Method for manufacturing oxyfluoride-based solid electrolyte and method for manufacturing all-solid-state lithium ion battery

Abstract

A method for manufacturing an oxyfluoride-based solid electrolyte comprising: a step for pulverizing and uniformly mixing raw materials containing Li, La, Nb and F to produce a raw material mixture with a BET specific surface area of 2.0 m2 / g or more; and a step for firing the raw material mixture at 600-1200°C to produce an oxyfluoride-based solid electrolyte represented by the composition formula: Aa2-xAb(1+x) / 3B2O6F (wherein Aa is an alkali metal; Ab contains at least a lanthanoid; B is a transition metal or a metal selected from Group 15 of the periodic table; and 0 ≤ x ≤ 1.0).

Description

Method for producing an acid fluoride-based solid electrolyte and a method for producing an all-solid-state lithium-ion battery

[0001] The present invention relates to a method for producing an acid fluoride-based solid electrolyte and a method for producing an all-solid-state lithium-ion battery.

[0002] In recent years, with the rapid proliferation of information-related devices and communication equipment such as personal computers, video cameras, and mobile phones, the development of batteries used as power sources has become increasingly important. Among these batteries, lithium-ion batteries are attracting attention due to their high energy density. Furthermore, improvements in energy density and battery characteristics are also required for large-scale applications such as automotive power sources and load leveling lithium secondary batteries.

[0003] Furthermore, from the perspective of improving safety, lithium-ion batteries that do not use organic solvents as electrolytes, and in which the entire battery is solidified using a solid electrolyte, are attracting attention. Acid fluoride-based solid electrolytes have been proposed as solid electrolytes to be used in such lithium-ion batteries.

[0004] Oxyfluoride-based solid electrolytes used in all-solid-state lithium-ion batteries are non-flammable, highly stable in the atmosphere, and have higher ionic conductivity than general oxide-based solid electrolytes. Therefore, they are attracting attention as a component of next-generation batteries that offer high reliability, high power output, and high cycle characteristics.

[0005] Regarding such acid fluoride-based solid electrolytes, for example, Patent Document 1 describes one with the composition formula Aa 2-α Ab (1+α) / 3 B2O 7-β X β A solid electrolyte for secondary batteries comprising an oxide-based solid electrolyte having a pyrochlore structure represented by the formula, wherein Aa is an alkali metal, Ab contains at least a lanthanide, B is a cationic metal different from Aa and Ab, and X is an anion that can be substituted for the O atom constituting the pyrochlore structure, and in the composition formula, α is in the range of 0.6 < α < 2.0, and β is in the range of 0 < β ≤ 1, and the solid electrolyte for secondary batteries containing a defect structure and a method for manufacturing the same are disclosed.

[0006] Patent No. 7334813

[0007] Conventionally, the production of acid-fluoride solid electrolytes requires three calcination steps: (1) a calcination step to dry the raw materials, (2) a calcination step to synthesize oxide intermediates, and (3) a calcination step to fluoride the oxide intermediates and produce acid-fluorides. After drying the raw materials in (1), a further grinding and mixing step of the raw materials is essential, and after synthesizing the oxide intermediates in (2), a further addition of fluoride-based raw materials and a grinding and mixing step are essential. Thus, the production of acid-fluoride solid electrolytes has been problematic because it requires many steps.

[0008] The present invention was made to solve the above-mentioned problems, and aims to provide a method for producing a single-phase oxyfluoride-based solid electrolyte with good manufacturing efficiency, and a method for producing an all-solid-state lithium-ion battery with good manufacturing efficiency.

[0009] Based on the above findings, the present invention is defined as follows: (1) By crushing and uniformly mixing raw materials containing Li, La, Nb, and F, the BET specific surface area is 2.0 m². 2 A process to prepare a raw material mixture having a concentration of 1 / g or more, and a process to calcine the raw material mixture at 600 to 1200°C, thereby producing a composition formula: Aa 2-x Ab (1+x) / 3 A method for producing an acid fluoride-based solid electrolyte, comprising the steps of: (2) producing an acid fluoride-based solid electrolyte represented by B2O6F (wherein Aa is an alkali metal, Ab contains at least a lanthanide, B is a metal selected from transition metals or Group 15 elements, and 0 ≤ x ≤ 1.0); (3) producing an acid fluoride-based solid electrolyte according to (2), wherein the grinding and homogeneous mixing of the raw materials containing Li, La, Nb, and F are performed by mechanical grinding; (4) producing an acid fluoride-based solid electrolyte according to (2), wherein the mechanical grinding is performed by grinding with a planetary ball mill; and (5) having a BET specific surface area of ​​the raw materials after homogeneous mixing of 4.0 m². 2The method for producing a fluoride-based solid electrolyte according to any one of the above (1) to (3), which is ≥ / g. (5) The method for producing a fluoride-based solid electrolyte according to any one of the above (1) to (4), wherein the BET diameter of the raw material after the uniform mixing is 0.30 μm or less. (6) In the step of producing the fluoride-based solid electrolyte, by firing the raw material mixture, the composition formula: Li 2-x La (1+x) / 3 M2O6F (where M is at least one of Nb and Ta, and 0 ≤ x ≤ 1.0). The method for producing a fluoride-based solid electrolyte according to any one of the above (1) to (5), which produces a fluoride-based solid electrolyte represented by. (7) A method for producing an all-solid-state lithium-ion battery including a solid electrolyte layer, a positive electrode layer, and a negative electrode layer, using the fluoride-based solid electrolyte produced by the production method according to any one of the above (1) to (6).

[0010] According to the present invention, it is possible to provide a method for producing a single-phase fluoride-based solid electrolyte with good production efficiency, and a method for producing an all-solid-state lithium-ion battery with good production efficiency.

[0011] It is a schematic diagram of an all-solid-state lithium-ion battery according to this embodiment. It is an X-ray diffraction pattern of a reference compound and Examples 1 to 4. It is an X-ray diffraction pattern of a reference compound, Examples 1 and 2, and Comparative Examples . <00E0060> Next, modes for carrying out the present invention will be described in detail while referring to the drawings. It should be understood that the present invention is not limited to the following embodiments, and modifications, improvements, etc. of the design can be appropriately added based on the ordinary knowledge of those skilled in the art without departing from the gist of the present invention.

[0013] <Fluoride-based solid electrolyte> The fluoride-based solid electrolyte of this embodiment has a composition formula: Aa 2-x Ab (1+x) / 3 B2O6F (where Aa is an alkali metal, Ab contains at least a lanthanoid, B is a metal selected from a transition metal or a Group 15 element, and 0 ≤ x ≤ 1.0).

[0014] In the above compositional formula, any of Li, Na, or K can be used as the alkali metal represented by Aa.

[0015] In the above compositional formula, Ab contains at least one lanthanide. At least one of La, Ce, Nd, and Sm can be used as the lanthanide represented by Ab. The basic composition of Ab consists of lanthanides, and some of the lanthanides constituting Ab may be substituted with alkaline earth metals (Ca, Mg, Sr, etc.). Ab may consist of lanthanides.

[0016] In the above compositional formula, B is a metal selected from transition metals or Group 15 elements. Furthermore, B is a different metal from Ab. In the crystal, B forms an octahedron surrounded by six oxygen atoms. As the transition metal represented by B, a Group 4 or Group 5 transition metal can be used; more specifically, at least one of Nb, Ta, Ti, Zr, Hf, or V can be used. As the Group 15 element represented by B, Sb or Bi can be used.

[0017] The acid-fluoride-based solid electrolyte of this embodiment has the composition formula: Li 2-x La (1+x) / 3 It may also be expressed as M2O6F (wherein M is at least one of Nb and Ta, and 0 ≤ x ≤ 1.0).

[0018] The oxyfluoride-based solid electrolyte of this embodiment has a pyrochlore structure. The pyrochlore structure has a crystalline structure in which metal atoms are arranged at the vertices of a tetrahedron, and each vertex of the tetrahedron is shared. In the oxyfluoride-based solid electrolyte of this embodiment, the inclusion of the lanthanide La in the pyrochlore structure creates defects in the crystalline structure, improving the ionic conductivity.

[0019] In this embodiment, the acid-fluoride-based solid electrolyte has a composition formula where 0 ≤ x ≤ 1.0. Therefore, single-phase synthesis is facilitated. Furthermore, defects are generated in the crystal structure, which can improve ionic conductivity. In this embodiment, it is preferable that the acid-fluoride-based solid electrolyte has a composition formula where 0.5 ≤ x ≤ 0.8.

[0020] <Manufacturing Method of Acid Fluoride-Based Solid Electrolyte>The manufacturing method of the acid fluoride-based solid electrolyte of this embodiment will be described in detail below. First, prepare raw materials containing Li, La, Nb, and F. Specific examples of the raw materials include Li2CO3, La2O3, Nb2O5, LiF, and LaF3.

[0021] Next, pulverize and mix each raw material to prepare a raw material mixture. At this time, various raw materials are pulverized and uniformly mixed so that the BET specific surface area of the raw material mixture is 2.0 m 2 / g or more.

[0022] In this embodiment, pulverizing and uniformly mixing the raw materials means pulverizing and mixing the raw materials so that the mixing degree of the obtained raw material mixture is 0.950 or more. The mixing degree can be calculated from the elemental mapping image obtained by using SEM-EDX for the raw material mixture. Elemental mapping is performed on Nb, which has the highest proportion among the raw materials, and by performing image analysis, the proportion of Nb2O5 in the elemental mapping image of the mixture is calculated, and the mixing degree is obtained from the following mixing degree formula (1).

[0023]

[0024] In the above mixing degree formula (1), σ 2 represents the mixing degree, and the closer it is to 1, the better dispersed it is. N is the number of divided regions in the elemental mapping image obtained by using SEM-EDX, x i is the proportion of the particle area in the divided image, indicates the proportion of the grain area in the entire image.

[0025] Note that the above mixing degree formula (1) is an adjusted version of the mixing degree formula described in the "Dictionary of Powder Engineering Terms" on the website of the Powder Technology Society of Japan (https: / / www.sptj.jp / powderpedia / words / 10748 / ) for image analysis.

[0026] It is preferable to grind and mix the raw materials so that the degree of mixing of the raw material mixture is 0.960 or higher, more preferable to grind and mix the raw materials so that the degree of mixing is 0.980 or higher, and even more preferable to grind and mix the raw materials so that the degree of mixing is 0.990 or higher.

[0027] When the firing temperature and firing time are constant, the diffusion distance d of the elements is also constant. When the raw material particles are coarse and the particle size r is greater than the diffusion distance d of the elements (r > d), the solid-phase reaction due to firing is difficult to proceed. On the other hand, when the raw material particles are fine and the particle size r is less than or equal to the diffusion distance d of the elements (r ≤ d), the solid-phase reaction due to firing is easier to proceed. In this embodiment, before firing, the BET specific surface area of ​​the raw material mixture is 2.0 m². 2 By grinding and mixing the various raw materials to achieve a concentration of 1 / g or higher, the raw material particle size is fine and the contact area is large, promoting the solid-phase reaction even at low temperatures, and yielding only the LLNOF phase. The fact that only the LLNOF phase is obtained is confirmed by XRD measurement (confirming that it is a single phase composed of Li, La, Nb, O, and F atoms).

[0028] The BET specific surface area of ​​the raw material mixture after homogeneous mixing is 4.0 m². 2 Preferably, it is 6.0 m or more. 2 It is more preferable to be 10.0 m / g or more. 2 It is even more preferable that the value is 1 / g or more. The numerical range including the upper limit of the BET specific surface area of ​​the raw material mixture after homogeneous mixing is 2.0 to 31.0 m². 2 It may also be / g, and 4.0 to 31.0 m 2 It may also be / g, and 6.0 to 31.0 m 2 / g is also acceptable.

[0029] The average particle diameter (BET diameter) of the raw material mixture after uniform mixing can be calculated by converting the above-mentioned BET specific surface area using the true sphere model. The BET diameter is preferably 0.35 μm or less, more preferably less than 0.35 μm, still more preferably 0.30 μm or less, and even more preferably 0.20 μm or less. The numerical range including the lower limit value of the BET diameter of the raw material mixture after uniform mixing may be 0.05 to 0.35 μm, may be 0.05 to 0.30 μm, or may be 0.05 to 0.20 μm.

[0030] The pulverization and mixing time can be appropriately set according to the equipment used, etc., the BET specific surface area of the desired raw material mixture, and / or the BET diameter.

[0031] The pulverization and uniform mixing of the above-mentioned raw materials are preferably carried out by mechanical pulverization. As the mechanical pulverization, for example, pulverization using a planetary ball mill is preferred. By putting the above five kinds of raw materials and zirconia beads with a diameter of 20 mm or less into the container (jar) of the planetary ball mill and rotating the container both自转 and公转, the above five kinds of raw materials can be pulverized and mixed. The revolution rotation speed of the planetary ball mill is preferably in the range of 100 rpm to 5**00 rpm.

[0032] Next, by placing the raw material mixture, for example, in an alumina crucible and firing it at 600 to 1200 °C, a composition formula: Aa 2-x Ab (1+x) / 3 B2O6F (where Aa is an alkali metal, Ab contains at least a lanthanoid, B is a metal selected from transition metals or Group 15 elements, and 0 ≦ x ≦ 1.0). The fluoride-based solid electrolyte of the present embodiment can be produced. The firing atmosphere is not particularly limited, but it is preferably carried out under a gas atmosphere such as argon, nitrogen, or oxygen.

[0033] In the present embodiment, as described above, in the pulverization and mixing of the raw material mixture before firing, the BET specific surface area of the raw material mixture is 2.0 m 2 It should be noted that there seems to be some incomplete or incorrect expressions in the original text, such as "自转 and公转" which may need to be corrected to more accurate terms like "rotation and revolution" for better understanding. Also, "5**00 rpm" might be a typo and should probably be "500 rpm".The raw materials are crushed and mixed so that the amount is greater than or equal to 1 / g and the raw material mixture is uniformly mixed. This allows the solid-phase reaction to proceed smoothly, making it possible to produce a single-phase oxyfluoride-based solid electrolyte at a low calcination temperature of 600 to 1200°C and in only one calcination step. Therefore, the number of steps in the production of oxyfluoride-based solid electrolytes is reduced, improving manufacturing efficiency.

[0034] <All-Solid-State Lithium-Ion Battery> An all-solid-state lithium-ion battery according to an embodiment of the present invention includes a solid electrolyte layer, a positive electrode layer, and a negative electrode layer. An all-solid-state lithium-ion battery according to an embodiment of the present invention can be configured as shown in Figure 1 using the solid electrolyte layer, the positive electrode layer, and the negative electrode layer.

[0035] (Solid Electrolyte Layer) The solid electrolyte layer of this embodiment is formed from the acid-fluoride-based solid electrolyte of this embodiment described above. Thus, the all-solid-state lithium-ion battery according to this embodiment uses an acid-fluoride-based solid electrolyte that is manufactured with good manufacturing efficiency, and therefore also has good manufacturing efficiency. The average thickness of the solid electrolyte layer is not particularly limited and can be designed as appropriate depending on the purpose. The average thickness of the solid electrolyte layer of this embodiment may be, for example, 50 μm to 500 μm, or 50 μm to 100 μm.

[0036] The method for forming the solid electrolyte layer in this embodiment is not particularly limited and can be appropriately selected depending on the purpose. Examples of methods for forming the solid electrolyte layer in this embodiment include sputtering using the target material of the solid electrolyte of this embodiment described above, or compression molding of the solid electrolyte of this embodiment described above.

[0037] (Positive Electrode Layer) The positive electrode layer of this embodiment is formed in layers by mixing a known positive electrode active material for lithium-ion batteries with the above-described oxyfluoride-based solid electrolyte or another solid electrolyte. The content of the positive electrode active material in the positive electrode layer is preferably, for example, 50% by mass or more and 99% by mass or less, and more preferably 60% by mass or more and 90% by mass or less.

[0038] Known positive electrode active materials for lithium-ion batteries include, for example, composition formula 2: Li a Ni b Co c Mn d The material contains a positive electrode active material represented by O2 (in composition formula 2, 1.00 ≤ a ≤ 1.08, 0.60 ≤ b ≤ 0.90, and b + c + d = 1.0). When the positive electrode active material of this embodiment is a high-nickel NCM positive electrode active material with a high Ni ratio of 0.60 to 0.90 as shown in composition formula 2, the capacity of the all-solid-state lithium-ion battery is generally higher. Furthermore, from this viewpoint, it is more preferable that 0.80 ≤ b ≤ 0.90 is set in composition formula 2.

[0039] The positive electrode composite may further contain a conductive additive. This conductive additive may be a carbon material, a metallic material, or a mixture thereof. The conductive additive may include, for example, at least one element selected from the group consisting of carbon, nickel, copper, aluminum, indium, silver, cobalt, magnesium, lithium, chromium, gold, ruthenium, platinum, beryllium, iridium, molybdenum, niobium, osnium, rhodium, tungsten, and zinc. The conductive additive is preferably a highly conductive element of carbon, a metallic element containing carbon, nickel, copper, silver, cobalt, magnesium, lithium, ruthenium, gold, platinum, niobium, osnium, or rhodium, or a mixture or compound thereof. As carbon materials, for example, carbon black such as Ketjenblack, acetylene black, Denka black, thermal black, and channel black, graphite, carbon fiber, activated carbon, etc., can be used.

[0040] The average thickness of the positive electrode layer of an all-solid-state lithium-ion battery is not particularly limited and can be designed appropriately depending on the purpose. The average thickness of the positive electrode layer of an all-solid-state lithium-ion battery may be, for example, 1 μm to 100 μm, or 1 μm to 10 μm.

[0041] The method for forming the positive electrode layer of an all-solid-state lithium-ion battery is not particularly limited and can be appropriately selected depending on the purpose. Examples of methods for forming the positive electrode layer of an all-solid-state lithium-ion battery include a method of compression molding the positive electrode active material for the all-solid-state lithium-ion battery.

[0042] (Negative electrode layer) The negative electrode layer of an all-solid-state lithium-ion battery may be formed by layering known negative electrode active materials for all-solid-state lithium-ion batteries. Alternatively, the negative electrode layer may be formed by layering a negative electrode composite material obtained by mixing a known negative electrode active material for all-solid-state lithium-ion batteries with a solid electrolyte. The content of the negative electrode active material in the negative electrode layer is preferably 10% by mass or more and 99% by mass or less, and more preferably 20% by mass or more and 90% by mass or less.

[0043] The negative electrode layer, like the positive electrode layer, may contain a conductive additive. The conductive additive may be the same material as the material described for the positive electrode layer. As the negative electrode active material, for example, carbon materials can be used, specifically artificial graphite, graphite carbon fiber, resin-calcined carbon, pyrolysis vapor-grown carbon, coke, mesocarbon microbeads (MCMB), furfuryl alcohol resin-calcined carbon, polyacene, pitch-based carbon fiber, vapor-grown carbon fiber, natural graphite, and non-graphitizable carbon, or mixtures thereof. Furthermore, as the negative electrode material, for example, metallic lithium, metallic indium, metallic aluminum, metallic silicon, or alloys combined with other elements or compounds can be used.

[0044] The average thickness of the negative electrode layer of an all-solid-state lithium-ion battery is not particularly limited and can be appropriately selected depending on the purpose. The average thickness of the negative electrode layer of an all-solid-state lithium-ion battery may be, for example, 1 μm to 100 μm, or 1 μm to 10 μm.

[0045] The method for forming the negative electrode layer of an all-solid-state lithium-ion battery is not particularly limited and can be appropriately selected depending on the purpose. Examples of methods for forming the negative electrode layer of an all-solid-state lithium-ion battery include a method of compression molding of negative electrode active material particles and a method of vapor deposition of negative electrode active material.

[0046] Other components constituting the lithium-ion battery are not particularly limited and can be appropriately selected depending on the purpose. Examples include a positive electrode current collector, a negative electrode current collector, and a battery case.

[0047] The size and structure of the positive electrode current collector are not particularly limited and can be appropriately selected according to the purpose. Examples of materials for the positive electrode current collector include die steel, stainless steel, aluminum, aluminum alloy, titanium alloy, copper, gold, and nickel. Examples of shapes for the positive electrode current collector include foil, plate, and mesh. The average thickness of the positive electrode current collector may be, for example, 10 μm to 500 μm, or 50 μm to 100 μm.

[0048] The size and structure of the negative electrode current collector are not particularly limited and can be appropriately selected according to the purpose. Examples of materials for the negative electrode current collector include die steel, gold, indium, nickel, copper, and stainless steel. Examples of shapes for the negative electrode current collector include foil, plate, and mesh. The average thickness of the negative electrode current collector may be, for example, 10 μm to 500 μm, or 50 μm to 100 μm.

[0049] The battery case is not particularly limited and can be appropriately selected depending on the purpose, for example, known laminate films that can be used with conventional all-solid-state batteries. Examples of laminate films include resin laminate films and films in which metal has been vapor-deposited onto a resin laminate film. The shape of the battery is not particularly limited and can be appropriately selected depending on the purpose, for example, cylindrical, rectangular, button-shaped, coin-shaped, and flat-shaped batteries.

[0050] The following examples are provided to better understand the present invention and its advantages, but the present invention is not limited to these examples.

[0051] <Preparation of Acid Fluoride Solid Electrolytes> (Example 1) Five raw materials, Li2CO3, La2O3, Nb2O5, LiF, and LaF3, were weighed so that the raw material composition would be the stoichiometric composition of the target compound. A raw material mixture was prepared by mixing these materials for 24 hours using a planetary ball mill. More specifically, the five raw materials and zirconia beads with a diameter of 1.5 mm or less were placed in the container (jar) of the planetary ball mill, and the five raw materials were crushed and mixed by rotating and revolving the container. The rotational speed of the planetary ball mill was set to a range of 100 rpm to 500 rpm.

[0052] (BET specific surface area, BET diameter) 1.0 g of the obtained raw material mixture was weighed into a glass cell, set in a degasser, filled with nitrogen gas, and then heat-treated at 40°C for 20 minutes in a nitrogen gas atmosphere to degas it. After that, the glass cell containing the degassed sample (powder) was set in a Quantachrome Monosorb Model MS-21 specific surface area analyzer, and the specific surface area (BET specific surface area) was measured by the BET method (single-point method) while flowing a mixed gas of He:70at%-N2:30at% as the adsorption gas. The average particle diameter (BET diameter) was calculated by converting the BET specific surface area using a spherical model. The evaluation results are shown in Table 1.

[0053]

[0054] As described above, the five raw materials were crushed and mixed using a planetary ball mill. The resulting mixture was then placed in an alumina sagger and fired at 700°C under a nitrogen atmosphere to produce an acid-fluoride-based solid electrolyte.

[0055] (Example 2) An acid-fluoride-based solid electrolyte was prepared in the same manner as in Example 1, except that the firing temperature was set to 800°C.

[0056] (Example 3) An acid-fluoride-based solid electrolyte was prepared in the same manner as in Example 1, except that the firing temperature was set to 900°C.

[0057] (Example 4) An acid-fluoride-based solid electrolyte was prepared in the same manner as in Example 1, except that the firing temperature was set to 1000°C.

[0058] (Comparative Example 1) Five types of raw materials were crushed and mixed using a crushing device (ANM-150, manufactured by Nittokagaku Co., Ltd.). The ANM-150 is a device that has an alumina mortar and pestle installed, and automatically crushes the materials (automatic mortar crushing) by rotating the mortar at 6 rpm and the pestle at 100 rpm. After that, the raw material mixture was fired at 700°C. Otherwise, an acid fluoride-based solid electrolyte was prepared in the same manner as in Example 1.

[0059] (Comparative Example 2) The five raw materials were crushed and mixed using a grinding device (ANM-150, manufactured by Nittokagaku Co., Ltd.) in the same manner as in Comparative Example 1. The resulting raw material mixture was then fired at 800°C. Otherwise, an acid fluoride-based solid electrolyte was prepared in the same manner as in Example 1.

[0060] (Comparative Example 3) Five types of raw materials were crushed and mixed in an agate mortar, and the resulting raw material mixture was calcined at 700°C. Otherwise, an acid fluoride-based solid electrolyte was prepared in the same manner as in Example 1.

[0061] (Comparative Example 4) Five types of raw materials were crushed and mixed in an agate mortar, and the resulting raw material mixture was calcined at 800°C. Otherwise, an acid fluoride-based solid electrolyte was prepared in the same manner as in Example 1.

[0062] (Degree of Mixing) The degree of mixing of the raw material mixtures obtained in Examples 1 to 4 and Comparative Examples 1 to 4 was calculated from elemental mapping images obtained using SEM-EDX. Elemental mapping was performed on Nb, which was the most abundant element in the raw materials, and image analysis was performed to calculate the proportion of Nb2O5 in the elemental mapping image of the mixture. The degree of mixing was then obtained from the above-mentioned equation (1) for degree of mixing. Image analysis was performed with N=12 in equation (1) for degree of mixing, and the degree of mixing of the raw material mixtures obtained by each grinding method is shown in Table 2.

[0063]

[0064] <XRD Evaluation of Acid Fluoride Solid Electrolytes> Each acid fluoride solid electrolyte obtained in Examples 1-4 and Comparative Examples 1-4 was evaluated by XRD under the following conditions: • X-ray diffractometer: SmartLab, Rigaku Corporation • Light source: CuKα rays • Voltage: 40kV • Current: 30mA • Scan speed: 2θ = 10° / min Figure 2 shows the reference compound (Li 1.25 La 0.58 Figure 3 shows the X-ray diffraction patterns of the reference compound (Li 1.25 La 0.58 The X-ray diffraction patterns for Nb2O6F), Examples 1 and 2, and Comparative Examples 1 to 4 are shown.

[0065] (Evaluation Results) As shown in Figure 2, in Examples 1 to 4, by grinding and uniformly mixing raw materials containing Li, La, Nb, and F, the BET specific surface area was 2.0 m². 2 A raw material mixture with a concentration of 1 / g or more was prepared, and by calcining this mixture at 600 to 1200°C, a single phase of an acid-fluoride-based solid electrolyte was obtained. Thus, in Examples 1 to 4, the desired single phase of an acid-fluoride-based solid electrolyte was obtained in only one calcination step, demonstrating good manufacturing efficiency for producing acid-fluoride-based solid electrolytes. Furthermore, the mixing degree of the raw material mixtures obtained in Examples 1 to 4 was close to 1, indicating that each raw material was uniformly and finely mixed. As a result, LLNOF could be obtained even at the low temperature of 700°C, where the diffusion distance of elements is small. On the other hand, the mixing degree of the raw material mixtures obtained in Comparative Examples 1 to 4 was low, and the pulverization and mixing of each raw material were insufficient. Therefore, elemental diffusion was insufficient at 700°C, and the solid-phase reaction did not proceed sufficiently, so a single phase of LLNOF could not be obtained. Examples 1 to 4 show that the raw material particles are well-ground, as can be seen from the BET specific surface area and BET diameter, and that the finely ground raw material is well-mixed, as can be seen from the degree of mixing.

[0066] According to the XRD pattern shown in Figure 3, the precursor, which is a mixture of raw materials ground in an agate mortar, has a smaller BET specific surface area and inferior grinding ability compared to the precursor ground in an automatic mortar, but it has superior mixing ability, and it can be seen that a precursor powder in which each raw material is uniformly mixed was obtained. As a result, for the sample fluorinated by calcination at 700°C, the precursor prepared in an agate mortar (Comparative Example 3) produced a larger amount of LLNOF than the precursor prepared in an automatic mortar (Comparative Example 1). These results indicate that not only the particle size of the ground raw materials but also the uniform mixing of each raw material is important for LLNOF production. It can be seen that when a planetary ball mill with superior grinding and mixing ability is used, the amount of LLNOF produced is even greater, even with fluorination by calcination at the same 700°C.

[0067] According to one embodiment of the present invention, it is possible to provide a method for producing an oxyfluoride-based solid electrolyte with good manufacturing efficiency, and a method for producing an all-solid-state lithium-ion battery with good manufacturing efficiency. This could lead to the widespread use of non-fossil energy, reduce the use of fossil energy such as oil and gas which currently account for a large portion of energy generation, and potentially contribute to mitigating global warming. Furthermore, since the main materials used are substances with low environmental impact such as lithium, carbon, manganese, nickel, and cobalt, and harmful substances such as cadmium, lead, and mercury are not used, it is possible to reduce the environmental burden. For this reason, one embodiment of the present invention may contribute to Goal 7, "Ensure access to affordable, reliable, sustainable, and modern energy for all," Goal 9, "Build resilient infrastructure, promote inclusive and sustainable industrialization and foster innovation," and Goal 12, "Ensure sustainable consumption and production patterns," all of which are led by the United Nations.

Claims

1. By crushing and uniformly mixing raw materials containing Li, La, Nb, and F, a BET specific surface area of ​​2.0 m² is obtained. 2 A process to prepare a raw material mixture having a concentration of 1 / g or more, and a process to calcine the raw material mixture at 600 to 1200°C, thereby producing a composition formula: Aa 2-x Ab (1+x) / 3 A method for producing an acid fluoride-based solid electrolyte, comprising the steps of: preparing an acid fluoride-based solid electrolyte represented by the formula B2O6F (wherein Aa is an alkali metal, Ab contains at least a lanthanide, B is a metal selected from transition metals or Group 15 elements, and 0 ≤ x ≤ 1.0); and 2. The method for producing an acid fluoride-based solid electrolyte according to claim 1, wherein the pulverization and homogeneous mixing of the raw materials containing Li, La, Nb, and F are performed by mechanical pulverization.

3. The method for producing an acid fluoride-based solid electrolyte according to claim 2, wherein the mechanical grinding is performed by grinding using a planetary ball mill.

4. The BET specific surface area of ​​the raw materials after uniform mixing is 4.0 m². 2 A method for producing an acid fluoride-based solid electrolyte according to claim 1, wherein the amount is 1 / g or more.

5. The method for producing an acid fluoride-based solid electrolyte according to claim 1, wherein the BET diameter of the raw materials after homogeneous mixing is 0.30 μm or less.

6. In the process of producing the acid fluoride-based solid electrolyte, the raw material mixture is calcined to produce a compound formula: Li 2-x La (1+x) / 3 A method for producing an acid fluoride-based solid electrolyte according to claim 1, comprising producing an acid fluoride-based solid electrolyte represented by the formula M2O6F (wherein M is at least one of Nb and Ta, and 0 ≤ x ≤ 1.0).

7. A method for producing an all-solid-state lithium-ion battery comprising a solid electrolyte layer, a positive electrode layer, and a negative electrode layer, using an acid-fluoride-based solid electrolyte produced by the manufacturing method described in any one of claims 1 to 6.

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