4)3YCl6 of Comparative Example 2.

[0151] In Comparative Example 2, the same procedure as in Example 1 was followed to calculate the mass reduction rate.

[0152] <Comparative Example 3>

[0153] (Preparation of halide solid electrolytes)

[0154] Using (NH4)3YCl6 from Comparative Example 1 instead of (NH4)3YCl6 from Example 1, and operating in the same manner as in Example 3, the halide solid electrolyte of Comparative Example 3 was prepared. A mixture containing (NH4)3YCl6 and LiBr was placed in two alumina crucibles. The two crucibles were arranged adjacent to the two alumina crucibles placed in the electric furnace in Example 3. The mixture was then calcined.

[0155] (Evaluation of ionic conductivity)

[0156] The ionic conductivity of the halide solid electrolyte of Comparative Example 3 was measured in the same manner as in Example 3.

[0157] The mass reduction rates in Examples 1, 2, Comparative Example 1, and Comparative Example 2 are shown in Table 1.

[0158] [Table 1]

[0159]

[0160] <Inspection>

[0161] As shown in Table 1, by pre-crushing the NH4Cl raw material powder, the difference in average particle size between the NH4Cl and Y2O3 raw material powders is reduced, resulting in a mass change rate that is almost consistent with the theoretical value. In other words, impurities are reduced.

[0162] It should be noted that the theoretical value of the rate of mass change is calculated based on the following chemical reaction formula, that is, corresponding to the decrease in mass of NH3 and H2O.

[0163] Y₂O₃ + 12NH₄Cl + xNH₄Cl

[0164] →2(NH4)3YCl6+xNH4Cl+6NH3+3H2O (x: excess NH4Cl)

[0165] On the other hand, regarding Comparative Examples 1 and 2, which did not undergo prior pulverization, it can be inferred that due to insufficient reaction, some of the raw materials remained.

[0166] The ionic conductivity of the solid electrolytes of Example 3 and Comparative Example 3 is shown in Table 2.

[0167] [Table 2]

[0168]

[0169] <Inspection>

[0170] As shown in Table 2, the halide solid electrolyte of Example 3 exhibits a higher ionic conductivity than that of Comparative Example 3. Furthermore, this result is independent of the calcination process. In the case of the Comparative Example, it is presumed that the low ionic conductivity is due to the influence of unreacted substances remaining in the (NH4)3YCl6 raw material. The halide solid electrolyte of the Examples contains fewer impurities, thus utilizing the inherent ionic conductivity of halide solid electrolytes.

[0171] The results above show that the solid electrolyte synthesized by the manufacturing method of this disclosure exhibits high lithium-ion conductivity.

[0172] It should be noted that, according to predictions, in MO x When M is a rare earth element other than Y, when X in NH4X is a halogen element other than Cl, and when Z in LiZ is a halogen element other than Cl, the same effect as in Examples 1-3 can be obtained. This is because compounds composed of elements from the same group have generally similar physical properties, and the same effect can be expected even if the element species are changed. In fact, it has been confirmed that even when using NH4Br, the desired compound can be obtained.

[0173] Industrial availability

[0174] The manufacturing method disclosed herein can be used, for example, as a method for manufacturing solid electrolytes. Furthermore, the solid electrolyte manufactured by the manufacturing method of this disclosure can be used, for example, in batteries (e.g., all-solid-state secondary batteries).

[0175] Explanation of symbols

[0176] 101 Solid Electrolyte Powder

[0177] 300 Pressure Forming Die

[0178] 301 Upper part of the punch

[0179] 302 Module

[0180] 303 Lower part of the punch

Claims

1. A method for producing a halide, comprising: [the process of] mixing a compound containing MO... x The mixture of powder and NH4X powder is sintered in an inert gas atmosphere or in a vacuum. M is at least one element selected from rare earth elements, X is at least one element selected from F, Cl, Br, and I, x is 1 or more and 2 or less, In the MO x When the average particle size of the powder is defined as D1, and the average particle size of the NH4X powder is defined as D2, the following necessary conditions (a) or (b) must be met. D1 ≤ D2 and D2 - D1 ≤ 0.5 × D2 (a) D2 < D1 and D1 - D2 ≤ 0.5 × D1 (b) The MO x The difference between the average particle size D1 of the powder and the average particle size D2 of the NH4X powder is less than 0.3 μm.

2. The manufacturing method according to claim 1, wherein, The MO x The average particle size D1 of the powder and the average particle size D2 of the NH4X powder are both below 100 μm.

5. The manufacturing method according to claim 1 or 2, further comprising crushing at least one of the plurality of materials that should be included in the mixed material, The matter of crushing the at least one material is performed before preparing the mixed material and firing the mixed material.

4. The manufacturing method according to claim 1 or 2, further comprising: dissolving at least one of the plurality of materials that should be included in the mixed material in a solvent to obtain a solution; and removing the solvent from the solution, The matter of obtaining the solution and the matter of removing the solvent are performed before firing the mixed material.

5. The manufacturing method according to claim 1 or 2, further comprising firing the material containing a halide and LiZ obtained by firing the mixed material, Z is at least one element selected from F, Cl, Br, and I.

6. The manufacturing method according to claim 3, further comprising firing the material containing a halide and LiZ obtained by firing the mixed material, Z is at least one element selected from F, Cl, Br, and I.

7. The manufacturing method according to claim 4, further comprising firing the material containing a halide and LiZ obtained by firing the mixed material, Z is at least one element selected from F, Cl, Br, and I.

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