Active material layer, negative electrode, and all-solid-state battery

Abstract

To provide an active material layer with high energy density, a negative electrode, and an all-solid-state battery.SOLUTION: An active material layer according to an embodiment includes an active material, and a compound represented by the chemical formula AαMβXγ and having crystallinity. In the above chemical formula, A is an alkali metal or alkaline earth metal; M is a transition metal; X is a halogen; α satisfies 1≤α≤3; β satisfies 0.5≤β≤1.5; and γ satisfies 5≤γ≤7. The active material has an electrode potential in the range of 1.0 V or more and 2.0 V or less based on the Li+ / Li equilibrium potential.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to an active material layer, a negative electrode, and an all-solid-state battery.

Background Art

[0002] In recent years, the development of electronics technology has been remarkable, and portable electronic devices have been made smaller, lighter, thinner, and more multifunctional. Along with this, there is a strong demand for batteries that power electronic devices to be smaller, lighter, thinner, and more reliable, and all-solid-state batteries using solid electrolytes as electrolytes have attracted attention.

[0003] As an example of a method for manufacturing an all-solid-state battery, there are a sintering method and a powder molding method. In the sintering method, a negative electrode, a solid electrolyte layer, and a positive electrode are laminated and then sintered to form an all-solid-state battery. In the powder molding method, a negative electrode, a solid electrolyte layer, and a positive electrode are laminated and then pressure is applied to form an all-solid-state battery. The materials that can be used for the solid electrolyte layer differ depending on the manufacturing method. Known solid electrolytes include oxide-based solid electrolytes, sulfide-based solid electrolytes, complex hydride-based solid electrolytes (such as LiBH 4 etc.).

[0004] For example, Patent Document 1 discloses a solid electrolyte material represented by Li 6-3Z Y Z X 6 (0 < Z < 2, X is Cl or Br). Patent Document 1 also discloses an all-solid-state battery containing this solid electrolyte material in at least one of the negative electrode and the positive electrode.

Prior Art Documents

Patent Documents

[0005]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0006] However, Patent Document 1 describes changing the electrode potential between the solid electrolyte and the active material so that the solid electrolyte does not react at the charge-discharge potential (for example, paragraph 0213). In Patent Document 1, the electrode potentials of the solid electrolyte and the active material are made not to overlap.

[0007] Therefore, in the all-solid-state battery in Patent Document 1, the solid electrolyte does not contribute to the charge-discharge reaction, and the solid electrolyte contained in the electrode does not affect the battery capacity. In other words, the all-solid-state battery described in Patent Document 1 loses battery capacity by the volume in which the solid electrolyte exists, and the overall energy density is reduced.

[0008] The present invention has been made in view of the above problems, and an object thereof is to provide an active material layer, a negative electrode, and an all-solid-state battery having a high energy density.

Means for Solving the Problems

[0009] In order to solve the above problems, the following means are provided.

[0010] (1) The active material layer according to the first aspect includes an active material and a compound represented by the chemical formula of A α M β X γ and having crystallinity. In the chemical formula, A is an alkali metal or an alkaline earth metal, M is a transition metal, X is a halogen, α satisfies 1 ≦ α ≦ 3, β satisfies 0.5 ≦ β ≦ 1.5, γ satisfies 5 ≦ γ ≦ 7, and the active material has an electrode potential in the range of 1.0 V or more and 2.0 V or less based on the Li + / Li equilibrium potential.

[0011] (2) In the active material layer according to the above aspect, the content of the compound with respect to the total of the active material and the compound may be 21% by weight or more and 70% by weight or less.

[0012] (3) When performing X-ray diffraction measurement using CuKα rays, the half-value width of the diffraction peak showing the strongest intensity among the peaks derived from the compound in the active material layer according to the above aspect may be within 2.0°.

[0013] (4) In the active material layer according to the above aspect, the diffraction peak showing the strongest intensity among the peaks derived from the compound may be within the range of 31° < 2θ < 33°.

[0014] (5) In the active material layer according to the above aspect, the active material may be a titanium oxide.

[0015] (6) The negative electrode according to the second aspect has the active material layer according to the above aspect and a current collector in contact with the active material layer.

[0016] (7) The all-solid-state battery according to the third aspect includes the negative electrode according to the above aspect.

Advantages of the Invention

[0017] The active material layer, negative electrode, and all-solid-state battery according to the above aspect have a high energy density.

Brief Description of the Drawings

[0018]

Figure 1

Modes for Carrying Out the Invention

[0019] Hereinafter, the present 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 the sake of clarity of 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 modified and implemented without changing the gist thereof.

[0020] [All-Solid-State Battery] Figure 1 is a schematic cross-sectional view of all-solid-state battery 10 according to the present embodiment. All-solid-state battery 10 has a laminate 4 and terminal electrodes 5 and 6. Terminal electrodes 5 and 6 are in contact with opposite surfaces of laminate 4, respectively. Terminal electrodes 5 and 6 extend in a direction intersecting (orthogonal to) the lamination plane of laminate 4.

[0021] Laminate 4 has a positive electrode 1, a negative electrode 2, and a solid electrolyte 3. The number of layers of positive electrode 1 and negative electrode 2 is not limited. There is a solid electrolyte 3 between positive electrode 1 and negative electrode 2. One end of positive electrode 1 is connected to terminal electrode 5. One end of negative electrode 2 is connected to terminal electrode 6. There is, for example, a solid electrolyte 3 between positive electrode 1 and terminal electrode 6 and between negative electrode 2 and terminal electrode 5.

[0022] All-solid-state battery 10 is charged or discharged by the transfer of ions through solid electrolyte 3 between positive electrode 1 and negative electrode 2. In FIG. 1, a laminated battery is shown, but a wound battery may also be used. All-solid-state battery 10 is used, for example, in laminated batteries, prismatic batteries, cylindrical batteries, coin-type batteries, button-type batteries, etc. Also, all-solid-state battery 10 may be a liquid-injection type in which solid electrolyte 3 is dissolved or dispersed in a solvent.

[0023] "Positive electrode" As shown in FIG. 1, positive electrode 1 has, for example, a positive electrode current collector 1A and a positive electrode active material layer 1B containing a positive electrode active material.

[0024] (Positive electrode current collector) Positive electrode current collector 1A preferably has high conductivity. For example, metals such as silver, palladium, gold, platinum, aluminum, copper, nickel, titanium, stainless steel, and their alloys, or conductive resins can be used. Positive electrode current collector 1A may be in the form of powder, foil, punching, or expansion.

[0025] (Positive electrode active material layer) Positive electrode active material layer 1B is formed on one or both sides of positive electrode current collector 1A. Positive electrode active material layer 1B contains a positive electrode active material and may, if necessary, contain a conductive assistant, a binder, a solid electrolyte described later, and a compound described later.

[0026] (Positive electrode active material) The positive electrode active material contained in the positive electrode active material layer 1B is, for example, a lithium-containing transition metal oxide, a transition metal fluoride, a polyanion, a transition metal sulfide, a transition metal oxyfluoride, a transition metal oxysulfide, or a transition metal oxynitride.

[0027] The positive electrode active material is not particularly limited as long as it can reversibly proceed with the release and occlusion of lithium ions and the desorption and insertion of lithium ions. For example, the positive electrode active materials used in known lithium-ion secondary batteries can be used.

[0028] The positive electrode active material is, for example, a composite metal oxide. The positive electrode active material is, for example, lithium cobalt oxide (LiCoO 2 ), lithium nickel oxide (LiNiO 2 ), lithium manganese spinel (LiMn 2 O 4 ), and a composite metal oxide represented by the general formula: LiNi x Co y Mn z M a O 2 (x + y + z + a = 1, 0 ≤ x ≤ 1, 0 ≤ y ≤ 1, 0 ≤ z ≤ 1, 0 ≤ a ≤ 1, M is one or more elements selected from Al, Mg, Nb, Ti, Cu, Zn, Cr), lithium vanadium compound (LiV 2 O 5 , Li 3 V 2 (PO 4 ) 3 , LiVOPO 4 ), olivine-type LiMPO 4 (where M represents one or more elements selected from Co, Ni, Mn, Fe, Mg, V, Nb, Ti, Al, Zr), lithium titanate (Li 4 Ti 5 O 12 ), LiNi x Co y Al z O 2 (0.9 < x + y + z < 1.1), etc.

[0029] In addition, as the positive electrode active material, a positive electrode active material that does not contain lithium can also be used. These positive electrode active materials can be used by arranging a negative electrode active material previously doped with metallic lithium or lithium ions in the negative electrode and starting the battery from discharge. For example, lithium-free metal oxides (MnO 2 、V 2 O 5 etc.), lithium-free metal sulfides (MoS 2 etc.), lithium-free fluorides (FeF 3 、VF 3 etc.) and the like are examples of these positive electrode active materials.

[0030] (Conductive aid) The conductive aid is not particularly limited as long as it can improve the electron conductivity in the positive electrode active material layer 1B, and known conductive aids can be used. Examples of the conductive aid include carbon-based materials such as graphite, carbon black, graphene, and carbon nanotubes, metals such as gold, platinum, silver, palladium, aluminum, copper, nickel, stainless steel, and iron, conductive oxides such as ITO, or mixtures thereof. The conductive aid may be in the form of powder or fiber.

[0031] (Binder) The binder joins the positive electrode current collector 1A and the positive electrode active material layer 1B, the positive electrode active material layer 1B and the solid electrolyte 3, and various materials constituting the positive electrode active material layer 1B.

[0032] The binder can be used within a range that does not impair the function of the positive electrode active material layer 1B. The binder may not be contained if it is not necessary. The content of the binder in the positive electrode active material layer 1B is, for example, 0.5 to 30% by volume of the positive electrode active material layer. If the content of the binder is within this range, the resistance of the positive electrode active material layer 1B becomes sufficiently low.

[0033] The binder may be any material capable of the above-described bonding. For example, fluororesins such as polyvinylidene fluoride (PVDF) and polytetrafluoroethylene (PTFE) can be mentioned. Furthermore, in addition to the above, as the binder, for example, cellulose, styrene-butadiene rubber, ethylene-propylene rubber, polyimide resin, polyamideimide resin, etc. may be used. Also, a conductive polymer having electronic conductivity or an ion conductive polymer having ion conductivity may be used as the binder. Examples of the conductive polymer having electronic conductivity include polyacetylene. In this case, since the binder also exhibits the function of the conductive auxiliary agent particles, it is not necessary to add a conductive auxiliary agent. As the ion conductive polymer having ion conductivity, for example, those capable of conducting lithium ions can be used, and a monomer of a polymer compound (polyether-based polymer compounds such as polyethylene oxide and polypropylene oxide, polyphosphazene, etc.) and LiClO 4 , LiBF 4 , LiPF 6 and other lithium salts or alkali metal salts mainly composed of lithium, etc. can be mentioned. Examples of the polymerization initiator used for the composite include a photopolymerization initiator or a thermal polymerization initiator suitable for the above monomers. The properties required for the binder include oxidation-reduction resistance and good adhesiveness.

[0034] (Solid electrolyte) The solid electrolyte contained in the positive electrode active material layer 1B improves ion conduction in the positive electrode active material layer 1B. Details of the solid electrolyte will be described later.

[0035] "Negative electrode" As shown in FIG. 1, the negative electrode 2 has, for example, a negative electrode current collector 2A and a negative electrode active material layer 2B containing a negative electrode active material.

[0036] (Negative electrode current collector) The negative electrode current collector 2A preferably has a high conductivity. For example, it is preferable to use metals such as silver, palladium, gold, platinum, aluminum, copper, nickel, stainless steel, iron, and their alloys, or conductive resins. The negative electrode current collector 2A may be in the form of powder, foil, punching, or expansion.

[0037] (Negative electrode active material layer) The negative electrode active material layer 2B is formed on one or both sides of the negative electrode current collector 2A. The negative electrode active material layer 2B contains a negative electrode active material and a predetermined compound, and may contain a conductive assistant, a binder, and the above-mentioned solid electrolyte as required.

[0038] (Negative electrode active material) The negative electrode active material contained in the negative electrode active material layer 2B is a compound capable of occluding and releasing mobile ions. The negative electrode active material has an electrode potential in the range of 1.0 V or more and 2.0 V or less based on the Li + / Li equilibrium potential. The electrode potential of the negative electrode active material is, for example, 1.0 V vs Li + / Li or more and 2.0 V vs Li + / Li or less. If the electrode potential of the negative electrode active material is within this range, the electrode potential is approximated to the compound described later, and variations in the operating potential of the entire all-solid-state battery 10 can be suppressed.

[0039] The negative electrode active material layer 2B is, for example, lithium titanate (LTO: for example, Li 4 Ti 5 O 12 ), titanium oxide (TiO 2 ), Ni-TiO 2 , titanium niobium oxide (TNO: TiNb 2 O 7 ), lithium oxide (LiO 2 ), titanium oxide (HTO: for example, H 2 Ti 12 O 25 ), sulfur-modified polyacrylonitrile (SPAN), etc. The negative electrode active material layer 2B preferably contains titanium and oxygen elements. For example, lithium titanate (LTO: for example, Li 4 Ti 5 O12 ) Titanium oxide (TiO 2 ), Ni-TiO 2 , titanium niobium oxide (TNO: TiNb 2 O 7 ) is preferred.

[0040] (Compound) The compound is responsible for the conduction of ions in the negative electrode active material layer 2B and stores and releases ions. The compound is A α M β X γ represented by the chemical formula of. A is an alkali metal or an alkaline earth metal. A is, for example, any one or more of Li, K, Na, and preferably Li. M is a transition metal. M is, for example, one or more elements selected from the group consisting of Zr, Hf, Ti, Sn, and Ge. Zr is low-cost, low-weight, and enhances the stability of the battery. X is a halogen. X is, for example, Cl. The elements constituting A, M, and X may each be one or more. α satisfies 1 ≦ α ≦ 3, β satisfies 0.5 ≦ β ≦ 1.5, and γ satisfies 5 ≦ γ ≦ 7. The compound is, for example, Li 3 ZrCl 6 .

[0041] The compound has crystallinity. Having crystallinity means that when X-ray diffraction measurement using CuKα rays is performed on the negative electrode active material layer 2B, diffraction peaks derived from the compound are confirmed. The negative electrode active material layer 2B also contains substances other than the compound, but these diffraction peaks and the diffraction peaks derived from the compound are separable. For example, by specifying the compound through compositional analysis, the diffraction peaks derived from the compound can be specified. For example, when the compound is Li 3 ZrCl 6 , the strongest diffraction peak derived from the compound occurs in the range of 31° ≦ 2θ < 33°.

[0042] When X-ray diffraction measurement is performed on the negative electrode active material layer 2B using CuKα rays, the half-value width of the diffraction peak showing the strongest intensity among the diffraction peaks derived from the compound is preferably within 2.0°, and more preferably within 1.0°. The higher the crystallinity of the compound, the less the capacity loss, and the higher the energy density of the all-solid-state battery 10 tends to be.

[0043] The content rate of the compound with respect to the total of the active material and the compound in the negative electrode active material layer 2B is, for example, 21% by weight or more and 70% by weight or less, preferably 21% by weight or more and 50% by weight or less, and more preferably 21% by weight or more and 30% by weight or less.

[0044] (Conductive assistant) The conductive assistant improves the electron conductivity of the negative electrode active material layer 2B. As the conductive assistant, the same material as that used for the positive electrode active material layer 1B can be used.

[0045] (Binder) The binder joins the negative electrode current collector 2A and the negative electrode active material layer 2B, the negative electrode active material layer 2B and the solid electrolyte 3, and various materials constituting the negative electrode active material layer 2B. As the binder, the same material as that used for the positive electrode active material layer 1B can be used. The content ratio of the binder can also be the same as that of the positive electrode active material layer 1B. If the binder is not necessary, it may not be contained.

[0046] "Solid electrolyte" The solid electrolyte 3 is a substance capable of moving ions by an externally applied electric field. For example, the solid electrolyte 3 conducts lithium ions and inhibits the movement of electrons.

[0047] The solid electrolyte 3 contains, for example, lithium. The solid electrolyte 3 may be, for example, an oxide-based material, a sulfide-based material, or a halide-based material.

[0048] The solid electrolyte 3 may be, for example, any of a perovskite-type compound, a silicon-type compound, a garnet-type compound, a NASICON-type compound, a thiolsilicon-type compound, a glass compound, and a phosphate compound. La 0.5 Li0.5 TiO 3 is an example of a perovskite-type compound. Li 14 Zn(GeO 4 ) 4 is an example of a silicon-type compound. L i7 La 3 Zr 2 O 12 is an example of a garnet-type compound. LiZr 2 (PO 4 ) 3 、Li 1.3 Al 0.3 Ti 1.7 (PO 4 ) 3、 Li 1.5 Al 0.5 Ge 1.5 (PO 4 ) 3 、Li 1.55 Al 0.2 Zr 1.7 Si 0.25 P 9.75 O 12 、Li 1.4 Na 0.1 Zr 1.5 Al 0.5 (PO 4 ) 3 、Li 1.4 Ca 0.25 Er 0.3 Zr 1.7 (PO 4 ) 3.2 、Li 1.4 Ca 0.25 Yb 0.3 Zr 1.7 (PO 4 ) 3.2 is an example of a NASICON-type compound. Li 3.25 Ge 0.25 P 0.75 S 4、 Li 3 PS 4 is an example of a thiosilicon-type compound. Li 2 S-P 2 S 5、 Li 2 O-V 2 O 5 -SiO 2 is an example of a glass compound. Li3 PO 4 、 Li 3.5 Si 0.5 P 0.5 O 4 、 Li 2.9 PO 3.3 N 0.46 is an example of a phosphate compound.

[0049] The solid electrolyte 3 may be, for example, a material similar to the compound contained in the above-described negative electrode active material layer 2B. The solid electrolyte 3 may be, for example, the same as the compound contained in the above-described negative electrode active material layer 2B. The solid electrolyte 3 is, for example, a halogenated compound.

[0050] The solid electrolyte 3 may contain substances other than the solid electrolyte material. For example, the solid electrolyte 3 may contain an oxide or halide of an alkali metal element, an oxide or halide of a transition metal element, etc. Further, the solid electrolyte 3 may have a binder. The binder is the same as those described above.

[0051] At least one of the positive electrode active material layer 1B, the negative electrode active material layer 2B, and the solid electrolyte 3 may contain a non-aqueous electrolyte, an ionic liquid, or a gel electrolyte. When these substances are contained in any of the above, the rate characteristics, which are one of the battery characteristics, are improved.

[0052] [Manufacturing Method of All-Solid-State Battery] The all-solid-state battery can be manufactured, for example, using a powder molding method. First, a resin holder having a through hole in the center, a lower punch, and an upper punch are prepared. The diameter of the through hole of the resin holder is, for example, 10 mm, and the diameters of the lower punch and the upper punch are, for example, 9.99 mm. The lower punch is inserted from below the through hole of the resin holder, and powdery solid electrolyte is introduced from the opening side of the resin holder. Next, the upper punch is inserted onto the introduced powdery solid electrolyte, placed on a press machine, and pressed. The pressing pressure is, for example, 373 MPa. The powdery solid electrolyte is pressed between the upper punch and the lower punch within the resin holder to become the solid electrolyte 3.

[0053] The powdery solid electrolyte is obtained by mixing and reacting raw material powders at a predetermined molar ratio so as to achieve the target composition. Any method of reaction can be used, such as the mechanochemical milling method, the sintering method, the melting method, the liquid phase method, the solid phase method, etc.

[0054] Next, the upper punch is removed once, and the material for the positive electrode active material layer is introduced onto the upper punch side of the solid electrolyte 3. Then, the upper punch is inserted again and pressed. The pressing pressure is, for example, 373 MPa. The material for the positive electrode active material layer becomes the positive electrode active material layer 1B by pressing.

[0055] Next, the lower punch is removed once, and the material for the negative electrode active material layer is introduced onto the lower punch side of the solid electrolyte layer 3. For example, the sample is turned upside down, and the material for the negative electrode active material layer is introduced onto the solid electrolyte 3. The compounds in the material for the negative electrode active material layer can be produced in the same manner as the solid electrolyte. For example, it can be obtained by mixing and reacting raw material powders at a predetermined molar ratio so as to achieve the composition of the target compound. Any method of reaction can be used, such as the mechanochemical milling method, the sintering method, the melting method, the liquid phase method, the solid phase method, etc.

[0056] Next, the lower punch is inserted again and pressed. The pressing pressure is, for example, 373 MPa. The material for the negative electrode active material layer becomes the negative electrode active material layer 2B by pressing. Through the above procedure, the all-solid-state battery 10 of this embodiment is obtained.

[0057] The all-solid-state battery 10 may be stacked in the order of a stainless steel disc having screw holes at four locations and a Teflon (registered trademark) disc as needed, i.e., stainless steel disc / Teflon (registered trademark) disc / all-solid-state battery 10 / Teflon (registered trademark) disc / stainless steel disc, and the four screws may be tightened. Also, the all-solid-state battery 10 may have a similar mechanism with a shape-retaining function.

[0058] Alternatively, if necessary, it may be inserted into an exterior body (aluminum laminate bag) with an externally drawn positive terminal and an externally drawn negative terminal attached, and the screw on the upper punch side surface may be connected to the externally drawn positive terminal inside the exterior body, and the screw on the lower punch side surface may be connected to the externally drawn negative terminal inside the exterior body with lead wires, and finally, the opening of the exterior body may be heat-sealed. The weather resistance is improved by the exterior body.

[0059] The manufacturing method of the all-solid-state battery 10 described above was explained by taking the powder molding method as an example, but it may also be manufactured by a sheet molding method containing a resin.

[0060] For example, first, a solid electrolyte paste containing a powdery solid electrolyte is prepared. The prepared solid electrolyte paste is applied to a PET film, a fluororesin film, etc., dried, and peeled off to produce the solid electrolyte 3. Also, a positive electrode active material paste containing a positive electrode active material is applied onto the positive electrode current collector 1A and dried to form the positive electrode active material layer 1B, thereby producing the positive electrode 1. Further, a paste containing a negative electrode active material and a compound is applied onto the negative electrode current collector 2A and dried to form the negative electrode active material layer 2B, thereby producing the negative electrode 2.

[0061] Next, the solid electrolyte 3 is sandwiched between the positive electrode 1 and the negative electrode 2, and the whole is pressurized and adhered. Through the above steps, the all-solid-state battery 10 of the present embodiment is obtained.

[0062] The all-solid-state battery 10 according to the present embodiment has little capacity loss and high energy density. This is because the negative electrode active material layer 2B contains a compound that is responsible for ion conduction and stores and releases ions.

[0063] In order to enhance the ionic conductivity within the negative electrode active material layer 2B, mixing a solid electrolyte into the negative electrode active material layer 2B has been carried out. However, the said solid electrolyte only undertakes the conduction of ions and does not contribute to charge and discharge. That is to say, the negative electrode active material layer 2B has a portion (the mixed solid electrolyte) that does not contribute to the capacity of the battery. The capacity of the all-solid-state battery 10 becomes smaller compared to the case where the portion that does not contribute to the capacity of this battery is filled with the active material. That is, mixing a solid electrolyte into the negative electrode active material layer 2B means sacrificing a part of the capacity to enhance the ionic conductivity.

[0064] In contrast, the compound contained in the negative electrode active material layer 2B according to this embodiment occludes and releases ions at an operating voltage that substantially coincides with the operating voltage of the negative electrode active material. Further, the said compound also undertakes the conduction of ions. That is, the said compound contributes to the capacity while ensuring the ionic conductivity within the negative electrode active material layer 2B. Therefore, the all-solid-state battery 10 according to this embodiment has a small proportion of the portion that does not contribute to the capacity of the battery in the entire all-solid-state battery 10 and has a high capacity. Also, the all-solid-state battery 10 according to this embodiment has a high energy density.

[0065] As described above, the embodiments of the present invention have been described in detail with reference to the drawings. However, each configuration and their combinations in each embodiment are examples, and additions, omissions, substitutions, and other changes of the configuration are possible within the scope not departing from the gist of the present invention.

Example

[0066] 「Example 1」 Synthesis of the solid electrolyte and fabrication of the all-solid-state battery were carried out in a glove box with a dew point of -99°C and an oxygen concentration of 1 ppm while circulating argon gas.

[0067] (Fabrication of the positive electrode composite material) First, as the positive electrode active material, LCO (LiCoO 2 ), as the conductive assistant, carbon black (SuperP), and as the solid electrolyte, LZC (Li 2 ZrCl 6) was prepared. Inside the glove box, LZC weighed out LiCl, which is the raw material powder, and ZrCl 4 so that the molar ratio was 2:1, placed them together with Zr balls with a diameter of 5 mm in a Zr container, and produced them by performing mechanochemical milling treatment using a planetary ball mill. The treatment was mixed for 50 hours under the condition of a rotation speed of 500 rpm, and then sieved through a 100 μm mesh sieve. Then, these were weighed so that the positive electrode active material: conductive assistant: solid electrolyte = 70 parts by weight: 3 parts by weight: 27 parts by weight, and mixed in an agate mortar to produce a positive electrode mixture.

[0068] (Preparation of negative electrode composite material) First, as the compound added to the negative electrode composite material, LZC (Li 2 ZrCl 6 ) was prepared. The manufacturing method of LZC was the same as that of the solid electrolyte of the positive electrode composite material.

[0069] Then, the obtained Li 2 ZrCl 6 powder was subjected to X-ray diffraction. Inside the glove box with a dew point of -99 °C and an oxygen concentration of 1 ppm where argon gas was circulating, the obtained Li 2 ZrCl 6 powder was filled into an XRD measurement holder. Then, a moisture-proof Kapton tape (vacuum-dried at 70 °C for 16 hours) was attached and sealed to cover the filling surface, and an XRD measurement sample was prepared. Next, it was taken out into the atmosphere, and XRD measurement was performed using an X-ray diffractometer (X'PertPro manufactured by PANalytical). As the X-ray source, Cu-Kα rays were used.

[0070] As a result, Li 2 ZrCl 6 had a diffraction peak near 2θ = 32°. The half-value width of the diffraction peak was 0.5°, and it was confirmed that Li 2 ZrCl 6 had high crystallinity.

[0071] Next, as the negative electrode active material, Li 4 Ti 5 O 12, carbon black (SuperP) was prepared as a conductive additive, and LZC was prepared as a compound (solid electrolyte). Then, these were weighed so that the positive electrode active material + compound: conductive additive = 95 parts by weight: 5 parts by weight, and mixed in an agate mortar to prepare a negative electrode mixture. In Example 1, the mixing ratio of the positive electrode active material and the compound was positive electrode active material: compound = 70:30. Also, X-ray diffraction was performed on the negative electrode composite material, and it was confirmed that there was no significant change in the diffraction peak of the compound.

[0072] (Preparation of Solid Electrolyte) The solid electrolyte was prepared by the same procedure as the above compound. Inside a glove box, LiCl and ZrCl 4 as raw material powders were weighed so that the molar ratio was 2:1, placed in a Zr container together with Zr balls with a diameter of 5 mm, and subjected to mechanochemical milling treatment using a planetary ball mill. The treatment was mixed for 50 hours under the condition of a rotation speed of 500 rpm, and then passed through a 100 μm mesh sieve. Thereby, Li 2 ZrCl 6 powder was obtained.

[0073] (Preparation of Battery Element) A resin holder, a lower punch (also serving as a negative electrode current collector), and an upper punch (also serving as a positive electrode current collector) were prepared. The lower punch was inserted from below the resin holder, and 110 mg of the solid electrolyte was introduced from above the resin holder. Next, the upper punch was inserted onto the solid electrolyte. This first unit was placed on a press, and the electrolyte layer was formed at a pressure of 373 MPa. The first unit was taken out of the press, and the upper punch was removed.

[0074] Next, 60 mg of the positive electrode mixture was introduced onto the electrolyte layer (upper punch side) within the resin holder. The upper punch was then inserted thereon, and the second unit was placed on the press machine and molded at a pressure of 373 MPa. Next, the second unit was taken out, turned upside down, and the lower punch was removed. The negative electrode mixture was introduced onto the electrolyte layer (lower punch side) so as to be 1 mAh on a substance basis. The lower punch was inserted thereon, and the third unit was placed on the press machine and molded at a pressure of 373 MPa. Thus, a battery element composed of a positive electrode current collector / positive electrode / electrolyte layer / negative electrode / negative electrode current collector was fabricated.

[0075] (Measurement of Charge Capacity and Discharge Capacity) The measurement of the charge capacity and the discharge capacity was performed in an environment at 25°C. For the charge capacity, a constant current of 0.1 C (100 μA) was applied until the battery voltage reached 2.7 V, and the capacity when held for 3 hours (constant current constant voltage charging (CCCV charging)) was measured. For the discharge capacity, after charging, constant current discharge (CC discharge) was performed at a constant current of 0.2 C (200 μA) until the battery voltage reached 1.5 V. The charge capacity and the discharge capacity are the capacities in the first charge and discharge.

[0076] "Examples 2 and 3" Examples 2 and 3 differ from Example 1 in that the manufacturing conditions of the compound contained in the negative electrode composite material were changed. Specifically, Example 2 differs from Example 1 in that the mixing time in the planetary ball mill was reduced to 24 hours, and Example 3 differs from Example 1 in that the mixing time in the planetary ball mill was reduced to 10 hours. Both Examples 2 and 3 obtained Li 2 ZrCl 6 As for Li 2 ZrCl 6 obtained in Examples 2 and 3, it had a diffraction peak in the vicinity of 2θ = 32° and had crystallinity. The half-value width of the diffraction peak of Li 2 ZrCl 6 in Example 2 was 1.5°, and its crystallinity was inferior to that of Li 2 ZrCl 6 in Example 1. The half-value width of the diffraction peak of Li 2 ZrCl 6 in Example 3 was 2.5, and Li in Examples 1 and 22 ZrCl 6 was less crystalline.

[0077] For each of Examples 2 and 3, the charge-discharge capacity was measured in the same manner as in Example 1.

[0078] "Examples 4 to 10" Examples 4 to 10 are different from Example 1 in that the mixing ratio of the compounds contained in the negative electrode composite material was changed. Specifically, the mixing ratio of the compound and the active material in the negative electrode composite material was changed. The mixing ratio of the positive electrode active material and the compound is as shown in the table.

[0079] For each of Examples 4 to 10, the charge-discharge capacity was measured in the same manner as in Example 1.

[0080] "Examples 11 and 12" Examples 11 and 12 are different from Example 1 in that the type of the negative electrode active material contained in the negative electrode composite material was changed. In Example 11, Li 4 Ti 5 O 12 was changed to TiO 2 as the negative electrode active material. In Example 12, Li 4 Ti 5 O 12 was changed to TiNb 2 O 7 as the negative electrode active material.

[0081] For each of Examples 11 and 12, the charge-discharge capacity was measured in the same manner as in Example 1.

[0082] "Comparative Example 1" Comparative Example 1 is different from Example 1 in that the production conditions of the compound contained in the negative electrode composite material were changed. Specifically, Comparative Example 1 is different from Example 1 in that the mixing time in a planetary ball mill was increased to 100 hours. The compound of Comparative Example 1 had a composition of Li 2 ZrCl 6 . Li 2 ZrCl 6No diffraction peak was observed near 2θ = 32°, and it was amorphous.

[0083] The charge-discharge capacity of Comparative Example 1 was measured in the same manner as in Example 1.

[0084] "Comparative Examples 2 and 3" Comparative Examples 2 and 3 differ from Comparative Example 1 in that the type of negative electrode active material contained in the negative electrode composite material was changed. Comparative Example 2 used TiO 4 Ti 5 O 12 instead of Li 2 as the negative electrode active material. Comparative Example 3 used TiNb 4 Ti 5 O 12 instead of Li 2 O 7 (TNO) as the negative electrode active material.

[0085] The charge-discharge capacity of each of Comparative Examples 2 and 3 was measured in the same manner as in Example 1.

[0086] "Comparative Examples 4 to 6" Comparative Examples 4 to 6 differ from Comparative Example 1 in that the type of compound contained in the negative electrode composite material was changed. Comparative Example 4 used LATP (Li 2 Al 6 Ti 1.3 Al 0.3 Ti 1.7 (PO 4 ) 3 ) as the compound instead of Li Comparative Example 5 used LAGP (Li 2 Al 6 Ge 1.5 Al 0.5 Ge 1.5 (PO 4 ) 3 as the compound instead of Li Comparative Example 6 used LGPS (Li 2 GeP 6 instead of Li 10 GeP 2 S 12 ) as the compound.

[0087] For each of Comparative Examples 4 to 6, the charge-discharge capacity was measured in the same manner as in Example 1.

[0088] The measurement results of Examples 1 to 12 and Comparative Examples 1 to 6 are summarized in Table 1. Each battery element is designed such that the design capacity is 1 mAh when all of the negative electrode composite material consists only of the negative electrode active material. Table 1 simultaneously shows the theoretical value of the discharge capacity when all of the negative electrode composite material consists only of the negative electrode active material as a reference value. The capacity loss reduction rate in Table 1 is the ratio with respect to the theoretical value of the discharge capacity in each example when the theoretical value of the discharge capacity when all of the negative electrode composite material consists only of the negative electrode active material is set to 100%.

[0089] In Table 1, the Coulomb efficiency is the ratio of the charge capacity to the discharge capacity. Also, in Table 1, the crystallinity is shown as "C1" when the half-value width of the strongest diffraction peak is 2θ = 1.0 or less, which is regarded as the best, "C2" when it is greater than 2θ = 1.0 and 2.0° or less, which is regarded as the next best, "C3" when a diffraction peak can be confirmed and is greater than 2θ = 2.0°, which is regarded as the next best, and "A" when no diffraction peak can be confirmed, which is the amorphous case.

[0090]

Table 1

[0091] As shown in Table 1, Examples 1 to 12 in which the negative electrode active material contains a predetermined compound had a high capacity loss reduction rate. That is, it can be said that Examples 1 to 12 maximally exhibited the capacity possible in design. Also, there was a tendency for the capacity loss to be smaller as the crystallinity of the compound was higher (see Examples 1 to 3), and there was a tendency for the capacity loss to be smaller in the range where the weight % of the compound was 21 wt% or more and 70 wt% or less (see Examples 4 to 10). Also, it was confirmed that the capacity loss could be suppressed in the same manner even when the material of the negative electrode active material layer was changed (see Examples 11 and 12).

Explanation of Reference Signs

[0092] 1…Positive electrode, 1A…Positive current collector, 1B…Positive active material layer, 2…Negative electrode, 2A…Negative current collector, 2B…Negative active material layer, 3…Solid electrolyte, 4…Laminate, 5, 6…Terminal electrodes, 10…All-solid-state battery

Claims

1. An active material and, A α M β X γ comprising a compound represented by the chemical formula thereof and having crystallinity In the chemical formula, A is an alkali metal or an alkaline earth metal, M is a transition metal, X is a halogen, α satisfies 1 ≤ α ≤ 3, β satisfies 0.5 ≤ β ≤ 1.5, γ satisfies 5 ≤ γ ≤ 7, The active material is Li ＋ and has an electrode potential in the range of 1.0 V or more and 2.0 V or less based on the Li ＋ / Li equilibrium potential. When X-ray diffraction measurement is performed using CuKα radiation, the full width at half maximum of the diffraction peak showing the strongest intensity among the peaks derived from the compound is within 2.0°, an active material layer.

2. The content of the compound with respect to the total of the active material and the compound is 21% by weight or more and 70% by weight or less, the active material layer according to Claim 1.

3. The diffraction peak showing the strongest intensity among the peaks derived from the compound is in the range of 31° < 2θ < 33°, the active material layer according to Claim 1.

4. The active material is an oxide containing a titanium element and an oxygen element, the active material layer according to any one of Claims 1 to 3.

5. An anode comprising the active material layer according to any one of Claims 1 to 4 and a current collector in contact with the active material layer.

6. An all-solid-state battery comprising the anode according to Claim 5.

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