Solid electrolyte, solid electrolyte layer, and solid electrolyte battery

Abstract

A solid electrolyte (10) according to the present invention contains LiaAbEc(SO4)dJeXfHh…(1). In formula (1), A is at least one element selected from an alkali metal and an alkaline earth metal of other than Li, E is at least one element selected from the group consisting of Al, Ga, In, Sc, Y, Ti, Zr, Hf, and lanthanoid, J is at least one group selected from the group consisting of OH, BO2, BO3, BO4, B3O6, B4O7, CO3, NO3, AlO2, SiO3, SiO4, Si2O7, Si3O9, Si4O11, Si6O18, PO3, PO4, P2O7, P3O10, SO3, SO5, S2O3, S2O4, S2O5, S2O6, S2O7, S2O8, BF4, PF6, BOB, (COO)2, N, AlCl4, CF3SO3, CH3COO, CF3COO, OOC-(CH2)2-COO, OOC-CH2-COO, OOC-CH(OH)-CH(OH)-COO, OOC-CH(OH)-CH2-COO, C6H5SO3, OOC-CH=CH-COO, OOC-CH=CH-COO, C(OH)(CH2COOH)2COO, AsO4, BiO4, CrO4, MnO4, PtF6, PtCl6, PtBr6, PtI6, SbO4, SeO4, TeO4, HCOO, and O, and X is at least one element selected from the group consisting of F, Cl, Br, and I, 0.5 ≤ a < 6, 0 ≤ b < 6, 0 < c < 2, 0.1 < d ≤ 6.0, 0 < e ≤ 6.0, 0 < f ≤ 6.1, and 0 ≤ h ≤ 0.2 are satisfied, and in an X-ray diffraction pattern with CuKα as the radiation source, a peak is confirmed at diffraction angle 2θ = 22.3°±1.0°.

Description

[Technical Field]

[0001] This invention relates to a solid electrolyte, a solid electrolyte layer, and a solid electrolyte battery. This application claims priority based on Japanese Patent Application No. 2022-038447, filed in Japan on March 11, 2022, and the contents of that application are incorporated herein by reference. [Background technology]

[0002] In recent years, advancements in electronics technology have been remarkable, leading to the miniaturization, weight reduction, thinning, and increased functionality of portable electronic devices. Consequently, there is a strong demand for smaller, lighter, thinner, and more reliable batteries, which power these devices, and solid-state electrolyte batteries, which use solid electrolytes, are attracting attention. Known solid electrolytes include oxide-based solid electrolytes, sulfide-based solid electrolytes, complex hydride-based solid electrolytes, and halide-based solid electrolytes.

[0003] For example, Non-Patent Document 1 states that the ionic conductivity of the halide-based solid electrolyte Li3ScCl6 is 3 mS / cm, and the potential window on the reducing side is 0.91 V (V vs. Li / Li + It is stated that... [Prior art documents] [Non-patent literature]

[0004] [Non-Patent Document 1] Jianwen Liang et al., Journal of American Chemical Society2020, 142, 7012-7022. [Overview of the Initiative] [Problems that the invention aims to solve]

[0005] Halide-based solid electrolytes are said to have higher ionic conductivity than oxide-based solid electrolytes, sulfide-based solid electrolytes, complex hydride-based solid electrolytes, etc. The ionic conductivity of Li3ScCl6 described in Non-Patent Document 1 (3 mS / cm) is high, but it is subject to various restrictions, and there are cases where the characteristics described in Non-Patent Document 1 do not appear as they are or other substances have to be selected. Therefore, in solid electrolytes with the same structure, a configuration that can relatively improve the ionic conductivity is required.

[0006] The present invention has been made in view of the above problems, and an object thereof is to provide a solid electrolyte, a solid electrolyte layer, and a solid electrolyte battery capable of improving ionic conductivity.

Means for Solving the Problems

[0007] In order to solve the above problems, the following means are provided.

[0008] (1) The solid electrolyte according to the first aspect contains Li a A b E c (SO4) d J e X f H h …(1). In formula (1), A is at least one element selected from alkali metals other than Li and alkaline earth metals, E is at least one element selected from the group consisting of Al, Ga, In, Sc, Y, Ti, Zr, Hf, and lanthanoids, and J is OH, BO2, BO3, BO4, B3O6, B4O7, CO3, NO3, AlO₂, SiO3, SiO4, Si2O7, Si3O9, Si4O 11 、Si6O 18 、PO3、PO4、P2O7、P3O 10It is at least one group selected from the group consisting of SO3, SO5, S2O3, S2O4, S2O5, S2O6, S2O7, S2O8, BF4, PF6, BOB, (COO)2, N, AlCl4, CF3SO3, CH3COO, CF3COO, OOC-(CH2)2-COO, OOC-CH2-COO, OOC-CH(OH)-CH(OH)-COO, OOC-CH(OH)-CH2-COO, C6H5SO3, OOC-CH=CH-COO, OOC-CH=CH-COO, C(OH)(CH2COOH)2COO, AsO4, BiO4, CrO4, MnO4, PtF6, PtCl6, PtBr6, PtI6, SbO4, SeO4, TeO4, HCOO, O, and X is at least one element selected from the group consisting of F, Cl, Br, I. Further, in formula (1), 0.5≦a<6, 0≦b<6, 0<c<2, 0.1<d≦6.0, 0<e≦6.0, 0<f≦6.1, 0≦h≦0.2 are satisfied. Also, in the X-ray diffraction pattern with Cu-Kα as the radiation source, a peak is confirmed at a diffraction angle 2θ = 22.3° ± 1.0° for the solid electrolyte according to the first aspect.

[0009] (2) In the X-ray diffraction pattern with Cu-Kα as the radiation source for the solid electrolyte according to the above aspect, a peak may be confirmed at a diffraction angle 2θ = 36.4° ± 1.0°.

[0010] (3) In X-ray photoelectron spectroscopy measurement for the solid electrolyte according to the above aspect, peaks may be confirmed at 170 ± 0.5 eV and 532 ± 0.5 eV.

[0011] (4) The ionic conductivity of the solid electrolyte according to the above aspect at 25°C may be 1 mS / cm or more.

[0012] (5) The solid electrolyte layer according to the second aspect contains the solid electrolyte according to the above aspect.

[0013] (6) The solid electrolyte battery according to the third aspect includes a negative electrode, a positive electrode, and a solid electrolyte layer containing a solid electrolyte between the negative electrode and the positive electrode. At least one of the negative electrode, the positive electrode, and the solid electrolyte layer contains the solid electrolyte according to the above aspect.

[0014] (7) The solid electrolyte battery according to the fourth aspect includes a negative electrode, a positive electrode, and a solid electrolyte layer according to the above aspect provided between the negative electrode and the positive electrode.

Advantages of the Invention

[0015] The solid electrolyte according to the above aspect can improve ion conductivity.

Brief Description of the Drawings

[0016] [Figure 1] This is the X-ray diffraction result of the solid electrolyte according to this embodiment. [Figure 2] This is the X-ray diffraction result of the solid electrolyte containing the compound of formula (1). [Figure 3A] Among the graphs showing the X-ray photoelectron spectroscopy measurement results of the solid electrolyte according to this embodiment, the range where the peak derived from O1s occurs is enlarged. [Figure 3B] Among the graphs showing the X-ray photoelectron spectroscopy measurement results of the solid electrolyte according to this embodiment, the range where the peak derived from S2p occurs is enlarged. [Figure 4] [[ID=3=3]]This is a schematic cross-sectional view of the solid electrolyte battery 100 according to this embodiment. [Figure 5] The X-ray diffraction result of Comparative Example 4 is shown. [Figure 6] These are the charge / discharge curves of Example 4 and Comparative Examples 3 and 4.

Modes for Carrying Out the Invention

[0017] Hereinafter, this embodiment will be described in detail with appropriate reference to the drawings. The drawings used in the following description may show the characteristic parts enlarged for convenience of understanding the features of the present invention, and the dimensional ratios of each component may be different from the actual ones. The materials, dimensions, etc. exemplified in the following description are merely examples, and the present invention is not limited thereto, and can be appropriately changed and implemented without changing the gist thereof.

[0018] "Solid electrolyte" Solid electrolytes are materials that can move ions by applying an external electric field. If the ionic conductivity of the solid electrolyte is high, the transfer of ions in the solid electrolyte battery becomes smoother, and the internal resistance becomes lower.

[0019] The solid electrolyte is Li a A b E c (SO4) d J e X f H h ...contains a halide-based solid electrolyte represented by (1). The solid electrolyte may include materials derived from the raw material powder in addition to the compound represented by formula (1) above. An example of a substance derived from the raw material powder is Li2SO4.

[0020] The solid electrolyte may be in the form of a powder (particles) or a sintered body formed by sintering powder. Alternatively, the solid electrolyte may be a molded body formed by compressing powder, a molded body formed by molding a mixture of powder and a binder, or a coating film formed by applying a paint containing powder, binder, and solvent, and then heating to remove the solvent. Furthermore, the main structure of the solid electrolyte may be amorphous or crystalline.

[0021] In formula (1), Li is a lithium ion. a satisfies 0.5 ≤ a < 6, preferably 2.0 ≤ a ≤ 4.0, and more preferably 2.5 ≤ a ≤ 3.5. When E is Zr or Hf, a is preferably 1.0 ≤ a ≤ 3.0, and more preferably 1.5 ≤ a ≤ 2.5. In the compound represented by formula (1), if a is 0.5 ≤ a < 6, the Li content in the compound becomes appropriate, and the ionic conductivity of the solid electrolyte layer 10 increases.

[0022] In formula (1), A is at least one element selected from alkali metals other than Li and alkaline earth metals. A is substituted for a part of Li ions. A is, for example, Na or Ca. When A is Na or Ca, the potential window on the reduction side of the solid electrolyte becomes wider. b satisfies 0 ≦ b < 6. Also, a + b satisfies 0.5 ≦ a + b < 6.

[0023] In formula (1), E is an essential component and is at least one element selected from the group consisting of Al, Ga, In, Sc, Y, Ti, Zr, Hf, and lanthanoids (La, Ce, Pr, Nd, Pm, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu). E preferably contains Al, Sc, Y, Zr, Hf, and La, and more preferably contains Zr and Y. E improves the ionic conductivity of the solid electrolyte. c satisfies 0 < b < 2. Since the effect of including E can be obtained more effectively, c is preferably 0.6 ≦ c. Also, E is an element that forms the skeleton of the solid electrolyte. c is more preferably c ≦ 1.

[0024] In formula (1), SO4 is a sulfate. d satisfies 0.1 < d ≦ 6.0, preferably satisfies 0.2 ≦ d ≦ 4.0, and more preferably satisfies 0.4 ≦ d ≦ 2.5. When the solid electrolyte contains a sulfate, the potential window on the reduction side of the solid electrolyte becomes wider and it becomes less likely to be reduced.

[0025] In formula (1), J is, for example, OH, BO2, BO3, BO4, B3O6, B4O7, CO3, NO3, AlO2, SiO3, SiO4, Si2O7, Si3O9, Si4O 11 、Si6O 18 、PO3、PO4、P2O7、P3O 10, at least one group selected from the group consisting of SO3, SO5, S2O3, S2O4, S2O5, S2O6, S2O7, S2O8, BF4, PF6, BOB (bisoxalate borate), (COO)2, N, AlCl4, CF3SO3, CH3COO, CF3COO, OOC-(CH2)2-COO (succinate), OOC-CH2-COO (malonate), OOC-CH(OH)-CH(OH)-COO (tartrate), OOC-CH(OH)-CH2-COO (malate), C6H5SO3 (benzenesulfonate), OOC-CH=CH-COO (fumarate), OOC-CH=CH-COO (maleate), C(OH)(CH2COOH)2COO (citrate), AsO4, BiO4, CrO4, MnO4, PtF6, PtCl6, PtBr6, PtI6, SbO4, SeO4, TeO4, HCOO, O. J is preferably at least one group selected from the group consisting of OH, SO4, CH3COO, CF3COO, HCOO, O. J is substituted with a part of sulfate.

[0026] e satisfies 0≦e≦6. Since the effect of widening the potential window on the reduction side due to the inclusion of J becomes more prominent, it is preferable that 0.5≦e. In order not to cause a decrease in the ionic conductivity of the solid electrolyte due to too much content of J, it is preferable that e≦3. Also, d + e satisfies 0.1<d≦6.0.

[0027] X is at least one selected from the group consisting of F, Cl, Br, I. In order to increase the ionic conductivity of the solid electrolyte, X is preferably at least one selected from the group consisting of Cl, Br, I, preferably contains Br and / or I, and particularly preferably contains I. When X contains F, since X becomes a solid electrolyte with high ionic conductivity, it is preferable that X contains F and two or more selected from the group consisting of Cl, Br, I.

[0028] When X is F, it becomes a solid electrolyte with sufficiently high ionic conductivity and excellent oxidation resistance. When X is Cl, it becomes a solid electrolyte with high ionic conductivity and a good balance between oxidation resistance and reduction resistance. When X is Br, it becomes a solid electrolyte with sufficiently high ionic conductivity and a good balance between oxidation resistance and reduction resistance. When X is I, it becomes a solid electrolyte with high ionic conductivity.

[0029] f satisfies 0 < f ≤ 6.1. It is preferable that d ≥ 1. When f ≥ 1, the strength of the pellet becomes high when the solid electrolyte is pressure-molded into a pellet shape. Also, when f ≥ 1, the ionic conductivity of the solid electrolyte becomes high. Further, it is preferable that f ≤ 5 so that the sulfate is not insufficient due to too much content of X and the potential window of the solid electrolyte does not become narrow.

[0030] In formula (1), H is hydrogen. h satisfies 0 ≤ h ≤ 0.2.

[0031] The solid electrolyte is, for example, Li2ZrSO4Cl4, Li3YSO4Cl4, Li3ScSO4Cl4, Li3InSO4Cl4.

[0032] FIG. 1 shows the result of X-ray diffraction (XRD) of the solid electrolyte according to this embodiment. The vertical axis in FIG. 1 is intensity, and the horizontal axis is 2θ. The X-ray diffraction was performed using a Cu-α ray source. The X-ray diffraction pattern shown in FIG. 1 is obtained by removing the background data of the polyimide tape from the measurement results. FIG. 1 shows the X-ray diffraction result of Example 4 described later. As shown in FIG. 1, in the X-ray diffraction pattern with Cu-Kα as the ray source, a peak is confirmed at a diffraction angle 2θ = 22.3° ± 1.0° for the solid electrolyte according to this embodiment. Also, in the X-ray diffraction pattern with Cu-Kα as the ray source for the solid electrolyte according to this embodiment, a peak may also be confirmed at a diffraction angle 2θ = 36.4° ± 1.0°.

[0033] These peaks are thought to originate from Li2SO4, the starting material used to prepare the compound of equation (1). The peak occurring at the diffraction angle 2θ = 22.3° ± 1.0° is the first peak, which shows the greatest intensity in the X-ray diffraction pattern of Li2SO4. The peak occurring at the diffraction angle 2θ = 36.4° ± 1.0° is a peak that shows a relatively large intensity in the X-ray diffraction pattern of Li2SO4.

[0034] These peaks disappear when the raw materials react sufficiently. Figure 2 shows the X-ray diffraction results of a solid electrolyte containing the compound of formula (1). The X-ray diffraction pattern shown in Figure 2 is the raw measured data and does not include background data from the polyimide tape. The reaction between the raw materials progresses from the foreground to the background of the paper. As shown in Figure 2, the peaks that occur at diffraction angles 2θ = 22.3° ± 1.0° and 2θ = 36.4° ± 1.0° disappear as the reaction between the raw materials progresses. Therefore, the presence of these peaks in the solid electrolyte according to this embodiment suggests that some unreacted raw material powder (LiSO4) remains.

[0035] Figures 3A and 3B show enlarged views of the peak ranges in the graphs illustrating the X-ray photoelectron spectroscopy results of the solid electrolyte according to this embodiment. In the solid electrolyte according to this embodiment, peaks are observed at, for example, 170±0.5eV and 532±0.5eV. The peak at 170±0.5eV is a peak originating from sulfur (S2p), which is observed when a sulfur-oxygen bonded structure is present, and the peak at 532±0.5eV is a peak originating from oxygen (O1s), which is also observed when a sulfur-oxygen bonded structure is present. In other words, the solid electrolyte has a portion with an SO4 structure, and this structure is thought to originate from unreacted raw material powder (LiSO4).

[0036] As described above, the solid electrolyte according to this embodiment exhibits a specific peak in X-ray diffraction and high ionic conductivity. For example, the ionic conductivity of the solid electrolyte according to this embodiment is 1 mS / cm or higher. The reason why the ionic conductivity of a solid electrolyte increases when it exhibits a specific peak in X-ray diffraction is not clear, but it is thought that the remaining crystalline LiSO4 acts as a starting point for forming a microstructure with channels through which Li ions can conduct within the solid electrolyte.

[0037] "Solid electrolyte battery" Figure 4 is a schematic cross-sectional view of the solid electrolyte battery 100 according to this embodiment. The solid electrolyte battery 100 shown in Figure 4 comprises a power generation element 40 and an outer casing 50. The outer casing 50 covers the periphery of the power generation element 40. The power generation element 40 is connected to the outside by a pair of connected terminals 60 and 62. Although Figure 1 shows a stacked battery, a wound-type battery may also be used. The solid electrolyte battery 100 can be used, for example, in laminated batteries, prismatic batteries, cylindrical batteries, coin-type batteries, button-type batteries, etc.

[0038] <Power generation element> The power generation element 40 comprises a solid electrolyte layer 10, a positive electrode 20, and a negative electrode 30. The power generation element 40 charges or discharges through the exchange of ions between the positive electrode 20 and the negative electrode 30 via the solid electrolyte layer 10 and through the exchange of electrons via an external circuit.

[0039] (solid electrolyte layer) The solid electrolyte layer 10 is sandwiched between the positive electrode 20 and the negative electrode 30. The solid electrolyte layer 10 contains a solid electrolyte that can move ions by an externally applied voltage. For example, the solid electrolyte conducts lithium ions and inhibits electron movement.

[0040] The solid electrolyte layer 10 is, for example, a halide-based solid electrolyte. The solid electrolyte layer 10 contains, for example, the solid electrolyte described above. If the positive electrode 20 or the negative electrode 30 contains the solid electrolyte described above, the solid electrolyte contained in the solid electrolyte layer 10 does not have to be the one described above.

[0041] (positive electrode) As shown in Figure 4, the positive electrode 20 has a plate-shaped (foil-shaped) positive electrode current collector 22 and a positive electrode mixture layer 24. The positive electrode mixture layer 24 is in contact with at least one surface of the positive electrode current collector 22.

[0042] The positive electrode current collector 22 can be made of any electronically conductive material that can withstand oxidation during charging and is resistant to corrosion. The positive electrode current collector 22 is, for example, a metal such as aluminum, stainless steel, nickel, or titanium, or a conductive resin. The positive electrode current collector 22 may also be in the form of powder, foil, punched, or expanded material.

[0043] The positive electrode mixture layer 24 contains a positive electrode active material and, if necessary, a solid electrolyte, a binder, and a conductive additive.

[0044] The positive electrode active material is not particularly limited as long as it can reversibly carry out intercalation and deintercalation of lithium ions, and any positive electrode active material used in known solid electrolyte batteries can be used. Examples of positive electrode active materials include lithium-containing metal oxides and lithium-containing metal phosphorus oxides.

[0045] Lithium-containing metal oxides include, for example, lithium cobalt oxide (LiCoO2), lithium nickel oxide (LiNiO2), lithium manganese spinel (LiMn2O4), and LiNi x Co y Mn z Composite metal oxides represented by O2(x+y+z=1), lithium vanadium compounds (LiVOPO4, Li3V2(PO4)3), olivine-type LiMPO4 (where M represents at least one selected from Co, Ni, Mn, and Fe), lithium titanate (Li4Ti5O 12 ) etc.

[0046] Furthermore, the positive electrode active material may not contain lithium. Examples of such positive electrode active materials include lithium-free metal oxides (MnO2, V2O5, etc.), lithium-free metal sulfides (MoS2, etc.), and lithium-free fluorides (FeF3, VF3, etc.). When using a lithium-free positive electrode active material, the negative electrode is pre-doped with lithium ions, or a negative electrode containing lithium ions is used.

[0047] The solid electrolyte contained in the positive electrode 20 is, for example, the solid electrolyte described above. The solid electrolyte contained in the positive electrode 20 may also be a halide-based solid electrolyte other than the solid electrolyte described above.

[0048] The content of the solid electrolyte in the positive electrode mixture layer 24 is not particularly limited, but is preferably 1% to 50% by mass, and more preferably 5% to 30% by mass, based on the total mass of the positive electrode active material, solid electrolyte, conductive additive, and binder.

[0049] The binder binds the positive electrode active material, solid electrolyte, and conductive additive together within the positive electrode mixture layer 24, and firmly adheres the positive electrode mixture layer 24 to the positive electrode current collector 22. The positive electrode mixture layer 24 preferably contains the binder. The binder preferably has oxidation resistance and good adhesion.

[0050] Examples of binders used in the positive electrode mixture layer 24 include polyvinylidene fluoride (PVDF) or its copolymer, polytetrafluoroethylene (PTFE), polyamide (PA), polyimide (PI), polyamideimide (PAI), polybenzimidazole (PBI), polyethersulfone (PES), polyacrylic acid (PA) and its copolymers, metal ion crosslinked polyacrylic acid (PA) and its copolymers, polypropylene (PP) grafted with maleic anhydride, polyethylene (PE) grafted with maleic anhydride, or mixtures thereof. Among these, PVDF is particularly preferred as the binder.

[0051] The binder content in the positive electrode mixture layer 24 is not particularly limited, but is preferably 1% to 15% by mass, and more preferably 3% to 5% by mass, based on the total mass of the positive electrode active material, solid electrolyte, conductive additive, and binder. If the amount of binder is too small, it tends not to be possible to form a positive electrode 20 with sufficient adhesive strength. Conversely, if the amount of binder is too large, since general binders are electrochemically inert, they do not contribute to the discharge capacity, and it tends not to be possible to obtain a sufficient volume or mass energy density.

[0052] The conductive additive improves the electronic conductivity of the positive electrode mixture layer 24. Known conductive additives can be used. Examples of conductive additives include carbon materials such as carbon black, graphite, carbon nanotubes, and graphene; metals such as aluminum, copper, nickel, stainless steel, iron, and amorphous metals; conductive oxides such as ITO; or mixtures thereof. The conductive additive may be in powder or fiber form.

[0053] The content of the conductive additive in the positive electrode mixture layer 24 is not particularly limited. When a conductive additive is added, the mass ratio of the conductive additive is usually preferably 0.5% to 20% by mass, and more preferably 1% to 5% by mass, based on the total mass of the positive electrode active material, solid electrolyte, conductive additive, and binder.

[0054] (Negative electrode) As shown in Figure 4, the negative electrode 30 has a negative electrode current collector 32 and a negative electrode mixture layer 34. The negative electrode mixture layer 34 is in contact with the negative electrode current collector 32.

[0055] The negative electrode current collector 32 only needs to be electrically conductive. The negative electrode current collector 32 can be, for example, a metal such as copper, aluminum, nickel, stainless steel, or iron, or a conductive resin. The negative electrode current collector 32 may also be in the form of powder, foil, punched, or expanded material.

[0056] The negative electrode mixture layer 34 contains a negative electrode active material and, if necessary, a solid electrolyte, a binder, and a conductive additive.

[0057] The negative electrode active material is not particularly limited, as long as it can reversibly carry out the intercalation and release of lithium ions, and the insertion and deintercalation of lithium ions. Any negative electrode active material used in known solid-state electrolyte batteries can be used.

[0058] The negative electrode active material can be, for example, carbon materials such as natural graphite, artificial graphite, mesocarbon microbeads, mesocarbon fiber (MCF), coke, glassy carbon, and calcined organic compounds, as well as Si and SiO2. x Metals that can combine with lithium, such as Sn and aluminum, alloys of these metals, composite materials of these metals and carbon materials, lithium titanate (Li4Ti5O 12 These include oxides such as SnO2 and metallic lithium. Natural graphite is preferred as the negative electrode active material.

[0059] The solid electrolyte contained in the negative electrode 30 is, for example, the solid electrolyte described above. The solid electrolyte contained in the negative electrode 30 may also be a halide-based solid electrolyte other than the solid electrolyte described above.

[0060] The binder and conductive additive contained in the negative electrode 30 are the same as those contained in the positive electrode 20.

[0061] <Exterior> The outer casing 50 houses the power generation element 40 inside. The outer casing 50 prevents moisture and other elements from entering the interior from the outside. The outer casing 50 has, for example, a metal foil 52 and resin layers 54 laminated on each surface of the metal foil 52, as shown in Figure 4. The outer casing 50 is a metal laminate film in which the metal foil 52 is coated on both sides with resin layers 54.

[0062] The metal foil 52 is, for example, aluminum foil or stainless steel foil. The resin layer 54 can be, for example, a resin film such as polypropylene. The materials constituting the resin layer 54 may be different on the inside and outside. For example, a polymer with a high melting point, such as polyethylene terephthalate (PET) or polyamide (PA), can be used as the outer material, while polyethylene (PE) or polypropylene (PP) can be used as the inner material.

[0063] <Terminal> Terminals 60 and 62 are connected to the positive electrode 20 and the negative electrode 30, respectively. Terminal 60, connected to the positive electrode 20, is the positive terminal, and terminal 62, connected to the negative electrode 30, is the negative terminal. Terminals 60 and 62 are responsible for electrical connections to the outside. Terminals 60 and 62 are made of conductive materials such as aluminum, nickel, and copper. The connection method may be welding or screw fastening. It is preferable to protect terminals 60 and 62 with insulating tape to prevent short circuits.

[0064] [Manufacturing method for solid electrolyte batteries] Next, a method for manufacturing a solid electrolyte battery according to this embodiment will be described. First, the solid electrolyte is prepared. The solid electrolyte can be manufactured, for example, by mixing raw material powders containing predetermined elements in a predetermined molar ratio and carrying out a mechanochemical reaction. When carrying out the mechanochemical reaction, adjustments are made so that unreacted raw materials remain in the solid electrolyte. Specifically, unreacted components of the raw materials can be left behind by changing the rotation speed, revolution speed, synthesis time, and the state of the raw material powder at the time of input of the planetary ball mill.

[0065] When a halogenated raw material is present in the raw material powder, the halogenated raw material tends to evaporate when the temperature is raised. For this reason, halogen gas may be present in the atmosphere during sintering to supplement the halogen. Alternatively, when a halogenated raw material is present in the raw material powder, sintering may be performed by hot pressing using a highly airtight mold. In this case, because the mold is highly airtight, evaporation of the halogenated raw material due to sintering can be suppressed. By sintering in this manner, a solid electrolyte in the form of a sintered body made of a compound having a predetermined composition can be obtained.

[0066] Next, the positive electrode 20 is prepared. The positive electrode is manufactured by applying a paste containing the positive electrode active material onto the positive electrode current collector 22 and drying it to form a positive electrode mixture layer 24. The above-mentioned solid electrolyte may be added to the paste containing the positive electrode active material.

[0067] Next, the negative electrode 30 is prepared. The negative electrode is manufactured by applying a paste containing the negative electrode active material onto the negative electrode current collector 32 and drying it to form a negative electrode mixture layer 34. The above-mentioned solid electrolyte may be added to the paste containing the negative electrode active material.

[0068] The power generation element 40 can be manufactured, for example, using a powder molding method. A guide with holes is placed on the positive electrode 20, and a solid electrolyte is filled into the guide. Then, the surface of the solid electrolyte is smoothed, and the negative electrode 30 is placed on top of the solid electrolyte. This sandwiches the solid electrolyte between the positive electrode 20 and the negative electrode 30. Then, pressure is applied to the positive electrode 20 and the negative electrode 30 to pressure-molde the solid electrolyte. By pressure molding, a laminate is obtained in which the positive electrode 20, the solid electrolyte layer 10, and the negative electrode 30 are stacked in that order.

[0069] Next, external terminals are welded to the positive electrode current collector 22 of the positive electrode 20 and the negative electrode current collector 32 of the negative electrode 30, respectively, using a known method, thereby electrically connecting the positive electrode current collector 22 or the negative electrode current collector 32 to the external terminals. After that, the laminate connected to the external terminals is housed in the outer casing 50, and the opening of the outer casing 50 is sealed by heat sealing. Through these steps, the solid electrolyte battery 100 of this embodiment is obtained.

[0070] Because the solid electrolyte battery 100 according to this embodiment contains the above-mentioned solid electrolyte, the conduction of Li ions is smooth and the internal resistance is low.

[0071] Although embodiments of the present invention have been described in detail above with reference to the drawings, the configurations and combinations thereof in each embodiment are merely examples, and additions, omissions, substitutions, and other modifications to the configurations are possible without departing from the spirit of the present invention. [Examples]

[0072] "Example 1" (Preparation of solid electrolytes) In a glove box with a dew point of approximately -75°C, the raw material powders of zirconium chloride (ZrCl4) and lithium sulfate (Li2SO4) were weighed in a molar ratio of 1:8. First, the Li2SO4 before mixing was ground for 1 hour using a planetary ball mill. The rotation speed during grinding was set to 300 rpm. Next, the raw material powders were placed into a zirconia sealed container for the planetary ball mill, which already contained zirconia balls. Then, the sealed container was covered with a lid, screwed to the container body, and the gap between the lid and the container was sealed with polyimide tape. The polyimide tape has the effect of blocking moisture. Next, the zirconia sealed container was set in the planetary ball mill. The rotation speed was set to 200 rpm and the revolution speed to 200 rpm, and the raw material powders were mixed with the rotation and revolution directions in opposite directions, and a mechanochemical reaction was carried out for 2 hours to obtain a solid electrolyte (Li4Zr). 0.25 (SO4)2Cl) was produced.

[0073] Planetary ball mills are typically installed in a normal atmosphere (air). The zirconia sealed container for the planetary ball mill is screwed in and further sealed with polyimide tape. When the zirconia sealed container is set on the planetary ball mill, it is firmly pressed and secured. Therefore, even in a normal atmosphere, it is considered that there is virtually no moisture contamination from the air inside the zirconia sealed container.

[0074] [XRD measurement] The prepared solid electrolyte was packed into an XRD measurement holder in a glove box with a dew point of approximately -70°C and circulating argon gas. Then, polyimide tape (vacuum-dried at 70°C for 16 hours) was applied to cover the packed surface for moisture protection and sealed, preparing the sample for XRD measurement. Next, it was removed to the air, and XRD measurements were performed using an X-ray diffractometer (Panalytical X'PertPro). The X-ray source used was Cu-Kα rays (measurement wavelength = 0.799407 Å).

[0075] Furthermore, under the same conditions as the XRD measurement described above, only the polyimide tape used for moisture protection was attached to the XRD measurement holder, and background measurements were performed. The X-ray diffraction pattern of the fabricated solid electrolyte had peaks at diffraction angles 2θ = 22.3° ± 1.0° and 2θ = 36.4° ± 1.0°.

[0076] [XPS measurement] X-ray photoelectron spectroscopy measurements were also performed. Sampling was carried out in a glove box with a dew point of approximately -70°C and circulating argon gas, and the samples were transported to the XPS measurement device in an air-free state. XPS measurements were performed using a Quantera2 from PHI. As a result, peaks were observed in the prepared solid electrolyte at 170±0.5eV and 532±0.5eV.

[0077] [Measurement of ionic conductivity] Next, the obtained solid electrolyte powder was filled into a pressure molding die in a glove box with a dew point of approximately -70°C and circulating argon gas. A cell for measuring ionic conductivity was then fabricated by pressure molding under a load of approximately 30 kN.

[0078] The compression molding die consists of a 10mm diameter PEEK (polyetheretherketone) cylinder, and an upper and lower punch made of SKD11 material with a diameter of 9.99mm.

[0079] Subsequently, a 50mm diameter, 5mm thick stainless steel disc and a Teflon (trademark registered) disc, both with four screw holes, were prepared, and the pressure forming die was set up as follows: Stainless steel disc / Teflon (trademark registered) disc / pressure forming die / Teflon (trademark registered) disc / stainless steel disc. The four screws were tightened to a torque of approximately 3 N·m. Screws were also inserted into the screw holes provided on the sides of the upper and lower punches to serve as external connection terminals.

[0080] The external connection terminal was connected to a potentiostat (VersaSTAT3, Princeton Applied Research, Inc.) equipped with a frequency response analyzer, and the ionic conductivity was measured using the impedance measurement method. Measurements were taken in the frequency range of 1 MHz to 0.1 Hz, with an amplitude of 10 mV and a temperature of 25°C. The ionic conductivity of the solid electrolyte in Example 1 was 1.1 × 10⁻¹⁶. -3 The value was S / cm.

[0081] Examples 2-8 Examples 2-8 differ from Example 1 in that the raw material powders and their molar ratios were changed. Similar to Example 1, solid electrolytes were measured in Examples 2-8. The composition, molar ratio, and measurement results of each raw material are shown in Table 1 below.

[0082] Examples 9-21 Examples 9-21 differ from Example 1 in that the raw material powder materials and molar ratios were changed, and the manufacturing conditions for the solid electrolyte were altered. In Examples 9-21, the solid electrolyte was measured in the same manner as in Example 1.

[0083] Examples 9-21 were prepared using the following procedure. First, zirconium chloride (ZrCl4), lithium sulfate (Li2SO4), and other raw materials were weighed in a glove box with a dew point of approximately -75°C to the predetermined molar ratio. Next, the Li2SO4 before mixing was ground using a planetary ball mill at a rotation speed of 300 rpm for 1 hour, then ZrCl4 was added and ground further at a rotation speed of 200 rpm for 1 hour. Then, the ground sample and other raw materials were placed in a zirconia sealed container for the planetary ball mill that already contained zirconia balls. The rotation speed was set to 200 rpm and the revolution speed to 200 rpm, with the rotation direction and revolution direction being opposite, and a mechanochemical reaction was carried out for a predetermined time to produce the desired solid electrolyte.

[0084] In Examples 9-21, the solid electrolyte was measured in the same manner as in Example 1. The composition, molar ratio, and measurement results of each raw material are shown in Table 1 below.

[0085] Examples 22-25 Examples 22-25 differ from Example 1 in that the raw material powders and their molar ratios were changed, and the manufacturing conditions for the solid electrolyte were altered. In Examples 22-25, the solid electrolyte was measured in the same manner as in Example 1.

[0086] Examples 22-25 were prepared using the following procedure. First, Li2O, ZrCl4, and Li2SO4 were weighed in a glove box with a dew point of approximately -75°C to the predetermined molar ratios. First, the Li2SO4 was pulverized at 200 rpm for 1 hour before mixing. Next, Li2O and ZrCl4 were mixed at 300 rpm for 48 hours, and then Li2SO4 was added and a mechanochemical reaction was carried out for a predetermined time to produce the desired solid electrolyte.

[0087] In Examples 22-25, the solid electrolyte was measured in the same manner as in Example 1. The composition, molar ratio, and measurement results of each raw material are shown in Table 2 below.

[0088] Example 26 Example 26 differs from Example 1 in that the raw material powder materials and molar ratios were changed, and the manufacturing conditions for the solid electrolyte were altered. In Example 26, the solid electrolyte was measured in the same manner as in Example 1.

[0089] First, in a glove box with a dew point of approximately -75°C, Li3PO4, ZrCl4, and Li2SO4 were weighed out in predetermined molar ratios. The Li2SO4 was first ground at 200 rpm for 1 hour before mixing. Next, Li3PO4 and ZrCl4 were mixed at 300 rpm for 24 hours, after which Li2SO4 was added and a mechanochemical reaction was carried out for a predetermined time to produce the desired solid electrolyte.

[0090] In Example 26, the solid electrolyte was measured in the same manner as in Example 1. The composition, molar ratio, and measurement results of each raw material are shown in Table 2 below.

[0091] Examples 27-29 Examples 27-29 differ from Example 1 in that the raw material powders and their molar ratios were changed, and the manufacturing conditions for the solid electrolyte were altered. In Examples 27-29, the solid electrolyte was measured in the same manner as in Example 1.

[0092] First, Li2O and LiX were mixed in a molar ratio of 2:1 in a glove box with a dew point of approximately -75°C. The mixing was carried out using the planetary ball mill described above at a rotation speed of 300 rpm for 48 hours. Next, LZSOC synthesized in Example 4 was added, and a mechanochemical reaction was carried out at a rotation speed of 200 rpm for a predetermined time to produce the desired solid electrolyte.

[0093] In Examples 27-29, the solid electrolyte was measured in the same manner as in Example 1. The composition, molar ratio, and measurement results of each raw material are shown in Table 2 below.

[0094] Examples 30 and 31 Examples 30 and 31 differ from Example 4 in that the dew point of the dry room during mixing was -40°C for Example 30 and -60°C for Example 31. All other conditions were the same as in Example 4, and the solid electrolyte was measured. The composition, molar ratio, and measurement results of each raw material are shown in Table 2 below.

[0095] Examples 32-34 Examples 32-34 differ from Example 1 in that the raw material powders and their molar ratios were changed, and the manufacturing conditions for the solid electrolyte were altered. In Examples 32-34, the solid electrolyte was measured in the same manner as in Example 1.

[0096] First, ZrCl4 and LiX were mixed in a predetermined molar ratio in a glove box with a dew point of approximately -75°C. The mixing was carried out using the planetary ball mill described above at a rotation speed of 300 rpm for 24 hours. Next, LZSOC synthesized in Example 4 was added, and a mechanochemical reaction was carried out at a rotation speed of 200 rpm for a predetermined time to produce the desired solid electrolyte.

[0097] In Examples 32-34, the solid electrolyte was measured in the same manner as in Example 1. The composition, molar ratio, and measurement results of each raw material are shown in Tables 3 and 4 below.

[0098] Examples 35-45 Examples 35-45 differ from Example 1 in that the raw material powders and their molar ratios were changed, and the manufacturing conditions for the solid electrolyte were altered. In Examples 35-45, the solid electrolyte was measured in the same manner as in Example 1.

[0099] First, ZrCl4, LiCl, and LiX were mixed in a predetermined molar ratio in a glove box with a dew point of approximately -75°C. The mixing was carried out using the planetary ball mill described above at a rotation speed of 300 rpm for 24 hours. Next, LZSOC synthesized in Example 4 was added, and a mechanochemical reaction was carried out at a rotation speed of 200 rpm for a predetermined time to produce the desired solid electrolyte.

[0100] In Examples 35-45, the solid electrolyte was measured in the same manner as in Example 1. The composition, molar ratio, and measurement results of each raw material are shown in Tables 3 and 4 below.

[0101] "Comparative Examples 1-11" Comparative Examples 1 to 11 differ from Example 1 in that the raw material powder materials and molar ratios were changed, and the manufacturing conditions for the solid electrolyte were altered. In Comparative Examples 1 to 11, the solid electrolyte was measured in the same manner as in Example 1.

[0102] The methods for producing solid electrolytes in Comparative Examples 1 to 11 differ from the method for producing solid electrolytes in Example 1 in that the rotational speed of the planetary balls during the mechanochemical reaction is set to 300 rpm and the revolutional speed is set to 300 rpm, Li2SO4 is used without being crushed before mixing, and the reaction time of the mechanochemical reaction (mixing time of the raw material powder) is different.

[0103] In Comparative Examples 1 to 11, the solid electrolyte was measured in the same manner as in Example 1. The composition, molar ratio, and measurement results of each raw material are shown in Table 2 below. Figure 5 shows the X-ray diffraction results for Comparative Example 4. In Comparative Example 4, no peaks were observed at diffraction angles 2θ = 22.3° ± 1.0° and 2θ = 36.4° ± 1.0°. The X-ray diffraction pattern shown in Figure 5 is obtained by removing the background data of the polyimide tape from the measurement results.

[0104] "Comparative Example 12" Comparative Example 12 differs from Example 4 in that the dew point of the dry room during mixing is -20°C. All other conditions were the same as in Example 4, and the solid electrolyte was measured. The composition, molar ratio, and measurement results of each raw material are shown in Table 2 below.

[0105] [Table 1]

[0106] [Table 2]

[0107] [Table 3]

[0108] [Table 4]

[0109] In Tables 1 and 2 above, LZOC is a mixture of Li2O and ZrCl4. LZSOC is a mixture of Li2SO4 and ZrCl4. LZPOC is a mixture of Li3PO4 and ZrCl4. In the XRD column, "A" indicates that a peak was observed, and "B" indicates that no peak was observed. In XPS analysis, peaks were observed at 170±0.5eV and 532±0.5eV in all examples and comparative examples.

[0110] (Fabrication of all-solid-state batteries) The all-solid-state batteries were also fabricated in a glove box with a dew point of approximately -70°C. The all-solid-state batteries were fabricated using a pellet fabrication jig. The pellet fabrication jig consists of a PEEK (polyetheretherketone) holder with an inner diameter of 10 mm, and an upper punch and a lower punch with a diameter of 9.99 mm. The upper and lower punches are made of die steel (SKD11 material).

[0111] A lower punch was inserted into the PEEK holder of the pellet manufacturing jig, and 50 mg of solid electrolyte was placed on top of the lower punch. Next, the resin holder was vibrated to level the surface of the solid electrolyte, and then an upper punch was inserted on top of the solid electrolyte and pressed with a load of approximately 4 kN using a press machine.

[0112] Next, the lower punch was removed, and 10 mg of negative electrode mixture was added on top of the solid electrolyte. Then, the PEEK holder was vibrated to level the surface of the negative electrode mixture, and the lower punch was inserted onto the negative electrode mixture and pressed with a load of 3 kN using a press machine. The negative electrode mixture consisted of a negative electrode active material and the solid electrolyte described above, with lithium titanate (LTO) having an average particle size of 6.0 μm being used as the negative electrode active material. Next, the upper punch was removed, and 10 mg of positive electrode mixture was added on top of the solid electrolyte layer. Then, the PEEK holder was vibrated to level the surface of the positive electrode mixture, and the upper punch was inserted onto the positive electrode mixture and pressed with a load of 3 kN using a press machine. The positive electrode mixture consisted of a positive electrode active material, a conductive additive carbon, and the solid electrolyte described above, with lithium cobaltate (LCO) having an average particle size of 7.5 μm being used as the positive electrode active material. In this way, an all-solid-state battery was fabricated in which a negative electrode mixture layer, a solid electrolyte layer, and a positive electrode mixture layer were stacked in that order.

[0113] In addition, two stainless steel plates with a diameter of 50 mm and a thickness of 5 mm, and two Bakelite® plates with a diameter of 50 mm and a thickness of 2 mm were prepared. Next, four holes for screws were made in each of the two stainless steel plates and the two Bakelite® plates. The holes for the screws were positioned so that when the electrochemical cell and the two stainless steel plates and the two Bakelite® plates are stacked, the two stainless steel plates and the two Bakelite® plates overlap in a plan view, but do not overlap with the electrochemical cell in a plan view.

[0114] Subsequently, stainless steel plates, Bakelite® plates, all-solid-state batteries, Bakelite® plates, and stainless steel plates were stacked in this order, and screws were inserted into the screw holes and tightened with a torque of 1 N·m. In this way, an all-solid-state battery was obtained in which the upper and lower punches of the electrochemical cell were insulated by Bakelite® plates. Next, the all-solid-state battery was left to stand in a constant temperature bath at 25°C for 48 hours to stabilize the open-circuit voltage.

[0115] The rate characteristics were evaluated using the fabricated all-solid-state battery. The rate characteristics were evaluated using the ratio of the discharge capacity when discharged at a discharge rate of 1C to the discharge capacity at a discharge rate of 0.1C (1C / 0.1C rate characteristics). The all-solid-state battery was charged with a constant current at a 0.1C rate (CC charging) at 25°C until the battery voltage reached 2.7V. After reaching 2.7V, it was charged until the current was equivalent to 0.05C (CV charging). Then, it was discharged at a constant current at a 0.1C rate until the battery voltage reached 1.5V (CC discharge), and the discharge capacity at 0.1C was measured. Next, the all-solid-state battery was charged again under the above conditions and discharged at a discharge rate of 1C until the battery voltage reached 1.5V, and the discharge capacity at 1C was measured. The measurement results are summarized in Tables 1, 2, 3, and 4.

[0116] Figure 6 shows the charge-discharge curves for Example 4 and Comparative Examples 3 and 4. Example 4 is shown by a dashed line, Comparative Example 3 by a dotted line, and Comparative Example 4 by a solid line. As shown in Figure 6, Example 4 demonstrated higher input / output characteristics than Comparative Examples 3 and 4. [Industrial applicability]

[0117] According to the present invention, a solid electrolyte with improved ionic conductivity can be obtained. [Explanation of Symbols]

[0118] 10 Solid electrolyte layer 20 positive electrode 22 Positive electrode current collector 24. Cathode mixture layer 30 negative electrode, 32 Negative electrode current collector 34. Negative electrode mixture layer 40 Power generation element 50 Exterior 52 Metal foil 54 Resin layer Terminals 60, 62 100 solid electrolyte battery

Claims

1. Li ａ A ｂ E ｃ (SO ４ ) ｄ J ｅ X ｆ H ｈ ...including (1), In equation (1), A is at least one element selected from alkali metals other than Li and alkaline earth metals. E is at least one element selected from the group consisting of Al, Ga, In, Sc, Y, Ti, Zr, Hf, and lanthanides. JはOH、BO ２ 、BO ３ 、BO ４ 、B ３ O ６ 、B ４ O ７ 、CO ３ 、NO ３ 、AlO ２ 、SiO ３ 、SiO ４ 、Si ２ O ７ 、Si ３ O ９ 、Si ４ O １１ 、Si ６ O １８ 、PO ３ 、PO ４ 、P ２ O ７ 、P ３ O １０ 、SO ３ 、SO ５ 、S ２ O ３ 、S ２ O ４ 、S ２ O ５ 、S ２ O ６ 、S ２ O ７ 、S ２ O ８ 、BF ４ 、PF ６ 、BOB、(COO) ２ 、N、AlCl ４ 、CF ３ SO ３ 、CH ３ COO、CF ３ COO、OOC-(CH ２ ) ２ -COO、OOC-CH ２ -COO、OOC-CH(OH)-CH(OH)-COO、OOC-CH(OH)-CH ２ -COO、C ６ H ５ SO ３ 、OOC-CH=CH-COO、OOC-CH=CH-COO、C(OH)(CH ２ COOH) ２ COO、AsO ４ Bio ４ ,CrO ４ MnO ４ , PtF ６ , PtCl ６ , PtBr ６ , PtI ６ SbO ４ SeO ４ TeO ４ It is at least one group selected from the group consisting of HCOO and O, X is at least one element selected from the group consisting of F, Cl, Br, and I. Satisfying 0.5 ≤ a < 6, 0 ≤ b < 6, 0 < c < 2, 0.1 < d ≤ 6.0, 0 < e ≤ 6.0, 0 < f ≤ 6.1, 0 ≤ h ≤ 0.2, A solid electrolyte in which a peak is observed at a diffraction angle 2θ = 22.3° ± 1.0° in the X-ray diffraction pattern using Cu-Kα as a source.

2. The solid electrolyte according to claim 1, wherein a peak is observed at a diffraction angle 2θ = 36.4° ± 1.0° in the X-ray diffraction pattern using Cu-Kα as a source.

3. The solid electrolyte according to claim 1 or 2, wherein peaks are observed at 170 ± 0.5 eV and 532 ± 0.5 eV in X-ray photoelectron spectroscopy measurements.

4. The solid electrolyte according to claim 1 or 2, wherein the ionic conductivity at 25°C is 1 mS / cm or more.

5. A solid electrolyte layer comprising the solid electrolyte described in claim 1 or 2.

6. The device comprises a negative electrode, a positive electrode, and a solid electrolyte layer located between the negative electrode and the positive electrode, which includes a solid electrolyte. A solid electrolyte battery in which at least one of the negative electrode, the positive electrode, and the solid electrolyte layer comprises the solid electrolyte described in claim 1 or 2.

7. A solid electrolyte battery comprising a negative electrode, a positive electrode, and a solid electrolyte layer according to claim 5, located between the negative electrode and the positive electrode.

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