WO2021251405A1 - 固体電解質材料、固体電解質、これらの製造方法および全固体電池 - Google Patents
固体電解質材料、固体電解質、これらの製造方法および全固体電池 Download PDFInfo
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- WO2021251405A1 WO2021251405A1 PCT/JP2021/021831 JP2021021831W WO2021251405A1 WO 2021251405 A1 WO2021251405 A1 WO 2021251405A1 JP 2021021831 W JP2021021831 W JP 2021021831W WO 2021251405 A1 WO2021251405 A1 WO 2021251405A1
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- H01M10/056—Accumulators with non-aqueous electrolyte characterised by the materials used as electrolytes, e.g. mixed inorganic/organic electrolytes
- H01M10/0561—Accumulators with non-aqueous electrolyte characterised by the materials used as electrolytes, e.g. mixed inorganic/organic electrolytes the electrolyte being constituted of inorganic materials only
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- H01B1/06—Conductors or conductive bodies characterised by the conductive materials; Selection of materials as conductors mainly consisting of other non-metallic substances
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- H01M4/00—Electrodes
- H01M4/02—Electrodes composed of, or comprising, active material
- H01M4/36—Selection of substances as active materials, active masses, active liquids
- H01M4/48—Selection of substances as active materials, active masses, active liquids of inorganic oxides or hydroxides
- H01M4/485—Selection of substances as active materials, active masses, active liquids of inorganic oxides or hydroxides of mixed oxides or hydroxides for inserting or intercalating light metals, e.g. LiTi2O4 or LiTi2OxFy
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- H01M4/00—Electrodes
- H01M4/02—Electrodes composed of, or comprising, active material
- H01M4/36—Selection of substances as active materials, active masses, active liquids
- H01M4/48—Selection of substances as active materials, active masses, active liquids of inorganic oxides or hydroxides
- H01M4/50—Selection of substances as active materials, active masses, active liquids of inorganic oxides or hydroxides of manganese
- H01M4/505—Selection of substances as active materials, active masses, active liquids of inorganic oxides or hydroxides of manganese of mixed oxides or hydroxides containing manganese for inserting or intercalating light metals, e.g. LiMn2O4 or LiMn2OxFy
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- H01M4/02—Electrodes composed of, or comprising, active material
- H01M4/36—Selection of substances as active materials, active masses, active liquids
- H01M4/48—Selection of substances as active materials, active masses, active liquids of inorganic oxides or hydroxides
- H01M4/52—Selection of substances as active materials, active masses, active liquids of inorganic oxides or hydroxides of nickel, cobalt or iron
- H01M4/525—Selection of substances as active materials, active masses, active liquids of inorganic oxides or hydroxides of nickel, cobalt or iron of mixed oxides or hydroxides containing iron, cobalt or nickel for inserting or intercalating light metals, e.g. LiNiO2, LiCoO2 or LiCoOxFy
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- H01M4/36—Selection of substances as active materials, active masses, active liquids
- H01M4/58—Selection of substances as active materials, active masses, active liquids of inorganic compounds other than oxides or hydroxides, e.g. sulfides, selenides, tellurides, halogenides or LiCoFy; of polyanionic structures, e.g. phosphates, silicates or borates
- H01M4/583—Carbonaceous material, e.g. graphite-intercalation compounds or CFx
- H01M4/587—Carbonaceous material, e.g. graphite-intercalation compounds or CFx for inserting or intercalating light metals
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- H01M2300/00—Electrolytes
- H01M2300/0017—Non-aqueous electrolytes
- H01M2300/0065—Solid electrolytes
- H01M2300/0068—Solid electrolytes inorganic
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- H01M2300/0085—Immobilising or gelification of electrolyte
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- Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
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Definitions
- One embodiment of the present invention relates to a solid electrolyte material, a solid electrolyte, a method for producing these, or an all-solid-state battery.
- an inorganic solid electrolyte As the solid electrolyte, an inorganic solid electrolyte has attracted attention, and as the inorganic solid electrolyte, mainly oxide-based and sulfide-based solid electrolytes are known.
- oxide-based and sulfide-based solid electrolytes are known.
- a sulfide-based solid electrolyte When a sulfide-based solid electrolyte is used, there are advantages such as being able to manufacture a battery by cold pressing, but it is unstable with respect to humidity and harmful hydrogen sulfide gas may be generated, so it is safe. Development of oxide-based solid electrolytes is underway in terms of properties and the like.
- Non-Patent Document 1 states that LiTa 2 PO 8 , which has a monoclinic crystal structure, has high lithium ion conductivity (total conductivity (25 ° C.): 2.5 ⁇ . It is described that 10 -4 S ⁇ cm -1) is shown.
- Oxide-based solid electrolytes have extremely high grain boundary resistance, and in order to obtain ionic conductivity that can be used in all-solid-state batteries, not only the solid electrolyte powder is pressure-molded, but also a high-density sintered body is used. There is a need. Then, in order to obtain such a high-density sintered body, it was necessary to fire it at a high temperature of, for example, about 1100 ° C. Further, when manufacturing an all-solid-state battery using an oxide-based solid electrolyte, it is necessary to sintered the battery together with a positive electrode material, a negative electrode material, and the like in order to obtain high ionic conductivity.
- One embodiment of the present invention provides a solid electrolyte material capable of obtaining a sintered body having sufficient ionic conductivity even when fired at a low temperature (eg, 900 ° C. or lower).
- the configuration example of the present invention is as follows.
- the compound (a) is Composition formula Li [ 1+ (5-a) x ] Ta 2-x M1 x PO 8 [M1 is one or more elements selected from the group consisting of Nb, Zr, Ga, Sn, Hf, W and Mo. Yes, 0.0 ⁇ x ⁇ 1.0, and a is the average valence of M1. ], Or the compound represented by Composition formula Li [1 + (5-b) y ] Ta 2 P 1-y M2 y O 8 [M2 is one or more elements selected from the group consisting of Si, Al and Ge, and 0.0 ⁇ y ⁇ 0.7 and b is the average valence of M2. ], The solid electrolyte material according to any one of [1] to [3].
- the boron compounds are LiBO 2 , LiB 3 O 5 , Li 2 B 4 O 7 , Li 3 B 11 O 18 , Li 3 BO 3 , Li 3 B 7 O 12 , Li 3.6 B 2 O 4.8 , Li. 3.2 B 2 O 4.6 , Li 4 B 2 O 5 , Li 6 B 4 O 9 , Li 3-x5 B 1-x5 C x5 O 3 (0 ⁇ x5 ⁇ 1), Li 4-x6 B 2-x6 C x6 It is at least one compound selected from the group consisting of O 5 (0 ⁇ x6 ⁇ 2), Li 2.4 Al 0.2 BO 3 , Li 2.7 Al 0.1 BO 3 , B 2 O 3 , and H 3 BO 3. 1]
- the solid electrolyte material according to any one of [8].
- the bismuth compound is at least one compound selected from the group consisting of LiBiO 2 , Li 3 BiO 3 , Li 4 Bi 2 O 5 , Li 2.4 Al 0.2 BiO 3 , and Bi 2 O 3.
- the solid electrolyte material according to any one of [1] to [9].
- a method for producing a solid electrolyte which comprises step 2 of firing the solid electrolyte material obtained in step 1.
- a positive electrode having a positive electrode active material and a positive electrode Negative electrode with negative electrode active material and negative electrode A solid electrolyte layer between the positive electrode and the negative electrode, Including The solid electrolyte layer comprises the solid electrolyte according to [14] or [15]. All-solid-state battery.
- the positive electrode active material is LiM3PO 4 [M3 is one or more elements selected from the group consisting of Mn, Co, Ni, Fe, Al, Ti and V, or two elements V and O. ], LiM5VO 4 [M5 is one or more elements selected from the group consisting of Fe, Mn, Co, Ni, Al and Ti. ], Li 2 M6P 2 O 7 [M6 is one or more elements selected from the group consisting of Fe, Mn, Co, Ni, Al, Ti and V, or two elements of V and O.
- M7 is Ti, Ge, Al, Ga and Zr. It is one or more elements selected from the group consisting of. ], Li 1 + x8 Al x8 M8 2-x8 (PO 4 ) 3 [0 ⁇ x8 ⁇ 0.8, M8 is one or more elements selected from the group consisting of Ti and Ge.
- the negative electrode active material is LiM3PO 4 [M3 is one or more elements selected from the group consisting of Mn, Co, Ni, Fe, Al, Ti and V, or two elements V and O. ], LiM5VO 4 [M5 is one or more elements selected from the group consisting of Fe, Mn, Co, Ni, Al and Ti. ], Li 2 M6P 2 O 7 [M6 is one or more elements selected from the group consisting of Fe, Mn, Co, Ni, Al, Ti and V, or two elements of V and O.
- M7 is Ti, Ge, Al, Ga and Zr. It is one or more elements selected from the group consisting of. ], Li 1 + x8 Al x8 M8 2-x8 (PO 4 ) 3 [0 ⁇ x8 ⁇ 0.8, M8 is one or more elements selected from the group consisting of Ti and Ge.
- M9 is, Mg, Al, be one or more elements selected from the group consisting of Ga and Zn
- M10 is one or more elements selected from the group consisting of Zn, Al, Ga, Si, Ge, P and Ti
- a9 are M9.
- Is the average valence of, and b9 is the average valence of M10.
- a sintered body having sufficient ionic conductivity, particularly sufficient lithium ion conductivity can be obtained even when fired at a low temperature (eg, 900 ° C. or lower). Therefore, by using the solid electrolyte material according to the embodiment of the present invention, it is excellent in economic efficiency, and a solid having sufficient ionic conductivity while suppressing decomposition and alteration of other materials such as positive electrode and negative electrode materials. An all-solid-state battery containing an electrolyte can be easily produced.
- FIG. 1 It is an XRD figure of LiTa 2 PO 8 synthesized in synthesis example 1.
- FIG. It is an XRD figure of Si-containing LTPO synthesized in synthesis example 2.
- FIG. It is an XRD figure of the Nb-containing LTPO synthesized in the synthesis example 3.
- FIG. It is an XRD figure of the solid electrolyte material produced in Example 1.
- the solid electrolyte material (hereinafter, also referred to as “the present material”) according to the embodiment of the present invention includes a lithium ion conductive compound (a) containing lithium, tantalum, phosphorus and oxygen as constituent elements, a boron compound and a bismuth compound. And at least one compound (b) selected from the phosphorus compound [however, the compound (b) is a compound different from the compound (a). ] And is included.
- the present material is not particularly limited as long as the compound (a) and the compound (b) are included, but can be produced, for example, by a method including a step of mixing the compound (a) and the compound (b).
- the compound (a) and the compound (b) are manufactured by a method including a step of pulverizing and mixing the compound (a) and the compound (b) from the viewpoint that the solid electrolyte having higher ionic conductivity can be easily obtained when the solid electrolyte is obtained from the compound (a). Is preferable.
- the present material obtained by pulverizing and mixing the compound (a) and the compound (b) contains the compound (a) and the compound (b), but in this case, Even so, the present material obtained by pulverizing and mixing compound (a) and compound (b) is said to contain compound (a) and compound (b).
- the present material is preferably amorphous.
- the amorphousness of this material can be determined, for example, by the fact that no peak is observed (a broad peak is observed) in an X-ray diffraction (XRD) figure. Since the present material is amorphous, the solid electrolyte obtained from the present material, particularly the solid electrolyte (sintered body) obtained by firing the present material, tends to exhibit higher ionic conductivity.
- the shape, size, etc. of the present material are not particularly limited, but are preferably in the form of particles (powder), and the average particle size (D50) of the present material, particularly the present material obtained by pulverizing and mixing, is preferable. Is 0.1 to 10 ⁇ m, more preferably 0.1 to 5 ⁇ m. When the average particle size of the present material is within the above range, the solid electrolyte obtained from the present material, particularly the solid electrolyte (sintered body) obtained by firing the present material, tends to exhibit higher ionic conductivity. It is in.
- the content of the lithium element in this material is preferably 5.0 to 20.0 atomic%, more preferably 9.0, from the viewpoint that a solid electrolyte having higher lithium ion conductivity can be easily obtained. It is ⁇ 15.0 atomic%.
- the content of the lithium element in the present material is the lithium element derived from the compound (a), and when a compound containing the lithium element is used as the compound (b), the lithium element derived from the compound (b) is used. Includes both. The same applies to the content of other elements in this material.
- each element in this material for example, a standard powder sample containing Mn, Co, and Ni in a ratio of 1: 1: 1 as a lithium-containing transition metal oxide such as LiCoO 2 is used.
- Auger electron spectroscopy (AES) can be measured by the absolute intensity quantification method.
- AES Auger electron spectroscopy
- it can be obtained by a conventionally known quantitative analysis.
- an acid can be added to a sample for thermal decomposition, the thermal decomposition product is defined, and the content of each element in the present material can be determined using a high frequency inductively coupled plasma (ICP) emission spectrometer.
- ICP inductively coupled plasma
- the content of the phosphorus element in this material is preferably 5.3 to 8.3 atomic%, more preferably 5.8, from the viewpoint that a solid electrolyte having higher lithium ion conductivity can be easily obtained. It is ⁇ 8.0 atomic%.
- the content of the tantalum element in this material is preferably 10.6 to 16.6 atomic%, more preferably 11.0, from the viewpoint that a solid electrolyte having higher lithium ion conductivity can be easily obtained. It is ⁇ 16.0 atomic%.
- the content of the boron element in this material is preferably 0.1 from the viewpoint that the firing temperature for obtaining a sintered body having sufficient ionic conductivity can be further lowered. It is ⁇ 5.0 atomic%, more preferably 0.5 to 3.0 atomic%.
- the content of bismuth element in this material is preferably 0.1 from the viewpoint that the firing temperature for obtaining a sintered body having sufficient ionic conductivity can be further lowered. It is about 5.0 atomic%, more preferably 0.1 to 2.0 atomic%.
- the present material may contain the metal element M1 [one or more elements selected from the group consisting of Nb, Zr, Ga, Sn, Hf, W and Mo], in which case the M1 element in the present material.
- the content is preferably 0.1 to 5.0 atomic%, more preferably 0.5 to 3.0 atomic%, from the viewpoint that a solid electrolyte having higher lithium ion conductivity can be easily obtained. be.
- the material may contain the metal element M2 [M2 is one or more elements selected from the group consisting of Si, Al and Ge], in which case the content of the M2 element in the material is lithium. It is preferably 0.1 to 5.0 atomic%, more preferably 0.5 to 3.0 atomic%, from the viewpoint that a solid electrolyte having higher ionic conductivity can be easily obtained.
- the compound (a) is a lithium ion conductive compound containing lithium, tantalum, phosphorus and oxygen as constituent elements, and is preferably an oxide containing these elements.
- the compound (a) contained in this material may be one kind or two or more kinds.
- the compound (a) before pulverization and mixing is preferably a compound having a monoclinic structure.
- the fact that compound (a) has a monoclinic structure is determined, for example, by Rietveld analysis of the X-ray diffraction (XRD) figure of compound (a), specifically by the method of the following example. be able to.
- XRD X-ray diffraction
- compound (a) is a compound having a monoclinic structure rather than a garnet-type, perovskite-type, or LISION-type structure, it can be used together with compound (b) at a low temperature (eg, 900 ° C. or lower). Even after firing, a sintered body having sufficient ionic conductivity can be obtained.
- the monoclinic structure in the present specification may include orthorhombic crystals having an ⁇ angle of 90 °.
- LiTa 2 PO 8 having a monoclinic structure has lattice constants a, b, and c of 9.712 ⁇ , 11.532 ⁇ , and 10.695 ⁇ , respectively, and an angle of ⁇ of 90.03 °, which is theoretical.
- the density is 5.85 (g / cm 3 ).
- the upper limit is not particularly limited, but is 100%.
- the compound (a) specifically contains lithium, tantalum, phosphorus and oxygen as constituent elements, and is one or more metals selected from the group consisting of Nb, Zr, Ga, Sn, Hf, W and Mo. It contains a compound (a1) which may contain the element M1 as a constituent element, lithium, tantalum, phosphorus and oxygen, and further contains one or more metal elements M2 selected from the group consisting of Si, Al and Ge.
- a good compound (a2) and the like can be mentioned.
- the compound (a) is preferably a compound containing only lithium, tantalum, phosphorus and oxygen as constituent elements, and LiTa 2 PO 8 is more preferable. ..
- the compound (a1) is preferably a compound in which LiTa 2 PO 8 or a part of Ta of LiTa 2 PO 8 is substituted with the metal element M1, and preferably has a monoclinic structure.
- the compound (a1) is specifically composed of the composition formula Li [ 1+ (5-a) x ] Ta 2-x M1 x PO 8 [M1 is derived from Nb, Zr, Ga, Sn, Hf, W and Mo. It is one or more elements selected from the group, 0.0 ⁇ x ⁇ 1.0, and a is the average valence of M1. ] Is preferable.
- Nb, W and Mo are more preferable, Nb and W are more preferable, and Nb is more preferable, from the viewpoint of increasing the lithium ion conductivity at the crystal grain boundaries and the like. Especially preferable.
- the x is preferably 0.95 or less, more preferably 0.90 or less, still more preferably 0.85 or less, still more preferably 0.80 or less, and particularly preferably 0.75 or less.
- x is in the above range, the lithium ion conductivity at the grain boundaries tends to be high in the solid electrolyte obtained by using the compound (a).
- the content of M1 can be determined by a conventionally known quantitative analysis as a percentage of the number of atoms of M1 with respect to the total number of atoms of tantalum and M1. For example, after adding an acid to compound (a) and thermally decomposing it, the pyrolyzed product can be determined and determined using a high frequency inductively coupled plasma (ICP) emission spectrometer.
- ICP inductively coupled plasma
- the percentage of the number of atoms of M1 to the total number of atoms of tantalum and M1 can be simply calculated from the amount of raw materials charged. Can be calculated.
- the amount of Li varies according to the average valence of M1 so that the charge neutrality of the compound (a) described above can be obtained.
- the average valence of M1 represented by a can be obtained as follows.
- the compound (a2) is preferably a compound in which LiTa 2 PO 8 or a part of P of LiTa 2 PO 8 is substituted with the metal element M2, and preferably has a monoclinic structure.
- the compound (a2) is specifically composed of the composition formula Li [1 + (5-b) y ] Ta 2 P 1-y M2 y O 8 [M2 is selected from the group consisting of Si, Al and Ge1. It is an element of species or more, 0.0 ⁇ y ⁇ 0.7, and b is the average valence of M2. ] Is preferable.
- Si and Al are more preferable, and Si is further preferable, from the viewpoint of increasing the lithium ion conductivity at the crystal grain boundaries.
- the y is preferably 0.65 or less, more preferably 0.60 or less, still more preferably 0.55 or less.
- the total ion conductivity which is the total of the lithium ion conductivity in the crystal grains and at the crystal grain boundaries, tends to be high.
- the content of M2 can be determined by a conventionally known quantitative analysis as a percentage of the number of atoms of M2 with respect to the total number of atoms of phosphorus and M2.
- the pyrolyzed product can be determined and determined using a high frequency inductively coupled plasma (ICP) emission spectrometer.
- ICP inductively coupled plasma
- phosphorus and M2 do not flow out of the system, so the percentage of the number of atoms of M2 to the total number of atoms of phosphorus and M2 is simply calculated from the amount of raw materials charged. Can be done.
- the average valence represented by b can be obtained in the same manner as the calculation method of the average valence a described above.
- the method for producing the compound (a) is not particularly limited, and for example, a conventionally known production method such as a solid phase reaction or a liquid phase reaction can be adopted. Specific examples of the manufacturing method include a method including at least one step of mixing step and firing step.
- a compound containing a lithium atom, a compound containing a tantalum atom, a compound containing a phosphorus atom, and, if necessary, a compound containing the metal element M1 and / or a metal, which are raw materials, are used.
- a compound containing the metal element M1 and / or a metal, which are raw materials are used.
- examples thereof include a step of mixing a compound containing the element M2.
- the compound containing a lithium atom is not particularly limited, but an inorganic compound is preferable from the viewpoint of ease of handling, and examples of the inorganic compound containing a lithium atom include lithium carbonate (Li 2 CO 3 ) and lithium oxide (Li 2 O). ), Lithium hydroxide (LiOH), lithium acetate (LiCH 3 COO) and hydrates thereof. Among these, lithium carbonate is preferable because it is easily decomposed and reacted.
- the compound containing a lithium atom one kind may be used, or two or more kinds may be used.
- the compound containing tantalum atom is not particularly limited, but an inorganic compound is preferable from the viewpoint of ease of handling, and examples of the inorganic compound containing tantalum atom include tantalum pentoxide (Ta 2 O 5 ) and tantalum nitrate (Ta (Ta (Ta)). NO 3 ) 5 ) can be mentioned. Among these, tantalum pentoxide is preferable from the viewpoint of cost. As the compound containing a tantalum atom, one kind may be used, or two or more kinds may be used.
- the compound containing a phosphorus atom is not particularly limited, but a phosphate is preferable, and the phosphate is easily decomposed and reacted. Therefore, for example, diammonium hydrogen phosphate ((NH 4 ) 2 HPO 4 ) and phosphorus. Diammonium dihydrogen acid (NH 4 H 2 PO 4 ) can be mentioned.
- the compound containing a phosphorus atom one kind may be used, or two or more kinds may be used.
- the compound containing the metal element M1 is not particularly limited, but an inorganic compound is preferable from the viewpoint of ease of handling, and examples thereof include oxides and nitrates of M1. Among these, oxides are preferable from the viewpoint of cost.
- the compound containing the metal element M1 one kind may be used, or two or more kinds may be used.
- examples of the oxide include niobium pentoxide (Nb 2 O 5 ), gallium oxide (Ga 2 O 3 ), tin oxide (SnO 2 ) and the like, respectively.
- examples of the oxide include zirconium oxide (ZrO 2 ), hafnium oxide (HfO 2 ), tungsten oxide (WO 3 ), molybdenum oxide (MoO 3 ) and the like, respectively. Will be.
- Tungous acid (H 2 WO 4 ) and molybdenum acid (H 2 MoO 4 ) can also be used.
- the compound containing the metal element M2 is not particularly limited, but an inorganic compound is preferable from the viewpoint of ease of handling, and examples thereof include simple substances of M2 and oxides. Among these, oxides are preferable from the viewpoint of ease of handling.
- the compound containing the metal element M2 one kind may be used, or two or more kinds may be used.
- examples of the oxide include silicon oxide (SiO 2 ), germanium oxide (GeO 2 ), aluminum oxide (Al 2 O 3 ) and the like, respectively.
- a method of mixing the raw materials for example, a method of mixing using a roll rolling mill, a ball mill, a small diameter ball mill (bead mill), a medium stirring mill, an air flow crusher, a mortar, an automatic kneading mortar, a tank mortar, a jet mill, or the like. Can be mentioned.
- the mixing ratio of the raw materials may be, for example, a stoichiometric ratio so as to obtain a desired composition of the compound (a).
- the compound containing the lithium atoms may be used in excess of about 10 to 20%.
- the compound containing a phosphorus atom may be excessively used by about 0.1 to 10%.
- the mixing may be carried out in the atmosphere, but is preferably carried out in an atmosphere of nitrogen gas and / or argon gas having an oxygen gas content adjusted in the range of 0 to 20% by volume.
- the firing step the mixture obtained in the mixing step is fired.
- a crushing step using a ball mill, a mortar or the like may be provided for the purpose of crushing or reducing the particle size of the baked product obtained in the baking step.
- a reaction intermediate may be present in the first firing. In this case, it is preferable to perform the first firing, perform the pulverization step, and then further perform the firing step.
- the firing step may be performed in the atmosphere, but it is preferably performed in the atmosphere of nitrogen gas and / or argon gas in which the oxygen gas content is adjusted in the range of 0 to 20% by volume.
- the firing temperature is preferably 800 to 1200 ° C, more preferably 950 to 1100 ° C, and even more preferably 950 to 1000 ° C, although it depends on the firing time.
- the calcination temperature is within the above range, lithium atoms are less likely to flow out of the system, and the compound (a) having high ionic conductivity tends to be easily obtained.
- the firing time (total firing time when the firing step is performed several times) is preferably 1 to 16 hours, more preferably 3 to 12 hours, although it depends on the firing temperature.
- the firing time is within the above range, lithium atoms are less likely to flow out of the system, and the compound (a) having high ionic conductivity tends to be easily obtained.
- the firing step may be, for example, a two-step step of low-temperature firing and high-temperature firing.
- examples of the low-temperature firing include firing at 400 to 800 ° C. for 2 to 12 hours.
- high-temperature firing may be performed twice.
- the firing temperature in the second firing step is preferably 800 to 1200 ° C, more preferably 950 to 1100 ° C, and even more preferably 950 to 1000 ° C.
- the firing time in each firing step is preferably 1 to 8 hours, more preferably 2 to 6 hours.
- the fired product obtained after the firing process is left in the atmosphere, it may absorb moisture or react with carbon dioxide to deteriorate. Therefore, it is preferable that the calcined product obtained after the calcining step is transferred to a dehumidified inert gas atmosphere and stored when the temperature drops to 200 ° C. or lower after the calcining step.
- the compound (b) is at least one compound selected from a boron compound, a bismuth compound and a phosphorus compound. Among these, a boron compound is preferable from the viewpoint that the effect of the present invention is more exhibited.
- the compound (b) is a compound different from the compound (a).
- the compound (b) contained in this material may be one kind or two or more kinds.
- the compound (b) is preferably an inorganic compound, more preferably a compound containing lithium or hydrogen as a constituent element, and further preferably a composite oxide containing lithium as a constituent element.
- the compound (b) may be produced and obtained by a conventionally known method, or a commercially available product may be used.
- the compound (b) before pulverization and mixing is preferably a crystalline compound.
- the fact that compound (b) is a crystalline compound can be determined, for example, from the X-ray diffraction (XRD) figure of compound (b).
- Examples of the boron compound include LiBO 2 , LiB 3 O 5 , Li 2 B 4 O 7 , Li 3 B 11 O 18 , Li 3 BO 3 , Li 3 B 7 O 12 , Li 3.6 B 2 O 4.8 , and Li 3.2.
- Li 3 BO 3 , Li 3.6 B 2 O 4.8 , Li 3.2 B 2 O 4.6 , Li 4 can be used to lower the firing temperature when obtaining a sintered body with sufficient ionic conductivity.
- B 2 O 5, LiBO 2, LiB 3 O 5, Li 3 BO 3, Li 4 B 2 O 5 is more preferable.
- Examples of the bismuth compound include LiBiO 2 , Li 3 BiO 3 , Li 4 Bi 2 O 5 , Li 2.4 Al 0.2 BiO 3 , and Bi 2 O 3 .
- LiBiO 2 and Li 3 BiO 3 are preferable, and LiBiO 2 is more preferable, from the viewpoint that the firing temperature for obtaining a sintered body having sufficient ionic conductivity can be further lowered.
- Examples of the phosphorus compound include LiPO 3 and Li 3 PO 4 .
- LiPO 3 is preferable from the viewpoint that the firing temperature for obtaining a sintered body having sufficient ionic conductivity can be further lowered.
- the method for producing the compound (b) is not particularly limited, and for example, a conventionally known production method such as a solid phase reaction or a liquid phase reaction can be adopted. Specific examples of the manufacturing method include a method including a mixing step and a firing step. A commercially available product may be used as the compound (b).
- the mixing step for example, in the case of producing a composite oxide containing lithium as a constituent element, a compound containing a lithium atom, a compound containing a boron atom, a compound containing a bismuth atom, or a compound containing a bismuth atom, which is a raw material, or Mix with a compound containing a phosphorus atom.
- this mixing step may not be performed.
- the compound containing a lithium atom is not particularly limited, but an inorganic compound is preferable from the viewpoint of ease of handling, and examples of the inorganic compound containing a lithium atom include lithium carbonate (Li 2 CO 3 ) and lithium oxide (Li 2 O). ), Lithium hydroxide (LiOH), lithium acetate (LiCH 3 COO) and hydrates thereof. Among these, lithium carbonate is preferable because it is easily decomposed and reacted. It is also preferable to use lithium hydroxide monohydrate (LiOH ⁇ H 2 O). As the compound containing a lithium atom, one kind may be used, or two or more kinds may be used.
- the compound containing a boron atom is not particularly limited, but an inorganic compound is preferable from the viewpoint of ease of handling, and examples of the inorganic compound containing a boron atom include boric acid (H 3 BO 3 ) and boron oxide (B 2 O). 3 ) can be mentioned. Among these, boric acid is preferable. As the compound containing a boron atom, one kind may be used, or two or more kinds may be used.
- the compound containing a bismuth atom is not particularly limited, but an inorganic compound is preferable from the viewpoint of ease of handling, and examples of the inorganic compound containing a bismuth atom include bismuth oxide and bismuth nitrate (Bi (NO 3 ) 3 ). Be done. Among these, bismuth oxide is preferable. As the compound containing a bismuth atom, one kind may be used, or two or more kinds may be used.
- the compound containing a phosphorus atom is not particularly limited, but a phosphate is preferable, and the phosphate is easily decomposed and reacted. Therefore, for example, diammonium hydrogen phosphate ((NH 4 ) 2 HPO 4 ) and phosphorus. Diammonium dihydrogen acid (NH 4 H 2 PO 4 ) can be mentioned.
- the compound containing a phosphorus atom one kind may be used, or two or more kinds may be used.
- a method of mixing the raw materials for example, a method of mixing using a roll rolling mill, a ball mill, a small diameter ball mill (bead mill), a medium stirring mill, an air flow crusher, a mortar, an automatic kneading mortar, a tank mortar, a jet mill, or the like. Can be mentioned.
- the mixing ratio of the raw materials may be, for example, a stoichiometric ratio so as to obtain a desired composition of the compound (b).
- the compound containing the lithium atoms may be used in excess of about 10 to 20%.
- the compound may be used in excess of about 0.1 to 10%.
- the mixing may be carried out in the atmosphere, but is preferably carried out in an atmosphere of nitrogen gas and / or argon gas having an oxygen gas content adjusted in the range of 0 to 20% by volume.
- the firing step the mixture obtained in the mixing step is fired.
- a crushing step using a ball mill, a mortar or the like may be provided for the purpose of crushing or reducing the particle size of the baked product obtained in the baking step.
- the firing step may be performed in the atmosphere, but it is preferably performed in the atmosphere of nitrogen gas and / or argon gas in which the oxygen gas content is adjusted in the range of 0 to 20% by volume.
- the firing temperature is preferably 400 to 1000 ° C, more preferably 500 to 900 ° C, although it depends on the firing time. When the firing temperature is within the above range, lithium atoms are less likely to flow out of the system, and the desired compound (b) tends to be easily obtained.
- the firing time (total firing time when the firing step is performed several times) is preferably 1 to 48 hours, more preferably 3 to 24 hours, although it depends on the firing temperature.
- the firing time is within the above range, the lithium atom does not easily flow out of the system, and the desired compound (b) tends to be easily obtained.
- the fired product obtained after the firing process is left in the atmosphere, it may absorb moisture or react with carbon dioxide to deteriorate. Therefore, it is preferable that the calcined product obtained after the calcining step is transferred to a dehumidified inert gas atmosphere and stored when the temperature drops to 200 ° C. or lower after the calcining step.
- the content of the compound (b) in the present material is 100 mol in total of the compounds (a) and (b) from the viewpoint that the firing temperature for obtaining a sintered body having sufficient ionic conductivity can be further lowered. It is preferably 1 to 40 mol%, more preferably 3 to 30 mol%, still more preferably 5 to 20 mol% with respect to%.
- the present material is not particularly limited as long as it contains the compound (a) and the compound (b), and may contain components other than the compounds (a) and (b).
- the other components include conventionally known materials used for solid electrolytes of all-solid-state batteries, for example, lithium ion conductive compounds other than compound (a), sintering aids other than compound (b), and oxidation.
- Aluminum (Al 2 O 3 ) can be mentioned.
- As each of the other components one kind may be used, or two or more kinds may be used.
- the content of the other components in the present material is preferably 40 mol% or less, more preferably 30 mol% or less, based on 100 mol% of the total of the compounds (a) and (b). It is preferable that the other components are not contained.
- the present material can be produced, for example, by a method including a step of mixing the compound (a) and the compound (b), and when a solid electrolyte is obtained from the present material, a solid electrolyte exhibiting higher ionic conductivity can be produced. From the viewpoint that it can be easily obtained, it is preferable to produce it by a method including a step of pulverizing and mixing the compound (a) and the compound (b). Further, when the compound (a) and the compound (b) are pulverized and mixed, the obtained material becomes amorphous by a mechanochemical reaction and / or the average particle size of the material is within the above range. It is preferable to grind and mix so as to be.
- the compound (a) and the compound (b) for example, a roll rolling mill, a ball mill, a small diameter ball mill (bead mill), a medium stirring mill, an air flow crusher, a mortar, an automatic kneading mortar, a tank mortar, and the like.
- a method of mixing using a jet mill or the like can be mentioned.
- the compound (a) and the compound (b) can be pulverized and mixed, and when a solid electrolyte is obtained from this material, a solid electrolyte having higher ionic conductivity can be easily obtained.
- a method of pulverizing and mixing using a ball mill or a bead mill is preferable, and a method of pulverizing and mixing with a ball mill using balls having a diameter of 0.1 to 10 mm is more preferable.
- the mixing ratio of the compound (a) and the compound (b) is preferably such that the content of the compound (b) is within the above range.
- the compound (a) and the compound (b) can be uniformly pulverized and mixed, and the material which is amorphous and has an average particle diameter (D50) in the above range can be easily pulverized and mixed. It is preferably 1 to 12 hours, more preferably 2 to 12 hours from the viewpoint of being able to be obtained.
- the pulverization and mixing may be performed while heating if necessary, but it is usually carried out at room temperature. Further, the pulverization and mixing may be carried out in the atmosphere, but it is preferably carried out in an atmosphere of nitrogen gas and / or argon gas in which the oxygen gas content is adjusted in the range of 0 to 20% by volume.
- the solid electrolyte according to one embodiment of the present invention (hereinafter, also referred to as “the present electrolyte”) is preferably a sintered body of the present material obtained by using the present material and obtained by firing the present material. ..
- the present electrolyte preferably has a monoclinic structure.
- the fact that the solid electrolyte has a monoclinic structure can be determined, for example, by Rietveld analysis of the X-ray diffraction (XRD) figure of the solid electrolyte, specifically by the method of the following embodiment.
- the upper limit is not particularly limited, but is 100%. When the simple crystal ratio of this electrolyte is in the above range, it tends to be a solid electrolyte having high ionic conductivity both in the crystal grains and at the grain boundaries.
- the relative density of the present electrolyte is preferably 60 to 100%, more preferably 80 to 100%, from the viewpoint that a solid electrolyte having higher ionic conductivity can be easily obtained.
- the relative density is measured by the following method. The mass of the produced solid electrolyte is measured using an electronic balance. Next, the volume is measured from the actual size of the solid electrolyte using a micrometer. By dividing the measured mass by the volume, the density (measured value) of the solid electrolyte can be calculated, and the relative density (%) can be obtained from the ratio between the theoretical value of the density of the solid electrolyte and the measured value.
- the theoretical density of the solid electrolyte is specifically calculated by weight averaging using the theoretical density of the crystal structure constituting the solid electrolyte and the content of the crystal structure. For example, when the solid electrolyte has a crystal structure 1 having a content of h% and a crystal structure 2 having a content of k%, it can be calculated by (theoretical density of crystal structure 1 ⁇ h + theoretical density of crystal structure 2 ⁇ k) / 100. ..
- the content of each crystal structure can be determined by Rietveld analysis.
- the total ionic conductivity of the sintered body of this material obtained by firing this material at 850 ° C. or higher and 900 ° C. or lower is preferably 2.00 ⁇ 10 -4 S ⁇ cm -1 or higher, more preferably 3.00. ⁇ 10 -4 S ⁇ cm -1 or more.
- the total ionic conductivity of the sintered body of this material obtained by firing this material at 750 ° C. or higher and lower than 850 ° C. is preferably 2.00 ⁇ 10 -5 S ⁇ cm -1 or higher, more preferably 4.00. ⁇ 10 -5 S ⁇ cm -1 or more.
- the total ionic conductivity of the sintered body of this material obtained by firing this material at 650 ° C or higher and lower than 700 ° C is preferably 1.00 ⁇ 10 -6 S ⁇ cm -1 or higher, more preferably 2.00. ⁇ 10 -6 S ⁇ cm -1 or more.
- the total ionic conductivity is within the above range, it can be said that the sintered body obtained by firing the present material at a low temperature has sufficient ionic conductivity.
- the total ionic conductivity can be measured by the method described in the following Examples.
- the method for producing a solid electrolyte (method for producing the present electrolyte) according to the embodiment of the present invention preferably includes a step A for firing the present material, and after molding the present material, the material is fired and then fired to obtain a sintered body. Is more preferable.
- the firing temperature in the step A is preferably 500 to 900 ° C, more preferably 600 to 900 ° C, and even more preferably 650 to 900 ° C. Since this material is used, a sintered body having sufficient ionic conductivity can be obtained even when fired at such a low temperature.
- the firing time in the step A is preferably 12 to 144 hours, more preferably 48 to 96 hours, although it depends on the firing temperature.
- the firing time is within the above range, a sintered body having sufficient ionic conductivity can be obtained even when fired at a low temperature.
- the firing in the step A may be carried out in the atmosphere, but it is preferably carried out in the atmosphere of nitrogen gas and / or argon gas in which the oxygen gas content is adjusted in the range of 0 to 20% by volume. Further, the firing in the step A may be performed in a reducing gas atmosphere such as a nitrogen-hydrogen mixed gas containing a reducing gas such as hydrogen gas. The ratio of the hydrogen gas contained in the nitrogen-hydrogen mixed gas is, for example, 1 to 10% by volume. As the reducing gas, ammonia gas, carbon monoxide gas, or the like may be used in addition to hydrogen gas.
- the step A it is preferable to fire the molded product obtained by molding the present material from the viewpoint that a solid electrolyte (sintered body) having higher ionic conductivity can be easily obtained, and the present material is press-molded. It is more preferable to bake the molded product.
- the pressure for press-molding the present material is not particularly limited, but is preferably 50 to 500 MPa, more preferably 100 to 400 MPa.
- the shape of the molded body obtained by press-molding the present material is not particularly limited, but it is preferably a shape suitable for the use of the sintered body (solid electrolyte) obtained by firing the molded body.
- the method for producing a solid electrolyte (method for producing the present electrolyte) according to an embodiment of the present invention is as follows.
- a lithium ion conductive compound (a) containing lithium, tantalum, phosphorus and oxygen as constituent elements, and at least one compound (b) selected from a boron compound, a bismuth compound and a phosphorus compound [However, the compound (b) is It is a compound different from the compound (a). ]
- step 2 of calcining the solid electrolyte material obtained in step 1.
- both the lithium ion conductive compound (a) and the compound (b) are crystalline, at least two of the crystalline compounds are pulverized and mixed to form an amorphous substance once by a mechanochemical reaction, and the amorphous compound thereof is formed.
- a quality material By firing a quality material, a solid electrolyte having high ionic conductivity can be easily obtained.
- Examples of the lithium ion conductive compound (a) containing lithium, tantalum, phosphorus and oxygen as constituent elements include the same compounds as the compound (a) mentioned in the column of the solid electrolyte material, and the compound (b) includes the compound (b). , The same compound as the compound (b) mentioned in the column of the solid electrolyte material can be mentioned.
- the step 1 the same steps as those mentioned in the column of the manufacturing method of the present material can be mentioned, and as the step 2, the same steps as the above-mentioned step A can be mentioned.
- components other than the present material may be used.
- the other component include conventionally known materials used for solid electrolytes of all-solid-state batteries, and examples of the lithium ion conductive compound include lithium ion conductive materials having structures such as NASICON type and LISION type. Be done.
- the other components one kind may be used, or two or more kinds may be used.
- the amount of the other component used is preferably 50% by mass or less, more preferably 30% by mass or less, based on 100% by mass of the total with the present material, and it is preferable not to use the other component.
- the all-solid-state battery (hereinafter, also referred to as “the battery”) according to the embodiment of the present invention is a positive electrode having a positive electrode active material, a negative electrode having a negative electrode active material, and a solid electrolyte between the positive electrode and the negative electrode.
- the solid electrolyte layer contains the present electrolyte.
- the present battery may be a primary battery or a secondary battery, but is preferably a secondary battery from the viewpoint of more exerting the effect of the present invention, and is preferably a lithium ion secondary battery. Is more preferable.
- the structure of the present battery is not particularly limited as long as a solid electrolyte layer is included between the positive electrode, the negative electrode, and the positive electrode and the negative electrode, and may be a so-called thin film type, laminated type, or bulk type.
- the solid electrolyte layer is not particularly limited as long as it contains the present electrolyte, and may contain conventionally known additives used for the solid electrolyte layer of the all-solid-state battery, if necessary, but it is preferably made of the present electrolyte.
- the thickness of the solid electrolyte layer may be appropriately selected depending on the structure (thin film type or the like) of the battery to be formed, but is preferably 50 nm to 1000 ⁇ m, more preferably 100 nm to 100 ⁇ m.
- the positive electrode is not particularly limited as long as it has a positive electrode active material, but a positive electrode having a positive electrode current collector and a positive electrode active material layer is preferable.
- the positive electrode active material layer is not particularly limited as long as it contains a positive electrode active material, but preferably contains a positive electrode active material and a solid electrolyte, and may further contain additives such as a conductive auxiliary agent and a sintering aid. ..
- the thickness of the positive electrode active material layer may be appropriately selected depending on the structure (thin film type, etc.) of the battery to be formed, but is preferably 10 to 200 ⁇ m, more preferably 30 to 150 ⁇ m, and further preferably 50 to 100 ⁇ m. ..
- the positive positive active material examples include LiCo oxide, LiNiCo oxide, LiNiCoMn oxide, LiNiMn oxide, LiMn oxide, LiMn-based spinel, LiMnNi oxide, LiMnAl oxide, LiMnMg oxide, and LiMnCo oxide.
- LiMnFe oxide, LiMnZn oxide, LiCrNiMn oxide, LiCrMn oxide, lithium titanate, lithium phosphate metal oxide, transition metal oxide, titanium sulfide, graphite, hard carbon, transition metal-containing lithium nitride, silicon oxide Examples thereof include lithium silicate, lithium metal, lithium alloy, Li-containing solid solution, and lithium-storable metal-to-metal compound.
- LiNiCoMn oxide, LiNiCo oxide, and LiCo oxide are preferable, and LiNiCoMn oxide is more preferable, from the viewpoint of increasing the capacity and the like.
- the surface of the positive electrode active material may be coated with lithium niobate, lithium phosphate, lithium borate, or the like, which are ionic conductive oxides.
- the positive electrode active material used for the positive electrode active material layer may be one kind or two or more kinds.
- Preferable examples of the positive electrode active material are LiM3PO 4 [M3 is one or more elements selected from the group consisting of Mn, Co, Ni, Fe, Al, Ti and V, or two elements V and O. .. ], LiM5VO 4 [M5 is one or more elements selected from the group consisting of Fe, Mn, Co, Ni, Al and Ti. ], Li 2 M6P 2 O 7 [M6 is one or more elements selected from the group consisting of Fe, Mn, Co, Ni, Al, Ti and V, or two elements of V and O.
- M7 is Ti, Ge, Al, Ga and Zr. It is one or more elements selected from the group consisting of. ], Li 1 + x8 Al x8 M8 2-x8 (PO 4 ) 3 [0 ⁇ x8 ⁇ 0.8, M8 is one or more elements selected from the group consisting of Ti and Ge.
- LiNi 1/3 Co 1/3 Mn 1/3 O 2 , LiCoO 2 , LiNiO 2 , LiMn 2 O 4 , Li 2 CoP 2 O 7 , Li 3 V 2 (PO 4 ) 3 , Li 3 Fe 2 ( PO 4 ) 3 , LiNi 0.5 Mn 1.5 O 4 , and Li 4 Ti 5 O 12 are also mentioned.
- the positive electrode active material is preferably in the form of particles.
- the 50% diameter in the volume-based particle size distribution is preferably 0.1 to 30 ⁇ m, more preferably 0.3 to 20 ⁇ m, still more preferably 0.4 to 10 ⁇ m, and particularly preferably 0.5 to 3 ⁇ m.
- the ratio of the length of the major axis to the length of the minor axis (length of the major axis / length of the minor axis), that is, the aspect ratio of the positive electrode active material is preferably less than 3, more preferably less than 2.
- the positive electrode active material may form secondary particles.
- the 50% diameter in the number-based particle size distribution of the primary particles is preferably 0.1 to 20 ⁇ m, more preferably 0.3 to 15 ⁇ m, still more preferably 0.4 to 10 ⁇ m, and particularly preferably 0.5 to 2 ⁇ m. Is.
- the content of the positive electrode active material in the positive electrode active material layer is preferably 20 to 80% by volume, more preferably 30 to 70% by volume.
- the positive electrode active material functions favorably, and a battery having a high energy density tends to be easily obtained.
- the solid electrolyte that can be used for the positive electrode active material layer is not particularly limited, and a conventionally known solid electrolyte can be used, but the present electrolyte is used from the viewpoint of further exerting the effect of the present invention. Is preferable.
- the solid electrolyte used for the positive electrode active material layer may be one kind or two or more kinds.
- the conductive auxiliary agent include metal materials such as Ag, Au, Pd, Pt, Cu and Sn, and carbon materials such as acetylene black, ketjen black, carbon nanotubes and carbon nanofibers.
- metal materials such as Ag, Au, Pd, Pt, Cu and Sn
- carbon materials such as acetylene black, ketjen black, carbon nanotubes and carbon nanofibers.
- sintering aid a compound similar to the compound (b) listed in the column of the solid electrolyte material is preferable.
- the additive used for the positive electrode active material layer may be one kind or two or more kinds, respectively.
- the positive electrode current collector is not particularly limited as long as the material is one that conducts electrons without causing an electrochemical reaction.
- the material of the positive electrode current collector include simple substances of metals such as copper, aluminum, and iron, alloys containing these metals, and conductive metal oxides such as antimony-doped tin oxide (ATO) and tin-doped indium oxide (ITO). Can be mentioned.
- ATO antimony-doped tin oxide
- ITO tin-doped indium oxide
- a current collector having a conductive adhesive layer provided on the surface of the conductor can also be used.
- the conductive adhesive layer include a layer containing a granular conductive material, a fibrous conductive material, and the like.
- the negative electrode is not particularly limited as long as it has a negative electrode active material, but a negative electrode having a negative electrode current collector and a negative electrode active material layer is preferable.
- the negative electrode active material layer is not particularly limited as long as it contains the negative electrode active material, but preferably contains the negative electrode active material and the solid electrolyte, and may further contain additives such as a conductive auxiliary agent and a sintering aid. ..
- the thickness of the negative electrode active material layer may be appropriately selected according to the structure (thin film type, etc.) of the battery to be formed, but is preferably 10 to 200 ⁇ m, more preferably 30 to 150 ⁇ m, and further preferably 50 to 100 ⁇ m. ..
- Negative electrode active material examples include lithium alloy, metal oxide, graphite, hard carbon, soft carbon, silicon, silicon alloy, silicon oxide SiO n (0 ⁇ n ⁇ 2), and silicon / carbon composite material.
- Examples thereof include a composite material containing a silicon domain in the pores of porous carbon, lithium titanate, and graphite coated with lithium titanate.
- a silicon / carbon composite material or a composite material containing a silicon domain in the pores of porous carbon is preferable because it has a high specific capacity and can increase the energy density and the battery capacity.
- the silicon domain is amorphous, the size of the silicon domain is 10 nm or less, and the pores derived from the porous carbon are present in the vicinity of the silicon domain. It is a composite material to be included.
- the negative electrode active material are LiM3PO 4 [M3 is one or more elements selected from the group consisting of Mn, Co, Ni, Fe, Al, Ti and V, or two elements V and O. .. ], LiM5VO 4 [M5 is one or more elements selected from the group consisting of Fe, Mn, Co, Ni, Al and Ti. ], Li 2 M6P 2 O 7 [M6 is one or more elements selected from the group consisting of Fe, Mn, Co, Ni, Al, Ti and V, or two elements of V and O.
- M7 is Ti, Ge, Al, Ga and Zr. It is one or more elements selected from the group consisting of. ], Li 1 + x8 Al x8 M8 2-x8 (PO 4 ) 3 [0 ⁇ x8 ⁇ 0.8, M8 is one or more elements selected from the group consisting of Ti and Ge.
- M9 is, Mg, Al, be one or more elements selected from the group consisting of Ga and Zn
- M10 is one or more elements selected from the group consisting of Zn, Al, Ga, Si, Ge, P and Ti
- a9 are M9.
- Is the average valence of, and b9 is the average valence of M10.
- LiNb 2 O 7 Li 4 Ti 5 O 12
- Li 4 Ti 5 PO 12 Li 4 Ti 5 PO 12
- TiO 2 LiSi, and graphite.
- the negative electrode active material is preferably in the form of particles.
- the 50% diameter in the volume-based particle size distribution, the aspect ratio, and the 50% diameter in the number-based particle size distribution of the primary particles when the negative electrode active material forms the secondary particles are in the same range as the positive electrode active material. It is preferable to have.
- the content of the negative electrode active material in the negative electrode active material layer is preferably 20 to 80% by volume, more preferably 30 to 70% by volume.
- the negative electrode active material functions favorably, and a battery having a high energy density tends to be easily obtained.
- the solid electrolyte that can be used for the negative electrode active material layer is not particularly limited, and a conventionally known solid electrolyte can be used. However, the present electrolyte is used from the viewpoint of further exerting the effect of the present invention. Is preferable.
- the solid electrolyte used for the negative electrode active material layer may be one kind or two or more kinds.
- the conductive auxiliary agent include metal materials such as Ag, Au, Pd, Pt, Cu and Sn, and carbon materials such as acetylene black, ketjen black, carbon nanotubes and carbon nanofibers.
- metal materials such as Ag, Au, Pd, Pt, Cu and Sn
- carbon materials such as acetylene black, ketjen black, carbon nanotubes and carbon nanofibers.
- sintering aid a compound similar to the compound (b) listed in the column of the solid electrolyte material is preferable.
- the additive used for the negative electrode active material layer may be one kind or two or more kinds, respectively.
- the negative electrode current collector the same current collector as the positive electrode current collector can be used.
- the all-solid-state battery can be formed, for example, by a known powder molding method.
- the positive electrode current collector, the powder for the positive electrode active material layer, the powder for the solid electrolyte layer, the powder for the negative electrode active material layer, and the negative electrode current collector are superposed in this order, and they are simultaneously powder-molded. Formation of each layer of positive electrode active material layer, solid electrolyte layer and negative electrode active material layer, and connection between positive electrode current collector, positive electrode active material layer, solid electrolyte layer, negative electrode active material layer and negative electrode current collector, respectively. Can be done at the same time.
- the positive electrode active material layer, the solid electrolyte layer, and the negative electrode active material layer may be powder-molded, respectively. However, when an all-solid-state battery is produced using each of the obtained layers, each layer is pressed. It is preferable to bake.
- the all-solid-state battery can also be manufactured by, for example, the following method.
- a paste for forming each layer is prepared by appropriately mixing a solvent, a resin, etc. with the material for forming the positive electrode active material layer, the material for forming the solid electrolyte layer, and the material for forming the negative electrode active material layer, and the paste is used as a base. By applying it on a sheet and drying it, a green sheet for a positive electrode active material layer, a green sheet for a solid electrolyte layer, and a green sheet for a negative electrode active material layer are produced.
- the green sheet for the positive electrode active material layer, the green sheet for the solid electrolyte layer, and the green sheet for the negative electrode active material layer from which the base sheet was peeled off from each green sheet were sequentially laminated, heat-pressed at a predetermined pressure, and then placed in a container.
- a laminated structure is produced by enclosing and pressurizing with a hot isotropic press, a cold isotropic press, a hydrostatic press, or the like.
- the laminated structure is degreased at a predetermined temperature and then fired to prepare a laminated sintered body.
- the firing temperature in this firing process is preferably the same as the firing temperature in the step A.
- an all-solid-state battery is formed by forming a positive electrode current collector and a negative electrode current collector on both main surfaces of the laminated sintered body by a sputtering method, a vacuum vapor deposition method, application of a metal paste, or dipping. It can also be made.
- XRD ⁇ Powder X-ray diffraction
- XRD X-ray diffraction measurement of the powder and solid electrolyte material obtained in the following synthetic example using the powder X-ray diffraction measuring device Panasonic MPD (manufactured by Spectris Co., Ltd.) (Cu-K ⁇ ray (output: 45 kV, 40 mA), times.
- Fold angle 2 ⁇ 10 to 50 °, step width: 0.013 °, incident side Sollerslit: 0.04rad, incident side Anti-scatter slit: 2 °, light receiving side Sollerslit: 0.04rad, light receiving side Anti-scatter slit : 5 mm) was performed to obtain an X-ray diffraction (XRD) figure.
- the obtained XRD figure can be obtained from the known analysis software RIETAN-FP (creator; Fujio Izumi's homepage "RIETAN-FP / VENUS system distribution file" (http://fujioizumi.verse.jp/download/download.html)).
- the crystal structure was confirmed by performing a Rietbelt analysis using (available).
- the obtained mixture is placed in an alumina boat, and the temperature is raised to 1000 ° C. under the condition of a heating rate of 10 ° C./min in an atmosphere of air (flow rate: 100 mL / min) using a rotary firing furnace (manufactured by Motoyama Co., Ltd.). Then, it was calcined at 1000 ° C. for 4 hours to obtain a primary calcined product.
- the obtained primary calcined product is crushed and mixed in a Menou mortar for 15 minutes, the obtained mixture is placed in an alumina boat, and an air (flow rate: 100 mL / min) atmosphere is used in a rotary calcining furnace (manufactured by Motoyama Co., Ltd.). Below, the temperature was raised to 1000 ° C. under the condition of a heating rate of 10 ° C./min, and firing was performed at 1000 ° C. for 1 hour to obtain a secondary fired product (LiTa 2 PO 8). The obtained secondary calcined product was cooled to room temperature, then taken out from the rotary calcining furnace, transferred to a dehumidified nitrogen gas atmosphere, and stored.
- SiO 2 Silicon (SiO 2 ) (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd., purity 99.9%) has an atomic number ratio of lithium, tantalum, phosphorus and silicon (Li: Ta: P: Si) of 1.38 :. It was produced in the same manner as in Synthesis Example 1 except that it was weighed so as to be 2.00: 0.85: 0.20, and a secondary fired product (abbreviated as Si-containing LTPO) was obtained.
- Si-containing LTPO a secondary fired product
- the XRD figure of the obtained secondary fired product is shown in FIG.
- the secondary fired product obtained from this XRD figure was a crystal having a monoclinic crystal ratio of 100%.
- Nb-containing LTPO secondary fired product
- the XRD figure of the obtained secondary fired product is shown in FIG.
- the secondary fired product obtained from this XRD figure was a crystal having a monoclinic crystal ratio of 100%.
- the obtained mixture is placed in an alumina boat, and the temperature is raised to 500 ° C. under the condition of a heating rate of 10 ° C./min in an atmosphere of air (flow rate: 100 mL / min) using a rotary firing furnace (manufactured by Motoyama Co., Ltd.). Then, it was fired at 500 ° C. for 2 hours to obtain a primary fired product.
- the obtained primary calcined product is crushed and mixed in a Menou mortar for 15 minutes, the obtained mixture is placed in an alumina boat, and an air (flow rate: 100 mL / min) atmosphere is used in a rotary calcining furnace (manufactured by Motoyama Co., Ltd.). Below, the temperature was raised to 630 ° C. under the condition of a temperature rising rate of 10 ° C./min, and firing was performed at 630 ° C. for 24 hours to obtain a secondary fired product (Li 3 BO 3). The obtained secondary calcined product was cooled to room temperature, then taken out from the rotary calcining furnace, transferred to a dehumidified nitrogen gas atmosphere, and stored.
- the obtained mixture was prepared in the same manner as in Synthesis Example 4 to obtain a secondary fired product (Li 3.6 B 1.6 C 0.4 O 5 ). From the XRD figure of the obtained fired product, it was found that the obtained fired product was crystalline.
- the obtained mixture was placed in an alumina boat, and the temperature was raised to 600 ° C. using a rotary baking furnace (manufactured by Motoyama Co., Ltd.) in an atmosphere of air (flow rate: 100 mL / min) at a heating rate of 10 ° C./min. Then, it was fired at 600 ° C. for 3 hours to obtain a fired product (LiPO 3). After the temperature of the obtained calcined product was lowered to room temperature, it was taken out from the rotary calcining furnace, transferred to a dehumidified nitrogen gas atmosphere, and stored.
- a rotary baking furnace manufactured by Motoyama Co., Ltd.
- the obtained mixture was placed in an alumina boat, and the temperature was raised to 600 ° C. using a rotary baking furnace (manufactured by Motoyama Co., Ltd.) in an atmosphere of air (flow rate: 100 mL / min) at a heating rate of 10 ° C./min. Then, it was fired at 600 ° C. for 4 hours to obtain a fired product (LiBio 2). After the temperature of the obtained calcined product was lowered to room temperature, it was taken out from the rotary calcining furnace, transferred to a dehumidified nitrogen gas atmosphere, and stored.
- a rotary baking furnace manufactured by Motoyama Co., Ltd.
- Example 1 The molar ratio (LiTa 2 PO 8 : Li 3 BO 3 ) of LiTa 2 PO 8 obtained in Synthesis Example 1 and Li 3 BO 3 obtained in Synthesis Example 4 was 0.975: 0.025. Weighed so that Each of the weighed compounds was placed in a zirconia ball mill, an appropriate amount of toluene was added thereto, and the mixture was pulverized and mixed using zirconia balls having a diameter of 1 mm for 2 hours to obtain a solid electrolyte material (mixture).
- the XRD figure of the obtained solid electrolyte material is shown in FIG. From this XRD figure, it was found that the obtained solid electrolyte material was amorphous.
- ⁇ Making pellets> By applying a pressure of 40 MPa with a hydraulic press to the obtained solid electrolyte material using a tablet molding machine, a disk-shaped molded body having a diameter of 10 mm and a thickness of 1 mm is formed, and then CIP (cold hydrostatic isotropic pressure pressing) is performed. ), A pellet was prepared by applying a pressure of 300 MPa to the disk-shaped molded body.
- ⁇ Total conductivity> By forming gold layers on both sides of the obtained sintered body using a sputtering machine, measurement pellets for ionic conductivity evaluation were obtained. The obtained measurement pellets were kept in a constant temperature bath at 25 ° C. for 2 hours before measurement. Next, at 25 ° C., AC impedance measurement was performed in a frequency range of 1 Hz to 10 MHz using an impedance analyzer (manufactured by Solartron Analytical Co., Ltd., model number: 1260 A) under the condition of an amplitude of 25 mV.
- an impedance analyzer manufactured by Solartron Analytical Co., Ltd., model number: 1260 A
- the obtained impedance spectrum is fitted in an equivalent circuit using the equivalent circuit analysis software ZView attached to the device to obtain each lithium ion conductivity in the crystal grain and at the grain boundary, and the total conduction is obtained by totaling these. The degree was calculated. The results are shown in Table 1.
- Examples 2 to 10 and Comparative Example 1 Using the compound (a) shown in Table 1, a solid electrolyte material was prepared in the same manner as in Example 1 except that the mixing amount and firing temperature of Li 3 BO 3 were changed as shown in Table 1, and then a solid electrolyte material was prepared. The total conductivity of the sintered body obtained by firing the obtained solid electrolyte material at the firing temperatures shown in Table 1 was measured. The results are shown in Table 1.
- the solid electrolyte materials obtained in Examples 2 to 10 were amorphous as a result of XRD measurement.
- the solid electrolyte material containing the lithium ion conductive compound (a) containing lithium, tantalum, phosphorus and oxygen as constituent elements and the boron compound (Li 3 BO 3 ) as the compound (b) has a temperature of 900 ° C. or lower. It can be seen that a sintered body having sufficient ionic conductivity was obtained even when the compound was fired at a low temperature of.
- Examples 11 to 19 This was carried out except that the compound (a) shown in Table 2 was used, Li 4 B 2 O 5 was used as the compound (b), and the mixing amount and firing temperature of Li 4 B 2 O 5 were changed as shown in Table 2.
- a solid electrolyte material was prepared in the same manner as in Example 1, and then the obtained solid electrolyte material was fired at the firing temperatures shown in Table 2 to measure the total conductivity of the sintered body obtained. The results are shown in Table 2.
- the solid electrolyte materials obtained in Examples 11 to 19 were amorphous as a result of XRD measurement.
- the solid electrolyte material containing the lithium ion conductive compound (a) containing lithium, tantalum, phosphorus and oxygen as constituent elements and the boron compound (Li 4 B 2 O 5) as the compound (b) is 900. It can be seen that a sintered body having sufficient ionic conductivity was obtained even when the compound was fired at a low temperature of ° C. or lower.
- Example 20 to 26 Using the compounds (a) and (b) shown in Table 3, a solid electrolyte material was prepared in the same manner as in Example 1 except that the mixing amount and firing temperature of the compound (b) were changed as shown in Table 3. Then, the obtained solid electrolyte material was fired at the firing temperatures shown in Table 3, and the total conductivity of the sintered body obtained was measured. The results are shown in Table 3.
- the solid electrolyte materials obtained in Examples 20 to 26 were amorphous as a result of XRD measurement.
- the solid electrolyte material according to the embodiment of the present invention can obtain a sintered body having sufficient ionic conductivity even when fired at a low temperature (eg, 900 ° C. or lower), and is a solid electrolyte of a lithium ion secondary battery. Can be suitably used as.
Abstract
Description
硫化物系の固体電解質を用いた場合、コールドプレスなどにより電池を作製できるなどの利点はあるものの、湿度に対して不安定であり、有害な硫化水素ガスが発生する可能性があるため、安全性等の点から酸化物系の固体電解質の開発が進められている。
また、酸化物系の固体電解質を用いて全固体電池を作製する際に、高いイオン伝導度を得るには、正極材料、負極材料等と併せて焼結することが必要とされる。
本発明の構成例は以下のとおりである。
ホウ素化合物、ビスマス化合物およびリン化合物から選ばれる少なくとも1種の化合物(b)[但し、化合物(b)は、化合物(a)とは異なる化合物である。]と
を含む固体電解質材料。
組成式Li〔1+(5-a)x〕Ta2-xM1xPO8[M1は、Nb、Zr、Ga、Sn、Hf、WおよびMoからなる群より選ばれる1種以上の元素であり、0.0≦x<1.0であり、aはM1の平均価数である。]で表される化合物、または、
組成式Li〔1+(5-b)y〕Ta2P1-yM2yO8[M2は、Si、AlおよびGeからなる群より選ばれる1種以上の元素であり、0.0≦y<0.7であり、bはM2の平均価数である。]で表される化合物
である、[1]~[3]のいずれかに記載の固体電解質材料。
[7] リン元素の含有量が5.3~8.3原子%である、[1]~[6]のいずれかに記載の固体電解質材料。
[8] リチウム元素の含有量が5.0~20.0原子%である、[1]~[7]のいずれかに記載の固体電解質材料。
[15] [1]~[12]のいずれかに記載の固体電解質材料の焼結体である、固体電解質。
工程1で得られた固体電解質材料を焼成する工程2と
を含む、固体電解質の製造方法。
負極活物質を有する負極と、
前記正極と前記負極との間に固体電解質層と、
を含み、
前記固体電解質層が、[14]または[15]に記載の固体電解質を含む、
全固体電池。
本発明の一実施形態に係る固体電解質材料(以下「本材料」ともいう。)は、リチウム、タンタル、リンおよび酸素を構成元素として含むリチウムイオン伝導性化合物(a)と、ホウ素化合物、ビスマス化合物およびリン化合物から選ばれる少なくとも1種の化合物(b)[但し、化合物(b)は、化合物(a)とは異なる化合物である。]とを含む。
化合物(a)と化合物(b)とを粉砕混合して得られる本材料は、化合物(a)と化合物(b)とが含まれていることが必ずしも明らかではない場合があるが、この場合であっても、化合物(a)と化合物(b)とを粉砕混合して得られた本材料は、化合物(a)と化合物(b)とを含むという。
本材料が非晶質であることで、該本材料から得られる固体電解質、特に、本材料を焼成して得られる固体電解質(焼結体)は、より高いイオン伝導度を奏する傾向にある。
本材料の平均粒子径が前記範囲にあることで、該本材料から得られる固体電解質、特に、本材料を焼成して得られる固体電解質(焼結体)は、より高いイオン伝導度を奏する傾向にある。
なお、前記本材料中のリチウム元素の含有量は、化合物(a)由来のリチウム元素、および、化合物(b)としてリチウム元素を含む化合物を用いる場合には、該化合物(b)由来リチウム元素の両方を含む。本材料中の他の元素の含有量も同様である。
化合物(a)は、リチウム、タンタル、リンおよび酸素を構成元素として含むリチウムイオン伝導性の化合物であり、これらの元素を含む酸化物であることが好ましい。
本材料中に含まれる化合物(a)は、1種でも、2種以上でもよい。
化合物(a)が、ガーネット型、ペロブスカイト型、LISICON型構造ではなく、単斜晶型構造を有する化合物である場合には、化合物(b)とともに用いることで、低温(例:900℃以下)で焼成しても、十分なイオン伝導度の焼結体を得ることができる。
単斜晶率が前記範囲にある化合物(a)を用いることで、結晶粒内と結晶粒界との両方においてイオン伝導度が高い固体電解質を容易に得ることができる傾向にある。
前記単斜晶率は、X線回折(XRD)図形をリートベルト解析することで、具体的には、下記実施例の方法で判断することができる。
前記化合物(a1)は、LiTa2PO8、または、LiTa2PO8のTaの一部が、金属元素M1で置換された化合物であることが好ましく、単斜晶型構造を有することが好ましい。
化合物(a1)は、具体的には、組成式Li〔1+(5-a)x〕Ta2-xM1xPO8[M1は、Nb、Zr、Ga、Sn、Hf、WおよびMoからなる群より選ばれる1種以上の元素であり、0.0≦x<1.0であり、aはM1の平均価数である。]で表される化合物であることが好ましい。
xが前記範囲にあると、化合物(a)を用いて得られる固体電解質において、結晶粒界におけるリチウムイオン伝導度が高くなる傾向にある。
M1が2種以上の元素から構成される場合、前記aは、それぞれの元素の価数とそれぞれの元素の含有量とを用いて加重平均することで算出する。例えば、M1が80原子%のNbと、20原子%のZrとを含む場合、aは、(+5×0.8)+(+4×0.2)=+4.8と算出される。また、M1が80原子%のNbと、20原子%のWで構成される場合、aは、(+5×0.8)+(+6×0.2)=+5.2と算出される。
前記化合物(a2)は、LiTa2PO8、または、LiTa2PO8のPの一部が、金属元素M2で置換された化合物であることが好ましく、単斜晶型構造を有することが好ましい。
化合物(a2)は、具体的には、組成式Li〔1+(5-b)y〕Ta2P1-yM2yO8[M2は、Si、AlおよびGeからなる群より選ばれる1種以上の元素であり、0.0≦y<0.7であり、bはM2の平均価数である。]で表される化合物であることが好ましい。
yが前記範囲にあると、化合物(a)を用いて得られる固体電解質において、結晶粒内と結晶粒界のリチウムイオン伝導度の合計であるトータルイオン伝導度が高くなる傾向にある。
化合物(a)の製造方法としては特に制限されず、例えば、固相反応、液相反応等の従来公知の製造方法を採用することができる。該製造方法としては、具体的には、少なくともそれぞれ1段階の混合工程と焼成工程とを含む方法が挙げられる。
前記混合工程としては、例えば、原材料である、リチウム原子を含む化合物、タンタル原子を含む化合物、リン原子を含む化合物、ならびに、必要により、金属元素M1を含む化合物、および/または、金属元素M2を含む化合物を混合する工程が挙げられる。
リチウム原子を含む化合物は、1種を用いてもよく、2種以上を用いてもよい。
タンタル原子を含む化合物は、1種を用いてもよく、2種以上を用いてもよい。
リン原子を含む化合物は、1種を用いてもよく、2種以上を用いてもよい。
金属元素M1を含む化合物は、1種を用いてもよく、2種以上を用いてもよい。
金属元素M2を含む化合物は、1種を用いてもよく、2種以上を用いてもよい。
なお、後述する焼成工程において、リチウム原子が系外に流出しやすいので、前記リチウム原子を含む化合物を1~2割程度過剰に用いてもよい。また、後述する焼成工程において、副生成物の発生を抑制するために、前記リン原子を含む化合物を0.1~1割程度過剰に用いてもよい。
また、前記混合は、大気下で行ってもよいが、0~20体積%の範囲で酸素ガス含有量の調整された、窒素ガスおよび/またはアルゴンガスの雰囲気下で行うことが好ましい。
前記焼成工程では、混合工程で得た混合物を焼成する。焼成工程を複数回行う場合には、焼成工程で得られた焼成物を粉砕または小粒径化することを目的として、ボールミルや乳鉢等を用いた粉砕工程を設けてもよい。特に、化合物(a)は、相生成の反応速度が遅いため、1回目の焼成では反応中間体が存在する場合がある。この場合には、1回目の焼成を行い、粉砕工程を行った後、さらに焼成工程を行うことが好ましい。
焼成温度が前記範囲にあると、リチウム原子が系外へ流出しにくく、イオン伝導度の高い化合物(a)が得られやすい傾向にある。
焼成時間が前記範囲にあると、リチウム原子が系外へ流出しにくく、イオン伝導度の高い化合物(a)が得られやすい傾向にある。
この場合、低温焼成としては、例えば、400~800℃で、2~12時間焼成することが挙げられる。
また、副生成物の残存を抑制するために、高温焼成を2回行ってもよい。2回目の焼成工程の焼成温度は、好ましくは800~1200℃、より好ましくは950~1100℃、さらに好ましくは950~1000℃である。
各焼成工程の焼成時間は、好ましくは1~8時間、より好ましくは2~6時間である。
化合物(b)は、ホウ素化合物、ビスマス化合物およびリン化合物から選ばれる少なくとも1種の化合物である。これらの中でも、本発明の効果がより発揮される等の点から、ホウ素化合物が好ましい。
なお、化合物(b)は、化合物(a)とは異なる化合物である。
本材料中に含まれる化合物(b)は、1種でも、2種以上でもよい。
化合物(b)は、従来公知の方法で製造して得てもよく、市販品を用いてもよい。
化合物(b)の製造方法としては特に制限されず、例えば、固相反応、液相反応等の従来公知の製造方法を採用することができる。該製造方法としては、具体的には、混合工程と焼成工程とを含む方法が挙げられる。
なお、化合物(b)として市販品を用いてもよい。
前記混合工程としては、例えば、リチウムを構成元素として含む複合酸化物を製造する場合には、原材料である、リチウム原子を含む化合物と、ホウ素原子を含む化合物、ビスマス原子を含む化合物またはリン原子を含む化合物とを混合する。
化合物(b)の種類によっては、この混合工程を行わなくてもよい。
リチウム原子を含む化合物は、1種を用いてもよく、2種以上を用いてもよい。
ホウ素原子を含む化合物は、1種を用いてもよく、2種以上を用いてもよい。
ビスマス原子を含む化合物は、1種を用いてもよく、2種以上を用いてもよい。
リン原子を含む化合物は、1種を用いてもよく、2種以上を用いてもよい。
なお、後述する焼成工程において、リチウム原子が系外に流出しやすいので、前記リチウム原子を含む化合物を1~2割程度過剰に用いてもよい。また、後述する焼成工程において、副生成物の発生を抑制するために、前記リン原子を含む化合物を用いる場合、該化合物を0.1~1割程度過剰に用いてもよい。
また、前記混合は、大気下で行ってもよいが、0~20体積%の範囲で酸素ガス含有量の調整された、窒素ガスおよび/またはアルゴンガスの雰囲気下で行うことが好ましい。
前記焼成工程では、混合工程で得た混合物を焼成する。焼成工程を複数回行う場合には、焼成工程で得られた焼成物を粉砕または小粒径化することを目的として、ボールミルや乳鉢等を用いた粉砕工程を設けてもよい。
焼成温度が前記範囲にあると、リチウム原子が系外へ流出しにくく、所望の化合物(b)が得られやすい傾向にある。
焼成時間が前記範囲にあると、リチウム原子が系外へ流出しにくく、所望の化合物(b)が得られやすい傾向にある。
本材料は、化合物(a)と化合物(b)とを含めば特に制限されず、化合物(a)および(b)以外の他の成分を含んでいてもよい。該他の成分としては、全固体電池の固体電解質に用いられる従来公知の材料が挙げられ、例えば、化合物(a)以外のリチウムイオン伝導性化合物、化合物(b)以外の焼結助剤、酸化アルミニウム(Al2O3)が挙げられる。
前記他の成分はそれぞれ、1種を用いてもよく、2種以上を用いてもよい。
本材料中の前記他の成分の含有量は、化合物(a)および(b)の合計100モル%に対し、好ましくは40モル%以下、より好ましくは30モル%以下であり、本材料は、前記他の成分を含まないことが好ましい。
本材料は、例えば、化合物(a)と化合物(b)とを混合する工程を含む方法で製造することができ、本材料から固体電解質を得る際に、より高いイオン伝導度を奏する固体電解質を容易に得ることができる等の点から、化合物(a)と化合物(b)とを粉砕混合する工程を含む方法で製造することが好ましい。
また、化合物(a)と化合物(b)とを粉砕混合する際には、得られる本材料がメカノケミカル反応により非晶質となるように、および/または、本材料の平均粒子径が前記範囲となるように粉砕混合することが好ましい。
また、前記粉砕混合は、大気下で行ってもよいが、0~20体積%の範囲で酸素ガス含有量の調整された、窒素ガスおよび/またはアルゴンガスの雰囲気下で行うことが好ましい。
本発明の一実施形態に係る固体電解質(以下「本電解質」ともいう。)は、前記本材料を用いて得られ、本材料を焼成して得られる本材料の焼結体であることが好ましい。
本電解質の単斜晶率(=単斜晶の結晶量×100/確認された結晶の合計結晶量)は、好ましくは70%以上、より好ましくは80%以上、さらに好ましくは90%以上であり、上限は特に制限されないが100%である。
本電解質の単斜晶率が前記範囲にあると、結晶粒内と結晶粒界との両方においてイオン伝導度が高い固体電解質となる傾向にある。
該相対密度は、具体的には、次の方法で測定する。
作製した固体電解質の質量を、電子天秤を用いて測定する。次に、マイクロメーターを用いて固体電解質の実寸から体積を測定する。測定した質量を体積で除することにより、固体電解質の密度(測定値)を算出し、固体電解質の密度の理論値と該測定値との割合から相対密度(%)を求めることができる。
なお、固体電解質の理論密度は、具体的には、固体電解質を構成する結晶構造の理論密度と、該結晶構造の含有量を用いて加重平均することによって算出される。例えば、固体電解質が、含有量h%の結晶構造1および含有量k%の結晶構造2を有する場合、(結晶構造1の理論密度×h+結晶構造2の理論密度×k)/100で算出できる。
各結晶構造の含有量は、リートベルト解析で求めることができる。
本材料を750℃以上850℃未満で焼成して得られる本材料の焼結体のトータルイオン伝導度は、好ましくは2.00×10-5S・cm-1以上、より好ましくは4.00×10-5S・cm-1以上である。
本材料を700℃以上750℃未満で焼成して得られる本材料の焼結体のトータルイオン伝導度は、好ましくは1.00×10-5S・cm-1以上、より好ましくは2.00×10-5S・cm-1以上である。
本材料を650℃以上700℃未満で焼成して得られる本材料の焼結体のトータルイオン伝導度は、好ましくは1.00×10-6S・cm-1以上、より好ましくは2.00×10-6S・cm-1以上である。
該トータルイオン伝導度が前記範囲にあると、本材料を低温で焼成して得られる焼結体は、十分なイオン伝導度を有するといえる。
該トータルイオン伝導度は、具体的には、下記実施例に記載の方法で測定できる。
本発明の一実施形態に係る固体電解質の製造方法(本電解質の製造方法)は、前記本材料を焼成する工程Aを含むことが好ましく、前記本材料を成形した後、焼成して焼結体とする方法であることがより好ましい。
本材料を用いるため、このような低温で焼成しても、十分なイオン伝導度の焼結体を得ることができる。
焼成時間が前記範囲にあると、低温で焼成しても、十分なイオン伝導度の焼結体を得ることができる。
また、前記工程Aにおける焼成は、水素ガスなどの還元性ガスを含む、窒素水素混合ガス等の還元性ガス雰囲気下で行ってもよい。窒素水素混合ガスが含む水素ガスの比率は、例えば1~10体積%が挙げられる。還元性ガスとしては、水素ガス以外に、アンモニアガス、一酸化炭素ガスなどを用いてもよい。
本材料をプレス成形する際の圧力としては特に制限されないが、好ましくは50~500MPa、より好ましくは100~400MPaである。
本材料をプレス成形した成形体の形状も特に制限されないが、該成形体を焼成して得られる焼結体(固体電解質)の用途に応じた形状であることが好ましい。
リチウム、タンタル、リンおよび酸素を構成元素として含むリチウムイオン伝導性化合物(a)と、ホウ素化合物、ビスマス化合物およびリン化合物から選ばれる少なくとも1種の化合物(b)[但し、化合物(b)は、化合物(a)とは異なる化合物である。]とを粉砕混合して非晶質の固体電解質材料を作製する工程1と、
工程1で得られた固体電解質材料を焼成する工程2と
を含む。
特に、リチウムイオン伝導性化合物(a)と化合物(b)とがともに結晶である場合に、結晶であった少なくとも2つの化合物を粉砕混合してメカノケミカル反応により一旦非晶質にし、その非晶質の材料を焼成することで、イオン伝導度が高い固体電解質を容易に得ることができる。
工程1としては、前記本材料の製造方法の欄で挙げた工程と同様の工程が挙げられ、工程2としては、前記工程Aと同様の工程が挙げられる。
前記他の成分はそれぞれ、1種を用いてもよく、2種以上を用いてもよい。
前記他の成分の使用量は、本材料との合計100質量%に対し、好ましくは50質量%以下、より好ましくは30質量%以下であり、前記他の成分を使用しないことが好ましい。
本発明の一実施形態に係る全固体電池(以下「本電池」ともいう。)は、正極活物質を有する正極と、負極活物質を有する負極と、前記正極と前記負極との間に固体電解質層とを含み、前記固体電解質層が本電解質を含む。
本電池は、一次電池であってもよく、二次電池であってもよいが、本発明の効果がより発揮される等の点から、二次電池であることが好ましく、リチウムイオン二次電池であることがより好ましい。
本電池の構造は、正極と、負極と、該正極と負極との間に固体電解質層を含めば特に制限されず、いわゆる、薄膜型、積層型、バルク型のいずれであってもよい。
固体電解質層は、本電解質を含めば特に制限されず、必要により、全固体電池の固体電解質層に用いられる従来公知の添加剤を含んでいてもよいが、本電解質からなることが好ましい。
固体電解質層の厚さは、形成したい電池の構造(薄膜型等)に応じて適宜選択すればよいが、好ましくは50nm~1000μm、より好ましくは100nm~100μmである。
正極は正極活物質を有すれば特に制限されないが、好ましくは、正極集電体と正極活物質層とを有する正極が挙げられる。
正極活物質層は、正極活物質を含めば特に制限されないが、正極活物質と固体電解質とを含むことが好ましく、さらに、導電助剤や焼結助剤等の添加剤を含んでいてもよい。
正極活物質層の厚さは、形成したい電池の構造(薄膜型等)に応じて適宜選択すればよいが、好ましくは10~200μm、より好ましくは30~150μm、さらに好ましくは50~100μmである。
正極活物質としては、例えば、LiCo酸化物、LiNiCo酸化物、LiNiCoMn酸化物、LiNiMn酸化物、LiMn酸化物、LiMn系スピネル、LiMnNi酸化物、LiMnAl酸化物、LiMnMg酸化物、LiMnCo酸化物、LiMnFe酸化物、LiMnZn酸化物、LiCrNiMn酸化物、LiCrMn酸化物、チタン酸リチウム、リン酸金属リチウム、遷移金属酸化物、硫化チタン、グラファイト、ハードカーボン、遷移金属含有リチウム窒化物、酸化ケイ素、ケイ酸リチウム、リチウム金属、リチウム合金、Li含有固溶体、リチウム貯蔵性金属間化合物が挙げられる。
これらの中でも、固体電解質との親和性がよく、マクロ導電性、ミクロ導電性およびイオン伝導性のバランスに優れ、また、平均電位が高く、比容量と安定性とのバランスにおいて、エネルギー密度や電池容量を高めることができる等の点から、LiNiCoMn酸化物、LiNiCo酸化物、LiCo酸化物が好ましく、LiNiCoMn酸化物がより好ましい。
また、正極活物質は、イオン伝導性酸化物であるニオブ酸リチウム、リン酸リチウムまたはホウ酸リチウム等で表面が被覆されていてもよい。
正極活物質層に用いられる正極活物質は、1種でもよく、2種以上でもよい。
また、正極活物質の、短径の長さに対する長径の長さの比(長径の長さ/短径の長さ)、すなわちアスペクト比は、好ましくは3未満、より好ましくは2未満である。
正極活物質の含有量が前記範囲にあると、正極活物質が好適に機能し、エネルギー密度の高い電池を容易に得ることができる傾向にある。
正極活物質層に用いられ得る固体電解質としては特に制限されず、従来公知の固体電解質を用いることができるが、本発明の効果がより発揮される等の点から、本電解質を用いることが好ましい。
正極活物質層に用いられる固体電解質は、1種でもよく、2種以上でもよい。
前記導電助剤の好適例としては、Ag、Au、Pd、Pt、Cu、Snなどの金属材料、アセチレンブラック、ケッチェンブラック、カーボンナノチューブ、カーボンナノファイバーなどの炭素材料が挙げられる。
前記焼結助剤としては、前記固体電解質材料の欄で挙げた化合物(b)と同様の化合物が好ましい。
正極活物質層に用いられる添加剤はそれぞれ、1種でもよく、2種以上でもよい。
正極集電体は、その材質が電気化学反応を起こさずに電子を導電するものであれば特に限定されない。正極集電体の材質としては、例えば、銅、アルミニウム、鉄等の金属の単体、これらの金属を含む合金、アンチモンドープ酸化スズ(ATO)、スズドープ酸化インジウム(ITO)などの導電性金属酸化物が挙げられる。
なお、正極集電体としては、導電体の表面に導電性接着層を設けた集電体を用いることもできる。該導電性接着層としては、例えば、粒状導電材や繊維状導電材などを含む層が挙げられる。
負極は負極活物質を有すれば特に制限されないが、好ましくは、負極集電体と負極活物質層とを有する負極が挙げられる。
負極活物質層は、負極活物質を含めば特に制限されないが、負極活物質と固体電解質とを含むことが好ましく、さらに、導電助剤や焼結助剤等の添加剤を含んでいてもよい。
負極活物質層の厚さは、形成したい電池の構造(薄膜型等)に応じて適宜選択すればよいが、好ましくは10~200μm、より好ましくは30~150μm、さらに好ましくは50~100μmである。
負極活物質としては、例えば、リチウム合金、金属酸化物、グラファイト、ハードカーボン、ソフトカーボン、ケイ素、ケイ素合金、ケイ素酸化物SiOn(0<n≦2)、ケイ素/炭素複合材、多孔質炭素の細孔内にケイ素ドメインを内包する複合材、チタン酸リチウム、チタン酸リチウムで被覆されたグラファイトが挙げられる。
これらの中でも、ケイ素/炭素複合材や多孔質炭素の細孔内にケイ素ドメインを内包する複合材は、比容量が高く、エネルギー密度や電池容量を高めることができるため好ましい。より好ましくは、多孔質炭素の細孔内にケイ素ドメインを内包する複合材であり、ケイ素のリチウム吸蔵/放出に伴う体積膨張の緩和性に優れ、マクロ導電性、ミクロ導電性およびイオン伝導性のバランスを良好に維持することができる。特に好ましくは、ケイ素ドメインが非晶質であり、ケイ素ドメインのサイズが10nm以下であり、ケイ素ドメインの近傍に多孔質炭素由来の細孔が存在する、多孔質炭素の細孔内にケイ素ドメインを内包する複合材である。
負極活物質の含有量が前記範囲にあると、負極活物質が好適に機能し、エネルギー密度の高い電池を容易に得ることができる傾向にある。
負極活物質層に用いられ得る固体電解質としては特に制限されず、従来公知の固体電解質を用いることができるが、本発明の効果がより発揮される等の点から、本電解質を用いることが好ましい。
負極活物質層に用いられる固体電解質は、1種でもよく、2種以上でもよい。
前記導電助剤の好適例としては、Ag、Au、Pd、Pt、Cu、Snなどの金属材料、アセチレンブラック、ケッチェンブラック、カーボンナノチューブ、カーボンナノファイバーなどの炭素材料が挙げられる。
前記焼結助剤としては、前記固体電解質材料の欄で挙げた化合物(b)と同様の化合物が好ましい。
負極活物質層に用いられる添加剤はそれぞれ、1種でもよく、2種以上でもよい。
負極集電体としては、正極集電体と同様の集電体を用いることができる。
全固体電池は、例えば、公知の粉末成形法によって形成することができる。例えば、正極集電体、正極活物質層用の粉末、固体電解質層用の粉末、負極活物質層用の粉末および負極集電体をこの順に重ね合わせて、それらを同時に粉末成形することによって、正極活物質層、固体電解質層および負極活物質層のそれぞれの層の形成と、正極集電体、正極活物質層、固体電解質層、負極活物質層および負極集電体のそれぞれの間の接続を同時に行うことができる。
本発明の一実施形態によれば、この全固体電池を作製する際の焼成温度を低温で行っても、十分なイオン伝導度を奏する全固体電池が得られるため、正極や負極材料などの他の材料の分解や変質等を抑制しながらも、経済性に優れ、省設備で全固体電池を作製することができる。
正極活物質層形成用の材料、固体電解質層形成用の材料、負極活物質層形成用の材料に、溶剤、樹脂等を適宜混合することにより、各層形成用ペーストを調製し、そのペーストをベースシート上に塗布し、乾燥させることで、正極活物質層用グリーンシート、固体電解質層用グリーンシート、負極活物質層用グリーンシートを作製する。次に、各グリーンシートからベースシートを剥離した、正極活物質層用グリーンシート、固体電解質層用グリーンシートおよび負極活物質層用グリーンシートを順次積層し、所定圧力で熱圧着した後、容器に封入し、熱間等方圧プレス、冷間等方圧プレス、静水圧プレス等により加圧することで、積層構造体を作製する。
この焼成処理における焼成温度は、前記工程Aにおける焼成温度と同様の温度であることが好ましい。
粉末X線回折測定装置パナリティカルMPD(スペクトリス(株)製)を用い、下記合成例で得られた粉末および固体電解質材料のX線回折測定(Cu-Kα線(出力:45kV、40mA)、回折角2θ=10~50°の範囲、ステップ幅:0.013°、入射側Sollerslit:0.04rad、入射側Anti-scatter slit:2°、受光側Sollerslit:0.04rad、受光側Anti-scatter slit:5mm)を行い、X線回折(XRD)図形を得た。得られたXRD図形を、公知の解析ソフトウェアRIETAN-FP(作成者;泉富士夫のホームページ「RIETAN-FP・VENUS システム配布ファイル」(http://fujioizumi.verse.jp/download/download.html)から入手することができる。)を用いてリートベルト解析を行うことで、結晶構造を確認した。
炭酸リチウム(Li2CO3)(シグマアルドリッチ社製、純度99.0%以上)、五酸化タンタル(Ta2O5)(富士フイルム和光純薬(株)製、純度99.9%)、および、リン酸水素二アンモニウム((NH4)2HPO4)(シグマアルドリッチ社製、純度98%以上)を、リチウム、タンタルおよびリンの原子数比(Li:Ta:P)が、1.10:2.00:1.06となるように秤量した。秤量した各原料粉末に、適量のトルエンを加え、ジルコニアボールミル(ジルコニアボール:直径1mm)を用いて2時間粉砕混合した。
得られた二次焼成物を室温まで降温後、回転焼成炉から取り出し、除湿された窒素ガス雰囲気下に移して保管した。
炭酸リチウム(Li2CO3)(シグマアルドリッチ社製、純度99.0%以上)、五酸化タンタル(Ta2O5)(富士フイルム和光純薬(株)製、純度99.9%)、リン酸水素二アンモニウム((NH4)2HPO4)(シグマアルドリッチ社製、純度98%以上)、および、酸化ケイ素(SiO2)(富士フイルム和光純薬(株)製、純度99.9%)を、リチウム、タンタル、リンおよびケイ素の原子数比(Li:Ta:P:Si)が、1.38:2.00:0.85:0.20となるように秤量した以外は合成例1と同様に作製して、二次焼成物(Si含有LTPOと略す)を得た。
炭酸リチウム(Li2CO3)(シグマアルドリッチ社製、純度99.0%以上)、五酸化タンタル(Ta2O5)(富士フイルム和光純薬(株)製、純度99.9%)、リン酸水素二アンモニウム((NH4)2HPO4)(シグマアルドリッチ社製、純度98%以上)、および、五酸化ニオブ(Nb2O5)(富士フイルム和光純薬(株)製、純度99.9%)を、リチウム、タンタル、リンおよびニオブの原子数比(Li:Ta:P:Nb)が、1.10:1.80:1.06:0.20となるように秤量した以外は合成例1と同様に作製して、二次焼成物(Nb含有LTPOと略す)を得た。
水酸化リチウム一水和物(LiOH・H2O)(富士フイルム和光純薬(株)製、純度98.0%以上)、および、ホウ酸(H3BO3)(富士フイルム和光純薬(株)製、純度99.5%以上)を、リチウムおよびホウ素の原子数比(Li:B)が、3.00:1.00となるように秤量した。秤量した各原料粉末を、メノウ乳鉢で15分間粉砕混合し、混合物を得た。
得られた二次焼成物を室温まで降温後、回転焼成炉から取り出し、除湿された窒素ガス雰囲気下に移して保管した。
水酸化リチウム一水和物(LiOH・H2O)(富士フイルム和光純薬(株)製、純度98.0%以上)、および、ホウ酸(H3BO3)(富士フイルム和光純薬(株)製、純度99.5%以上)を、リチウムおよびホウ素の原子数比(Li:B)が、2.00:1.00となるように秤量した以外は合成例4と同様に作製して、二次焼成物(Li4B2O5)を得た。
水酸化リチウム一水和物(LiOH・H2O)(富士フイルム和光純薬(株)製、純度98.0%以上)、および、ホウ酸(H3BO3)(富士フイルム和光純薬(株)製、純度99.5%以上)を、リチウムおよびホウ素の原子数比(Li:B)が、1.80:1.00となるように秤量した以外は合成例4と同様に作製して、二次焼成物(Li3.6B2O4.8)を得た。
水酸化リチウム一水和物(LiOH・H2O)(富士フイルム和光純薬(株)製、純度98.0%以上)、および、ホウ酸(H3BO3)(富士フイルム和光純薬(株)製、純度99.5%以上)を、リチウムおよびホウ素の原子数比(Li:B)が、1.60:1.00となるように秤量した以外は合成例4と同様に作製して、二次焼成物(Li3.2B2O4.6)を得た。
水酸化リチウム一水和物(LiOH・H2O)(富士フイルム和光純薬(株)製、純度98.0%以上)、ホウ酸(H3BO3)(富士フイルム和光純薬(株)製、純度99.5%以上)、および、炭酸リチウム(Li2CO3)(シグマアルドリッチ社製、純度99.0%以上)を、リチウム、ホウ素および炭素の原子数比(Li:B:C)が、3.6:1.6:0.4となるように秤量した。秤量した各原料粉末を、メノウ乳鉢で15分間粉砕混合し、混合物を得た。
得られた焼成物のXRD図形から、得られた焼成物は、結晶であることが分かった。
炭酸リチウム(Li2CO3)(シグマアルドリッチ社製、純度99.0%以上)、および、リン酸水素二アンモニウム((NH4)2HPO4)(シグマアルドリッチ社製、純度98%以上)を、リチウムおよびリンの原子数比(Li:P)が、1:1となるように秤量した。秤量した各原料粉末を、メノウ乳鉢で15分間粉砕混合し、混合物を得た。
得られた焼成物を室温まで降温後、回転焼成炉から取り出し、除湿された窒素ガス雰囲気下に移して保管した。
水酸化リチウム一水和物(LiOH・H2O)(富士フイルム和光純薬(株)製、純度98.0%以上)、および、酸化ビスマス(富士フイルム和光純薬(株)製、純度99.9%)を、リチウムおよびビスマスの原子数比(Li:Bi)が、1:1となるように秤量した。秤量した各原料粉末を、メノウ乳鉢で15分間粉砕混合し、混合物を得た。
得られた焼成物を室温まで降温後、回転焼成炉から取り出し、除湿された窒素ガス雰囲気下に移して保管した。
市販品のホウ酸(H3BO3)(富士フイルム和光純薬(株)製、純度99.5%以上)を、そのまま用いた。
合成例1で得られたLiTa2PO8 と、合成例4で得られたLi3BO3 とを、モル比(LiTa2PO8:Li3BO3)が、0.975:0.025となるように秤量した。秤量した各化合物をジルコニアボールミルに入れ、そこに、適量のトルエンを加えて、直径1mmのジルコニアボールを用いて2時間粉砕混合することで、固体電解質材料(混合物)を得た。
錠剤成形機を用い、得られた固体電解質材料に、油圧プレスで40MPaの圧力をかけることで、直径10mm、厚さ1mmの円盤状成形体を形成し、次いでCIP(冷間静水等方圧プレス)により、円盤状成形体に300MPaの圧力をかけることでペレットを作製した。
得られたペレットをアルミナボートに入れ、回転焼成炉((株)モトヤマ製)を用い、空気(流量:100mL/分)の雰囲気下、昇温速度10℃/分の条件で850℃まで昇温し、該温度において96時間焼成を行い、固体電解質である焼結体を得た。
得られた焼結体を室温まで降温後、回転焼成炉から取り出し、除湿された窒素ガス雰囲気下に移して保管した。
得られた焼結体の両面に、スパッタ機を用いて金層を形成することで、イオン伝導度評価用の測定ペレットを得た。
得られた測定ペレットを、測定前に25℃の恒温槽に2時間保持した。次いで、25℃において、インピーダンスアナライザー(ソーラトロンアナリティカル社製、型番:1260A)を用い、振幅25mVの条件で、周波数1Hz~10MHzの範囲におけるACインピーダンス測定を行った。得られたインピーダンススペクトルを、装置付属の等価回路解析ソフトウェアZViewを用いて等価回路でフィッティングして、結晶粒内および結晶粒界における各リチウムイオン伝導度を求め、これらを合計することで、トータル伝導度を算出した。結果を表1に示す。
表1に記載の化合物(a)を用い、Li3BO3の混合量および焼成温度を表1の通りに変更した以外は、実施例1と同様にして、固体電解質材料を作製し、次いで、得た固体電解質材料を表1に記載の焼成温度で焼成して得た焼結体のトータル伝導度を測定した。結果を表1に示す。
なお、実施例2~10で得られた固体電解質材料は、XRD測定の結果、それぞれ非晶質であった。
表2に記載の化合物(a)を用い、化合物(b)としてLi4B2O5を用い、Li4B2O5の混合量および焼成温度を表2の通りに変更した以外は、実施例1と同様にして、固体電解質材料を作製し、次いで、得た固体電解質材料を表2に記載の焼成温度で焼成して得た焼結体のトータル伝導度を測定した。結果を表2に示す。
なお、実施例11~19で得られた固体電解質材料は、XRD測定の結果、それぞれ非晶質であった。
表3に記載の化合物(a)および(b)を用い、化合物(b)の混合量および焼成温度を表3の通りに変更した以外は、実施例1と同様にして、固体電解質材料を作製し、次いで、得た固体電解質材料を表3に記載の焼成温度で焼成して得た焼結体のトータル伝導度を測定した。結果を表3に示す。
なお、実施例20~26で得られた固体電解質材料は、XRD測定の結果、それぞれ非晶質であった。
Claims (21)
- リチウム、タンタル、リンおよび酸素を構成元素として含むリチウムイオン伝導性化合物(a)と、
ホウ素化合物、ビスマス化合物およびリン化合物から選ばれる少なくとも1種の前記リチウムイオン伝導性化合物(a)とは異なる化合物(b)と
を含む固体電解質材料。 - 非晶質である、請求項1に記載の固体電解質材料。
- 前記化合物(a)が単斜晶型構造を有する、請求項1に記載の固体電解質材料。
- 前記化合物(a)が、
組成式Li〔1+(5-a)x〕Ta2-xM1xPO8で表される化合物、または、組成式Li〔1+(5-b)y〕Ta2P1-yM2yO8で表される化合物であり、
ここで、M1は、Nb、Zr、Ga、Sn、Hf、WおよびMoからなる群より選ばれる1種以上の元素であり、0.0≦x<1.0であり、aはM1の平均価数であり、
M2は、Si、AlおよびGeからなる群より選ばれる1種以上の元素であり、0.0≦y<0.7であり、bはM2の平均価数である、
請求項1~3のいずれか1項に記載の固体電解質材料。 - 前記化合物(b)が、リチウムまたは水素を構成元素として含む化合物である、請求項1~4のいずれか1項に記載の固体電解質材料。
- タンタル元素の含有量が10.6~16.6原子%である、請求項1~5のいずれか1項に記載の固体電解質材料。
- リン元素の含有量が5.3~8.3原子%である、請求項1~6のいずれか1項に記載の固体電解質材料。
- リチウム元素の含有量が5.0~20.0原子%である、請求項1~7のいずれか1項に記載の固体電解質材料。
- 前記ホウ素化合物が、LiBO2、LiB3O5、Li2B4O7、Li3B11O18、Li3BO3、Li3B7O12、Li3.6B2O4.8、Li3.2B2O4.6、Li4B2O5、Li6B4O9、Li3-x5B1-x5Cx5O3、Li4-x6B2-x6Cx6O5、Li2.4Al0.2BO3、Li2.7Al0.1BO3、B2O3、および、H3BO3からなる群より選ばれる少なくとも1種の化合物であり、
0<x5<1であり、0<x6<2である、
請求項1~8のいずれか1項に記載の固体電解質材料。 - 前記ビスマス化合物が、LiBiO2、Li3BiO3、Li4Bi2O5、Li2.4Al0.2BiO3、および、Bi2O3からなる群より選ばれる少なくとも1種の化合物である、請求項1~9のいずれか1項に記載の固体電解質材料。
- 前記リン化合物が、LiPO3、および、Li3PO4からなる群より選ばれる少なくとも1種の化合物である、請求項1~10のいずれか1項に記載の固体電解質材料。
- 前記化合物(b)の含有量が、化合物(a)および(b)の合計100モル%に対し、1~40モル%である、請求項1~11のいずれか1項に記載の固体電解質材料。
- 前記化合物(a)と前記化合物(b)とを粉砕混合する工程を含む、請求項1~12のいずれか1項に記載の固体電解質材料の製造方法。
- 請求項1~12のいずれか1項に記載の固体電解質材料を用いて得られた固体電解質。
- 請求項1~12のいずれか1項に記載の固体電解質材料の焼結体である、固体電解質。
- 請求項1~12のいずれか1項に記載の固体電解質材料を500~900℃で焼成する工程を含む、請求項14または15に記載の固体電解質の製造方法。
- リチウム、タンタル、リンおよび酸素を構成元素として含むリチウムイオン伝導性化合物(a)と、ホウ素化合物、ビスマス化合物およびリン化合物から選ばれる少なくとも1種の前記リチウムイオン伝導性化合物(a)とは異なる化合物(b)とを粉砕混合して非晶質の固体電解質材料を作製する工程1と、
工程1で得られた固体電解質材料を焼成する工程2と
を含む、固体電解質の製造方法。 - 正極活物質を有する正極と、
負極活物質を有する負極と、
前記正極と前記負極との間に固体電解質層と、
を含み、
前記固体電解質層が、請求項14または15に記載の固体電解質を含む、
全固体電池。 - 前記正極活物質が、LiM3PO4、LiM5VO4、Li2M6P2O7、LiVP2O7、Lix7Vy7M7z7、Li1+x8Alx8M82-x8(PO4)3、LiNi1/3Co1/3Mn1/3O2、LiCoO2、LiNiO2、LiMn2O4、Li2CoP2O7、Li3V2(PO4)3、Li3Fe2(PO4)3、LiNi0.5Mn1.5O4およびLi4Ti5O12からなる群より選ばれる1種以上の化合物を含み、
M3は、Mn、Co、Ni、Fe、Al、TiおよびVからなる群より選ばれる1種以上の元素、またはVおよびOの2元素であり、
M5は、Fe、Mn、Co、Ni、AlおよびTiからなる群より選ばれる1種以上の元素であり、
M6は、Fe、Mn、Co、Ni、Al、TiおよびVからなる群より選ばれる1種以上の元素、またはVおよびOの2元素であり、
2≦x7≦4、1≦y7≦3、0≦z7≦1、1≦y7+z7≦3、M7は、Ti、Ge、Al、GaおよびZrからなる群より選ばれる1種以上の元素であり、
0≦x8≦0.8、M8は、TiおよびGeからなる群より選ばれる1種以上の元素である、
請求項18に記載の全固体電池。 - 前記負極活物質が、LiM3PO4、LiM5VO4、Li2M6P2O7、LiVP2O7、Lix7Vy7M7z7、Li1+x8Alx8M82-x8(PO4)3、(Li3-a9x9+(5-b9)y9M9x9)(V1-y9M10y9)O4、LiNb2O7、Li4Ti5O12、Li4Ti5PO12、TiO2、LiSiおよびグラファイトからなる群より選ばれる1種以上の化合物を含み、
M3は、Mn、Co、Ni、Fe、Al、TiおよびVからなる群より選ばれる1種以上の元素、またはVおよびOの2元素であり、
M5は、Fe、Mn、Co、Ni、AlおよびTiからなる群より選ばれる1種以上の元素であり、
M6は、Fe、Mn、Co、Ni、Al、TiおよびVからなる群より選ばれる1種以上の元素、またはVおよびOの2元素であり、
2≦x7≦4、1≦y7≦3、0≦z7≦1、1≦y7+z7≦3、M7は、Ti、Ge、Al、GaおよびZrからなる群より選ばれる1種以上の元素であり、
0≦x8≦0.8、M8は、TiおよびGeからなる群より選ばれる1種以上の元素であり、
M9は、Mg、Al、GaおよびZnからなる群より選ばれる1種以上の元素であり、M10は、Zn、Al、Ga、Si、Ge、PおよびTiからなる群より選ばれる1種以上の元素であり、0≦x9≦1.0、0≦y9≦0.6、a9はM9の平均価数であり、b9はM10の平均価数である、
請求項18または19に記載の全固体電池。 - 前記正極および負極が、請求項14または15に記載の固体電解質を含有する、請求項18~20のいずれか1項に記載の全固体電池。
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