Positive electrode material for all-solid-state battery and all-solid-state battery

Abstract

To suppress reaction between a positive electrode active material and a solid electrolyte, and to facilitate manufacturing.SOLUTION: A positive electrode material 11 for an all-solid-state battery is a material used as a positive electrode of an all-solid-state battery 1, and includes: a plurality of positive electrode active material grain bodies 14 formed of a positive electrode active material represented by a chemical formula Li2CoP2O7; and a plurality of coating films 15 respectively coating surfaces of the plurality of positive electrode active material grain bodies 14. The plurality of coating films 15 are formed of aluminum phosphate AlPO4 or boron phosphate BPO4.SELECTED DRAWING: Figure 2

Description

Technical Field

[0001] The technology of the present disclosure relates to a positive electrode material for an all-solid-state battery and an all-solid-state battery.

Background Art

[0002] There is known an all-solid-state battery in which a positive electrode material in powder form, in which the surface of particles formed from a positive electrode active material is coated with a coating material formed from a compound Li4P2O7, is used for the positive electrode (Patent Document 1). When such an all-solid-state battery is fired during manufacturing, it is possible to suppress the reaction between the positive electrode active material and the solid electrolyte, and to suppress the reduction of the active material and the generation of heterogeneous phases that do not contribute to charge and discharge.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] When coating a positive electrode active material with the compound Li4P2O7, citric acid is used, and a large amount of bubbles are generated during heat treatment. For this reason, there is a problem that the yield of the positive electrode material may decrease.

[0005] The disclosed technology has been made in view of such points, and an object thereof is to provide a positive electrode material for an all-solid-state battery and an all-solid-state battery that suppress the reaction between a positive electrode active material and a solid electrolyte and are easily manufactured.

Means for Solving the Problems

[0006] An all-solid-state battery according to one aspect of the present disclosure is a positive electrode material for an all-solid-state battery used as a positive electrode of the all-solid-state battery, and has a chemical formula Li2Co 1-x M x P2-y A y Comprising a plurality of particle bodies formed from a positive electrode active material represented by O7, and a plurality of coatings respectively covering the surfaces of the plurality of particle bodies, wherein the element M is at least one metal among titanium Ti, vanadium V, chromium Cr, nickel Ni, and iron Fe, the element A is at least one element among boron B, carbon C, aluminum Al, silicon Si, gallium Ga, and germanium Ge, and the values of x and y satisfy the following equations: 0 ≦ x < 1 0 ≦ y ≦ 0.07 and the plurality of coatings are formed from an inorganic compound containing PO4 in its chemical formula.

Advantages of the Invention

[0007] The disclosed positive electrode material for all-solid-state batteries and all-solid-state batteries can suppress the reaction between the positive electrode active material and the solid electrolyte, and can be easily manufactured.

Brief Description of the Drawings

[0008]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Mode for Carrying Out the Invention

[0009] Hereinafter, a positive electrode material for an all-solid-state battery and an all-solid-state battery according to an embodiment disclosed in the present application will be described with reference to the drawings. Note that the technology of the present disclosure is not limited by the following description. Also, in the following description, the same reference numerals are given to the same components, and duplicate descriptions are omitted.

[0010] As shown in FIG. 1, the all-solid-state battery 1 includes a positive electrode current collector layer 2, a negative electrode current collector layer 3, a solid electrolyte layer 5, a positive electrode layer 6, and a negative electrode layer 7. FIG. 1 is a cross-sectional view showing the schematic structure of the all-solid-state battery 1 of the embodiment. The positive electrode current collector layer 2 is formed of a conductor exemplified by a metal and is formed in a film shape. The negative electrode current collector layer 3 is formed of a conductor exemplified by a metal and is formed in a film shape.

[0011] The solid electrolyte layer 5 contains a solid electrolyte LAGP represented by the following chemical formula. Li 1+x Al x Ge 2-x (PO4)3 The value x satisfies the following equation. 0 < x ≦ 1 The solid electrolyte layer 5 is formed in a film shape. The solid electrolyte layer 5 is disposed between the positive electrode current collector layer 2 and the negative electrode current collector layer 3.

[0012] The positive electrode layer 6 is formed in a film shape. The positive electrode layer 6 is disposed between the positive electrode current collector layer 2 and the solid electrolyte layer 5. One surface of the positive electrode layer 6 is in contact with the positive electrode current collector layer 2, and the other surface of the positive electrode layer 6 is in contact with the solid electrolyte layer 5.

[0013] The negative electrode layer 7 contains a negative electrode active material, a solid electrolyte LAGP, and a conductive assistant. As the negative electrode active material, lithium vanadium phosphate Li3V2(PO4)3, lithium titanate Li4Ti5O 12, titanium dioxide TiO2, niobium pentoxide Nb2O5 are exemplified. The negative electrode layer 7 is formed in a film shape. The negative electrode layer 7 is disposed between the negative electrode side current collector layer 3 and the solid electrolyte layer 5. One surface of the negative electrode layer 7 is in contact with the negative electrode side current collector layer 3, and the other surface of the negative electrode layer 7 is in contact with the solid electrolyte layer 5.

[0014] Figure 2 is a schematic diagram showing the structure of the positive electrode layer 6. The positive electrode layer 6 includes a positive electrode material 11 for all-solid-state batteries and a solid electrolyte powder material 12. The solid electrolyte powder material 12 is formed from the solid electrolyte LAGP and is formed in a powder shape. The positive electrode material 11 for all-solid-state batteries is formed in a powder shape. Each of the plurality of particles forming the positive electrode material 11 for all-solid-state batteries includes a positive electrode active material particle main body 14 and a coating film 15. The positive electrode active material particle main body 14 is formed from a positive electrode active material LCPO represented by the following chemical formula. Li2CoP2O7 The coating film 15 is formed from a coating material which is an inorganic compound containing PO4 in the chemical formula. Examples of the coating material include aluminum phosphate AlPO4 or boron phosphate BPO4. The surface of the positive electrode active material particle main body 14 is covered by the coating film 15. The positive electrode layer 6 further includes a conductive assistant (not shown).

[0015] In the all-solid-state battery 1, since the surface of the cathode active material particle main body 14 is covered by the coating 15, the cathode active material contained in the cathode layer 6 can be prevented from directly contacting the solid electrolyte contained in the cathode layer 6 or the solid electrolyte layer 5. Since the contact between the cathode active material and the solid electrolyte is prevented in the all-solid-state battery 1, the reaction between the cathode active material and the solid electrolyte can be prevented. Since the reaction between the cathode active material and the solid electrolyte is prevented in the all-solid-state battery 1, the reduction of the cathode active material and the solid electrolyte can be prevented, and the generation of heterogeneous phases that do not contribute to the charge and discharge of the all-solid-state battery 1 can be prevented. Since the reduction of the cathode active material and the solid electrolyte is prevented in the all-solid-state battery 1, the reduction of the discharge capacity of the all-solid-state battery 1 can be suppressed. Since the generation of heterogeneous phases that do not contribute to the charge and discharge of the all-solid-state battery 1 is prevented in the all-solid-state battery 1, the increase in the internal resistance can be suppressed.

[0016] [Manufacturing Method of All-Solid-State Battery 1] FIG. 3 is a flowchart showing a manufacturing method for fabricating the all-solid-state battery 1. In the production of the cathode layer material (step s1a), a powder of the cathode active material LCPO, a raw material of the coating material, and water in predetermined amounts are prepared. The coating material is an inorganic phosphate containing PO4 in its chemical formula, for example, aluminum phosphate AlPO4 or boron phosphate BPO4.

[0017] When aluminum phosphate AlPO4 is used as the coating material, aluminum nitrate Al(NO3)3 and ammonium dihydrogen phosphate NH4H2PO4 are prepared as raw materials for the coating material. Aluminum nitrate Al(NO3)3 and ammonium dihydrogen phosphate NH4H2PO4 are added to water and stirred to prepare an aqueous solution in which the raw materials of aluminum phosphate AlPO4 are dissolved. The powder of the positive electrode active material LCPO is added to the aqueous solution in which the raw materials of aluminum phosphate AlPO4 are dissolved to prepare a dispersion. In the dispersion, the raw materials of aluminum phosphate AlPO4 are dissolved and the powder of the positive electrode active material LCPO is dispersed. The dispersion is heat-treated, and aluminum phosphate AlPO4 is synthesized on the surface of the particles of the positive electrode active material LCPO. In the heat treatment, after the dispersion is dried in an atmosphere of 90 °C, it is held at 250 °C for 6 hours in the air atmosphere, put into a crucible, and held at 600 °C for 2 hours in the air atmosphere. By synthesizing aluminum phosphate AlPO4 on the surface of the particles of the positive electrode active material LCPO, a positive electrode material 11 for an all-solid-state battery is produced, which is formed from a plurality of particles whose surfaces of the particles of the positive electrode active material LCPO are coated with aluminum phosphate AlPO4 of the coating material.

[0018] When boron phosphate BPO4 is used as the coating material, boric acid H3BO3 and phosphoric acid H3PO4 are prepared as raw materials for the coating material. Boric acid H3BO3 is added to water and stirred to prepare an aqueous solution in which boric acid H3BO3 is dissolved. To the aqueous solution in which boric acid H3BO3 is dissolved, phosphoric acid H3PO4 is added and stirred to prepare an aqueous solution in which the raw materials of boron phosphate BPO4 are dissolved. Powders of the positive electrode active material LCPO are added to the aqueous solution in which the raw materials of boron phosphate BPO4 are dissolved to prepare a dispersion. In the dispersion, the raw materials of boron phosphate BPO4 are dissolved and the powders of the positive electrode active material LCPO are dispersed. The dispersion is heat-treated, and boron phosphate BPO4 is synthesized on the surface of the particles of the positive electrode active material LCPO. In this heat treatment, the dispersion is dried and heat-treated in an atmosphere of 120°C. By synthesizing boron phosphate BPO4 on the surface of the particles of the positive electrode active material LCPO, a positive electrode material 11 for an all-solid-state battery is produced, which is formed from a plurality of particles whose surfaces of the particles of the positive electrode active material LCPO are coated with boron phosphate BPO4 as the coating material.

[0019] Next, powders of the solid electrolyte LAGP, a binder, a solvent (anhydrous alcohol), and a conductive assistant are prepared. The positive electrode material 11 for an all-solid-state battery and the powders of the solid electrolyte LAGP are mixed at a predetermined mass ratio (for example, 50:50) to prepare a powder for a positive electrode layer. To the powder for a positive electrode layer, a binder, a solvent, and a conductive assistant are added and mixed to prepare a slurry-like positive electrode layer material (step s1a). The slurry-like positive electrode layer material is formed into a sheet shape to produce a plurality of green sheets for a positive electrode layer. The plurality of green sheets for a positive electrode layer are laminated, press-bonded, and adjusted to a predetermined thickness. The laminated and press-bonded green sheets for a positive electrode layer are cut to a predetermined size to produce a positive electrode layer sheet (step s2a).

[0020] In the production of the electrolyte layer material (step s1b), powders of the solid electrolyte LAGP, a binder, a dispersant, a plasticizer, and a non-aqueous solvent are prepared. The powders of the solid electrolyte LAGP are kneaded together with the binder, the dispersant, the plasticizer, and the non-aqueous solvent to prepare a slurry-like electrolyte layer material (step s1b). The slurry-like electrolyte layer material is formed into a sheet shape to produce a plurality of electrolyte layer green sheets. The plurality of electrolyte layer green sheets are laminated, press-bonded, and adjusted to a predetermined thickness. The electrolyte layer green sheet with the adjusted thickness is cut to a predetermined size to produce a solid electrolyte layer sheet (step s2b).

[0021] In the production of the negative electrode layer material (step s1c), powders of the negative electrode active material, powders of the solid electrolyte LAGP, a binder, a solvent (anhydrous alcohol), and a conductive assistant are prepared. The powders of the negative electrode active material and the powders of the solid electrolyte LAGP are mixed at a predetermined mass ratio (for example, 50:50) to prepare a powder for the negative electrode layer. The powder for the negative electrode layer is added with the binder, the solvent, and the conductive assistant and mixed to prepare a slurry-like negative electrode layer material (step s1c). The slurry-like negative electrode layer material is formed into a sheet shape to produce a plurality of negative electrode layer green sheets. The plurality of negative electrode layer green sheets are laminated, press-bonded, and adjusted to a predetermined thickness. The negative electrode layer green sheet with the adjusted thickness is cut to a predetermined size to produce a negative electrode layer sheet (step s2c).

[0022] The solid electrolyte layer sheet, the positive electrode layer sheet, and the negative electrode layer sheet are laminated and press-bonded so that the solid electrolyte layer sheet is sandwiched between the positive electrode layer sheet and the negative electrode layer sheet to produce a laminate (step s3). The laminate is heat-treated at a predetermined temperature to be degreased (step s4). The binder contained in the solid electrolyte layer sheet, the positive electrode layer sheet, and the negative electrode layer sheet is thermally decomposed by this heat treatment.

[0023] The degreased laminate is fired at a predetermined firing temperature to produce a sintered body, which is a laminated electrode body (step s6). Further, the solid electrolyte LAGP contained in the solid electrolyte layer sheet, the positive electrode layer sheet, and the negative electrode layer sheet is sintered by this heat treatment. At this time, the surface of the positive electrode active material particles main body 14 is covered by the coating 15, so that the positive electrode active material is not in direct contact with the solid electrolyte. Since the positive electrode active material is not in direct contact with the solid electrolyte, the positive electrode active material does not react with the solid electrolyte by this heat treatment. Since the positive electrode active material does not react with the solid electrolyte, in this heat treatment, the positive electrode active material and the solid electrolyte are not reduced in weight, and no heterogeneous phase that does not contribute to the charge and discharge of the all-solid-state battery 1 is generated.

[0024] Both sides of the laminated electrode body are coated with a metal foil by sputtering or vapor deposition to produce the all-solid-state battery 1 (step s7). At this time, the metal foil covering the surface on the positive electrode layer sheet side of the laminated electrode body corresponds to the positive electrode side current collector layer 2. The metal foil covering the surface on the negative electrode layer sheet side of the laminated electrode body corresponds to the negative electrode side current collector layer 3. The portion formed from the solid electrolyte layer sheet corresponds to the solid electrolyte layer 5. The portion formed from the positive electrode layer sheet corresponds to the positive electrode layer 6. The portion formed from the negative electrode layer sheet corresponds to the negative electrode layer 7.

[0025] [Positive Electrode Material for All-Solid-State Battery of Comparative Example] The positive electrode material for the all-solid-state battery of the comparative example is formed in a powder form, similar to the above-described positive electrode material 11 for the all-solid-state battery, and the coating 15 of the above-described positive electrode material 11 for the all-solid-state battery is replaced with another coating. The replaced coating is formed from lithium pyrophosphate Li4P2O7. In the synthesis of lithium pyrophosphate Li4P2O7, lithium carbonate Li2CO3, ammonium dihydrogen phosphate NH4H2PO4, citric acid, and water are prepared. In a container, lithium carbonate Li2CO3, ammonium dihydrogen phosphate NH4H2PO4, and citric acid are added to water and mixed. The aqueous solution prepared by the mixing is stirred at 85 °C and gelled. The gelled material is held at 250 °C for 7 hours in an air atmosphere, dried, and a powdery coating material is prepared. The powdery coating material is placed in a crucible, held at 600 °C for 2 hours, and lithium pyrophosphate Li4P2O7 is synthesized. When the gelled material is held at 250 °C for 7 hours in an air atmosphere, it may foam and overflow from the container, and the yield of lithium pyrophosphate Li4P2O7 may decrease.

[0026] When coating the main body 14 of the positive electrode active material particles with a coating formed from lithium pyrophosphate Li4P2O7, the above-described aqueous solution is stirred at 85 °C and gelled after being mixed with the powder of the positive electrode active material. The gelled material is held at 250 °C for 7 hours in an air atmosphere and dried. The dried material is placed in a crucible, held at 600 °C for 2 hours, and the positive electrode material for the all-solid-state battery of the comparative example is prepared. The positive electrode material for the all-solid-state battery of the comparative example may foam and overflow from the container when the gelled material is held at 250 °C for 7 hours in an air atmosphere, and the yield may decrease.

[0027] Since foaming does not occur when the above-described positive electrode material 11 for the all-solid-state battery synthesizes the inorganic phosphate, it is possible to suppress a decrease in the yield, and the yield is larger compared to the positive electrode material for the all-solid-state battery of the comparative example. For this reason, the all-solid-state battery 1 does not need to execute countermeasures against foaming exemplified by using a sufficiently large container and can be easily manufactured.

[0028] To confirm the effects of the all-solid-state battery 1 described above, a plurality of samples have been fabricated. Table 1 shows a plurality of fabrication conditions corresponding to the plurality of samples.

Table 1

[0029] The plurality of samples includes a first sample, a second sample, a third sample, and a fourth sample. The first sample is a 50:50 mixture of aluminum phosphate AlPO4 powder and the cathode active material LCPO powder. The second sample is a 50:50 mixture of aluminum phosphate AlPO4 powder and the solid electrolyte LAGP powder. The third sample is a 50:50 mixture of boron phosphate BPO4 powder and the cathode active material LCPO powder. The fourth sample is a 50:50 mixture of boron phosphate BPO4 powder and the solid electrolyte LAGP powder.

[0030] The plurality of samples has further undergone heat treatment. In the heat treatment, after the plurality of samples are heated at 100 °C per hour in an air atmosphere, the plurality of samples are held at 600 °C for 2 hours in an air atmosphere. After such heat treatment is performed on the plurality of samples, X-ray diffraction measurement is performed. In the X-ray diffraction measurement, a plurality of X-ray diffraction measurement patterns corresponding to the plurality of samples are obtained. The X-ray diffraction measurement pattern shows an approximate continuous function associating the incident angle 2θ (deg) with the intensity (counts), and a plurality of peaks corresponding to the substances contained in the sample on which the X-ray diffraction measurement is performed are formed.

[0031] Figure 4 is a graph showing an X-ray diffraction measurement pattern obtained by performing an X-ray diffraction measurement on a first sample. Curve 20 shows an X-ray diffraction measurement pattern obtained by performing an X-ray diffraction measurement on the first sample. Curve 21 shows an X-ray diffraction measurement pattern obtained by performing an X-ray diffraction measurement on aluminum phosphate AlPO4. Curve 22 shows an X-ray diffraction measurement pattern obtained by performing an X-ray diffraction measurement on the positive electrode active material LCPO.

[0032] Figure 4 shows that peaks corresponding to different incident angles for a plurality of peaks formed in curve 21 and a plurality of peaks formed in curve 22 are not formed in curve 20. That is, Figure 4 shows that the first sample does not contain other substances different from aluminum phosphate AlPO4 and the positive electrode active material LCPO, and shows that aluminum phosphate AlPO4 and the positive electrode active material LCPO do not react by heat treatment.

[0033] Figure 5 is a graph showing an X-ray diffraction measurement pattern obtained by performing an X-ray diffraction measurement on a second sample. Curve 30 shows an X-ray diffraction measurement pattern obtained by performing an X-ray diffraction measurement on the second sample. Curve 31 shows an X-ray diffraction measurement pattern obtained by performing an X-ray diffraction measurement on aluminum phosphate AlPO4. Curve 32 shows an X-ray diffraction measurement pattern obtained by performing an X-ray diffraction measurement on the solid electrolyte LAGP.

[0034] Figure 5 shows that peaks corresponding to different incident angles for a plurality of peaks formed in curve 31 and a plurality of peaks formed in curve 32 are not formed in curve 30. That is, Figure 5 shows that the second sample does not contain other substances different from aluminum phosphate AlPO4 and the solid electrolyte LAGP, and shows that aluminum phosphate AlPO4 and the solid electrolyte LAGP do not react by heat treatment.

[0035] Figure 6 is a graph showing an X-ray diffraction measurement pattern obtained by performing an X-ray diffraction measurement on a third sample. Curve 40 shows the X-ray diffraction measurement pattern obtained by performing an X-ray diffraction measurement on the third sample. Curve 41 shows the X-ray diffraction measurement pattern obtained by performing an X-ray diffraction measurement on boron phosphate BPO4. Curve 42 shows the X-ray diffraction measurement pattern obtained by performing an X-ray diffraction measurement on the positive electrode active material LCPO.

[0036] Figure 6 shows that peaks corresponding to different incident angles for a plurality of peaks formed in curve 41 and a plurality of peaks formed in curve 42 are not formed in curve 40. That is, Figure 6 shows that the third sample does not contain other substances different from boron phosphate BPO4 and the positive electrode active material LCPO, and shows that boron phosphate BPO4 and the positive electrode active material LCPO do not react by heat treatment.

[0037] Figure 7 is a graph showing an X-ray diffraction measurement pattern obtained by performing an X-ray diffraction measurement on a fourth sample. Curve 50 shows the X-ray diffraction measurement pattern obtained by performing an X-ray diffraction measurement on the fourth sample. Curve 51 shows the X-ray diffraction measurement pattern obtained by performing an X-ray diffraction measurement on boron phosphate BPO4. Curve 52 shows the X-ray diffraction measurement pattern obtained by performing an X-ray diffraction measurement on the solid electrolyte LAGP.

[0038] Figure 7 shows that peaks corresponding to different incident angles for a plurality of peaks formed in curve 51 and a plurality of peaks formed in curve 52 are not formed in curve 50. That is, Figure 7 shows that the fourth sample does not contain other substances different from boron phosphate BPO4 and the solid electrolyte LAGP, and shows that boron phosphate BPO4 and the solid electrolyte LAGP do not react by heat treatment.

[0039] That is, FIGS. 4 to 7 show that since the surface of the positive electrode active material particle body 14 is covered with the coating film 15, the positive electrode material 11 for all-solid-state batteries can prevent the positive electrode active material and the solid electrolyte from reacting during the manufacture of the all-solid-state battery 1.

[0040] [Effect of the positive electrode material 11 for all-solid-state batteries of the embodiment] The positive electrode material 11 for all-solid-state batteries of the embodiment is used as the positive electrode of the all-solid-state battery 1. The positive electrode material 11 for all-solid-state batteries of the embodiment includes a plurality of positive electrode active material particle bodies 14 formed from a positive electrode active material LCPO represented by the chemical formula Li2CoP2O7, and a plurality of coating films 15 that respectively cover the surfaces of the plurality of positive electrode active material particle bodies 14. The plurality of coating films 15 are formed from aluminum phosphate AlPO4 or boron phosphate BPO4.

[0041] Even when such a positive electrode material 11 for all-solid-state batteries comes into contact with the solid electrolyte LAGP, the coating film 15 separates the positive electrode active material LCPO and the solid electrolyte LAGP, and it is possible to prevent the positive electrode active material LCPO and the solid electrolyte LAGP from directly contacting each other. Since such a positive electrode material 11 for all-solid-state batteries prevents the direct contact between the positive electrode active material LCPO and the solid electrolyte LAGP, it is possible to prevent the reaction between the positive electrode active material LCPO and the solid electrolyte LAGP. Inorganic phosphate can be easily produced as compared with lithium pyrophosphate Li4P2O7. For this reason, the positive electrode material 11 for all-solid-state batteries can be easily produced as compared with the positive electrode material for all-solid-state batteries of the comparative example in which the positive electrode active material particle body 14 is coated with lithium pyrophosphate Li4P2O7.

[0042] Further, the all-solid-state battery 1 of the embodiment includes a positive electrode layer 6 including the positive electrode material 11 for all-solid-state batteries and the solid electrolyte LAGP, a solid electrolyte layer 5 including the solid electrolyte LAGP, and a negative electrode layer 7 including a negative electrode active material and the solid electrolyte LAGP. The solid electrolyte layer 5 is sandwiched between the positive electrode layer 6 and the negative electrode layer 7. The solid electrolyte LAGP has the chemical formula Li 1+z Alz Ge 2-z It is represented by (PO4)3. Here, the value Z satisfies the following equation. 0 < z ≤ 1 At this time, the all-solid-state battery 1 can prevent the reaction between the positive electrode active material LCPO and the solid electrolyte LAGP, and can be easily manufactured.

[0043] By the way, the positive electrode active material particle main body 14 of the positive electrode layer 6 of the all-solid-state battery 1 described above is formed from the positive electrode active material LCPO, but it can be formed from another positive electrode active material different from the positive electrode active material LCPO. Examples of other positive electrode active materials include compounds represented by the following chemical formula. Li2Co 1-x M x P 2-y A y O7 Here, the element M is at least one metal among titanium Ti, vanadium V, chromium Cr, nickel Ni, and iron Fe. The element A is at least one element among boron B, carbon C, aluminum Al, silicon Si, gallium Ga, and germanium Ge. The value x and the value y satisfy the following equations: 0 ≤ x < 1 0 ≤ y ≤ 0.07 For other all-solid-state batteries in which the positive electrode active material particle main body 14 is formed from such a positive electrode active material, similar to the all-solid-state battery 1 described above, the reaction between the positive electrode active material and the solid electrolyte can be prevented, and the manufacturing can be facilitated.

[0044] By the way, the coating 15 of the positive electrode layer 6 of the all-solid-state battery 1 described above is formed from aluminum phosphate AlPO4 or boron phosphate BPO4, but it can be formed from other inorganic phosphates containing PO4 in the chemical formula. For other all-solid-state batteries in which the coating 15 is formed from such an inorganic phosphate, similar to the all-solid-state battery 1 described above, the reaction between the positive electrode active material and the solid electrolyte can be prevented, and the manufacturing can be facilitated.

[0045] The above describes the embodiments, but the embodiments are not limited by the foregoing content. Further, the foregoing components include those that can be easily assumed by those skilled in the art, those that are substantially the same, and those within the so-called equivalent range. Furthermore, the foregoing components can be combined as appropriate. Still further, at least one of various omissions, substitutions, and changes of the components can be made without departing from the gist of the embodiments.

Description of Reference Numerals

[0046] 1: All-solid-state battery 5: Solid electrolyte layer 6: Positive electrode layer 7: Negative electrode layer 11: Positive electrode material for all-solid-state battery 12: Solid electrolyte powder material 14: Positive electrode active material particle body 15: Coating

Claims

1. A positive electrode material for an all-solid-state battery used as a positive electrode of an all-solid-state battery, Chemical formula Li ２ Co １－ｘ M ｘ P ２－ｙ A ｙ O ７ a plurality of particle bodies formed from a positive electrode active material represented by comprising a plurality of coatings each covering the surface of the plurality of particle bodies, wherein the element M is at least one metal among titanium (Ti), vanadium (V), chromium (Cr), nickel (Ni), and iron (Fe), the element A is at least one element among boron (B), carbon (C), aluminum (Al), silicon (Si), gallium (Ga), and germanium (Ge), the value x and the value y satisfy the following formula: 0 ≤ x < 1 0 ≤ y ≤ 0.07 and The plurality of coatings are formed from an inorganic compound containing PO in its chemical formula ４ ​ a positive electrode material for an all-solid-state battery.

2. The positive electrode active material has a chemical formula Li ２ CoP ２ O ７ represented by The positive electrode material for an all-solid-state battery according to Claim 1.

3. The inorganic compound is aluminum phosphate AlPO ４ is The positive electrode material for an all-solid-state battery according to Claim 1 or Claim 2.

4. The inorganic compound is boron phosphate BPO ４ is The positive electrode material for an all-solid-state battery according to Claim 1 or Claim 2.

5. a positive electrode layer including a positive electrode material for an all-solid-state battery and a solid electrolyte, a solid electrolyte layer including the solid electrolyte, a negative electrode layer including a negative electrode active material and the solid electrolyte, wherein the solid electrolyte layer is sandwiched between the positive electrode layer and the negative electrode layer, the positive electrode material for an all-solid-state battery Chemical formula Li ２ Co １－ｘ M ｘ P ２－ｙ A ｙ O ７ a plurality of particle bodies formed from a positive electrode active material represented by comprises a plurality of coatings each covering the surface of the plurality of particle bodies, the element M is at least one metal among titanium (Ti), vanadium (V), chromium (Cr), nickel (Ni), and iron (Fe), the element A is at least one element among boron (B), carbon (C), aluminum (Al), silicon (Si), gallium (Ga), and germanium (Ge), the value x and the value y satisfy the following formula: 0 ≤ x < 1 0 ≤ y ≤ 0.07 and The plurality of coatings are formed from an inorganic compound containing PO in its chemical formula ４ and The solid electrolyte has the chemical formula Li １＋ｚ Al ｚ Ge ２－ｚ (PO ４ ) ３ and is represented by the value Z satisfies the following formula: 0 < z ≤ 1 and an all-solid-state battery.

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