Electrodes and all-solid-state batteries

Abstract

This electrode comprises a compound that includes Li, one or more elements selected from Group 3–15 elements, and S. The peak intensity Ra of SO3 - and the peak intensity Rb of SO4 -, which are obtained through negative ion analysis by a time-of-flight secondary ion mass spectrometry, satisfy the relationship Ra > Rb.

Description

Technical Field

[0001] The present invention relates to an electrode and a all-solid-state battery. This application claims priority based on Japanese Patent Application No. 2023-058719 filed in Japan on March 31, 2023, and incorporates its content herein.

Background Art

[0002] In recent years, all-solid-state batteries have attracted attention from the viewpoints of improving safety and increasing output power. One of the characteristics of all-solid-state batteries is that a solid is used as the electrolyte. Here, the properties required for the solid electrolyte include ion conductivity, oxidation-reduction resistance, and moldability. One of the problems is to improve the ion conductivity compared with conventional organic electrolytic solutions. Generally, many solid electrolytes have lower conductivity compared with organic electrolytic solutions.

[0003] Patent Document 1 discloses a solid electrolyte represented by the following compositional formula (1) (where 0 < z < 2 and X is Cl or Br). Li 6-3z Y z X6···Formula (1)

[0004] Patent Document 2 discloses a solid electrolyte composed of a compound represented by the following formula (2) (where A is at least one element selected from the group consisting of Li, Cs, and Ca, and X is at least one element selected from the group consisting of F, Cl, Br, and I). AaEbGcXd···(2)

Prior Art Documents

Patent Documents

[0005]

Patent Document 1

Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0006] Such a solid electrolyte is used not only for the solid electrolyte layer but may also be used together with an active material for the electrode. It is also desirable that the solid electrolyte contained in the electrode has the same high ionic conductivity as the solid electrolyte used for the solid electrolyte layer.

[0007] The present invention has been made in view of the problems of the above prior art, and provides an electrode and an all-solid-state battery including a solid electrolyte having high ionic conductivity.

Means for Solving the Problems

[0008] In order to solve the above problems, the present invention provides the following means.

[0009] Aspect 1 of the present invention includes Li, one or more elements selected from Group 3 to Group 15 elements, and S, and SO3 obtained by negative ion analysis by time-of-flight secondary ion mass spectrometry - The electrode is a compound in which the peak intensity Ra of and the peak intensity Rb of SO4 - satisfy Ra > Rb.

[0010] Aspect 2 of the present invention is the electrode according to Aspect 1, wherein the peak intensity ratio R1 (Ra / Rb) of the peak intensity Ra of SO3 - and the peak intensity Rb of SO4 - in the compound satisfies 6.0 > R1 > 1.0.

[0011] Aspect 3 of the present invention is the electrode according to Aspect 1, wherein the peak intensity ratio R1 (Ra / Rb) of the peak intensity Ra of SO3 - and the peak intensity Rb of SO4 - in the compound satisfies 1.8 > R1 > 1.2.

[0012] Aspect 4 of the present invention is the electrode according to Aspect 1, wherein the peak intensity Ra of SO3 - and the peak intensity Rb of SO4 -The peak intensity ratio R1(Ra / Rb) of the peak intensity Rb satisfies 1.7 > R1 > 1.4.

[0013] Aspect 5 of the present invention is an electrode in any one of aspects 1 to 4 wherein the compound is, in negative ion analysis by time-of-flight secondary ion mass spectrometry, SO - Peak, SO2 - Peak, SO3 - Peak, SO4 - Each of the following peaks was detected, and of the four peaks, SO3 - The peak at this point satisfies the strongest peak intensity.

[0014] Aspect 6 of the present invention is an electrode in any one of aspects 1 to 5 in which the compound is represented by the following formula (1); LiaEbGcXd···(1) (In formula (1), E is at least one element selected from the group consisting of Al, Sc, Y, Zr, Hf, and lanthanides. G is at least one group selected from the group consisting of SO3, SO4, SO5, S2O3, S2O4, S2O5, S2O6, S2O7, and S2O8. X is at least one element selected from the group consisting of F, Cl, Br, and I. 0.5≦a<6, 0 <b<2、0.1<c≦6、0<d≦6.1である。)

[0015] Embodiment 7 of the present invention is an all-solid-state battery in which a positive electrode and a negative electrode face each other via a solid electrolyte layer, and at least one of the solid electrolyte layer, the positive electrode, and the negative electrode includes one electrode from Embodiments 1 to 6.

[0016] Aspect 8 of the present invention relates to the all-solid-state battery of aspect 7, wherein the solid electrolyte layer contains a compound represented by the following formula (2). LiaEbGcXd···(2) (In formula (2), E is at least one element selected from the group consisting of Al, Sc, Y, Zr, Hf, and lanthanides. G is at least one group selected from the group consisting of SO3, SO4, SO5, S2O3, S2O4, S2O5, S2O6, S2O7, and S2O8. X is at least one element selected from the group consisting of F, Cl, Br, and I. 0.5≦a<6, 0 <b<2、0.1<c≦6、0<d≦6.1である。) [Effects of the Invention]

[0017] The electrode of the present invention provides an electrode containing a solid electrolyte having high ionic conductivity. [Brief explanation of the drawing]

[0018] [Figure 1] This is a schematic cross-sectional view of the all-solid-state battery according to this embodiment. [Modes for carrying out the invention]

[0019] The present embodiment will be described in detail below with reference to the drawings as appropriate. The drawings used in the following description may be enlarged for convenience to clearly illustrate the features of the present invention, and the dimensional ratios of each component may differ from those in reality. The materials, dimensions, etc., exemplified in the following description are examples only, and the present invention is not limited to them. It can be implemented with appropriate modifications without altering its essence.

[0020] [All-solid battery] Figure 1 is a schematic cross-sectional view of the all-solid-state battery 100 according to this embodiment. The all-solid-state battery 100 shown in Figure 1 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 all-solid-state battery 100 can be used, for example, in laminated batteries, prismatic batteries, cylindrical batteries, coin-type batteries, button-type batteries, etc.

[0021] <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.

[0022] In the all-solid-state battery 100 according to this embodiment, at least one of the electrodes, the positive electrode 20 and the negative electrode 30, has an electrode mixture layer containing Li, one or more elements selected from group 3 to group 15 elements, and S, and SO3 obtained by negative ion analysis by time-of-flight secondary ion mass spectrometry. - Peak intensity Ra and SO4 - The present invention includes compounds whose peak intensity Rb satisfies the condition Ra > Rb. In the following explanation, we will use the case where the compound is included in both the positive electrode 20 and the negative electrode 30 as an example.

[0023] "Positive electrode" As shown in Figure 1, 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.

[0024] (Positive electrode current collector) 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.

[0025] (Positive electrode mixture layer) The positive electrode mixture layer 24 comprises a positive electrode active material and a solid electrolyte, and may also contain a binder and a conductive additive. Known binders and conductive additives can be used. A conductive additive is, for example, carbon black. The conductive additive may also be vapor-processed carbon fibers, carbon nanotubes, metals, etc.

[0026] (Cathode active material) 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 lithium-ion secondary batteries can be used. Examples of positive electrode active materials include lithium-containing metal oxides and lithium-containing metal phosphorus oxides.

[0027] 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.

[0028] 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.), lithium-free fluorides (FeF3, VF3, etc.), and sulfur-modified polyacrylonitrile. When using a lithium-free positive electrode active material, the negative electrode may be pre-doped with lithium ions, or a negative electrode containing lithium ions may be used.

[0029] The content of the positive electrode active material in the positive electrode mixture layer 24 is not particularly limited, but is preferably 50% to 98% by mass, and more preferably 55% to 95% by mass, based on the total mass of the positive electrode active material, solid electrolyte, conductive additive, and binder.

[0030] (solid electrolyte) The solid electrolyte contained in the positive electrode mixture layer 24 contains Li, one or more elements selected from group 3 to group 15 elements, and S, and is obtained by negative ion analysis by time-of-flight secondary ion mass spectrometry as SO3. - Peak intensity Ra and SO4 - The compound contains such that the peak intensity Rb of Ra > Rb. The configuration in which the solid electrolyte contained in the positive electrode mixture layer 24 contains the compound includes a configuration in which the solid electrolyte contained in the positive electrode mixture layer 24 consists of the compound. The compound itself is a solid electrolyte (solid electrolyte material). 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 an all-solid-state battery becomes smoother, and the internal resistance decreases.

[0031] SO3 in the compound - Peak intensity Ra and SO4 - The peak intensity ratio R1 (Ra / Rb) of the peak intensity Rb of the compound preferably satisfies the condition 6.0 > R1 > 1.0. When R1 satisfies this inequality, the ionic conductivity of the compound is 0.1 mS / cm or higher. SO3 in the compound - Peak intensity Ra and SO4 - The peak intensity ratio R1 (Ra / Rb) of the peak intensity Rb of the compound more preferably satisfies the condition 1.8 > R1 > 1.2. When R1 satisfies this inequality, the ionic conductivity of the compound is 0.5 mS / cm or higher. SO3 in the compound - Peak intensity Ra and SO4 - It is even more preferable that the peak intensity ratio R1 (Ra / Rb) of the peak intensity Rb satisfies 1.7 > R1 > 1.4. When R1 satisfies this inequality, the ionic conductivity of the compound is 1 mS / cm or more.

[0032] Furthermore, in negative ion analysis by time-of-flight secondary ion mass spectrometry, the compound was found to be SO - Peak, SO2 - Peak, SO3 - Peak, SO4 -Each of the four peaks was detected, and of the four peaks, SO3 - The peak that satisfies the strongest peak intensity can be considered as the one that meets the criteria.

[0033] (Negative ion analysis by time-of-flight secondary ion mass spectrometry) Time-of-Flight Secondary Ion Mass Spectrometry (TOF-SIMS) is a technique that irradiates the surface of a solid sample with an ion beam (primary ions) and separates the ions (secondary ions) emitted from the surface by utilizing the difference in their time of flight (the time of flight is proportional to the square root of the ion's mass). In TOF-SIMS spectral data, the horizontal axis represents time and the vertical axis represents ion counts (intensity). However, by converting the time axis to mass number, the horizontal axis becomes mass number, and the mass distribution of secondary ions, i.e., the mass spectrum, can be obtained.

[0034] "SO3 - "Peak intensity of SO3" refers to SO3 - This is the number of (negative ions) detected. Also, "SO4 - "Peak intensity of SO4" refers to SO4 - This is the number of detected (negative ions). Therefore, SO3 - Peak intensity Ra and SO4 - The peak intensity Rb of SO3 satisfies the condition Ra > Rb. - The number of detected (negative ions) is SO4 - This means the number of detected (negative ions) is greater than the number of detected ions.

[0035] The solid electrolyte contained in the positive electrode mixture layer 24 contains the above compound, which includes Li, one or more elements selected from group 3 to group 15 elements, and S, and in TOF-SIMS, SO4 - The peak intensity of SO3 is greater than that of Rb. - By increasing the peak intensity Ra, ionic conductivity can be improved. In SO4, the tetrahedral structure exhibits high ionic conductivity, and the bonding site of the oxygen (O) atom is different.- In addition, SO3 - It is believed that this was detected. Furthermore, it is thought that the difference in SO4 structure caused lattice distortion, resulting in high ionic conductivity.

[0036] In this invention, in a solid electrolyte containing Li, one or more elements selected from Group 3 to Group 15 elements, and S, the mass spectrum of SO3 in TOF-SIMS is - Peak intensity Ra and SO4 - We clarified that the peak intensity ratio R1(Ra / Rb) of the peak intensity Rb can be used as an indicator of ionic conductivity.

[0037] The above compound can be represented by the following formula (1). LiaEbGcXd···(1) (In formula (1), E is at least one element selected from the group consisting of Al, Sc, Y, Zr, Hf, and lanthanides. G is at least one group selected from the group consisting of SO3, SO4, SO5, S2O3, S2O4, S2O5, S2O6, S2O7, and S2O8. X is at least one element selected from the group consisting of F, Cl, Br, and I. 0.5≦a<6, 0 <b<2、0.1<c≦6、0<d≦6.1である。)

[0038] In formula (1), a satisfies 0.5 ≤ a < 6, and when E is Al, Sc, Y, or a lanthanide, it preferably satisfies 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.

[0039] In formula (1), E is an essential component and is at least one element selected from the group consisting of Al, Sc, Y, Zr, Hf, and lanthanoids. E improves the ionic conductivity of the solid electrolyte. 0 < b < 2. Since the effect of including E can be obtained more effectively, it is preferable that 0.6 ≤ b. Also, E is an element that forms the skeleton of the solid electrolyte. When b ≤ 1, a solid electrolyte with a low density is obtained, which is preferable.

[0040] In the halide-based solid electrolyte represented by formula (1), 0.1 < c ≤ 6 is satisfied. Since the effect of widening the reduction-side potential window by including G becomes more remarkable, it is more preferable that 0.5 ≤ c. It is preferable that c ≤ 3 so that the decrease in the ionic conductivity of the solid electrolyte due to too much content of G does not occur.

[0041] In the halide-based solid electrolyte represented by formula (1), X is an essential component. X is at least one or more selected from the group consisting of F, Cl, Br, and I. X has a large ionic radius per valence. Therefore, when the halide-based solid electrolyte represented by formula (1) contains X, the effect that lithium ions flow easily and the ionic conductivity increases is obtained. As X, it is preferable to contain Cl because a solid electrolyte with high ionic conductivity is obtained. Furthermore, when X contains F, since X becomes a solid electrolyte with high ionic conductivity, it is preferable to contain F and two or more selected from the group consisting of Cl, Br, and I.

[0042] 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.

[0043] In the halide-based solid electrolyte represented by formula (1), d satisfies 0 < d ≤ 6.1. It is preferable that d ≥ 1. When d ≥ 1, when the solid electrolyte is pressure-molded into a pellet shape, the strength of the pellet increases. Also, when d ≥ 1, the ionic conductivity of the solid electrolyte increases. Further, it is preferable that d ≤ 5 so that the potential window of the solid electrolyte does not become narrow due to insufficient G caused by too much content of X.

[0044] The halide-based solid electrolyte represented by formula (1) is, for example, Li2Zr(SO4)Cl4, Li2Zr(SO3)Cl4, Li2Zr(SO4) 0.3 (SO3) 0.7 Cl4, Li2Zr(SO4) 0.5 (SO3) 0.5 Cl4, Li2Zr(SO4) 0.7 (SO3) 0.3 Cl4, Li2Zr(S2O3)Cl4, Li2Zr(SO4) 0.3 (S2O3) 0.7 Cl4, Li2Zr(SO4) 0.5 (S2O3) 0.5 Cl4, Li2Zr(SO4) 0.7 (S2O3) 0.3 Cl4, and so on.

[0045] (Binder) The binder binds the positive electrode active material, the solid electrolyte, and the conductive assistant to each other within the positive electrode mixture layer 24, and firmly adheres the positive electrode mixture layer 24 and the positive electrode current collector 22. The positive electrode mixture layer 24 preferably contains a binder. The binder preferably has oxidation resistance and good adhesiveness.

[0046] 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.

[0047] 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.

[0048] The binder content in the positive electrode mixture layer 24 is not particularly limited, but is preferably 0.1% to 10% by mass, and more preferably 0.1% 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.

[0049] (Conductive additive) 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.

[0050] 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.

[0051] "Negative electrode" As shown in Figure 1, 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. In the following description of the "negative electrode," components common to both the "negative electrode" and the "positive electrode" may be omitted from the explanation.

[0052] (Negative electrode current collector) 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.

[0053] (Negative electrode mixture layer) The negative electrode mixture layer 34 contains a negative electrode active material and a solid electrolyte. The negative electrode mixture layer 34 may contain a binder and a conductive additive. Known binders and conductive additives can be used. A conductive additive is, for example, carbon black. The conductive additive may also be vapor-phase carbon fiber, carbon nanotubes, metals, etc. The binder and conductive additive can be used in the same proportions as those described for the positive electrode mixture layer 24.

[0054] 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 lithium-ion secondary batteries can be used.

[0055] The negative electrode active material may be a carbon material such as natural graphite, artificial graphite, mesocarbon microbeads, mesocarbon fiber (MCF), cokes, glassy carbon, or calcined organic compounds; a metal that can combine with lithium such as Si, SiOx, Sn, or aluminum; an alloy of these metals; a composite material of these metals and carbon materials; or lithium titanate (Li4Ti5O4). 12 These include oxides such as ), SnO2, sulfur-modified polyacrylonitrile, and metallic lithium. The negative electrode active material is natural graphite or lithium titanate (Li4Ti5O2). 12 ) is preferable.

[0056] The content of the negative electrode active material in the negative electrode mixture layer 34 is not particularly limited, but is preferably 50% to 98% by mass, and more preferably 55% to 95% by mass, based on the total mass of the negative electrode active material, solid electrolyte, conductive additive, and binder.

[0057] (solid electrolyte) The solid electrolyte contained in the negative electrode mixture layer 34, like that in the positive electrode mixture layer 24, contains Li, one or more elements selected from Group 3 to Group 15 elements, and S, and is obtained by negative ion analysis by time-of-flight secondary ion mass spectrometry as SO3. - Peak intensity Ra and SO4 - The compound contains such that the peak intensity Rb of Ra > Rb. The configuration in which the solid electrolyte contained in the negative electrode mixture layer 34 contains the compound includes a configuration in which the solid electrolyte contained in the negative electrode mixture layer 34 consists of the compound. The compound in question may have the same structure as that described for the positive electrode mixture layer 24. Further explanation is omitted below.

[0058] The content of the solid electrolyte in the negative electrode mixture layer 34 is not particularly limited, but is preferably 1% to 60% by mass, and more preferably 10% to 55% by mass, based on the total mass of the negative electrode active material, solid electrolyte, conductive additive, and binder.

[0059] The binder content in the negative electrode mixture layer 34 is not particularly limited, but is preferably 0.1% to 10% by mass, and more preferably 0.1% to 5% by mass, based on the total mass of the negative 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 negative electrode 30 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.

[0060] The content of the conductive additive in the negative electrode mixture layer 34 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 negative electrode active material, solid electrolyte, conductive additive, and binder.

[0061] "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.

[0062] The solid electrolyte may include, for example, lithium. The solid electrolyte may also be, for example, an oxide-based material, a sulfide-based material, or a halide-based material. Alternatively, the compound (solid electrolyte) contained in the electrode according to the above embodiment may be used, or may be included in part.

[0063] The solid electrolyte may be in the form of a powder (particles) or a sintered body formed by sintering the powder. Alternatively, the solid electrolyte may be a molded body formed by compressing the 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.

[0064] The solid electrolyte can be, for example, a halide-based solid electrolyte represented by the following formula (2). LiaEbGcXd···(2)

[0065] In formula (2), a satisfies 0.5 ≤ a < 6. When E is Al, Sc, Y, or a lanthanoid, it preferably satisfies 2.0 ≤ a ≤ 4.0, and more preferably satisfies 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 (2), if 0.5 ≤ a < 6, the content of Li contained in the compound becomes appropriate, and the ionic conductivity of the solid electrolyte layer 10 increases.

[0066] In formula (2), E is an essential component and is at least one element selected from the group consisting of Al, Sc, Y, Zr, Hf, and lanthanoids. E improves the ionic conductivity of the solid electrolyte. 0 < c < 2. Since the effect of including E can be obtained more effectively, it is preferable that b ≥ 0.6. Also, E is an element that forms the skeleton of the solid electrolyte. Since a solid electrolyte with a small density is obtained when b ≤ 1, it is preferable.

[0067] In the halide-based solid electrolyte represented by formula (2), 0.1 < c ≤ 6 is satisfied. Since the effect of widening the reduction-side potential window by including G becomes more prominent, it is more preferable that c ≥ 0.5. It is preferable that c ≤ 3 so that the decrease in the ionic conductivity of the solid electrolyte caused by too much content of G does not occur.

[0068] In the halide-based solid electrolyte represented by formula (2), X is an essential component. X is at least one selected from the group consisting of F, Cl, Br, and I. X has a large ionic radius per valence. Therefore, when the halide-based solid electrolyte represented by formula (2) contains X, lithium ions can flow easily, and the effect of increasing the ionic conductivity is obtained. As X, it is preferable to contain Cl in order to obtain a solid electrolyte with high ionic conductivity. Further, when X contains F, since X becomes a solid electrolyte with high ionic conductivity, it is preferable to contain F and two or more selected from the group consisting of Cl, Br, and I.

[0069] 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.

[0070] In the halide-based solid electrolyte represented by formula (2), d satisfies 0 < d ≤ 6.1. It is preferable that 1 ≤ d. When 1 ≤ d, when the solid electrolyte is pressure-molded into a pellet shape, the strength of the pellet increases. Also, when 1 ≤ d, the ionic conductivity of the solid electrolyte increases. Also, it is preferable that d ≤ 5 so that the potential window of the solid electrolyte does not become narrow due to an excessive content of X resulting in a shortage of G.

[0071] The halide-based solid electrolyte represented by formula (2) is, for example, Li2Zr(SO4)Cl4, Li2Zr(SO3)Cl4, Li2Zr(SO4) 0.3 (SO3) 0.7 Cl4, Li2Zr(SO4) 0.5 (SO3) 0.5 Cl4, Li2Zr(SO4) 0.7 (SO3) 0.3 Cl4, Li2Zr(S2O3)Cl4, Li2Zr(SO4) 0.3 (S2O3) 0.7Cl4, Li2Zr(SO4) 0.5 (S2O3) 0.5 Cl4, Li2Zr(SO4) 0.7 (S2O3) 0.3 It is Cl4.

[0072] Furthermore, the solid electrolyte can be a sulfide-based solid electrolyte, and as the sulfide-based solid electrolyte, a compound containing Li, S, Si and / or P can be used. The sulfide-based solid electrolyte may further contain Ge, Cl, Br, and I. The sulfide-based solid electrolyte may be amorphous, crystalline, or argyrodite type. An example of a sulfide-based solid electrolyte is the Li2S-P2S5 solid electrolyte (Li7P3S 11 , Li3PS4, Li8P2S9, etc.), Li2S-SiS2, LiI-Li2S-SiS2, LiI-Li2S-P2S5, LiI-LiBr-Li2S-P2S5, Li2S-P2S5-GeS2 solid electrolytes (Li 13 GeP3S 16 Li 10 GeP2S 12 ), LiI-Li2S-P2O5, LiI-Li3PO4-P2S5, Li 7-x PS 6-x Cl x (x can range from 1.0 to 1.9)

[0073] The sulfide-based solid electrolyte may be a compound represented by the following formula (3). LiqMrPsOtXuSv···(3) In equation (3), Li is lithium, M is a tetravalent metal, P is phosphorus, O is oxygen, S is sulfur, X is at least one selected from the group consisting of F, Cl, Br, and I, and q, r, s, t, u, and v are numbers that satisfy 1 ≤ q ≤ 20, 0 ≤ r ≤ 2, 1 ≤ s ≤ 5, 0 ≤ t ≤ 5, 0 ≤ u ≤ 5, and v = q / 2 + 2 × r + 2.5 × stu / 2, respectively. M is preferably Si or Ge.

[0074] <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 1. The outer casing 50 is a metal laminate film in which the metal foil 52 is coated on both sides with resin layers 54.

[0075] 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.

[0076] <Terminal> Terminals 60 and 62 are connected to the positive electrode 20 and the negative electrode 30, respectively. Terminal 62, connected to the positive electrode 20, is the positive terminal, and terminal 60, 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.

[0077] [Manufacturing method for all-solid-state batteries] Next, a method for manufacturing the all-solid-state battery according to this embodiment will be described. The all-solid-state battery according to this embodiment contains the above compound (solid electrolyte) in at least one of the positive electrode and the negative electrode. That is, at least one of the positive electrode and the negative electrode contains Li, one or more elements selected from Group 3 to Group 15 elements, and S, and TOF-SIMS SO3 - Peak intensity Ra and SO4 - This includes compounds where the peak intensity Rb satisfies Ra > Rb.

[0078] First, a solid electrolyte is prepared. This solid electrolyte includes both the solid electrolyte that constitutes the solid electrolyte layer and the compound (solid electrolyte) contained in the electrode. Solid electrolytes can be produced, for example, by mixing raw material powders containing specific elements in a predetermined molar ratio and carrying out a mechanochemical reaction. When carrying out the mechanochemical reaction, the state of SxOy after synthesis is adjusted to vary. Specifically, unreacted components of the raw materials can be retained by changing the rotation speed and revolution speed of the planetary ball mill, the synthesis time, the state of the raw material powder at the time of input, and the atmosphere inside the pot.

[0079] 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.

[0080] 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.

[0081] 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.

[0082] 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.

[0083] 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 all-solid-state battery 100 of this embodiment is obtained.

[0084] Because the all-solid-state 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.

[0085] 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]

[0086] <Example of positive electrode> [Positive electrode example 1] (Preparation of compounds (solid electrolytes)) The compound (solid electrolyte) according to this embodiment was prepared as follows. In a glove box with an Ar gas atmosphere, raw material powders of lithium sulfate (Li2SO4) and zirconium chloride (ZrCl4) were weighed so that their molar ratio was 1:1. The raw material powders were put into a hermetic zirconia container for a planetary ball mill which had zirconia balls put in it beforehand. Next, the hermetic container was covered with a lid, the lid was screwed to the container body, and further, the space between the lid and the container was sealed with a polyimide tape. The polyimide tape has the effect of blocking moisture. Next, the hermetic zirconia container was set in the planetary ball mill. A mechanochemical reaction was carried out for 24 hours at a rotation speed of 500 rpm for the rotation of the container around its own axis and a revolution speed of 500 rpm (the rotation direction of the rotation around its own axis and the revolution direction are opposite) to obtain a powder of Li2Zr(SO4)Cl4 of Cathode Example 1.

[0087] The planetary ball mill is installed in an Ar gas atmosphere. The hermetic zirconia container for the planetary ball mill is screwed and further sealed with a polyimide tape. When the hermetic zirconia container is set in the planetary ball mill, since the hermetic zirconia container is firmly pressed and fixed, it is considered that there is almost no moisture mixing from the atmosphere into the hermetic zirconia container.

[0088] <Measurement of mass spectrum by TOF - SIMS> Regarding the solid electrolyte (Li2Zr(SO4)Cl4) of Cathode Example 1, a mass spectrum was measured by time - of - flight secondary ion mass spectrometry, and the peak intensity Ra of SO3 - and the peak intensity Rb of SO4 - were obtained.

[0089] Measurement was carried out by TOF - SIMS with the following apparatus and conditions. (1) Apparatus: TOF - SIMS5 manufactured by ION - TOF (2) Measurement conditions Measurement mode: Spectrometry Primary ion: Bi3 ++ Acceleration voltage: 25 kV Measurement area: 40000 μm 2 (200 μm × 200 μm) Measured ion species: Negative Electronic neutralization: Yes

[0090] <Measurement of ionic conductivity> The ionic conductivity of the solid electrolyte (Li2ZrSO4Cl4) of positive electrode example 1 was measured as follows. In a glove box with a dew point of approximately -70°C and circulating argon gas, the obtained solid electrolyte (Li2Zr(SO4)Cl4) powder was filled into a pressure molding die and pressure-molded under a load of approximately 30KN to produce a cell for measuring ionic conductivity.

[0091] 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.

[0092] Subsequently, a 50mm diameter, 5mm thick stainless steel disc and a Teflon® disc, both with screw holes in four locations, were prepared, and the pressure forming die was set up as follows: Stainless steel disc / Teflon® disc / pressure forming die / Teflon® disc / stainless steel disc. The four screws were tightened to a torque of approximately 3 N·m. Screws were also inserted into screw holes on the sides of the upper and lower punches to serve as external connection terminals.

[0093] 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 a 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 above compound (solid electrolyte) (Li2Zr(SO4)Cl4) of positive electrode example 1 was 2.4 × 10⁻¹⁰. -3 The value was S / cm.

[0094] (Preparation of positive electrode mixture) To prepare the cathode mixture, lithium cobalt oxide (LiCoO2) and Li2Zr(SO4)Cl4 from cathode example 1 were prepared as the cathode active material. The cathode active material and Li2Zr(SO4)Cl4 from cathode example 1 were weighed to 65 wt% and 35 wt%, respectively. The weighed cathode active material and Li2Zr(SO4)Cl4 from cathode example 1 were mixed in an agate mortar for 15 minutes to obtain the cathode mixture.

[0095] (Preparation of half-cells for charging and discharging) The half-cells for charging and discharging were fabricated inside a glove box with a dew point of approximately -70°C. For half-cell production, a pellet manufacturing jig was used for preparation. The pellet manufacturing jig consists of a PEEK (polyetheretherketone) cylinder with an outer diameter of 30 mm, an inner diameter of 10 mm, and a height of 20 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).

[0096] A lower punch was inserted into a PEEK cylinder, and 110 mg of solid electrolyte Li2Zr(SO4)Cl4 was placed on top of the lower punch. Next, the PEEK cylinder was vibrated to level the surface of the solid electrolyte, and then an upper punch was inserted on top of the solid electrolyte. A press was then used to press the solid electrolyte layer with a load of 373 MPa.

[0097] Next, the upper punch was removed, and 15 mg of the above-mentioned positive electrode mixture was placed on top of the solid electrolyte layer. Then, the PEEK cylinder was vibrated to level the surface of the positive electrode mixture, and the upper punch was inserted on top of the positive electrode mixture and pressed with a press machine at a load of 373 MPa. Next, the lower punch was removed, a lithium foil with a diameter of 10 mm and a thickness of 100 μm was placed on top of the solid electrolyte layer, and the lower punch was inserted. The configuration of the half cell is (LiCoO2 + Li2Zr(SO4)Cl4) / Li2Zr(SO4)Cl4 / Li.

[0098] 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 half 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 half cell in a plan view.

[0099] Subsequently, stainless steel plates, bakelite® plates, half cells, 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, a half cell was obtained in which the upper and lower punches of the electrochemical cell were insulated by bakelite® plates. Next, the half cell was left to stand in a 25°C constant temperature bath for 48 hours to stabilize the open-circuit voltage.

[0100] <Measuring Rate Characteristics> The fabricated half-cells were charged and discharged under the following conditions. The voltage range was 2.8V to 4.2V. Charging was performed using a constant current of 0.1C, and charging was terminated when the current reached the equivalent of 0.05C after the voltage was set to constant. Discharging was performed at 0.1C and 1.0C, and the ratio of the discharge capacity at 1C to the discharge capacity at 0.1C (rate characteristic (unit: %)) was determined. The obtained results are shown in Table 1.

[0101] The characteristics of the solid electrolyte (compound) of Cathode Example 1, including the combination of raw materials, synthesis time, and synthesis process, are summarized in Table 1 below. The measurement results of the solid electrolyte properties are summarized in Table 2 below. Furthermore, the measurement results of the half-cell rate characteristics are summarized in Table 3 below. Note that the contents of Tables 1 and 2 are common to both the positive electrode and negative electrode examples. For example, Example 1 refers to the solid electrolyte of positive electrode Example 1 and the solid electrolyte of negative electrode Example 1.

[0102] [Positive electrode example 2] The solid electrolyte (Li2Zr(SO4)Cl4) for cathode example 2 was synthesized in the same manner as cathode example 1, except that the raw materials were weighed in a glove box with a mixed atmosphere of dry air with a dew point of approximately -40°C and argon gas in a volume ratio of 20%:80%, and the synthesis was carried out by setting up a planetary ball mill in the same mixed atmosphere of dry air with a dew point of approximately -40°C and argon gas in a volume ratio of 20%:80%, thereby obtaining the powder of the solid electrolyte (Li2Zr(SO4)Cl4) for cathode example 2.

[0103] The characteristics of the solid electrolyte (compound) of cathode example 2, including the combination of raw materials, synthesis time, and synthesis process, are summarized in Table 1 below. The measurement results of the solid electrolyte properties are summarized in Table 2 below. Furthermore, the measurement results of the half-cell rate characteristics are summarized in Table 3 below.

[0104] [Positive electrode example 3] The solid electrolyte (Li2Zr(SO4)Cl4) for cathode example 3 was synthesized in the same manner as cathode example 1, except that the raw materials were weighed in a glove box with a mixed atmosphere of dry air with a dew point of approximately -40°C and argon gas in a volume ratio of 40%:60%, and the synthesis was carried out by setting up a planetary ball mill in the same mixed atmosphere of dry air with a dew point of approximately -40°C and argon gas in a volume ratio of 40%:60%, thereby obtaining the powder of the solid electrolyte (Li2Zr(SO4)Cl4) for cathode example 3.

[0105] Table 1 below summarizes the characteristics of the solid electrolyte (compound) of cathode example 3, including the combination of raw materials, synthesis time, and synthesis process. Table 2 below summarizes the measurement results of the solid electrolyte properties. Table 3 below summarizes the measurement results of the half-cell rate characteristics.

[0106] [Positive electrode example 4] The solid electrolyte (Li2Zr(SO3)Cl4) of positive electrode Example 4 was synthesized in the same manner as in positive electrode Example 1, except that lithium sulfite (Li2SO3) and zirconium chloride (ZrCl4) were used as raw materials, to obtain the powder of the solid electrolyte (Li2Zr(SO3)Cl4) of positive electrode Example 4.

[0107] Table 1 below summarizes the characteristics of the solid electrolyte (compound) of cathode example 4, including the combination of raw materials, synthesis time, and synthesis process. Table 2 below summarizes the measurement results of the solid electrolyte properties. Table 3 below summarizes the measurement results of the half-cell rate characteristics.

[0108] [Positive electrode example 5] The solid electrolyte (Li2Zr(SO3)Cl4) for cathode example 5 was synthesized in the same manner as cathode example 4, except that the raw materials were weighed in a glove box with a mixed atmosphere of dry air with a dew point of approximately -40°C and argon gas in a volume ratio of 40%:60%, and the synthesis was carried out by setting up a planetary ball mill in the same mixed atmosphere of dry air with a dew point of approximately -40°C and argon gas in a volume ratio of 40%:60%, thereby obtaining a powder of solid electrolyte (Li2Zr(SO3)Cl4).

[0109] The characteristics of the solid electrolyte (compound) of cathode example 5, including the combination of raw materials, synthesis time, and synthesis process, are summarized in Table 1 below. The measurement results of the solid electrolyte properties are summarized in Table 2 below. Furthermore, the measurement results of the half-cell rate characteristics are summarized in Table 3 below.

[0110] [Positive electrode example 6] Solid electrolyte of positive electrode example 6 (Li2Zr(SO4) 0.3 (SO3) 0.7 Cl4) was synthesized in the same manner as in Cathode Example 1, except that lithium sulfate (Li2SO4), lithium sulfite (Li2SO3), and zirconium chloride (ZrCl4) were weighed out in a molar ratio of 3:7:10 to prepare the raw material powder. The solid electrolyte (Li2Zr(SO4)) of Cathode Example 6 was then prepared. 0.3 (SO3) 0.7 This is a powder of Cl4 obtained.

[0111] For the solid electrolyte (compound) of Positive Electrode Example 6, the combinations of raw materials, synthesis time, and characteristics of the synthesis process are summarized in Table 1 below. Also, the measurement results of the characteristics of the solid electrolyte are summarized in Table 2 below. Further, the measurement results of the rate characteristics of the half-cell are summarized in Table 3 below.

[0112] 〔Positive Electrode Example 7〕 The solid electrolyte (Li2Zr(SO4) 0.5 (SO3) 0.5 Cl4) of Positive Electrode Example 7 was synthesized in the same manner as Positive Electrode Example 1, except that lithium sulfate (Li2SO4), lithium sulfite (Li2SO3), and zirconium chloride (ZrCl4) were weighed as raw materials so that the molar ratio was 1:1:2 to prepare a raw material powder, and the weighing of the raw materials was carried out in a glove box with a mixed atmosphere of dry air with a dew point of about -40°C and argon gas at a volume ratio of 20%:80%, and also, a planetary ball mill was installed in a mixed atmosphere of dry air with a dew point of about -40°C and argon gas at a volume ratio of 20%:80% for synthesis. As a result, the powder of the solid electrolyte (Li2Zr(SO4) 0.5 (SO3) 0.5 Cl4) of Positive Electrode Example 7 was obtained.

[0113] For the solid electrolyte (compound) of Positive Electrode Example 7, the combinations of raw materials, synthesis time, and characteristics of the synthesis process are summarized in Table 1 below. Also, the measurement results of the characteristics of the solid electrolyte are summarized in Table 2 below. Further, the measurement results of the rate characteristics of the half-cell are summarized in Table 3 below.

[0114] 〔Positive Electrode Example 8〕 The solid electrolyte (Li2Zr(SO4) 0.7 (SO3) 0.3Cl4) was synthesized in the same manner as in Cathode Example 1, except that lithium sulfate (Li2SO4), lithium sulfite (Li2SO3), and zirconium chloride (ZrCl4) were weighed in a molar ratio of 7:3:10 to prepare the raw material powder, and the raw materials were weighed in a glove box with a mixed atmosphere of dry air with a dew point of approximately -40°C and argon gas in a volume ratio of 40%:60%, and the synthesis was carried out by setting up a planetary ball mill in the same mixed atmosphere of dry air with a dew point of approximately -40°C and argon gas in a volume ratio of 40%:60%, and thus the solid electrolyte (Li2Zr(SO4)) of Cathode Example 8 was synthesized. 0.7 (SO3) 0.3 This is a powder of Cl4 obtained.

[0115] The characteristics of the solid electrolyte (compound) of cathode example 8, including the combination of raw materials, synthesis time, and synthesis process, are summarized in Table 1 below. The measurement results of the solid electrolyte properties are summarized in Table 2 below. Furthermore, the measurement results of the half-cell rate characteristics are summarized in Table 3 below.

[0116] [Positive electrode example 9] The solid electrolyte (Li2Zr(S2O3)Cl4) of positive electrode example 9 was synthesized in the same manner as in positive electrode example 1, except that Li2S2O3 and zirconium chloride (ZrCl4) were used as raw materials, to obtain the powder of the solid electrolyte (Li2Zr(S2O3)Cl4) of positive electrode example 9.

[0117] Table 1 below summarizes the characteristics of the solid electrolyte (compound) of cathode example 9, including the combination of raw materials, synthesis time, and synthesis process. Table 2 below summarizes the measurement results of the solid electrolyte properties. Table 3 below summarizes the measurement results of the half-cell rate characteristics.

[0118] [Positive electrode example 10] The solid electrolyte (Li2Zr(S2O3)Cl4) for cathode example 10 was synthesized in the same manner as cathode example 9, except that the raw materials were weighed in a glove box with a mixed atmosphere of dry air with a dew point of approximately -40°C and argon gas in a volume ratio of 40%:60%, and the synthesis was carried out by setting up a planetary ball mill in the same mixed atmosphere of dry air with a dew point of approximately -40°C and argon gas in a volume ratio of 40%:60%, thereby obtaining the Li2Zr(S2O3)Cl4 powder for cathode example 10.

[0119] The characteristics of the solid electrolyte (compound) of cathode example 10, including the combination of raw materials, synthesis time, and synthesis process, are summarized in Table 1 below. The measurement results of the solid electrolyte properties are summarized in Table 2 below. Furthermore, the measurement results of the half-cell rate characteristics are summarized in Table 3 below.

[0120] [Positive electrode example 11] Solid electrolyte of positive electrode example 11 (Li2Zr(SO4) 0.3 (S2O3) 0.7 Cl4) was synthesized in the same manner as in Cathode Example 1, except that lithium sulfate (Li2SO4), Li2S2O3, and zirconium chloride (ZrCl4) were weighed out in a molar ratio of 3:7:10 to prepare the raw material powder. The solid electrolyte (Li2Zr(SO4)) of Cathode Example 11 was then prepared. 0.3 (S2O3) 0.7 This is a powder of Cl4 obtained.

[0121] The characteristics of the solid electrolyte (compound) of cathode example 11, including the combination of raw materials, synthesis time, and synthesis process, are summarized in Table 1 below. The measurement results of the solid electrolyte properties are summarized in Table 2 below. Furthermore, the measurement results of the half-cell rate characteristics are summarized in Table 3 below.

[0122] [Positive electrode example 12] Solid electrolyte of positive electrode example 12 (Li2Zr(SO4) 0.5 (S2O3) 0.5Cl4) was synthesized in the same manner as in Cathode Example 1, except that lithium sulfate (Li2SO4), Li2S2O3, and zirconium chloride (ZrCl4) were weighed in a molar ratio of 1:1:2 to prepare the raw material powder, and the raw materials were weighed in a glove box with a mixed atmosphere of dry air with a dew point of approximately -40°C and argon gas in a volume ratio of 20%:80%, and the synthesis was carried out by setting up a planetary ball mill in the same mixed atmosphere of dry air with a dew point of approximately -40°C and argon gas in a volume ratio of 20%:80%, and the solid electrolyte (Li2Zr(SO4)) of Cathode Example 12 was synthesized. 0.5 (S2O3) 0.5 This is a powder of Cl4 obtained.

[0123] The characteristics of the solid electrolyte (compound) of cathode example 12, including the combination of raw materials, synthesis time, and synthesis process, are summarized in Table 1 below. The measurement results of the solid electrolyte properties are summarized in Table 2 below. Furthermore, the measurement results of the half-cell rate characteristics are summarized in Table 3 below.

[0124] [Positive electrode example 13] Solid electrolyte of positive electrode example 13 (Li2Zr(SO4) 0.7 (S2O3) 0.3 Cl4) was synthesized in the same manner as in Cathode Example 1, except that lithium sulfate (Li2SO4), Li2S2O3, and zirconium chloride (ZrCl4) were weighed in a molar ratio of 7:3:10 to prepare the raw material powder, and the raw materials were weighed in a glove box with a mixed atmosphere of dry air with a dew point of approximately -40°C and argon gas in a volume ratio of 40%:60%, and the synthesis was carried out by setting up a planetary ball mill in the same mixed atmosphere of dry air with a dew point of approximately -40°C and argon gas in a volume ratio of 40%:60%, and thus the solid electrolyte (Li2Zr(SO4)) of Cathode Example 13 was synthesized. 0.7 (S2O3) 0.3 This is a powder of Cl4 obtained.

[0125] Table 1 below summarizes the characteristics of the solid electrolyte (compound) of cathode example 13, including the combination of raw materials, synthesis time, and synthesis process. Table 2 below summarizes the measurement results of the solid electrolyte properties. Table 3 below summarizes the measurement results of the half-cell rate characteristics.

[0126] [Positive electrode example 14] The solid electrolyte (Li6PS5Cl) of positive electrode example 14 was prepared by weighing lithium sulfide (Li2S), phosphorus sulfide (P2S5), and lithium chloride (LiCl) in a molar ratio of 5:1:2 to prepare the raw material powders, and then adding all of these raw material powders simultaneously to obtain the powder of the solid electrolyte (Li6PS5Cl) of positive electrode example 14.

[0127] The characteristics of the solid electrolyte (compound) of cathode example 14, including the combination of raw materials, synthesis time, and synthesis process, are summarized in Table 1 below. The measurement results of the solid electrolyte properties are summarized in Table 2 below. Furthermore, the measurement results of the half-cell rate characteristics are summarized in Table 3 below.

[0128] [Positive electrode example 15] Solid electrolyte (Li) of positive electrode example 15 9.54 Si 1.74 P 1.44 S 11.7 Cl 0.3 ) was synthesized in the same manner as in Cathode Example 1, except that lithium sulfide (Li2S), silicon sulfide (SiS2), phosphorus sulfide (P2S5), and lithium chloride (LiCl) were weighed in a molar ratio of 4.62:1.74:0.72:0.3 to prepare the raw material powders, and all of these raw material powders were added simultaneously during synthesis. 9.54 Si 1.74 P 1.44 S 11.7 Cl 0.3 ) was synthesized.

[0129] The characteristics of the solid electrolyte (compound) of cathode example 15, including the combination of raw materials, synthesis time, and synthesis process, are summarized in Table 1 below. The measurement results of the solid electrolyte properties are summarized in Table 2 below. Furthermore, the measurement results of the half-cell rate characteristics are summarized in Table 3 below.

[0130] [Positive electrode example 16] The solid electrolyte (Li2Zr(SO3)Cl4) for cathode example 16 was synthesized in the same manner as in cathode example 4, except that a mechanochemical reaction was carried out for 48 hours, to obtain a powder of solid electrolyte (Li2Zr(SO3)Cl4).

[0131] The characteristics of the solid electrolyte (compound) of cathode example 16, including the combination of raw materials, synthesis time, and synthesis process, are summarized in Table 1 below. The measurement results of the solid electrolyte properties are summarized in Table 2 below. Furthermore, the measurement results of the half-cell rate characteristics are summarized in Table 3 below.

[0132] [Positive electrode example 17] The solid electrolyte (Li2Zr(SO3)Cl4) for cathode example 17 was synthesized in the same manner as in cathode example 4, except that a mechanochemical reaction was carried out for 72 hours, to obtain a powder of solid electrolyte (Li2Zr(SO3)Cl4).

[0133] The characteristics of the solid electrolyte (compound) of cathode example 17, including the combination of raw materials, synthesis time, and synthesis process, are summarized in Table 1 below. The measurement results of the solid electrolyte properties are summarized in Table 2 below. Furthermore, the measurement results of the half-cell rate characteristics are summarized in Table 3 below.

[0134] <Example of a positive electrode> [Positive electrode comparison example 1] The solid electrolyte (Li2ZrCl6) of positive electrode comparative example 1 was synthesized in the same manner as positive electrode example 1, except that lithium chloride (LiCl) and zirconium chloride (ZrCl4) were weighed in a molar ratio of 2:1 to prepare the raw material powder.

[0135] Table 1 below summarizes the characteristics of the solid electrolyte (compound) of comparative example 1 of the positive electrode, including the combination of raw materials, synthesis time, and synthesis process. Table 2 below summarizes the measurement results of the solid electrolyte properties. Table 3 below summarizes the measurement results of the half-cell rate characteristics.

[0136] [Positive electrode comparative example 2] The solid electrolyte (Li3YCl6) of comparative example 2 of the positive electrode was synthesized in the same manner as in example 1, except that lithium chloride (LiCl) and yttrium chloride (YCl3) were weighed out in a molar ratio of 3:1 to prepare the raw material powder.

[0137] Table 1 below summarizes the characteristics of the solid electrolyte (compound) of comparative example 2 of the positive electrode, including the combination of raw materials, synthesis time, and synthesis process. Table 2 below summarizes the measurement results of the solid electrolyte properties. Table 3 below summarizes the measurement results of the half-cell rate characteristics.

[0138] [Positive electrode comparative example 3] The solid electrolyte (Li3ZrPO4Cl4) of positive electrode comparative example 3 was synthesized in the same manner as positive electrode example 1, except that lithium phosphate (Li3PO4) and zirconium chloride (ZrCl4) were weighed in a molar ratio of 1:1 to prepare the raw material powder.

[0139] Table 1 below summarizes the characteristics of the solid electrolyte (compound) of comparative example 3 of the positive electrode, including the combination of raw materials, synthesis time, and synthesis process. Table 2 below summarizes the measurement results of the solid electrolyte properties. Table 3 below summarizes the measurement results of the half-cell rate characteristics.

[0140] [Positive electrode comparative example 4] The solid electrolyte (Li2Zr(SO4)Cl4) for Cathode Comparative Example 4 was synthesized in the same manner as Cathode Example 1, except that the raw materials were weighed in a glove box with a mixed atmosphere of dry air with a dew point of approximately -40°C and argon gas in a volume ratio of 60%:40%, and the synthesis was carried out by setting up a planetary ball mill in the same mixed atmosphere of dry air with a dew point of approximately -40°C and argon gas in a volume ratio of 60%:40%, thereby obtaining the powder of the solid electrolyte (Li2Zr(SO4)Cl4) for Cathode Comparative Example 4.

[0141] Table 1 below summarizes the characteristics of the solid electrolyte (compound) of comparative example 4 of the positive electrode, including the combination of raw materials, synthesis time, and synthesis process. Table 2 below summarizes the measurement results of the solid electrolyte properties. Table 3 below summarizes the measurement results of the half-cell rate characteristics.

[0142] [Positive electrode comparative example 5] The solid electrolyte (Li2Zr(SO3)Cl4) for Cathode Comparative Example 5 was synthesized in the same manner as Cathode Example 1, except that the raw materials were weighed in a glove box with a mixed atmosphere of dry air with a dew point of approximately -40°C and argon gas in a volume ratio of 60%:40%, and the synthesis was carried out by setting up a planetary ball mill in the same mixed atmosphere of dry air with a dew point of approximately -40°C and argon gas in a volume ratio of 60%:40%, thereby obtaining the powder of the solid electrolyte (Li2Zr(SO3)Cl4) for Cathode Comparative Example 5.

[0143] Table 1 below summarizes the characteristics of the solid electrolyte (compound) of comparative example 5 of the positive electrode, including the combination of raw materials, synthesis time, and synthesis process. Table 2 below summarizes the measurement results of the solid electrolyte properties. Table 3 below summarizes the measurement results of the half-cell rate characteristics.

[0144] [Positive electrode comparative example 6] The solid electrolyte (Li2Zr(S2O3)Cl4) for Cathode Comparative Example 6 was synthesized in the same manner as Cathode Example 1, except that the raw materials were weighed in a glove box with a mixed atmosphere of dry air with a dew point of approximately -40°C and argon gas in a volume ratio of 60%:40%, and the synthesis was carried out by setting up a planetary ball mill in the same mixed atmosphere of dry air with a dew point of approximately -40°C and argon gas in a volume ratio of 60%:40%, thereby obtaining the Li2Zr(S2O3)Cl4 powder for Cathode Comparative Example 6.

[0145] Table 1 below summarizes the characteristics of the solid electrolyte (compound) of comparative example 6 of the positive electrode, including the combination of raw materials, synthesis time, and synthesis process. Table 2 below summarizes the measurement results of the solid electrolyte properties. Table 3 below summarizes the measurement results of the half-cell rate characteristics.

[0146] <Example of negative electrode> The solid electrolytes (compounds) in negative electrode examples 1 to 17 are the same as the solid electrolytes (compounds) in positive electrode examples 1 to 17, and correspond to the compounds in examples 1 to 17 listed in Table 1. Furthermore, the characteristics of negative electrode examples 1 to 17 correspond to the characteristics of examples 1 to 17 listed in Table 2.

[0147] [Table 1]

[0148] [Table 2]

[0149] [Table 3]

[0150] (Preparation of negative electrode mixture) For the preparation of the negative electrode mixture, lithium titanate (Li4Ti5O) is used as the negative electrode active material. 12The negative electrode active material and Li2Zr(SO4)Cl4 from negative electrode example 1 were prepared. The negative electrode active material and Li2Zr(SO4)Cl4 from negative electrode example 1 were weighed to be 60 wt% and 40 wt%, respectively. The weighed negative electrode active material and Li2Zr(SO4)Cl4 from negative electrode example 1 were mixed in an agate mortar for 15 minutes to obtain the negative electrode mixture.

[0151] (Preparation of half-cells for charging and discharging) The half-cells for charging and discharging were fabricated inside a glove box with a dew point of approximately -70°C. For half-cell production, a pellet manufacturing jig was used for preparation. The pellet manufacturing jig consists of a PEEK (polyetheretherketone) cylinder with an outer diameter of 30 mm, an inner diameter of 10 mm, and a height of 20 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).

[0152] A lower punch was inserted into a PEEK cylinder, and 110 mg of solid electrolyte Li2Zr(SO4)Cl4 was placed on top of the lower punch. Next, the PEEK cylinder was vibrated to level the surface of the solid electrolyte, and then an upper punch was inserted on top of the solid electrolyte. A press was then used to press the solid electrolyte layer with a load of 373 MPa.

[0153] Next, the upper punch was removed, and 15 mg of the above-mentioned negative electrode mixture was placed on top of the solid electrolyte layer. Then, the PEEK cylinder was vibrated to level the surface of the negative electrode mixture, and the upper punch was inserted on top of the negative electrode mixture and pressed with a press machine at a load of 373 MPa. Next, the lower punch was removed, a lithium foil with a diameter of 10 mm and a thickness of 100 μm was placed on top of the solid electrolyte layer, and the lower punch was inserted. The configuration of the half cell is (Li4Ti5O 12 The formula becomes +Li2Zr(SO4)Cl4) / Li2Zr(SO4)Cl4 / Li.

[0154] 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 half 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 half cell in a plan view.

[0155] Subsequently, stainless steel plates, bakelite® plates, half cells, 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, a half cell was obtained in which the upper and lower punches of the electrochemical cell were insulated by bakelite® plates. Next, the half cell was left to stand in a 25°C constant temperature bath for 48 hours to stabilize the open-circuit voltage.

[0156] <Measuring Rate Characteristics> The fabricated half-cells were charged and discharged under the following conditions. The voltage range was set from 1.0V to 2.5V. Charging was performed using a constant current of 0.1C, and after the voltage was set, charging was terminated when the current reached the equivalent of 0.05C. Discharging was performed at 0.1C and 1.0C, and the ratio of the discharge capacity at 1C to the discharge capacity at 0.1C (rate characteristic (unit: %)) was determined, with the discharge capacity at 0.1C being set to 100%. The obtained results are shown in Table 1.

[0157] The measurement results of the rate characteristics of half-cells of the solid electrolytes for negative electrode examples 1 to 17 are summarized in Table 4 below.

[0158] <Negative electrode comparison example> The solid electrolytes (compounds) of negative electrode comparative examples 1 to 6 are the same as the solid electrolytes (compounds) of positive electrode comparative examples 1 to 6, and correspond to the compounds of comparative examples 1 to 6 listed in Table 1. Furthermore, the properties of negative electrode comparative examples 1 to 6 correspond to the properties of comparative examples 1 to 6 listed in Table 2. Furthermore, half-cells of the solid electrolytes (compounds) of negative electrode comparative examples 1 to 6 were prepared in the same manner as the half-cells of the solid electrolytes (compounds) of negative electrode examples 1 to 17, and their rate characteristics were measured. The measurement results are summarized in Table 4 below.

[0159] [Table 4]

[0160] Examples 1-17 and Comparative Examples 4-6 showed SO3 - Peak intensity Ra and SO4 - Comparing the peak intensity ratio R1 (Ra / Rb) of the peak intensity Rb, it can be seen that the ionic conductivity of Examples 1 to 17, where the peak intensity ratio R1 is greater than 1, is greater than that of Comparative Examples 4 to 6, where the peak intensity ratio R1 is less than 1. Specifically, among Examples 1 to 17, Example 17, which has the lowest ionic conductivity, has an ionic conductivity of 2.8 × 10⁻⁶. -4 While the value is [S / cm], among Comparative Examples 4 to 6, Comparative Example 5, which has the highest ionic conductivity, has an ionic conductivity of 1.0 × 10⁻⁶. -4 The value is [S / cm]. Thus, the peak intensity ratio R1 (Ra / Rb) can be used as an indicator of ionic conductivity.

[0161] Furthermore, the peak intensity ratio R1 (Ra / Rb) satisfies 6.0 > R1 > 1.0 for Examples 1 to 17, with 5.71 (Example 17) ≥ R1 ≥ 1.18 (Example 10). Also, the ionic conductivity for Examples 1 to 15 is 3.1 × 10⁻⁶. -4 [S / cm] (Example 3) Above, 5.4 × 10 -3 [S / cm] (Example 15) is less than or equal to the specified value.

[0162] Furthermore, the peak intensity ratio R1 (Ra / Rb) satisfies 1.8 > R1 > 1.2 for Examples 1, 2, 4, 6, 7, 8, 9, and 11-15. Additionally, the ionic conductivity for Examples 1, 2, 4, 6, 7, 8, 9, and 11-15 is 9.4 × 10⁻⁶. ‐4 (Example 8) Above, 5.4 × 10 -3 [S / cm] (Example 15) is less than or equal to the specified value. When 1.8 > R1 > 1.2, the ionic conductivity is 9.4 × 10⁻⁶. ‐4 The value is greater than or equal to [S / cm]. Thus, the peak intensity ratio R1 (Ra / Rb) can be used as an indicator of ionic conductivity.

[0163] Furthermore, the peak intensity ratio R1 (Ra / Rb) satisfies 1.7 > R1 > 1.4 for Examples 1, 2, 4, 6, 7, 9, 11, 12, 14, and 15.

[0164] Furthermore, although Examples 1-3 consist of compounds with the same composition, their ionic conductivity differs. This is due to differences in the atmosphere in which the synthesis was carried out (synthesis atmosphere). Thus, ionic conductivity can be adjusted by adjusting the synthesis atmosphere. Similarly, although Examples 4 and 5 are compounds with the same composition, their ionic conductivity differs due to the different synthesis atmospheres. Similarly, although Examples 9 and 10 are compounds with the same composition, their ionic conductivity differs due to the different synthesis atmospheres.

[0165] Examples 6-8 are compounds with the same constituent elements, but the ratio of SO4 to SO3 differs, resulting in different ionic conductivity. This is due to differences in the proportions of the raw materials used in synthesis and the different synthesis atmospheres. Thus, by adjusting the synthesis atmosphere, the ratio of SO4 to SO3 can be adjusted, and thus the ionic conductivity can be controlled. Similarly, while Examples 11-13 consist of compounds with the same constituent elements, they differ in the ratio of SO4 to SO3, resulting in different ionic conductivity. This is due to the different synthesis atmospheres. Thus, by adjusting the synthesis atmosphere, the ratio of SO4 to SO3 can be adjusted, and the ionic conductivity can be controlled.

[0166] Examples 4, 16, and 17 are compounds with the same composition, but their ionic conductivity differs. This is due to differences in synthesis time. Thus, ionic conductivity can also be adjusted by controlling the synthesis time. The synthesis times for Examples 4, 16, and 17 were 24 hours, 48 ​​hours, and 72 hours, respectively, and the ionic conductivity was 3.1 × 10⁻⁶ for each example. -3 [S / cm], 3.0 × 10 -4 [S / cm], 2.8 × 10 -4 The ionic conductivity is [S / cm]. Example 4, with a synthesis time of 24 hours, showed the highest ionic conductivity. The ionic conductivity of Example 4 was an order of magnitude higher than that of Examples 16 and 17. Thus, by adjusting the synthesis time, it is possible to improve the ionic conductivity by more than an order of magnitude even for compounds with the same composition.

[0167] When comparing compounds of the same composition, among three synthetic atmospheres—Ar gas atmosphere, a mixed atmosphere of dry air with a dew point of approximately -40°C and argon gas in a volume ratio of 20%:80%, and a mixed atmosphere of dry air with a dew point of approximately -40°C and argon gas in a volume ratio of 40%:60%—the Ar gas atmosphere showed the highest ionic conductivity. [Explanation of Symbols]

[0168] 10...solid electrolyte layer, 20...Positive electrode, 22...Positive electrode current collector, 24...Positive electrode mixture layer, 30...Negative electrode, 32...Negative electrode current collector, 34... Negative electrode mixture layer, 40... Power generation element, 50... Exterior body, 52…metal foil, 54… Resin layer, Terminals 60, 62, etc. 100…All-solid-state battery

Claims

1. It contains Li, one or more elements selected from Group 3 to Group 15, and S. SO obtained by negative ion analysis using time-of-flight secondary ion mass spectrometry ３ － Peak intensity Ra and SO ４ － An electrode containing a compound whose peak intensity Rb satisfies the condition Ra > Rb.

2. SO in the aforementioned compound ３ － Peak intensity Ra and SO ４ － The electrode according to claim 1, wherein the peak intensity ratio R1 (Ra / Rb) with respect to the peak intensity Rb satisfies 6.0 > R1 > 1.

0.

3. SO in the compound ３ － The peak intensity ratio R1 (Ra / Rb) of the peak intensity Ra of and SO ４ － and the peak intensity Rb of satisfies 1.8 > R1 > 1.2, The electrode according to claim 1.

4. SO in the aforementioned compound ３ － Peak intensity Ra and SO ４ － The electrode according to claim 1, wherein the peak intensity ratio R1 (Ra / Rb) with respect to the peak intensity Rb satisfies 1.7 > R1 > 1.

4.

5. The aforementioned compound was found to be SO in negative ion analysis by time-of-flight secondary ion mass spectrometry. － The peak of SO ２ － The peak of SO ３ － The peak of SO ４ － Each of the four peaks was detected, and of the four peaks, SO ３ － The electrode according to claim 1, wherein the peak satisfies the strongest peak intensity.

6. The electrode according to claim 1, wherein the compound is represented by the following formula (1). LiaEbGcXd...(1) (In formula (1), E is at least one element selected from the group consisting of Al, Sc, Y, Zr, Hf, and lanthanides. G is SO ３ SO ４ 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 X is at least one group selected from the group consisting of F, Cl, Br, and I. (0.5 ≤ a < 6, 0 < b < 2, 0.1 < c ≤ 6, 0 < d ≤ 6.1.)

7. The positive electrode and the negative electrode face each other across a solid electrolyte layer. A solid-state battery comprising at least one of the positive electrode and the negative electrode, which is an electrode according to any one of claims 1 to 6.

8. The all-solid-state battery according to claim 7, wherein the solid electrolyte layer contains a compound represented by the following formula (2). LiaEbGcXd...(2) (In formula (2), E is at least one element selected from the group consisting of Al, Sc, Y, Zr, Hf, and lanthanides. G is SO ３ SO ４ 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 X is at least one group selected from the group consisting of F, Cl, Br, and I. (0.5 ≤ a < 6, 0 < b < 2, 0.1 < c ≤ 6, 0 < d ≤ 6.1.)

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