Silver-containing oxides and methods for producing the same

Abstract

Provided is a silver-containing oxide represented by general formula (1): Ag2+xM1 2+yTeO6+z [wherein M1 represents at least one component selected from the group consisting of an alkaline earth metal element and a 3d transition metal element; x represents -0.50 to 4.0; y represents -0.30 to 0.30; and z represents -0.50 to 0.50] and having such a crystal structure that two layers each occupied by Ag are present between a layer occupied by the M1 and a layer occupied by Te. The silver-containing oxide has a high ion conductivity and is a single-phase silver-containing solid electrolyte.

Description

[Technical Field]

[0001] This invention relates to silver-containing oxides and methods for producing the same. [Background technology]

[0002] Silver ion secondary batteries (especially all-solid-state silver ion secondary batteries), which use silver ions as charge carriers, are attractive as novel high-power batteries because they allow for faster diffusion compared to secondary batteries that use alkali ions such as lithium ions as charge carriers.

[0003] However, the operating voltage is low, and the thermodynamic stability of conventional silver-containing electrolytes is poor, severely limiting their applications. This is because all conventionally known halide-based silver ion conductors have low thermal stability.

[0004] On the other hand, Ag2Ni2TeO6 is also known as a silver-containing oxide, in which only one layer occupied by Ag is inserted between layers occupied by Ni and Te (see, for example, Non-Patent Document 1). [Prior art documents] [Non-patent literature]

[0005] [Non-Patent Document 1] Dalton Transactions,2013,42,14992-14998 [Overview of the Initiative] [Problems that the invention aims to solve]

[0006] However, Non-Patent Document 1 states that Ag2Ni2TeO6 could only be used to produce solid electrolytes containing a considerable amount of impurity phases, and it was not possible to produce solid electrolytes consisting of a single-phase silver-containing oxide, nor was the ionic conductivity sufficient.

[0007] The present invention has been made in view of the above-described prior art situation, and its main object is to provide a single-phase silver-containing solid electrolyte having high ionic conductivity.

Means for Solving the Problems

[0008] The inventors of the present invention have conducted intensive studies to achieve the above object. As a result, Ag , 1 , 2+y , , 2+x , , , 6+z , , 1 ,

[0009] M 1 2+y TeO 6+z (1) [In the formula, M 1 represents at least one selected from the group consisting of alkaline earth metal elements and 3d transition metal elements. x represents -0.50 to 4.0. y represents -0.30 to 0.30. z represents -0.50 to 0.50.] having a composition represented by, and between the layers occupied by M 1 and Te, there are two layers of layers occupied by Ag, or Ag 2+x M 1a 2+y TeO 6+z (1A) [In the formula, M 1a represents at least one selected from the group consisting of alkaline earth metal elements, Co, Cu, and Zn. x represents -0.50 to 4.0. y represents -0.30 to 0.30. z represents -0.50 to 0.50.] It has been found that by having the composition, the above problems can be solved and a silver-containing solid electrolyte having high ionic conductivity can be provided. Based on such findings, the inventors of the present invention have conducted further studies and completed the present invention. That is, the present invention includes the following configurations.

[0009] Item 1. General formula (1): Ag 2+x M 1 2+y TeO 6+z (1) [In the formula, M 1x represents at least one element selected from the group consisting of alkaline earth metal elements and 3d transition metal elements. x represents -0.50 to 4.0. y represents -0.30 to 0.30. z represents -0.50 to 0.50. It is represented as, Said M 1 A silver-containing oxide having a crystalline structure in which two layers occupied by Ag are sandwiched between layers occupied by Te.

[0010] Section 2. Said M 1 The silver-containing oxide described in item 1, wherein the silver-containing oxide is at least one selected from the group consisting of Mg, Co, Ni, Cu, Zn, Cr, Mn, and Fe.

[0011] Section 3. General formula (1A): Ag 2+x M 1a 2+y TeO 6+z (1A) [In the formula, M 1a x represents at least one element selected from the group consisting of alkaline earth metal elements, Co, Cu, Zn, Cr, Mn, and Fe. x represents a range of -0.50 to 4.0. y represents a range of -0.30 to 0.30. z represents a range of -0.50 to 0.50. A silver-containing oxide represented by [the specified symbol].

[0012] Section 4. Said M 1a The silver-containing oxide according to item 3, wherein the silver-containing oxide is at least one selected from the group consisting of Mg, Co, and Zn.

[0013] Section 5. Said M 1a The silver-containing oxide according to item 3 or 4, having a crystal structure in which two layers occupied by Ag are between layers occupied by Te.

[0014] Section 6. Said M 1 and the layer occupied by Te, or the M 1a The silver-containing oxide according to item 1, 2, or 5, wherein the interlayer distance of the Te-occupied layer is 0.70 nm or more.

[0015] Item 7. A silver-containing oxide according to item 1, 2, 5, or 6, which is a single phase having a crystalline structure having two layers occupied by Ag.

[0016] Item 8. A silver-containing honeycomb layered oxide as described in any one of items 1 to 7.

[0017] Item 9. A silver-containing oxide according to any one of items 1 to 8, having a non-periodic crystalline structure in which the arrangement of slabs is zigzag in the

[0110] plane.

[0018] Item 10. A method for producing a silver-containing oxide as described in any one of items 1 to 9, General formula (2) or (2A): M 2 2M 1 2+y TeO 6+z (2) M 2 2M 1a 2+y TeO 6+z (2A) [In the formula, M 1 M 1a y and z are the same as above. M 2 This indicates an alkali metal element. A process of reacting an oxide represented by with a silver compound. A manufacturing method that includes the following features.

[0019] Item 11. The manufacturing method according to Item 10, wherein the reaction temperature in the step of reacting the oxide with silver nitrate is 210 to 439°C.

[0020] Item 12. A solid electrolyte comprising a silver-containing oxide as described in any one of items 1 to 9.

[0021] Item 13. A solid electrolyte for silver ion secondary batteries, as described in Item 12.

[0022] Item 14. A solid electrolyte according to item 12 or 13, which is a solid electrolyte for an all-solid-state silver-ion secondary battery.

[0023] Item 15. A positive electrode active material comprising a silver-containing oxide as described in any one of items 1 to 9.

[0024] Item 16. A positive electrode active material for a silver ion secondary battery, as described in Item 15.

[0025] Item 17. A positive electrode active material for an all-solid-state silver-ion secondary battery, as described in item 15 or 16.

[0026] Item 18. A silver-ion secondary battery containing a solid electrolyte as described in any one of items 12-14 and / or a positive electrode active material as described in any one of items 15-17.

[0027] Item 19. A silver ion secondary battery as described in Item 18, which is an all-solid-state silver ion secondary battery.

[0028] Item 20. A magnetic material comprising a silver-containing oxide as described in any one of items 1 to 9. [Effects of the Invention]

[0029] According to the present invention, a single-phase silver-containing solid electrolyte with high ionic conductivity can be provided. [Brief explanation of the drawing]

[0030] [Figure 1] The X-ray diffraction patterns of the samples obtained in Examples 1, 2-1, 3-1, and 4-6 are shown. [Figure 2] Scanning electron microscope (SEM) images (5000x and 10000x) of the sample obtained in Example 1 are shown. [Figure 3] Scanning electron microscope (SEM) images (5000x and 10000x) of the sample obtained in Example 2-1 are shown. [Figure 4] Scanning electron microscope (SEM) images (1000x and 5000x) of the sample obtained in Example 3-1 are shown. [Figure 5] Scanning electron microscope (SEM) images (1000x and 2500x) of the sample obtained in Example 4 are shown. [Figure 6]Scanning electron microscope (SEM) images (1000x and 2500x) of the sample obtained in Example 5 are shown. [Figure 7] Scanning electron microscope (SEM) images (1000x and 2500x) of the sample obtained in Example 6 are shown. [Figure 8] The images of the

[0100] and

[0110] planes of the sample obtained in Example 1, taken using high-angle scattering annular dark-field scanning transmission microscope (HAADF-STEM) and annular bright-field scanning transmission microscope (ABF-STEM), are shown. [Figure 9] The images of the

[0110] plane of the sample obtained in Example 2-1, obtained using high-angle scattering annular dark-field scanning transmission microscopy (HAADF-STEM) and annular bright-field scanning transmission microscopy (ABF-STEM), are shown. [Figure 10] The images of the

[0100] and

[0110] planes of the sample obtained in Example 3-1, taken using high-angle scattering annular dark-field scanning transmission microscope (HAADF-STEM) and annular bright-field scanning transmission microscope (ABF-STEM), are shown. [Figure 11] The images of the

[0100] and

[0110] planes of the sample obtained in Example 4, taken using high-angle scattering annular dark-field scanning transmission microscope (HAADF-STEM) and annular bright-field scanning transmission microscope (ABF-STEM), are shown. [Figure 12] The images of the

[0100] and

[0110] planes of the sample obtained in Example 5, taken using high-angle scattering annular dark-field scanning transmission microscope (HAADF-STEM) and annular bright-field scanning transmission microscope (ABF-STEM), are shown. [Figure 13] The results of the AC impedance measurement of the sample obtained in Example 1 are shown. [Figure 14] The results of thermal stability measurements (TG-DTA) of the samples obtained in Examples 1, 2-1, and 3-1 are shown. [Modes for carrying out the invention]

[0031] In this specification, "contains" is a concept that encompasses all of the following: "contains," "consist essentially of," and "consist of." Furthermore, in this specification, when a numerical range is indicated as "A~B," it means A or greater and B or less.

[0032] 1. Silver-containing oxide (first aspect) A silver-containing oxide according to a first aspect of the present invention is general formula (1): Ag 2+x M 1 2+y TeO 6+z (1) [In the formula, M 1 x represents at least one element selected from the group consisting of alkaline earth metal elements and 3d transition metal elements. x represents -0.50 to 4.0. y represents -0.30 to 0.30. z represents -0.50 to 0.50. It is represented as, Said M 1 It has a crystal structure in which there are two layers occupied by Ag between the layers occupied by Te.

[0033] In general formula (1), M 1 Examples of alkaline earth metals represented by include Mg and Ca. Among these, Mg is preferred from the viewpoint of silver ion conductivity, thermal stability, battery performance, and magnetism.

[0034] In general formula (1), M 1 Examples of 3d transition metal elements represented by include Co, Ni, Cu, Zn, Cr, Mn, and Fe. Among these, Co, Ni, Cu, and Zn are preferred from the viewpoint of silver ion conductivity, thermal stability, battery performance, and magnetism.

[0035] In general formula (1), M 1 While there are no particular limitations, Mg, Co, Ni, Cu, Zn, etc. are preferred from the viewpoint of silver ion conductivity, thermal stability, battery performance, and magnetism.

[0036] In general formula (1), M 1 It can be used alone, or in combination of two or more types.

[0037] In general formula (1), x is between -0.50 and 4.0, preferably between -0.40 and 2.0, and more preferably between -0.30 and 1.0. When x is less than -0.50, it tends to form a mixture, making it difficult to establish a crystalline structure, resulting in poor silver ion conductivity, thermal stability, battery performance, and magnetism. Silver-containing oxides with x greater than 4.0 are difficult to manufacture.

[0038] In general formula (1), y is between -0.30 and 0.30, preferably between -0.28 and 0.28, and more preferably between -0.25 and 0.25. If y is less than -0.30, it is likely to form a mixture, making it difficult to form a crystalline structure, resulting in poor silver ion conductivity and thermal stability. Similarly, if y is greater than 0.30, it is also likely to form a mixture, making it difficult to form a crystalline structure, resulting in poor silver ion conductivity, thermal stability, battery performance, and magnetism.

[0039] In general formula (1), z is between -0.50 and 0.50, preferably between -0.30 and 0.30, and more preferably between -0.20 and 0.20. If z is less than -0.50, it is likely to form a mixture, making it difficult to form a crystalline structure, and the silver ion conductivity and thermal stability are poor. Similarly, if z is greater than 0.50, it is likely to form a mixture, making it difficult to form a crystalline structure, and the silver ion conductivity, thermal stability, battery performance, and magnetism are poor.

[0040] Examples of silver-containing oxides that satisfy the above conditions of the present invention include Ag 2+x Mg 2+y TeO6, Ag 2+x Co 2+y TeO6, Ag 2+x Ni 2+y TeO6, Ag 2+x Cu 2+y TeO6, Ag 2+x Zn 2+y TeO6, Ag 2+x (Ni y1 Co 1-y1 ) 2+yExamples include TeO6. Here, x and y are as described above, and 0 < y1 < 1 is preferred, 0.1 ≦ y1 ≦ 0.9 is more preferred, and 0.2 ≦ y1 ≦ 0.8 is even more preferred.

[0041] The silver-containing oxide according to the first aspect of the present invention has the composition as described above, but M 1 has a crystal structure having two layers of layers occupied by Ag between the layers occupied by M and Te.

[0042] Generally, it is thought that there are many cases where there is only one layer of layers occupied by Ag between the layers occupied by M 1 and Te. In the present invention, however, it has a specific crystal structure having two layers of layers occupied by Ag between the layers occupied by M 1 and Te. As a result, the interlayer distance between the layers occupied by M 1 and Te is enlarged, and the amount of Ag inserted between the layers increases, so that the silver ion conductivity is improved and it is also useful as a magnetic material.

[0043] Note that the "layer occupied by M 1 and Te" mainly means a layer composed of M 1 and Te, and a part of Ag may be mixed therein. Therefore, in the layer occupied by M 1 and Te, it is preferable that M 1 and Te are contained in a total of 50 to 100 atomic%, preferably 70 to 100 atomic%, particularly preferably 80 to 100 atomic%.

[0044] Also, the "layer occupied by Ag" mainly means a layer composed of Ag, and a part of M, Te, etc. may be mixed therein. Therefore, in the layer occupied by Ag, it is preferable that Ag is contained in a total of 50 to 100 atomic%, preferably 70 to 100 atomic%, particularly preferably 80 to 100 atomic%.

[0045] As described above, in the present invention, by having two layers of layers occupied by Ag between the layers occupied by M 1 and Te, M 1Furthermore, the interlayer distance of the Te-occupied layer is increased. As a result, the amount of Ag inserted between layers increases, improving silver ion conductivity and making it useful for magnetic materials. Therefore, M 1 The interlayer distance of the layers occupied by Te is preferably 0.70 nm or more (7.0 Å or more), more preferably 0.75 to 1.10 nm (7.5 to 11.0 Å), and even more preferably 0.80 to 1.00 nm (8.0 to 10.0 Å).

[0046] Such silver-containing oxides of the present invention are M, from the viewpoint of thermal stability, battery performance (especially voltage), magnetism (unique magnetic ground state), etc. 1 Preferably, the oxide is a honeycomb-layered oxide in which Te is arranged in a honeycomb-like structure.

[0047] From the viewpoint of easily exhibiting a unique magnetic structure, it is preferable that the silver-containing oxide of the present invention has a non-periodic crystalline structure in which the slab arrangement is zigzag in the

[0110] plane.

[0048] The silver-containing oxide of the present invention can have high ionic conductivity (especially silver ion conductivity) by having these conditions. Specifically, the ionic conductivity of the silver-containing oxide of the present invention is 1.00 × 10 at 25°C. -5 S / cm or more, preferably 1.50 × 10 -5 ~1.00×10 -4 S / cm, more preferably 2.00 × 10 -5 ~8.00 x 10 -5 It is possible to express the conductivity as S / cm. Ionic conductivity is measured by AC impedance method after the obtained powder is formed into tablets.

[0049] The silver-containing oxide of the present invention is as described above. 1 The crystal structure should include two layers occupied by Ag between the layers occupied by Te, and may also contain other impurity phases within a range that does not significantly affect silver ion conductivity, thermal stability, battery performance, magnetism, etc. Examples of such impurity phases include the raw materials shown in the manufacturing method described later. However, in the present invention, M 1And between the layers occupied by Te, there are two layers occupied by Ag, M 1 Furthermore, the interlayer distance of the Te-occupied layer is increased. As a result, the amount of Ag inserted between layers increases, improving silver ion conductivity and also being useful as a magnetic material; therefore, a low proportion of the impurity phase is preferable. From this viewpoint, when the silver-containing oxide of the present invention has an impurity phase, it is generally preferable that the impurity phase is 0.1 to 10% by mass (particularly 0.2 to 5% by mass), with the total amount of the silver-containing oxide of the present invention being 100% by mass. However, according to the present invention, it is possible to produce a single-phase silver-containing oxide, and as a result, it is possible to particularly improve various physical properties such as ionic conductivity; therefore, a single phase is preferable. In this specification, "single phase" includes not only cases where no impurity phase is present at all, but also cases where a very small amount of impurity phase is present (for example, 0 to 1.0% by mass, preferably about 0 to 0.1% by mass).

[0050] The shape of the silver-containing oxide of the present invention that satisfies the above conditions is not particularly limited, and any shape such as powder, granules, pellets, fibers, or sheets can be used. Furthermore, sheet-shaped silver-containing oxide is easily produced by the manufacturing method described later.

[0051] The silver-containing oxide of the present invention, satisfying the above conditions, exhibits excellent ionic conductivity (particularly silver ion conductivity). Therefore, it is useful as a solid electrolyte constituting the electrolyte layer for silver-ion secondary batteries. Furthermore, the silver-containing oxide of the present invention is also useful as a positive electrode active material for silver-ion secondary batteries, and as a magnetic material.

[0052] 2. Silver-containing oxide (second aspect) A silver-containing oxide according to a second aspect of the present invention is of general formula (1A): Ag 2+x M 1a 2+y TeO 6+z (1A) [In the formula, M 1arepresents at least one selected from the group consisting of alkaline earth metal elements, Co, Cu, Zn, Cr, Mn, and Fe. x represents -0.50 to 4.0. y represents -0.30 to 0.30. z represents -0.50 to 0.50. is represented by

[0053] In the general formula (1A), M 1a Examples of the alkaline earth metal represented by include Mg, Ca, etc. Among them, Mg is preferable from the viewpoints of silver ion conductivity, thermal stability, battery performance, magnetism, etc.

[0054] In the general formula (1A), M 1a is not particularly limited, but from the viewpoints of silver ion conductivity, thermal stability, battery performance, magnetism, etc., Mg, Co, Cu, Zn, etc. are preferable.

[0055] In the general formula (1A), M 1a can be used alone or in combination of two or more.

[0056] In the general formula (1A), x is -0.50 to 4.0, preferably -0.40 to 2.0, more preferably -0.30 to 1.0. If x is less than -0.50, it tends to be a mixture, difficult to form a crystal structure, and inferior in silver ion conductivity, thermal stability, battery performance, and magnetism. Silver-containing oxides exceeding 4.0 in x are difficult to manufacture.

[0057] In the general formula (1A), y is -0.30 to 0.30, preferably -0.28 to 0.28, more preferably -0.25 to 0.25. If y is less than -0.30, it tends to be a mixture, difficult to form a crystal structure, and inferior in silver ion conductivity and thermal stability. Also, when y exceeds 0.30, it also tends to be a mixture, difficult to form a crystal structure, and inferior in silver ion conductivity, thermal stability, battery performance, and magnetism.

[0058] In general formula (1), z is from -0.50 to 0.50, preferably from -0.30 to 0.30, more preferably from -0.20 to 0.20. When z is less than -0.50, it tends to form a mixture and is difficult to form a crystal structure, resulting in inferior silver ion conductivity and thermal stability. Also, when z exceeds 0.50, it also tends to form a mixture and is difficult to form a crystal structure, leading to inferior silver ion conductivity, thermal stability, battery performance, and magnetism.

[0059] Examples of the silver-containing oxide of the present invention that satisfies the above conditions include, for example, Ag 2+x Mg 2+y TeO6, Ag 2+x Co 2+y TeO6, Ag 2+x Cu 2+y TeO6, Ag 2+x Zn 2+y TeO6 and the like. Note that x and y are as described above.

[0060] The silver-containing oxide according to the second aspect of the present invention has the above-described composition. From the viewpoints of silver ion conductivity, thermal stability, battery performance, magnetism, etc., it preferably has a crystal structure having two layers of layers occupied by Ag between the layers occupied by M 1a and Te.

[0061] Generally, it is considered that there are often crystal structures having only one layer of layers occupied by Ag between the layers occupied by M 1a and Te. In the present invention, it preferably has a specific crystal structure having two layers of layers occupied by Ag between the layers occupied by M 1a and Te. As a result, the interlayer distance between the layers occupied by M 1a and Te is enlarged, and the amount of Ag inserted between the layers increases, so the silver ion conductivity is likely to be improved and it is also useful as a magnetic material.

[0062] Note that the "layer occupied by M 1a and Te" mainly means a layer composed mainly of M 1a and Te, and a part of Ag may be mixed therein. For this reason, M 1aAnd in the layer occupied by Te, M 1a It is preferable that the total amount of Te is 50 to 100 atomic%, preferably 70 to 100 atomic%, and particularly preferably 80 to 100 atomic%.

[0063] Furthermore, "the layer occupied by Ag" refers to a layer that is mainly composed of Ag, and partly composed of M 1a It is acceptable for Te and other elements to be present. For this reason, it is preferable that the layer occupied by Ag contains a total of 50 to 100 atomic percent of Ag, preferably 70 to 100 atomic percent, and particularly preferably 80 to 100 atomic percent.

[0064] As described above, in the present invention, M 1a And it is preferable to have two layers occupied by Ag between the layers occupied by Te, M 1a Furthermore, it is preferable that the interlayer distance of the Te-occupied layer is increased. As a result, the amount of Ag inserted between layers increases, which improves silver ion conductivity and is also useful for magnetic materials. Therefore, M 1a The interlayer distance of the layers occupied by Te is preferably 0.70 nm or more (7.0 Å or more), more preferably 0.75 to 1.10 nm (7.5 to 11.0 Å), and even more preferably 0.80 to 1.00 nm (8.0 to 10.0 Å).

[0065] Such silver-containing oxides of the present invention are M, from the viewpoint of thermal stability, battery performance (especially voltage), magnetism (unique magnetic ground state), etc. 1a Preferably, the oxide is a honeycomb-layered oxide in which Te is arranged in a honeycomb-like structure.

[0066] From the viewpoint of easily exhibiting a unique magnetic structure, it is preferable that the silver-containing oxide of the present invention has a non-periodic crystalline structure in which the slab arrangement is zigzag in the

[0110] plane.

[0067] The silver-containing oxide of the present invention can have high ionic conductivity (especially silver ion conductivity) by having these conditions. Specifically, the ionic conductivity of the silver-containing oxide of the present invention is 1.00 × 10 at 25°C.-5 S / cm or more, preferably 1.50 × 10 -5 ~1.00×10 -4 S / cm, more preferably 2.00 × 10 -5 ~8.00 x 10 -5 It is possible to express the conductivity as S / cm. Ionic conductivity is measured by AC impedance method after the obtained powder is formed into tablets.

[0068] The silver-containing oxide of the present invention is as described above. 1a Preferably, the crystal structure includes two layers occupied by Ag between the layers occupied by Te, and may also contain other impurity phases within a range that does not significantly affect silver ion conductivity, thermal stability, battery performance, magnetism, etc. Examples of such impurity phases include the raw materials shown in the manufacturing method described later. However, in the present invention, M 1a And between the layers occupied by Te, there are two layers occupied by Ag, M 1a It is preferable that the interlayer distance of the Te-occupied layer is increased. As a result, the amount of Ag inserted between layers increases, which improves silver ion conductivity and is also useful for magnetic materials, so it is preferable that the proportion of the impurity phase be low. From this viewpoint, when the silver-containing oxide of the present invention has an impurity phase, it is usually preferable that the impurity phase is 0.1 to 10% by mass (particularly 0.2 to 5% by mass), with the total amount of the silver-containing oxide of the present invention being 100% by mass. However, according to the present invention, it is possible to produce a single-phase silver-containing oxide, and as a result, it is possible to particularly improve various physical properties such as ionic conductivity, so it is preferable that it be a single phase. In this specification, "single phase" includes not only cases where there is no impurity phase at all, but also cases where there is a very small amount of impurity phase (for example, 0 to 1.0% by mass, preferably about 0 to 0.1% by mass).

[0069] The shape of the silver-containing oxide of the present invention that satisfies the above conditions is not particularly limited, and any shape such as powder, granules, pellets, fibers, or sheets can be used. Furthermore, sheet-shaped silver-containing oxide is easily produced by the manufacturing method described later.

[0070] The silver-containing oxide of the present invention, satisfying the above conditions, exhibits excellent ionic conductivity (particularly silver ion conductivity). Therefore, it is useful as a solid electrolyte constituting the electrolyte layer for silver-ion secondary batteries. Furthermore, the silver-containing oxide of the present invention is also useful as a positive electrode active material for silver-ion secondary batteries, and as a magnetic material.

[0071] 3. Method for producing silver-containing oxides The silver-containing oxide of the present invention is, for example, of general formula (2) or (2A): M 2 2+x M 1 2+y TeO 6+z (2) M 2 2+x M 1a 2+y TeO 6+z (2A) [In the formula, M 1 M 1a , x, y and z are the same as above. M 2 This indicates an alkali metal element. A process of reacting an oxide represented by with a silver compound. This can be obtained by a manufacturing method that includes [the specified features].

[0072] When producing a silver-containing oxide according to the first aspect of the present invention, it is preferable to use an oxide represented by general formula (2), and when producing a silver-containing oxide according to the second aspect of the present invention, it is preferable to use an oxide represented by general formula (2A).

[0073] In general formulas (2) and (2A), M 1 M 1a x, y, and z are as described above.

[0074] In general formulas (2) and (2A), M 2There are no particular limitations on the alkali metal represented by , and examples include lithium, sodium, potassium, cesium, rubidium, etc. From the viewpoint of yield of the silver-containing oxide of the present invention, lithium, sodium, potassium, etc. are preferred, and sodium, potassium, etc. are more preferred.

[0075] Examples of raw materials that satisfy the above conditions include Na 2+x Mg 2+y TeO6, Na 2+x Co 2+y TeO6, Na 2+x Ni 2+y TeO6, Na 2+x Cu 2+y TeO6, Na 2+x Zn 2+y TeO6, Na 2+x (Ni y1 Co 1-y1 ) 2+y TeO6, K 2+x Mg 2+y TeO6, K 2+x Co 2+y TeO6, K 2+x Ni 2+y TeO6, K 2+x Cu 2+y TeO6, K 2+x Zn 2+y TeO6, K 2+x (Ni y1 Co 1-y1 ) 2+y TeO6, Li 2+x Mg 2+y TeO6, Li 2+x Co 2+y TeO6, Li 2+x Ni 2+y TeO6, Li 2+x Cu 2+y TeO6, Li 2+x Zn 2+y TeO6, Li 2+x (Ni y1 Co 1-y1 ) 2+y TeO6, (NaK) 1+x Mg 2+y TeO6, (NaK) 1+x Co 2+y TeO6, (NaK) 1+x Ni 2+yTeO6, (NaK) 1+x Cu 2+y TeO6, (NaK) 1+x Zn 2+y TeO6, (NaK) 1+x (Ni y1 Co 1-y1 ) 2+y Examples include TeO6, etc. Note that y1 is as described above. These raw materials can be used individually or in combination of two or more. The lithium-based honeycomb type starting material is a layered compound. Furthermore, it is preferable to use raw materials with similar shapes to match the shape of the target silver-containing oxide.

[0076] While there are no particular limitations on the silver compounds used, examples of silver compounds that readily yield the silver-containing oxide of the present invention through reaction with the above-mentioned raw materials include AgNO3, AgI, AgOH, AgBr, AgCl, and AgC2H3O2. These silver compounds can be used individually or in combination of two or more.

[0077] The method for reacting the raw materials with the silver compound is not particularly limited. For example, the raw materials and the silver compound can be mixed by conventional methods. In this case, it is preferable to use an excess amount of the silver compound, for example, 3 to 30 moles, particularly 5 to 20 moles, per mole of raw material, in order to facilitate a sufficient reaction between the raw materials and the silver compound.

[0078] Furthermore, heating is preferable when reacting the raw materials with the silver compound. From the viewpoint of yielding the silver-containing oxide of the present invention, the reaction temperature is preferably 210 to 439°C, and more preferably 220 to 300°C.

[0079] Furthermore, the reaction time when reacting the raw material with the silver compound is preferably 1 to 200 hours, and more preferably 20 to 100 hours, from the viewpoint of the yield of the silver-containing oxide of the present invention.

[0080] In this way, the silver-containing oxide of the present invention is obtained, but after this, heat treatment can be applied as needed. This makes it easier to improve the yield of the silver-containing oxide of the present invention, M1 Furthermore, it is easy to improve the crystallinity of a crystal structure having two layers occupied by Ag between layers occupied by Te. In this case, there are no particular restrictions on the heating temperature, but 212 to 440°C is preferred, and 230 to 260°C is more preferred. Similarly, there are no particular restrictions on the heating time, but 1 to 200 hours is preferred, and 20 to 100 hours is more preferred.

[0081] 4. Silver ion rechargeable battery The silver-ion secondary battery using the silver-containing oxide of the present invention can be manufactured by known methods.

[0082] For example, when the silver-containing oxide of the present invention is used as a positive electrode active material, the positive electrode can be manufactured using a known method with the silver-containing oxide of the present invention as the positive electrode active material. In other words, the silver-containing oxide of the present invention can be used as a substitute material for commonly used positive electrode active materials to produce a positive electrode. When the silver-containing oxide of the present invention is not used as a positive electrode active material, a conventionally known positive electrode can be used.

[0083] Furthermore, a conventionally known negative electrode can be used as the negative electrode.

[0084] Furthermore, when using the silver-containing oxide of the present invention as a solid electrolyte in an electrolyte layer, the silver-containing oxide of the present invention can be formed into layers by a conventional method and used as an electrolyte layer.

[0085] Furthermore, a silver-ion secondary battery can be assembled using other known battery components in accordance with conventional methods. In this invention, "silver-ion secondary battery" refers to a secondary battery in which silver ions function as charge carriers, and is a concept that also includes "silver secondary batteries" in which metallic silver is used as the negative electrode material. [Examples]

[0086] The following examples and comparative examples will be shown to further clarify the features of the present invention, but the present invention is not limited to the following examples.

[0087] Example 1: Ag 2 Mg 2 TeO 6 (First and second aspects) Equivalent amounts of Na2CO3 (Purity: 99.8%, Kishida Chemicals), MgO (Purity: 99%, Kishida Chemicals), and TeO2 (Purity: 99+%, Sigma-Aldrich) were weighed in a molar ratio of 1:2:1 and ground and mixed in zirconia balls (15mmφ × 20 balls) at 400 rpm for 6 hours. Ethanol was then vaporized under reduced pressure, and the recovered powder was pelletized at 100 MPa. After calcining these pellets in air at 840°C for 48 hours, layered Na2Mg2TeO6 was obtained as the target material.

[0088] Next, in a glove box, the obtained layered Na2Mg2TeO6 and AgNO3 were weighed to a molar ratio of 1:10 and mixed in a mortar for 1 hour. The total volume was adjusted to 2 g. After mixing, the mixture was calcined in a glove box (porcelain crucible) under an air atmosphere at 250°C for 99 hours to dissolve the AgNO3. The resulting product was then vigorously washed with hot distilled water using a magnetic stirrer to dissolve any remaining AgNO3, filtered, and finally dried overnight in an oven at 80°C. The powder was collected from the container in a glove box to obtain the target product.

[0089] Example 2-1: Ag 2 Ni 2 TeO 6 (Part 1; First aspect) Equivalent amounts of Na2CO3 (Purity: 99.8%, Kishida Chemicals), NiO (Purity: 98%, Kishida Chemicals), and TeO2 (Purity: 99+%, Sigma-Aldrich) were weighed in a molar ratio of 1:2:1 and placed in a chromium copper container with zirconia balls (15mmφ × 20 pieces). Ethanol was added and the mixture was ground and mixed at 400 rpm for 6 hours using a planetary ball mill (Fritsch; P-7). The ethanol was then vaporized under reduced pressure, and the recovered powder was pelletized at 100 MPa. After calcining these pellets in air at 840°C for 99 hours, layered Na2Ni2TeO6 was obtained as the target material.

[0090] Inside a glove box, the obtained layered Na2Ni2TeO6 and AgNO3 were weighed to a molar ratio of 1:10 and mixed in a mortar for 1 hour. The total volume was adjusted to 2 g. After mixing, the mixture was calcined in a glove box under an air atmosphere at 250°C for 99 hours, and the powder was collected from the container inside the glove box to obtain the target product.

[0091] Example 2-2: Ag 2 Ni 2 TeO 6 (Part 2; First aspect) Equivalent molar amounts of K2CO3 (Purity: 99.5%, Kishida Chemicals), NiO (Purity: 98%, Kishida Chemicals), and TeO2 (Purity: 99+%, Sigma-Aldrich) were weighed in a molar ratio of 1:2:1 and placed in a chromium copper container with zirconia balls (15 mmφ × 20 pieces). Ethanol was added and the mixture was ground and mixed at 400 rpm for 6 hours using a planetary ball mill (Fritsch; P-7). The ethanol was then vaporized under reduced pressure, and the recovered powder was pelletized at 100 MPa. After calcining these pellets in air at 840°C for 99 hours, layered K2Ni2TeO6 was obtained as the target material.

[0092] Inside a glove box, the obtained layered K2Ni2TeO6 and AgNO3 were weighed to a molar ratio of 1:10 and mixed in a mortar for 1 hour. The total volume was adjusted to 2 g. After mixing, the mixture was calcined in a glove box under an air atmosphere at 250°C for 99 hours, and the powder was collected from the container inside the glove box to obtain the target product.

[0093] Examples 2-3: Ag 2 Ni 2 TeO 6 (Part 3; First aspect) Equivalent amounts of Na2CO3 (Purity: 99.8%, Kishida Chemicals), K2CO3 (Purity: 99.5%, Kishida Chemicals), NiO (Purity: 98%, Kishida Chemicals), and TeO2 (Purity: 99+%, Sigma-Aldrich) were weighed in a molar ratio of 0.5:0.5:2:1 and placed in a chromium copper container with zirconia balls (15mmφ × 20 pieces). Ethanol was added and the mixture was ground and mixed at 400 rpm for 6 hours using a planetary ball mill (Fritsch; P-7). The ethanol was then vaporized under reduced pressure, and the recovered powder was pelletized at 100 MPa. After calcining these pellets in air at 840°C for 48 hours, layered NaKNi2TeO6 was obtained as the target material.

[0094] Inside a glove box, the obtained layered NaKNi2TeO6 and AgNO3 were weighed to a molar ratio of 1:10 and mixed in a mortar for 1 hour. The total volume was adjusted to 2 g. After mixing, the mixture was calcined in a glove box under an air atmosphere at 250°C for 99 hours, and the powder was collected from the container inside the glove box to obtain the target product.

[0095] Example 3-1: Ag 2 NiCoTeO 6 (Part 1; First aspect) Equivalent amounts of Na2CO3 (Purity: 99.8%, Kishida Chemicals), NiO (Purity: 98%, Kishida Chemicals), CoO (Purity: 99%, Kojundo Chemicals), and TeO2 (Purity: 99+%, Sigma-Aldrich) were weighed in a molar ratio of 1:1:1:1. These were placed in a chromium copper container along with zirconia balls (15 mmφ × 20 pieces), and ethanol was added. The mixture was then ground and mixed at 400 rpm for 6 hours using a planetary ball mill (Fritsch; P-7). The ethanol was then vaporized under reduced pressure, and the recovered powder was pelletized at 100 MPa. These pellets were calcined in air at 840°C for 99 hours to obtain layered Na2NiCoTeO6 as the target material.

[0096] Inside a glove box, the obtained layered Na2NiCoTeO6 and AgNO3 were weighed to a molar ratio of 1:10 and mixed in a mortar for 1 hour. The total volume was adjusted to 2 g. After mixing, the mixture was calcined in a glove box under an air atmosphere at 250°C for 99 hours, and the powder was collected from the container inside the glove box to obtain the target product.

[0097] Example 3-2: Ag 2 NiCoTeO 6 (Part 2; First aspect) Equivalent amounts of K2CO3 (Purity: 99.5%, Kishida Chemicals), NiO (Purity: 98%, Kishida Chemicals), CoO (Purity: 99%, Kojundo Chemicals), and TeO2 (Purity: 99+%, Sigma-Aldrich) were weighed in a molar ratio of 1:1:1:1. These were placed in a chromium copper container along with 20 zirconia balls (15 mmφ each), and ethanol was added. The mixture was then ground and mixed at 400 rpm for 6 hours using a planetary ball mill (Fritsch; P-7). The ethanol was then vaporized under reduced pressure, and the recovered powder was pelletized at 100 MPa. These pellets were calcined in air at 840°C for 99 hours to obtain layered K2NiCoTeO6 as the target material.

[0098] Inside a glove box, the obtained layered K2NiCoTeO6 and AgNO3 were weighed to a molar ratio of 1:10 and mixed in a mortar for 1 hour. The total volume was adjusted to 2 g. After mixing, the mixture was calcined in a glove box under an air atmosphere at 250°C for 99 hours, and the powder was collected from the container inside the glove box to obtain the target product.

[0099] Example 4: Ag 2 Co 2 TeO 6 (First and second aspects) Equivalent amounts of Na2CO3 (Purity: 99.8%, Kishida Chemicals), Co3O4 (Purity: 99.8%, Sigma-Aldrich), and TeO2 (Purity: 99+%, Sigma-Aldrich) were weighed in a molar ratio of 3:2:3 and placed in a chromium copper container with zirconia balls (15mmφ × 20 pieces). Ethanol was added and the mixture was ground and mixed at 400 rpm for 6 hours using a planetary ball mill (Fritsch; P-7). The ethanol was then vaporized under reduced pressure, and the recovered powder was pelletized at 100 MPa. After calcining these pellets in air at 840°C for 99 hours, layered Na2Co2TeO6 was obtained as the target material.

[0100] Inside a glove box, the obtained layered Na2Co2TeO6 and AgNO3 were weighed to a molar ratio of 1:10 and mixed in a mortar for 1 hour. The total volume was adjusted to 2 g. After mixing, the mixture was calcined in a glove box under an air atmosphere at 250°C for 99 hours, and the powder was collected from the container inside the glove box to obtain the target product.

[0101] Example 5: Ag 2 Cu 2 TeO 6 (First and second aspects) Equivalent amounts of Na2CO3 (Purity: 99.8%, Kishida Chemicals), CuO (Purity: 99%, Kishida Chemicals), and TeO2 (Purity: 99+%, Sigma-Aldrich) were weighed in a molar ratio of 1:2:1 and placed in a chromium copper container with zirconia balls (15mmφ × 20 pieces). Ethanol was added and the mixture was ground and mixed at 400 rpm for 6 hours using a planetary ball mill (Fritsch; P-7). The ethanol was then vaporized under reduced pressure, and the recovered powder was pelletized at 100 MPa. After calcining these pellets in air at 840°C for 99 hours, layered Na2Cu2TeO6 was obtained as the target material.

[0102] Inside a glove box, the obtained layered Na2Cu2TeO6 and AgNO3 were weighed to a molar ratio of 1:10 and mixed in a mortar for 1 hour. The total volume was adjusted to 2 g. After mixing, the mixture was calcined in a glove box under an air atmosphere at 250°C for 99 hours, and the powder was collected from the container inside the glove box to obtain the target product.

[0103] Example 6: Ag 2 Zn 2 TeO 6 (First and second aspects) Equivalent amounts of Na2CO3 (Purity: 99.8%, Kishida Chemicals), ZnO (Purity: 99.5%, Kishida Chemicals), and TeO2 (Purity: 99+%, Sigma-Aldrich) were weighed in a molar ratio of 1:2:1 and placed in a chromium copper container with zirconia balls (15 mmφ × 20 pieces). Ethanol was added and the mixture was ground and mixed at 400 rpm for 6 hours using a planetary ball mill (Fritsch; P-7). The ethanol was then vaporized under reduced pressure, and the recovered powder was pelletized at 100 MPa. After calcining these pellets in air at 840°C for 48 hours, layered Na2Zn2TeO6 was obtained as the target material.

[0104] Inside a glove box, the obtained layered Na2Zn2TeO6 and AgNO3 were weighed to a molar ratio of 1:10 and mixed in a mortar for 1 hour. The total volume was adjusted to 2 g. After mixing, the mixture was calcined in a glove box under an air atmosphere at 250°C for 99 hours, and the powder was collected from the container inside the glove box to obtain the target product.

[0105] Test Example 1: X-ray structural analysis X-ray diffraction measurements using CuKα rays were performed on the samples obtained in Examples 1 to 6 in the range of 2θ = 5 to 90°. The results are shown in Figure 1. As a result, as in Example 6, the peak was broad, making X-ray structural analysis difficult.

[0106] Test Example 2: Composition Analysis Elemental analysis was performed on the samples obtained in Examples 1 to 6 by inductively coupled plasma atomic emission spectrometry (ICPAES). The results are shown in Table 1.

[0107] [Table 1]

[0108] Test Example 3: Electron Microscope Observation The particle morphology of the samples obtained in Examples 1 to 6 was observed using a scanning electron microscope (5000x and 10000x magnification). The results are shown in Figures 2 to 7. From these results, it can be seen that sheet-like (or plate-like (lamellar-like)) particles were obtained in all of the examples.

[0109] As can be seen from previous reports (Chem. Soc. Rev., 2021, 50, 3990-4030, etc.), layered Ag2M2TeO6 oxides with a honeycomb structure can exhibit the exotic magnetic properties predicted by the Kitaev magnetic material model. In the present invention, since it is a layered compound in which 3d transition metals are arranged in a honeycomb-like shape, it is expected to belong to the Kitaev material group and is useful as a magnetic material applied to fields such as 2D Spintronics and Topological Quantum Computing.

[0110] Next, the layered structure of the

[0100] and

[0110] planes was observed in the samples obtained in Examples 1, 2-1, 3-1, 4, and 5 using transmission electron microscopes, namely high-angle scattering annular dark-field scanning transmission microscope (HAADF-STEM) and annular bright-field scanning transmission microscope (ABF-STEM). The results are shown in Figures 8-12. As a result, in all cases, M 1 It was revealed that it is a single phase with a layered structure in which there are two layers occupied by Ag between layers occupied by Mg, Ni, Co, etc. and Te. Furthermore, in all cases, M 1 The interlayer distance between the layers occupied by Mg, Ni, Co, etc., and Te was approximately 0.9 nm (9.0 Å). In all cases, the Ag layer lacked periodicity in its stacking direction and exhibited a non-periodic structure with a zigzag arrangement of slag. Although this result is shown only for Examples 1, 2-1, 3-1, 4, and 5, it can be understood that other examples manufactured in the same way would have a similar structure. Thus, compared to conventional silver-containing oxides with layered structures, the increased interlayer distance suggests higher ionic conductivity.

[0111] Test Example 4: Ionic Conductivity The ionic conductivity of the sample obtained in Example 1 was measured by AC impedance measurement at 25 to 100°C. The results are shown in Figure 13. As a result, the ionic conductivity at 25°C was 3.51 × 10⁻¹⁰. -5 It is S / cm, and at 100℃ it is 1.00 × 10⁻⁶ -4The conductivity was S / cm. This indicates that high ionic conductivity was observed even without optimizing the powder manufacturing process.

[0112] Test Example 5: Thermal Stability Silver-containing halides, conventionally known as silver ion conductors, all have low thermal stability and undergo phase transformation at temperatures below 500°C.

[0113] In contrast, the thermal stability of the samples obtained in Examples 1, 2, 3-1, 4, 5, and 6 was evaluated by simultaneous thermogravimetric and differential thermal analysis (TG-DTA) in an Ar atmosphere at a heating rate of 300°C / min in the range of 0 to 1000°C. The results are shown in Figure 14. As a result, it can be seen that Ag2Mg2TeO6 in Example 1 undergoes phase transformation at 630°C and 940°C, Ag2Ni2TeO6 in Example 2-1 undergoes phase transformation at 900°C, Ag2NiCoTeO6 in Example 3-1 undergoes phase transformation at 890°C and 960°C, Ag2Co2TeO6 in Example 4 undergoes phase transformation at 768°C and 962°C, Ag2Cu2TeO6 in Example 5 undergoes phase transformation at 662°C, 774°C, 904°C and 950°C, and Ag2Zn2TeO6 in Example 6 undergoes phase transformation at 645°C and 962°C. As a result, it can be seen that the thermal stability is dramatically improved compared to silver-containing halides that have been conventionally known as silver ion conductors. [Industrial applicability]

[0114] The silver-containing oxide of the present invention exhibits excellent ionic conductivity (particularly silver ion conductivity) and can be obtained as a single phase. Therefore, it is useful as a solid electrolyte constituting the electrolyte layer for silver-ion secondary batteries. Furthermore, the silver-containing oxide of the present invention is also useful as a positive electrode active material for silver-ion secondary batteries, and as a magnetic material.

Claims

1. General formula (1): Aẹ ２＋ｘ M １ ２＋ｙ Tet ６＋ｚ (1) [In the formula, M １ x represents at least one element selected from the group consisting of alkaline earth metal elements and 3d transition metal elements. x represents a range of -0.50 to 4.

0. y represents a range of -0.30 to 0.

30. z represents a range of -0.50 to 0.

50. It is represented as, Said M １ A silver-containing oxide having a single phase consisting of a crystalline structure having two layers occupied by Ag between layers occupied by Te, and a silver-containing honeycomb layered oxide having a non-periodic crystalline structure in which the arrangement of slabs is zigzag on the [110] plane.

2. Said M １ The silver-containing oxide according to claim 1, wherein the silver-containing oxide is at least one selected from the group consisting of Mg, Co, Ni, Cu, Zn, Cr, Mn, and Fe.

3. Said M １ The silver-containing oxide according to claim 1, wherein the interlayer distance of the Te-occupied layer is 0.70 nm or more.

4. A method for producing a silver-containing oxide according to any one of claims 1 to 3, General formula (2): M ２ ２ M １ ２＋ｙ TeO ６＋ｚ (2) [In the formula, M １ y and z are the same as above. M ２ This indicates an alkali metal element. A process of reacting an oxide represented by with a silver compound. A manufacturing method that includes the following features.

5. The manufacturing method according to claim 4, wherein the reaction temperature in the step of reacting the oxide with silver nitrate is 210 to 439°C.

6. A solid electrolyte comprising a silver-containing oxide as described in any one of claims 1 to 3.

7. The solid electrolyte according to claim 6, which is a solid electrolyte for a silver ion secondary battery.

8. The solid electrolyte according to claim 6, which is a solid electrolyte for an all-solid-state silver ion secondary battery.

9. A positive electrode active material comprising a silver-containing oxide according to any one of claims 1 to 3.

10. The positive electrode active material for a silver ion secondary battery, as described in claim 9.

11. The positive electrode active material according to claim 9, which is a positive electrode active material for an all-solid-state silver ion secondary battery.

12. A silver ion secondary battery comprising a solid electrolyte and / or a positive electrode active material made of a silver-containing oxide as described in any one of claims 1 to 3.

13. The silver ion secondary battery according to claim 12, which is an all-solid-state silver ion secondary battery.

14. A magnetic material comprising a silver-containing oxide according to any one of claims 1 to 3.

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