All-solid-state battery, method for manufacturing an all-solid-state battery, raw material powder, and method for manufacturing raw material powder

Abstract

To provide an all-solid-state battery in which a decrease in ionic conductivity can be suppressed while an amount of Ge is reduced, a manufacturing method of an all-solid-state battery, base powder, and a production method of base powder.SOLUTION: An all-solid-state battery includes a solid electrolyte layer, a first electrode layer which is provided on a first main surface of the solid electrolyte layer and contains an electrode active material, and a second electrode layer which is provided on a second main surface of the solid electrolyte layer and contains an electrode active material. A solid electrolyte that is a main component of the solid electrolyte layer has a structure represented by (Li1+x+(4-A)yAlxMyGe2-x-y(PO4)3), and is formed of a glass ceramic in which a portion of glass is crystallized. The A represents the valence of the M that is metal, and 0<A×y≤0.8 is satisfied.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] This invention relates to an all-solid-state battery, a method for manufacturing an all-solid-state battery, a raw material powder, and a method for manufacturing the raw material powder. [Background technology]

[0002] Currently, lithium-ion secondary batteries are used in various fields such as smartphones and automobiles. However, commercially available lithium-ion secondary batteries contain organic electrolytes, which pose risks such as electrolyte leakage, smoke emission, and fire. Therefore, there is a need for the development of all-solid-state lithium-ion secondary batteries using oxide solid electrolytes that are stable in the atmosphere. NASICON-type solid electrolytes have been widely studied as oxide solid electrolytes that have relatively high ionic conductivity and are stable in the atmosphere (see, for example, Patent Document 1). [Prior art documents] [Patent Documents]

[0003] [Patent Document 1] Japanese Patent Publication No. 2018-73554 [Overview of the project] [Problems that the invention aims to solve]

[0004] LAGP(Li) is a glass solid electrolyte that precipitates crystals containing a NASICON-type crystal structure through heat treatment. 1+x Al x Ge 2-x (PO4)3) can be sintered at low temperatures. Furthermore, sintered bodies of LAGP have high ionic conductivity at room temperature. -4It shows (S / cm level). However, the problem with LAGP is that Ge is costly. Also, when sintering the aforementioned glass solid electrolyte simultaneously with a plurality of other materials, it is desirable to be able to control the sintering temperature. A technology that can control the sintering temperature while reducing the amount of Ge is needed. However, if Ge is partially substituted with other elements in order to reduce the amount of Ge, there is a possibility of reducing the ionic conductivity.

[0005] The present invention has been made in view of the above problems, and an object thereof is to provide a all-solid-state battery, a method for manufacturing a all-solid-state battery, raw material powder, and a method for manufacturing the raw material powder, which can suppress a decrease in ionic conductivity while reducing the amount of Ge.

Means for Solving the Problems

[0006] The all-solid-state battery according to the present invention includes a solid electrolyte layer, a first electrode layer provided on the first main surface of the solid electrolyte layer and containing an electrode active material, and a second electrode layer provided on the second main surface of the solid electrolyte layer and containing an electrode active material. The solid electrolyte that is the main component of the solid electrolyte layer is a solid electrolyte made of glass ceramics having a structure of (Li 1+x+(4-A)y Al x M y Ge 2-x-y (PO4)3), and a part of the glass is crystallized. A is the valence of M which is a metal, and it is characterized in that 0 < A×y ≤ 0.8.

[0007] In the above all-solid-state battery, M may be Zr, Sn, or Ti.

[0008] In the above all-solid-state battery, M may be Co, Mg, or Ca.

[0009] The manufacturing method of the all-solid-state battery according to the present invention includes a step of preparing a laminate having a green sheet containing solid electrolyte powder, a paste coating for a first electrode layer formed on a first main surface of the green sheet and containing an electrode active material, and a paste coating for a second electrode layer formed on a second main surface of the green sheet and containing an electrode active material, and a step of firing the laminate. The solid electrolyte powder is a glass solid electrolyte having a structure of (Li 1+x+(4-A)y Al x M y Ge 2-x-y (PO4)3), where A is the valence of the metal M, and 0 < A×y ≤ 0.8.

[0010] The raw material powder according to the present invention is a raw material powder containing solid electrolyte powder. The solid electrolyte powder is a glass solid electrolyte having a structure of (Li 1+x+(4-A)y Al x M y Ge 2-x-y (PO4)3), where A is the valence of the metal M, and 0 < A×y ≤ 0.8.

[0011] The manufacturing method of the raw material powder according to the present invention includes a step of using raw materials containing Li, Al, M which is a metal, Ge, P, and O, and generating a glass solid electrolyte having a structure of (Li 1+x+(4-A)y Al x M y Ge 2-x-y (PO4)3) by a melt quenching method. A is the valence of M, and 0 < A×y ≤ 0.8.

Advantages of the Invention

[0012] <000009!>According to the present invention, it is possible to provide an all-solid-state battery, a manufacturing method of an all-solid-state battery, a raw material powder, and a manufacturing method of a raw material powder that can suppress a decrease in ionic conductivity while reducing the amount of Ge.

Brief Description of the Drawings

[0013] [Figure 1] It is a schematic cross-sectional view showing the basic structure of an all-solid-state battery. [Figure 2] This is a schematic cross-sectional view of an all-solid-state battery according to an embodiment. [Figure 3] This is a schematic cross-sectional view of another all-solid-state battery. [Figure 4] This diagram illustrates a flow chart of the manufacturing process for all-solid-state batteries. [Figure 5] (a) and (b) are diagrams illustrating the lamination process. [Modes for carrying out the invention]

[0014] The embodiments will be described below with reference to the drawings.

[0015] (Embodiment) Figure 1 is a schematic cross-sectional view showing the basic structure of an all-solid-state battery 100. As illustrated in Figure 1, the all-solid-state battery 100 has a structure in which a solid electrolyte layer 30 is sandwiched between a first internal electrode 10 (first electrode layer) and a second internal electrode 20 (second electrode layer). The first internal electrode 10 is formed on the first main surface of the solid electrolyte layer 30. The second internal electrode 20 is formed on the second main surface of the solid electrolyte layer 30.

[0016] When the all-solid-state battery 100 is used as a secondary battery, one of the first internal electrode 10 and the second internal electrode 20 is used as the positive electrode and the other as the negative electrode. In this embodiment, as an example, the first internal electrode 10 is used as the positive electrode layer and the second internal electrode 20 is used as the negative electrode layer.

[0017] The solid electrolyte layer 30 mainly consists of a solid electrolyte having ion conductivity. The solid electrolyte that is the main component of the solid electrolyte layer 30 is an oxide-based solid electrolyte having lithium ion conductivity, and is a phosphate-based solid electrolyte having a NASICON structure. A phosphate-based solid electrolyte having a NASICON structure has the properties of high conductivity and stability in the atmosphere. The phosphate-based solid electrolyte is a lithium-containing phosphate. In this embodiment, as the solid electrolyte that is the main component of the solid electrolyte layer 30, a glass solid electrolyte LAGP(Li) is used, which precipitates crystals containing a NASICON-type crystal structure by crystallization through heat treatment. 1+x Al x Ge 2-x Use (PO4)3.

[0018] The first internal electrode 10, used as the positive electrode, contains a material having an olivine-type crystal structure as the electrode active material. It is preferable that the second internal electrode 20 also contains the same electrode active material. Examples of such electrode active materials include phosphates containing a transition metal and lithium. The olivine-type crystal structure is found in natural olivine and can be identified by X-ray diffraction.

[0019] Typical examples of electrode active materials with an olivine-type crystal structure include LiCoPO4 containing Co. Phosphates in which the transition metal Co is replaced in this chemical formula can also be used. Here, the ratio of Li and PO4 may vary depending on the valency. It is preferable to use Co, Mn, Fe, Ni, etc. as the transition metal.

[0020] Electrode active materials having an olivine-type crystal structure act as positive electrode active materials in the first internal electrode 10, which acts as the positive electrode. For example, if the electrode active material having an olivine-type crystal structure is contained only in the first internal electrode 10, then this electrode active material acts as the positive electrode active material. When the electrode active material having an olivine-type crystal structure is also contained in the second internal electrode 20, which acts as the negative electrode, although the mechanism of action is not fully understood, it is presumed that this is based on the formation of a partial solid solution state with the negative electrode active material, resulting in an increase in discharge capacity and an increase in the operating potential associated with discharge.

[0021] When both the first internal electrode 10 and the second internal electrode 20 contain electrode active materials having an olivine-type crystal structure, each electrode active material preferably contains a transition metal that may be the same or different from each other. "May be the same or different from each other" means that the electrode active materials contained in the first internal electrode 10 and the second internal electrode 20 may contain the same type of transition metal, or they may contain different types of transition metals. The first internal electrode 10 and the second internal electrode 20 may contain only one type of transition metal, or they may contain two or more types of transition metals. Preferably, the first internal electrode 10 and the second internal electrode 20 contain the same type of transition metal. More preferably, the electrode active materials contained in both electrodes have the same chemical composition. The inclusion of the same type of transition metal or the same composition of electrode active materials in the first internal electrode 10 and the second internal electrode 20 increases the similarity of the compositions of both internal electrode layers, which has the effect of allowing the all-solid-state battery 100 to withstand actual use without malfunction, depending on the application, even if the terminals are connected in reverse polarity.

[0022] The second internal electrode 20 contains a negative electrode active material. By containing the negative electrode active material in only one electrode, it becomes clear that the electrode in question acts as the negative electrode and the other electrode acts as the positive electrode. Alternatively, both electrodes may contain a known substance as the negative electrode active material. Regarding the negative electrode active material of the electrodes, prior art in secondary batteries can be appropriately referenced, and examples include compounds such as titanium oxide, lithium titanium composite oxide, lithium titanium composite phosphate, carbon, and lithium vanadium phosphate.

[0023] In the fabrication of the first internal electrode 10 and the second internal electrode 20, in addition to these electrode active materials, an ionic conductive solid electrolyte and a conductive material (conductive additive) are added. For these components, an internal electrode paste can be obtained by uniformly dispersing a binder and a plasticizer in water or an organic solvent. The conductive additive may include carbon materials. The conductive additive may also include metals. Examples of metals used as conductive additives include Pd, Ni, Cu, Fe, and alloys containing these. The solid electrolyte contained in the first internal electrode 10 and the second internal electrode 20 can be, for example, the same as the solid electrolyte that is the main component of the solid electrolyte layer 30.

[0024] The solid electrolyte (LAGP) used as the main component of the solid electrolyte layer 30 is made of Li-Al-Ge-PO4-based glass ceramics (glass ceramics in which part of the glass has crystallized), for example, (Li 1+x Al x Ge 2-x It can be expressed as (PO4)3). LAGP is a glass solid electrolyte that can be sintered at low temperatures. Furthermore, sintered LAGP bodies have high ionic conductivity (10) at room temperature. -4 It exhibits a resistance of approximately S / cm. However, because LAGP contains high-cost Ge, the cost of the all-solid-state battery 100 is high. Therefore, it is desirable to reduce the amount of Ge.

[0025] In addition, the solid electrolyte layer 30 will be fired simultaneously with the first internal electrode 10 and the second internal electrode 20. If the difference between the sintering temperature of the solid electrolyte layer 30 and the sintering temperatures of the first internal electrode 10 and the second internal electrode 20 is large, there is a risk of cracks and delamination occurring. Therefore, it is desirable that the sintering temperature of the solid electrolyte layer 30 can be controlled.

[0026] From the above, a technique that can control the sintering temperature of the solid electrolyte layer 30 while reducing the Ge content is desired. However, if some Ge is replaced with other elements in order to reduce the Ge content, the ionic conductivity of the solid electrolyte layer 30 may be decreased.

[0027] Therefore, the solid electrolyte, which is the main component of the solid electrolyte layer 30 according to the present embodiment, has a structure in which the Ge content is reduced while suppressing a decrease in ionic conductivity. Specifically, the solid electrolyte, which is the main component of the solid electrolyte layer 30, has a structure of LAGP (Li 1+x+(4-A)y Al x M y Ge 2-x-y (PO4)3). A is the valence of M. By setting 0 < y, the Ge content can be reduced.

[0028] By using a tetravalent metal as M, the sintering temperature of the solid electrolyte, which is the main component of the solid electrolyte layer 30, can be controlled to the high temperature side. This is presumably because the liquid phase formation temperature becomes high due to the high stability of the Li-Al-M-P-O bond in tetravalent metals other than Ge, resulting in a higher sintering temperature compared to LAGP. However, if the substitution amount y of Ge increases, vitrification may be inhibited, and there is a risk that sufficient ionic conductivity cannot be obtained. Therefore, an upper limit is set for the substitution amount y of Ge. In the present embodiment, if M is a tetravalent metal, 0 < y ≤ 0.2 is set.

[0029] When using a tetravalent metal as M, from the perspective of increasing the substitution amount y of Ge to reduce costs, the substitution amount y of Ge is preferably 0.03 or more, more preferably 0.05 or more, and even more preferably 0.10 or more.

[0030] On the other hand, when using a tetravalent metal as M, from the perspective of obtaining sufficient ionic conductivity, the substitution amount y of Ge is preferably 0.18 or less, and more preferably 0.15 or less.

[0031] As the tetravalent metal M, for example, Zr, Sn, Ti, etc. can be used. Among these, Zr can change the sintering temperature to the high temperature side even in a small amount. Therefore, it is preferable to use Zr as the tetravalent metal M.

[0032] By using a divalent metal as M, the sintering temperature of the solid electrolyte, which is the main component of the solid electrolyte layer 30, can be controlled to the low temperature side. This is presumably because the stability of the Li - Al - M - P - O bond is low in divalent metals, resulting in a lower liquid phase formation temperature and thus a lower sintering temperature compared to LAGP. However, if the substitution amount y of Ge increases, vitrification may be inhibited and sufficient ionic conductivity may not be obtained. Therefore, an upper limit is set for the substitution amount y of Ge. In this embodiment, if M is a divalent metal, 0 < y ≤ 0.4. As the divalent metal M, for example, Co, Mg, Ca, etc. can be used.

[0033] When using a divalent metal as M, from the perspective of increasing the substitution amount y of Ge to reduce costs, the substitution amount y of Ge is preferably 0.05 or more, more preferably 0.10 or more, and even more preferably 0.20 or more.

[0034] On the other hand, when using a divalent metal as M, from the perspective of obtaining sufficient ionic conductivity, the substitution amount y of Ge is preferably 0.35 or less, and more preferably 0.3 or less.

[0035] It is presumed that the reason why the preferable upper limit of the Ge substitution amount y differs between the case where the valence of M is tetravalent and the case where it is divalent is due to the stability of Li-Al-M-P-O. The divalent form is more likely to be vitrified, and the tetravalent form cannot be vitrified with a smaller substitution amount.

[0036] From the above description, the relationship of 0 < A × y ≤ 0.8 can be derived. In (Li 1+x+(4-A)y Al x M y Ge 2-x-y (PO4)3), x is, for example, 0.2 or more and 0.8 or less, preferably 0.3 or more and 0.7 or less, and more preferably 0.4 or more and 0.6 or less.

[0037] FIG. 2 is a schematic cross-sectional view of a laminated all-solid-state battery 100a in which a plurality of battery units are laminated. The all-solid-state battery 100a includes a laminated chip 60 having a substantially rectangular parallelepiped shape. In the laminated chip 60, a first external electrode 40a and a second external electrode 40b are provided so as to be in contact with two side surfaces out of the four side surfaces other than the upper and lower surfaces at the ends in the lamination direction. The two side surfaces may be two adjacent side surfaces or two opposite side surfaces. In the present embodiment, it is assumed that the first external electrode 40a and the second external electrode 40b are provided so as to be in contact with two opposite side surfaces (hereinafter referred to as two end surfaces).

[0038] In the following description, those having the same composition range, the same thickness range, and the same particle size distribution range as the all-solid-state battery 100 are denoted by the same reference numerals, and detailed description thereof is omitted.

[0039] In the all-solid-state battery 100a, multiple first internal electrodes 10 and multiple second internal electrodes 20 are alternately stacked via a solid electrolyte layer 30. The edges of the multiple first internal electrodes 10 are exposed on the first end face of the stacked chip 60, but not on the second end face. The edges of the multiple second internal electrodes 20 are exposed on the second end face of the stacked chip 60, but not on the first end face. As a result, the first internal electrodes 10 and the second internal electrodes 20 are alternately conductive to the first external electrode 40a and the second external electrode 40b. The solid electrolyte layer 30 extends from the first external electrode 40a to the second external electrode 40b. Thus, the all-solid-state battery 100a has a structure in which multiple battery units are stacked.

[0040] A cover layer 50 is laminated on the upper surface of the laminated structure of the first internal electrode 10, the solid electrolyte layer 30, and the second internal electrode 20 (in the example in Figure 2, the upper surface of the uppermost layer, the first internal electrode 10). Another cover layer 50 is laminated on the lower surface of the laminated structure (in the example in Figure 2, the lower surface of the lowest layer, the first internal electrode 10). The cover layer 50 is mainly composed of an inorganic material containing, for example, Al, Si, Zr, or Ti (e.g., Al2O3, SiO2, ZrO2, TiO2, etc.). The cover layer 50 may also mainly contain the solid electrolyte that is the main component of the solid electrolyte layer 30.

[0041] The first internal electrode 10 and the second internal electrode 20 may be provided with a current collector layer. For example, as illustrated in Figure 3, a first current collector layer 11 may be provided within the first internal electrode 10. Also, a second current collector layer 21 may be provided within the second internal electrode 20. The first current collector layer 11 and the second current collector layer 21 are mainly composed of a conductive material. For example, metal, carbon, etc. can be used as the conductive material for the first current collector layer 11 and the second current collector layer 21. By connecting the first current collector layer 11 to the first external electrode 40a and the second current collector layer 21 to the second external electrode 40b, the current collection efficiency is improved.

[0042] Next, we will explain the manufacturing method of the all-solid-state battery 100a illustrated in Figure 2. Figure 4 is a diagram illustrating the flow of the manufacturing method of the all-solid-state battery 100a.

[0043] (Process for preparing raw material powder for the solid electrolyte layer) First, the raw material powder for the solid electrolyte layer 30 is prepared. For example, raw materials containing Li, Al, divalent or tetravalent metal M, Ge, P, and O, along with additives, can be mixed and a molten-collapse method can be used to produce the raw material powder for the solid electrolyte layer (glass solid electrolyte). By using a molten-collapse method, the solid electrolyte, which is the main component of the solid electrolyte layer 30, can be vitrified. The obtained raw material powder can be adjusted to the desired average particle size by dry grinding. For example, the desired average particle size can be adjusted using a planetary ball mill with 5 mmφ ZrO2 balls.

[0044] The raw material powder is LAGP (Li 1+x+(4-A)y Al x M y Ge 2-x-y It has the structure (PO4)3). A is the valence of M, and 0 <A×y≦0.8である。

[0045] (Process for preparing raw material powder for the cover layer) First, the raw material powder for the ceramics that make up the cover layer 50 is prepared. For example, the raw material powder for the cover layer can be prepared by mixing raw materials and additives and using a solid-phase synthesis method. The obtained raw material powder can be adjusted to the desired average particle size by dry grinding. For example, the desired average particle size can be adjusted using a planetary ball mill with 5 mmφ ZrO2 balls.

[0046] (Process for preparing paste for internal electrodes) Next, an internal electrode paste is prepared for the fabrication of the first internal electrode 10 and the second internal electrode 20 described above. For example, an internal electrode paste can be obtained by uniformly dispersing a conductive additive, electrode active material, solid electrolyte material, sintering aid, binder, plasticizer, etc., in water or an organic solvent. The solid electrolyte paste described above may be used as the solid electrolyte material. Carbon materials may be used as the conductive additive. Metals may also be used as the conductive additive. Examples of metals used as conductive additives include Pd, Ni, Cu, Fe, and alloys containing these. Pd, Ni, Cu, Fe, alloys containing these, and various carbon materials may be used further. If the composition of the first internal electrode 10 and the second internal electrode 20 is different, each internal electrode paste may be prepared individually.

[0047] The paste for internal electrodes contains, for example, one or more glass components such as Li-BO compounds, Li-Si-O compounds, Li-CO compounds, Li-SO compounds, and Li-PO compounds as sintering aids.

[0048] (Process for preparing paste for external electrodes) Next, an external electrode paste is prepared for the fabrication of the first external electrode 40a and the second external electrode 40b described above. For example, an external electrode paste can be obtained by uniformly dispersing a conductive material, glass frit, binder, plasticizer, etc., in water or an organic solvent.

[0049] (Solid electrolyte green sheet manufacturing process) A solid electrolyte slurry having a desired average particle size is obtained by uniformly dispersing raw material powder for the solid electrolyte layer in an aqueous solvent or organic solvent together with a binder, dispersant, plasticizer, etc., and then performing wet grinding. At this time, a bead mill, wet jet mill, various kneaders, high-pressure homogenizer, etc. can be used, and it is preferable to use a bead mill from the viewpoint that particle size distribution adjustment and dispersion can be performed simultaneously. A binder is added to the obtained solid electrolyte slurry to obtain a solid electrolyte paste. A solid electrolyte green sheet 51 can be produced by coating with the obtained solid electrolyte paste. The coating method is not particularly limited, and a slot die method, reverse coating method, gravure coating method, bar coating method, doctor blade method, etc. can be used. The particle size distribution after wet grinding can be measured, for example, using a laser diffraction measuring device using the laser diffraction scattering method.

[0050] (Lamination process) As illustrated in Figure 5(a), an internal electrode paste 52 is printed on one surface of a solid electrolyte green sheet 51. An inverse pattern 53 is printed on the areas of the solid electrolyte green sheet 51 where the internal electrode paste 52 is not printed. The same material as the solid electrolyte green sheet 51 can be used as the inverse pattern 53. Multiple printed solid electrolyte green sheets 51 are stacked alternately with a slight offset. As illustrated in Figure 5(b), a laminate is obtained by pressing a cover sheet 54 onto the top and bottom of the stacking direction. In this case, a laminate with a roughly rectangular parallelepiped shape is obtained such that the internal electrode paste 52 for the first internal electrode 10 is exposed on one end face and the internal electrode paste 52 for the second internal electrode 20 is exposed on the other end face. The cover sheet 54 can be formed by coating the raw material powder for the cover layer using the same method as in the solid electrolyte green sheet manufacturing process. The cover sheet 54 is formed to be thicker than the solid electrolyte green sheet 51. The coating can be made thicker during application, or by layering multiple coated sheets.

[0051] Next, the external electrode paste 55 is applied to each of the two end faces using a dipping method or the like, and then dried. This yields a molded body for forming the all-solid-state battery 100a.

[0052] (Firing process) Next, the resulting laminate is fired. The firing conditions are under an oxidizing or non-oxidizing atmosphere, and the maximum temperature is preferably 400°C to 1000°C, more preferably 500°C to 900°C, but there are no particular limitations. To sufficiently remove the binder before reaching the maximum temperature, a step may be included in which the laminate is held at a temperature lower than the maximum temperature in an oxidizing atmosphere. To reduce process costs, it is desirable to fire at the lowest possible temperature. After firing, a re-oxidation treatment may be performed. Through the above steps, an all-solid-state battery 100a is produced.

[0053] Furthermore, by sequentially layering the internal electrode paste, the current collector paste containing a conductive material, and the internal electrode paste, a current collector layer can be formed within the first internal electrode 10 and the second internal electrode 20. [Examples]

[0054] A solid-state battery was fabricated according to the following embodiment, and its characteristics were investigated.

[0055] (Example 1) Li2CO3, Al2O3, GeO2, NH4H2PO4, and ZrO2 were weighed in molar ratios of Li:Al:Ge:Zr:P = 1.5:0.5:1.45:0.05:3.0, melted in a platinum crucible at 1300°C, and rapidly cooled. The amount of Ge substitution y was 0.05. The resulting solid was a transparent glassy state. When this was pulverized into a powder, pelletized, and fired, the sintering temperature was 10°C higher than that of the unsubstituted material, confirming that it became a solid electrolyte sintered body exhibiting ion conductivity.

[0056] (Example 2) A molten and rapidly cooled solid was obtained in the same manner as in Example 1, except that the molar ratio was Li:Al:Ge:Zr:P = 1.5:0.5:1.4:0.1:3.0. The amount of Ge substitution y was 0.10. The obtained solid was in a transparent glassy state. When this was pulverized into a powder, pelletized, and fired, the sintering temperature was 15°C higher than that of the unsubstituted solid, confirming that it became a solid electrolyte sintered body exhibiting ion conductivity.

[0057] (Example 3) A molten and rapidly cooled solid was obtained in the same manner as in Example 1, except that the molar ratio of Li:Al:Ge:Zr:P was 1.5:0.5:1.3:0.2:3.0. The amount of Ge substitution y was 0.20. The obtained solid was in a transparent glassy state. When this was pulverized into a powder, pelletized, and fired, the sintering temperature was 20°C higher than that of the unsubstituted solid, confirming that it became a solid electrolyte sintered body exhibiting ion conductivity.

[0058] (Comparative Example 1) A molten and rapidly cooled solid was obtained in the same manner as in Example 1, except that the molar ratio was Li:Al:Ge:Zr:P = 1.5:0.5:1.25:0.25:3.0. The amount of Ge substitution y was 0.25. The obtained solid was devitrified and partially crystalline. When this was pulverized into a powder, pelletized, and fired, the sintering temperature was 30°C higher than that of the unsubstituted solid, confirming that the sinterability was insufficient and that it resulted in a solid electrolyte sintered body with low ionic conductivity.

[0059] (Example 4) A molten and rapidly cooled solid was obtained in the same manner as in Example 3, except that ZrO2 was replaced with SnO2. The amount of Ge substitution y was 0.20. The obtained solid was in a transparent glassy state. When this was pulverized into a powder, the sintering temperature was 50°C higher than that of the unsubstituted solid, and when it was pelletized and fired, it was confirmed to become a solid electrolyte sintered body that exhibits ion conductivity.

[0060] (Comparative Example 2) A molten and rapidly cooled solid was obtained in the same manner as in Example 4, except that the molar ratio of Li:Al:Ge:Sn:P was set to 1.5:0.5:1.25:0.25:3.0. The amount of Ge substitution y was 0.25. The obtained solid was devitrified and partially crystalline. When this was pulverized into a powder, pelletized, and fired, the sintering temperature was 60°C higher than that of the unsubstituted solid, confirming that the sinterability was insufficient and that it resulted in a solid electrolyte sintered body with low ionic conductivity.

[0061] (Example 5) A molten and rapidly cooled solid was obtained in the same manner as in Example 3, except that ZrO2 was replaced with TiO2. The amount of Ge substitution y was 0.20. The obtained solid was in a transparent glassy state. When this was pulverized into a powder, the sintering temperature was 20°C higher than that of the unsubstituted solid, and when it was pelletized and fired, it was confirmed to become a solid electrolyte sintered body that exhibits ion conductivity.

[0062] (Comparative Example 3) A molten and rapidly cooled solid was obtained in the same manner as in Example 5, except that the molar ratio was Li:Al:Ge:Ti:P = 1.5:0.5:1.25:0.25:3.0. The amount of Ge substitution y was 0.25. The obtained solid was devitrified and partially crystalline. When this was pulverized into a powder, pelletized, and fired, the sintering temperature was 30°C higher than that of the unsubstituted solid, confirming that the sinterability was insufficient and that it resulted in a solid electrolyte sintered body with low ionic conductivity.

[0063] (Example 6) A molten and rapidly cooled solid was obtained in the same manner as in Example 3, except that ZrO2 was replaced with Co3O4. The amount of Ge substitution y was 0.20. The obtained solid was in a transparent glassy state. When this was pulverized into a powder, the sintering temperature was 20°C lower than that of the unsubstituted solid, and when it was pelletized and fired, it was confirmed to become a solid electrolyte sintered body that exhibits ion conductivity.

[0064] (Example 7) A molten and rapidly cooled solid was obtained in the same manner as in Example 6, except that the molar ratio of Li:Al:Ge:Co:P was 1.5:0.5:1.3:0.4:3.0. The amount of Ge substitution y was 0.40. The obtained solid was in a transparent glassy state. When this was pulverized into a powder, pelletized, and fired, the sintering temperature was 30°C lower than that of the unsubstituted solid, and it was confirmed that it became a solid electrolyte sintered body that exhibits ion conductivity.

[0065] (Comparative Example 4) A molten and rapidly cooled solid was obtained in the same manner as in Example 6, except that the molar ratio of Li:Al:Ge:Co:P was set to 1.5:0.5:1.25:0.5:3.0. The amount of Ge substitution y was 0.50. The obtained solid was devitrified and partially crystalline. When this was pulverized into a powder, pelletized, and fired, the sintering temperature was 30°C lower than that of the unsubstituted solid, confirming that it lacked sinterability and resulted in a solid electrolyte sintered body with low ionic conductivity.

[0066] (Example 8) A molten and rapidly cooled solid was obtained in the same manner as in Example 7, except that ZrO2 was replaced with MgO. The amount of Ge substitution y was 0.40. The obtained solid was in a transparent glassy state. When this was pulverized into a powder, the sintering temperature was 10°C lower than that of the unsubstituted solid, and when it was pelletized and fired, it was confirmed to become a solid electrolyte sintered body that exhibits ion conductivity.

[0067] (Comparative Example 5) A molten and rapidly cooled solid was obtained in the same manner as in Example 8, except that the molar ratio of Li:Al:Ge:Mg:P was set to 1.5:0.5:1.25:0.5:3.0. The amount of Ge substitution y was 0.50. The obtained solid was devitrified and partially crystalline. When this was pulverized into a powder, pelletized, and fired, the sintering temperature was 10°C lower than that of the unsubstituted solid, confirming that it lacked sinterability and resulted in a solid electrolyte sintered body with low ionic conductivity.

[0068] (Example 9) A molten and rapidly cooled solid was obtained in the same manner as in Example 7, except that ZrO2 was replaced with CaO. The amount of Ge substitution y was 0.40. The obtained solid was in a transparent glassy state. When this was pulverized into a powder, pelletized, and fired, the sintering temperature was 5°C lower than that of the unsubstituted solid, and it was confirmed that it became a solid electrolyte sintered body that exhibits ion conductivity.

[0069] (Comparative Example 6) A molten and rapidly cooled solid was obtained in the same manner as in Example 9, except that the molar ratio of Li:Al:Ge:Mg:P was set to 1.5:0.5:1.25:0.5:3.0. The amount of Ge substitution y was 0.50. The obtained solid was devitrified and partially crystalline. When this was pulverized into a powder, pelletized, and fired, the sintering temperature was 10°C lower than that of the unsubstituted solid, confirming that it lacked sinterability and resulted in a solid electrolyte sintered body with low ionic conductivity.

[0070] Table 1 shows the results for Examples 1-9 and Comparative Examples 1-6. The results from Examples 1-5 and Comparative Examples 1-3 indicate that the sintering temperature can be controlled to a higher temperature by substituting a portion of the Ge with a tetravalent metal. However, in Comparative Examples 1-3, vitrification was insufficient, and sufficient ionic conductivity was not obtained. This is thought to be because the amount of Ge substitution y exceeded 0.2. In contrast, in Examples 1-5, sufficient vitrification occurred, and sufficient ionic conductivity was obtained. This is thought to be because the amount of Ge substitution y was 0.2 or less. [Table 1]

[0071] The results from Examples 6-9 and Comparative Examples 4-6 show that the sintering temperature can be controlled to a lower temperature by substituting a portion of the Ge with a divalent metal. However, in Comparative Examples 4-6, vitrification was insufficient, and sufficient ionic conductivity was not obtained. This is thought to be because the amount of Ge substitution y exceeded 0.4. In contrast, in Examples 6-9, sufficient vitrification occurred, and sufficient ionic conductivity was obtained. This is thought to be because the amount of Ge substitution y was 0.4 or less.

[0072] Although embodiments of the present invention have been described in detail above, the present invention is not limited to these specific embodiments, and various modifications and changes are possible within the scope of the gist of the present invention as described in the claims. [Explanation of Symbols]

[0073] 10 1st internal electrode 11. First current collector layer 20 Second internal electrode 21. Second current collector layer 30 Solid electrolyte layer 40a First external electrode 40b 2nd external electrode 50 Cover Layers 51 Solid Electrolyte Green Sheet 52 Paste for internal electrodes 53 Reverse Pattern 54 Cover Sheets 55 Paste for external electrodes 60-layer chip 100,100a all solid state battery

Claims

1. A solid electrolyte layer, A first electrode layer containing an electrode active material is provided on the first main surface of the solid electrolyte layer, The solid electrolyte layer comprises a second electrode layer provided on the second main surface and containing an electrode active material, The solid electrolyte, which is the main component of the solid electrolyte layer, is (Li １＋ｘ＋（４－Ａ）ｙ Al ｘ M ｙ Ge ２－ｘ－ｙ (PO ４ ) ３ It is a solid electrolyte having the structure of glass ceramics in which part of the glass has crystallized, The aforementioned M is at least one of Sn and Ca, A is the valency of M, which is a metal. An all-solid-state battery characterized by the condition 0.2 ≤ A × y ≤ 0.

8.

2. A step of preparing a laminate comprising: a green sheet containing solid electrolyte powder; a paste coating for a first electrode layer containing electrode active material formed on the first main surface of the green sheet; and a paste coating for a second electrode layer containing electrode active material formed on the second main surface of the green sheet; The process includes firing the laminate, The solid electrolyte powder is a glass solid electrolyte having a structure of (Li １＋ｘ＋（４－Ａ）ｙ Al ｘ M ｙ Ge ２－ｘ－ｙ (PO ４ ) ３ ) The aforementioned M is at least one of Sn and Ca, A is the valency of M, which is a metal. A method for manufacturing an all-solid-state battery, characterized in that 0.2 ≤ A × y ≤ 0.

8.

3. A raw material powder containing a solid electrolyte powder, The solid electrolyte powder is (Li １＋ｘ＋（４－Ａ）ｙ Al ｘ M ｙ Ge ２－ｘ－ｙ (PO ４ ) ３ A glass solid electrolyte having the structure of, The aforementioned M is at least one of Sn and Ca, A is the valency of M, which is a metal. A raw material powder characterized by the condition 0.2 ≤ A × y ≤ 0.

8.

4. Using raw materials containing Li, Al, the metal M, Ge, P, and O, by the melt-and-cool method (Li １＋ｘ＋（４－Ａ）ｙ Al ｘ M ｙ Ge ２－ｘ－ｙ (PO ４ ) ３ The process includes a step of producing a glass solid electrolyte having the structure of ), The aforementioned M is at least one of Sn and Ca, A is the valence of M, A method for producing a raw material powder, characterized in that 0.2 ≤ A × y ≤ 0.8.

Images