JP2017091953A - Lithium ion conductor and lithium ion battery using the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide: a lithium ion conductor which is high in safety, easy to sinter, and high in lithium ion conductivity; and a lithium ion battery using such a lithium ion conductor.SOLUTION: A lithium ion conductor comprises a metal oxide expressed by the following general formula (1): LiABMO(1). {In the formula (1), A represents at least one element selected from a group consisting of H, Na, K, Rb, Cs, Ca, Sr, Ba, Y, La, Ce, Pr, Nd, Pm, Sm, Gd, Tb, Dy, Ho and Er; B represents boron; M represents at least one element selected from a group consisting of Mg, Al, Si, P, Sc, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, Ga, Ge, Zr, Nb, Mo, Ru, In, Sn, Sb, Bi, Te, Hf, Ta, W, Eu, Tm, Yb and Lu; "x" represents a Li composition ratio to the M element; "y" represents a composition ratio of the A element to the M element; 0<x≤2.5, 0≤y<2.5 and 0<x+y≤2.5; "z" represents a boron composition ratio to the M element, and 0<z≤0.5; (3+α) represents a composition ratio of oxygen atoms to the M element, and -1≤α≤3.} The metal oxide has peaks in ranges of diffraction angle 2θ=32.5±1.0°, 46.8±1.0° and 57.8±1.0° in X-ray diffraction.SELECTED DRAWING: None

Description

  The present invention relates to a lithium ion conductor and a lithium ion battery using the same.

  In recent years, as a power source for notebook computers, tablet terminals, mobile phones, smartphones, electric vehicles (EV), and the like, development of batteries with high output and high capacity has been demanded. Among them, development of lithium ion batteries that have a relatively high energy density and can be repeatedly charged and recharged has been actively conducted.

  As the lithium ion battery, an all solid lithium ion battery in which the liquid electrolyte is changed to a solid electrolyte layer is proposed along with a lithium ion battery using a liquid electrolyte such as an organic solvent. All-solid-state lithium ion batteries are attracting attention because they are excellent in safety, manufacturing cost, and productivity.

  The positive electrode layer and the negative electrode layer of a lithium ion battery may contain a lithium ion conductor in order to help occlude and release lithium ions. In the case of an all solid lithium ion battery, at least the solid electrolyte layer contains a lithium ion conductor. Development of a lithium ion conductor having high lithium ion conductivity is required from the viewpoint of increasing the output of the battery.

  As such a lithium ion conductor, for example, a sulfide solid electrolyte, a titanium-based oxide solid electrolyte, and a non-titanium-based oxide solid electrolyte have been proposed.

For example, Patent Document 1 (International Publication No. 2011/128977) is expressed by “general formula Li _x (La _2−a M1 _a ) (Ti _3−b M2 _b ) O _{9 + δ,} where x is 0 <x ≦. 1 satisfying 1 ≦ a satisfying 0 ≦ a ≦ 2; b satisfying 0 ≦ b ≦ 3; δ satisfying −2 ≦ δ ≦ 2; M1 including Sr, Na, Nd, Pr, It is at least one selected from the group consisting of Sm, Gd, Dy, Y, Eu, Tb, Ba, and M2 is Mg, W, Mn, Al, Ge, Ru, Nb, Ta, Co, Zr, Hf. , “Solid electrolyte material characterized in that it is at least one selected from the group consisting of Fe, Cr and Ga”.

Patent Document 2 (International Publication No. 2011/118801) states that “X-rays containing Cu element and containing M ₁ element (for example, Li element), M ₂ element (for example, Ge element and P element), and S element. having peaks at 2θ = 29.5 ° ± 0.50 ° in diffraction measurement, a peak diffraction intensity of the 2θ = 29.5 ° ± 0.50 ° and _{I a,} 2θ = 27.33 ± 0 the peak diffraction intensity of .50 ° when the I _B, describes a sulfide solid electrolyte material ", wherein the value of I B _/ I _a is less than 0.50.

International Publication No. 2011/128977 International Publication No. 2011/118801

  Although the oxide-based solid electrolyte described in Patent Document 1 is preferable from the viewpoint of safety, since the melting point is high, powder sintering usually requires a high temperature of 1200 ° C. or higher, and the productivity point There is a problem. A sulfide solid electrolyte as described in Patent Document 2 has a higher lithium ion conductivity than an oxide solid electrolyte, but easily reacts with water and an electrode active material. Therefore, a solid electrolyte having high safety and high lithium ion conductivity is required.

  An object of the present invention is to provide a lithium ion conductor having high safety, easy sintering, and high lithium ion conductivity, and a lithium ion battery using the same.

The present invention is as follows.
[1] The following general formula (1):
Li _x A _y B _z MO _{3 + α} (1)
{In Formula (1), A is H, Na, K, Rb, Cs, Ca, Sr, Ba, Y, La, Ce, Pr, Nd, Pm, Sm, Gd, Tb, Dy, Ho, and Er. Represents at least one element selected from the group consisting of: B represents boron; M represents Mg, Al, Si, P, Sc, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zn; Represents at least one element selected from the group consisting of Ga, Ge, Zr, Nb, Mo, Ru, In, Sn, Sb, Bi, Te, Hf, Ta, W, Eu, Tm, Yb, and Lu , X represents the composition ratio of Li to M element, y represents the composition ratio of A element to M element, 0 <x ≦ 2.5, 0 ≦ y <2.5, and 0 <x + y ≦ 2.5 Z represents the composition ratio of boron to M element, 0 <z ≦ 0.5, and (3 + α) is It represents a composition ratio of oxygen atoms to the element and is -1 ≦ α ≦ 3. }, The metal oxide has a diffraction angle 2θ in X-ray diffraction = 32.5 ± 1.0 °, 46.8 ± 1.0 °, and 57.8 ± 1. A lithium ion conductor having a peak in the range of 0 °.
[2] The lithium ion conductor according to item [1], wherein the metal oxide further has a peak at a diffraction angle 2θ = 22.6 ± 0.5 ° in X-ray diffraction.
[3] The lithium ion conductor according to item [1] or [2], wherein the metal oxide further has a peak at a diffraction angle 2θ = 40.3 ± 0.5 ° in X-ray diffraction.
[4] The lithium ion conductor according to any one of items [1] to [3], wherein the metal oxide further has a peak at a diffraction angle 2θ = 11.3 ± 0.5 ° in X-ray diffraction. .
[5] The lithium ion conductor according to any one of items [1] to [4], wherein the composition ratio of the metal oxide satisfies x-3z + y ≦ 1.
[6] A lithium ion battery having a positive electrode layer, a negative electrode layer, and a separator between the positive electrode layer and the negative electrode layer, wherein at least one of the positive electrode layer, the negative electrode layer, and the separator A lithium ion battery comprising the lithium ion conductor according to any one of 1] to [5].
[7] An all-solid lithium ion battery having a positive electrode layer, a negative electrode layer, and a solid electrolyte layer between the positive electrode layer and the negative electrode layer, wherein at least one of the positive electrode layer, the negative electrode layer, or the solid electrolyte layer An all-solid-state lithium ion battery having the lithium ion conductor according to any one of items [1] to [5].

  Since the lithium ion conductor of the present invention has a specific composition formula and contains a metal oxide having an X-ray diffraction peak in a specific range, the lithium ion conductor is high in safety, easy to sinter, and lithium ion. A highly conductive lithium ion conductor and a lithium ion battery using the same can be provided.

  The above description should not be construed as describing all embodiments of the present invention and all advantages related to the present invention.

  Hereinafter, the present invention will be described in more detail for the purpose of illustrating representative embodiments of the present invention, but the present invention is not limited to these embodiments.

《Lithium ion conductor》
<composition>
The lithium ion conductor in one embodiment of the present invention has the following general formula (1):
Li _x A _y B _z MO _{3 + α} (1)
{In Formula (1), A is H, Na, K, Rb, Cs, Ca, Sr, Ba, Y, La, Ce, Pr, Nd, Pm, Sm, Gd, Tb, Dy, Ho, and Er. Represents at least one element selected from the group consisting of: B represents boron; M represents Mg, Al, Si, P, Sc, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zn; Represents at least one element selected from the group consisting of Ga, Ge, Zr, Nb, Mo, Ru, In, Sn, Sb, Bi, Te, Hf, Ta, W, Eu, Tm, Yb, and Lu , X represents the composition ratio of Li to M element, y represents the composition ratio of A element to M element, 0 <x ≦ 2.5, 0 ≦ y <2.5, and 0 <x + y ≦ 2.5 Z represents the composition ratio of boron to M element, 0 <z ≦ 0.5, and (3 + α) is It represents a composition ratio of oxygen atoms to the element and is -1 ≦ α ≦ 3. } Is included.

  Since the lithium ion conductor of one embodiment of the present invention contains the metal oxide represented by the above general formula, safety, ease of sintering, and lithium ion conductivity are good.

In formula (1), A is from H, Na, K, Rb, Cs, Ca, Sr, Ba, Y, La, Ce, Pr, Nd, Pm, Sm, Gd, Tb, Dy, Ho, and Er. Represents at least one element selected from the group consisting of The reason is that ions of these elements are preferable from the viewpoint of charge balance because the oxidation number ranges from +1 to +3. A is preferably close to the oxygen ion O ₂ ²⁻ and has a radius that stabilizes the crystal structure, and is preferably Na, K, Rb, Cs, Ca, Sr, Ba, Y, La, Ce, Pr, Nd. Represents at least one element selected from the group consisting of Pm, Sm, Gd, Tb, Dy, Ho, and Er, and more preferably Na, K, Sr, La from the viewpoint of developing a large ion diffusion coefficient. And at least one element selected from the group consisting of Nd.

  In formula (1), B represents boron. Although not limited to theory, it is believed that boron acts as a flux that lowers the melting point of the glass and thus facilitates the sintering of the lithium ion conductor. Moreover, a lithium ion conductor having a large primary particle size can be selectively obtained by appropriately selecting the firing conditions by adding boron.

  In formula (1), M is Mg, Al, Si, P, Sc, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, Ga, Ge, Zr, Nb, Mo, Ru, In , Sn, Sb, Bi, Te, Hf, Ta, W, Eu, Tm, Yb, and at least one element selected from the group consisting of Lu. The reason is that the ions of these elements have an appropriate size for stabilizing the structure and can take 6-coordination as compared with oxygen ions and ions of the A element. M is preferably Al, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, Zr, Nb, Mo, Ru, In, Sn, Sb, Bi, Te, for ease of preparation. It represents at least one element selected from the group consisting of Hf, Ta, and W, and from the viewpoint of showing a large ion diffusion coefficient, more preferably at least selected from the group consisting of Ti, Zr, Nb, Ta, and W Represents one element.

  In the formula (1), x represents the composition ratio of Li to the M element, y represents the composition ratio of the A element to the M element, and 0 <x ≦ 2.5, 0 ≦ y <2.5, and 0 < x + y ≦ 2.5.

  x may be 0 <x ≦ 2.5, the ion content of the material is high, and preferably 0.05 ≦ x ≦ 2.5 from the viewpoint of ionic conductivity, from the viewpoint of ease of preparation Therefore, it is more preferable that 0.07 ≦ x ≦ 2.5. From the viewpoint of the ion diffusion coefficient, more preferably, 0.1 ≦ x <2.5, 0.2 ≦ x ≦ 2.5, or 0.3 ≦ x ≦ 2.5. y may be 0 ≦ y <2.5, for example, 0.05 ≦ y <2.5, 0.1 ≦ y <2.5, and 0.2 ≦ y <2.5. . (X + y) may be 0 <(x + y) ≦ 2.5, for example, 0.1 ≦ (x + y) ≦ 2.5, 0.2 ≦ (x + y) ≦ 2.5, or 0.2 ≦ ( x + y) ≦ 2.

  In the formula (1), z represents the composition ratio of B (boron) to the M element, and 0 <z ≦ 0.5 may be satisfied, and from the viewpoint of ease of sintering, 0.1 ≦ z is more preferable. ≦ 0.5, and more preferably 0.1 ≦ z ≦ 0.4.

  In the formula (1), (3 + α) represents the composition ratio of oxygen atoms to the M element, and should be −1 ≦ α ≦ 3. From the viewpoint of the stability of the crystal structure, preferably −0.5 ≦ α ≦. 3, from the viewpoint of ease of preparation, more preferably −0.4 ≦ α ≦ 3.

  When x, y, (x + y), z, and (3 + α) are within the above ranges, the metal oxide can easily take a crystal structure described below, and lithium ion conductivity is improved.

  The composition ratio of the metal oxide preferably satisfies x-3z + y ≦ 1. If x−3z + y> 1, a sub-crystal may be generated, which is not preferable from the viewpoint of productivity. More preferably, −1.5 <x−3z + y ≦ 0.8, and further preferably −1.5 <x−3z + y ≦ 0.6.

<X-ray diffraction peak and crystal structure>
In one embodiment of the present invention, the metal oxide has a diffraction angle 2θ = 32.5 ± 1.0 ° in X-ray diffraction (hereinafter also simply referred to as “XRD”) using CuKα rays as an X-ray source, and 46. It has peaks in the range of 8 ± 1.0 ° and 57.8 ± 1.0 °. In the present invention, XRD refers to XRD measured using CuKα rays as an X-ray source. Here, “having a peak” means at least a visual peak on an X-ray diffraction pattern in which the maximum intensity in the diffraction angle 2θ = 5 ° or more and 50 ° or less in the XRD pattern is the full scale of the vertical axis. Can be recognized, or the waveform processing apparatus can clearly distinguish it from the background noise and recognize it as a peak. From the viewpoint of lithium ion conductivity, preferably, the peak intensity is at least 0.5%, more preferably 1.0%, with respect to the maximum intensity peak height in the range of diffraction angle 2θ = 5 ° to 50 °. It is preferable to have.

  The inventors of the present application have found that when the metal oxide having the above composition has an X-ray diffraction peak in the above range, sintering is easy and lithium ion conductivity is increased. The reason for this is not clear, but compounds having peaks in these three ranges can maintain the crystal structure even in the presence of boron, and can form defects that assist the diffusion of lithium in the crystal structure by the action of boron. It is believed that there is.

  The fact that the metal oxide has an X-ray diffraction peak in the range of diffraction angle 2θ = 22.6 ± 0.5 ° can be attributed to the fact that the metal oxide forms a layered crystal structure. It is considered that the density of lithium ions can be increased because the metal oxide forms a layered crystal structure. From the viewpoint of easy diffusion of ions, it is more preferable that the metal oxide has a peak in the range of diffraction angle 2θ = 11.3 ± 0.5 ° and / or 40.3 ± 0.5 °. Furthermore, it is more preferable that the metal oxide has a peak in the range of diffraction angle 2θ = 67.9 ± 1.0 ° from the viewpoint of easy diffusion of ions.

<Lithium ion diffusion coefficient>
In one embodiment of the present invention, the metal oxide preferably has a lithium ion diffusion coefficient at 80 ° C. of 1.0 × 10 ⁻¹³ m ² / s or more. The lithium ion diffusion coefficient at 80 ° C. is more preferably 1.0 × 10 ⁻¹² m ² / s or more, and further preferably 1.0 × 10 ⁻¹¹ m ² / s or more. When the lithium ion diffusion coefficient at 80 ° C. is within the above range, the lithium ion conductivity tends to be higher.

<Others>
In one embodiment of the present invention, the metal oxide is preferably a powder having an average primary particle size of 0.5 μm or more and 500 μm or less. The average diameter of the primary particles is appropriately selected depending on the use, but is preferably 1 μm or more and 300 μm or less, more preferably 2 μm or more and 200 μm or less, further preferably 5 μm or more and 100 μm or less, and most preferably 10 μm or more and 100 μm or less. . The average primary particle diameter can be calculated from the ferret diameter of 1000 primary particles observed by SEM.

<< Production Method of Lithium Ion Conductor >>
The lithium ion conductor can be produced by a solid phase reaction. As raw materials for the solid phase reaction, Li, element A (Na, K, Rb, Cs, Ca, Sr, Ba, Y, La, Ce, Pr, Nd, Pm, Sm, Gd, Tb, Dy, Ho, and At least one selected from the group consisting of Er), B (boron), and element M (Mg, Al, Si, P, Sc, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, At least one oxide selected from the group consisting of Ga, Ge, Zr, Nb, Mo, Ru, In, Sn, Sb, Bi, Te, Hf, Ta, W, Eu, Tm, Yb, and Lu) Hydroxides, chlorides, carbonates, acetates, nitrates, sulfates, ammonium salts, alkoxides, and the like can be used. When the element A is H, for example, it is prepared by ion exchange of the element A of the lithium ion conductor with H in an acidic aqueous solution.

Examples of the boron source include boric acid such as orthoboric acid (H ₃ BO ₃ ), metaboric acid (HBO ₂ ) and tetraboric acid (H ₂ B ₄ O ₇ ), and boron such as diboron trioxide (B ₂ O ₃ ). Oxides, trilithium borate (Li ₃ BO ₃ ), lithium metaborate (LiBO ₂ ), lithium tetraborate (Li ₂ B ₄ O ₇ ), lithium pentaborate (LiB ₅ O ₈ ), and lithium perborate Lithium salt of boric acid such as (Li ₂ B ₂ O ₅ ) and hydrate of lithium salt of boric acid such as lithium tetraborate pentahydrate, ammonium metaborate (NH ₄ BO ₂ ) and tetraboric acid Boric acids such as ammonium ((NH ₄ ) ₂ B ₄ O ₇ ), ammonium pentaborate ((NH ₄ ) ₂ O.5B ₂ O ₃ ), and ammonium octaborate ((NH ₄ ) ₂ B ₈ O ₁₃ ) Ammonium salt and It can be used hydrates of pentaborate ammonium octahydrate and quaternary ammonium salts of boric acid, such as ammonium borate tetrahydrate, boron tribromide, boron alkoxides.

  When at least one element selected from the group consisting of Na, K, Sr, La, and Nd is used as the element A, 32.5 ± 1.0 °, 46.8 ± 1 It tends to have peaks at 0.0 ° and 57.8 ± 1.0 °, which is preferable. When at least one element selected from the group consisting of Ti, Zr, Nb, Ta, and W is used as the element M, 32.5 ± 1.0 from the viewpoint of ion radius and the like, from the viewpoint of ion radius and the like. It tends to have peaks at °, 46.8 ± 1.0 °, and 57.8 ± 1.0 °, which is preferable.

  The raw material can be pulverized and mixed with, for example, a ball mill, a planetary ball mill or the like and then fired to obtain a lithium ion conductor. From the viewpoint of mixing efficiency, a method in which various raw materials are dissolved in a solvent and then mixed, the mixed solution is evaporated to dryness, and then fired is preferable. As the solvent, an organic solvent such as alcohol can be used, but water is preferable from the viewpoint of solubility. When various raw materials are mixed, precipitation may occur by reaction. Evaporation to dryness may be performed under reduced pressure, for example, using an evaporator. Alternatively, a lithium ion conductor may be prepared by evaporating to dryness by a spray drying method using a uniform solution having no precipitate after mixing, and firing the obtained evaporated dry solid. The evaporation to dryness temperature by the spray drying method is preferably 100 ° C to 300 ° C. Spray drying can be simply performed by spraying the raw material preparation liquid on a plate such as an iron plate heated to 100 ° C to 300 ° C.

  For the element having low solubility in an aqueous solvent, a complex solution in which an organic ligand such as oxalic acid, citric acid, tartaric acid or malic acid is coordinated may be used as a raw material solution. For example, for Nb and Ta, an oxalic acid complex aqueous solution is preferably used as a raw material solution. The molar ratio of oxalic acid / niobium and oxalic acid / tantalum is 1 or more and 10 or less, preferably 2 or more and 4 or less.

  In order to improve the solubility and dispersibility of the raw material in the aqueous solvent, hydrogen peroxide water may be added. For example, the molar ratio of hydrogen peroxide solution / niobium is preferably 0.5 or more and 10 or less, more preferably 2 or more and 6 or less.

  When mixing materials using an aqueous solvent, the raw materials used are preferably organic metal complexes such as oxalic acid solutions and acetates, organic salts, nitrates, and chlorides from the viewpoints of solubility and thermal decomposability.

  The firing temperature of the raw material after pulverization and mixing and the evaporation dry solid of the raw material mixed using a solvent is appropriately selected depending on the composition and structure of the lithium ion conductor. Baking at 900 ° C. or higher from the viewpoint of easily having peaks at diffraction angles 2θ = 32.5 ± 1.0 °, 46.8 ± 1.0 °, and 57.8 ± 1.0 ° in X-ray diffraction It is preferable that the process to include is included. From the viewpoint of shortening the firing time and improving productivity, it is more preferable to include a step of firing at 1000 ° C. or higher. From the viewpoint of reducing the volatilization of lithium and facilitating the control of the composition, firing at 1300 ° C. or lower is preferable.

  When using raw materials having different decomposition temperatures, it is preferable to perform multi-stage firing at the decomposition temperature of each raw material in the order of the lower decomposition temperature of each raw material. From the viewpoint of uniformity of preparation, it is preferable to perform pulverization after firing at the decomposition temperature of each raw material. For the pulverization, a known pulverization method such as a mortar, a ball mill, or a planetary ball mill can be used.

  The firing time is appropriately selected according to the progress of the decomposition of the raw materials and the reaction of generating the lithium ion conductor, but the firing time under one firing temperature condition is preferably 30 minutes to 50 hours, more preferably 1 hour to 24 hours.

  The atmosphere at the time of firing may be air, but may be fired in an atmosphere of pure oxygen, nitrogen, argon or the like in order to set α to a desired value. Further, by adding an organic substance such as oxalic acid and baking, reductive baking can be performed to satisfy α <0.

  When firing at a temperature exceeding 800 ° C., the volatilization of lithium occurs. Therefore, it is preferable to mix a large amount of the lithium raw material when mixing the raw materials, and to prevent volatilization by covering with a lid. After firing, an aqueous lithium salt solution or a molten lithium salt may be used to ion exchange element A and Li in the lithium ion conductor to increase the lithium concentration of the lithium ion conductor.

  At the time of firing, die press molding, CIP molding or the like may be performed to form a molded body and then fired. Further, when molding the lithium ion conductor, it is possible to use molding methods such as die press molding, CIP molding, cast molding, injection molding, extrusion molding, and green sheet molding. From the viewpoint of ion conduction performance, it is preferable to fire after molding to obtain a dense sintered body. In molding, various molding aids such as polyvinyl alcohol, silica, and alumina may be added.

《Lithium ion battery》
The lithium ion battery in one embodiment of the present invention has a positive electrode layer, a negative electrode layer, and a separator between the positive electrode layer and the negative electrode layer, and at least one of the positive electrode layer, the negative electrode layer, or the separator, It has the lithium ion conductor of the present invention. By having the lithium ion conductor of the present invention in the positive electrode layer and / or the negative electrode layer, it is possible to help release and occlusion of lithium ions from the positive electrode layer and / or the negative electrode layer. When a separator has the lithium ion conductor of this invention, the lithium ion conduction between a positive electrode and a negative electrode can be assisted.

  When the lithium ion battery is a positive electrode layer, a negative electrode layer, and an all solid lithium ion battery having a solid electrolyte layer between the positive electrode layer and the negative electrode layer, the positive electrode layer, the negative electrode layer, or the solid electrolyte layer At least one of the lithium ion conductors of the present invention.

  A positive electrode layer contains a positive electrode active material, contains the lithium ion conductor of this invention, a conductive support agent, a binder, etc. as needed, and may further contain solid electrolytes other than the lithium ion conductor of this invention. Moreover, you may coat the lithium ion conductor of this invention on a positive electrode layer.

  A negative electrode layer contains a negative electrode active material, contains the lithium ion conductor of this invention, a conductive support agent, a binder, etc. as needed, and may further contain solid electrolytes other than the lithium ion conductor of this invention. Moreover, you may coat the lithium ion conductor of this invention on a negative electrode layer.

  The content or coating amount of the lithium ion conductor of the present invention in the positive electrode layer and the negative electrode layer is preferably independently 5% by mass or more and 70% by mass or less, more preferably 10% by mass or more and 60% by mass or less. be able to.

The positive electrode active material can be any material that can occlude lithium ions during discharge and release them during charge. Examples of the positive electrode active material include LiNiCoO ₂ , LiNi _1/3 Mn _1/3 Co _1/3 O ₂ , LiNiPO ₄ , LiMnPO _{4, and the} like.

  The negative electrode active material can be any material that can release lithium ions during discharge and occlude during charge. Examples of the negative electrode active material include carbon materials such as graphite, metal oxides, metal nitrides, and metal sulfides.

  As the separator, any material can be used as long as it has a function of preventing electrical contact between the positive electrode layer and the negative electrode layer. Examples of the material for the separator include resin materials such as polyethylene, polypropylene, polyester, cellulose, and polyamide. As a form of a separator, a nonwoven fabric, a porous body, etc. are mentioned.

  When the separator has the lithium ion conductor of the present invention, for example, the separator may contain the lithium ion conductor of the present invention, and the separator may be coated with the lithium ion conductor of the present invention.

  The solid electrolyte layer contains a lithium ion conductor, and optionally contains the lithium ion conductor of the present invention, a binder, and the like. The content and coating amount of the lithium ion conductor of the present invention in the solid electrolyte layer can be preferably 70% by mass or more, more preferably 80% by mass or more.

  The solid electrolyte other than the lithium ion conductor of the present invention can be any substance that has lithium ion conductivity and is solid at room temperature (15 to 25 ° C.). Examples of the solid electrolyte include a sulfide solid electrolyte, an oxide solid electrolyte, and a polymer solid electrolyte.

  It does not specifically limit as a manufacturing method of the lithium ion battery of this invention, and an all-solid-state lithium ion battery. For example, the positive electrode layer, the separator, and the negative electrode layer described above are laminated in this order to produce a laminate, and the lithium ion battery of the present invention is manufactured by impregnating the laminate with an arbitrary electrolytic solution. Can do. Moreover, an all-solid-state lithium ion battery can be manufactured by laminating | stacking the positive electrode layer, solid electrolyte layer, and negative electrode layer which were demonstrated above in this order.

  In the following examples, embodiments of the present disclosure will be described more specifically, but the scope of the present invention is not limited thereto.

[Measurement method of lithium ion diffusion coefficient]
The lithium ion diffusion coefficient was measured as follows using a pulse magnetic field gradient NMR method (PFG-NMR method). First, a lithium ion conductor sample was introduced into a Shigemi NMR symmetric microsample tube having a diameter of 5 mm so that the sample height was about 5 mm, and an ECA400 apparatus manufactured by JEOL Ltd. was used to measure a measurement temperature of 80 mm. The ⁷ Li-NMR spectrum was measured using the Stimulated Echo method as an NMR sequence at ° C. The SHIM adjustment was performed using DMSO-d6 introduced into an NMR symmetric micro sample tube as an external standard substance. The gyromagnetic ratio of the nuclear spin is γ (T ⁻¹ · s ⁻¹ ), the intensity of the magnetic field gradient pulse (PFG) is g (T / m), the width of the PFG is δ (s), and the interval between the two PFGs is Δ ( s), Δ = 20 × 10 ⁻³ (s), δ = 0.3 × 10 ⁻³ (s), g = 0.2 (T / m), and Grad recover = 0.3 (ms), The NMR peak intensity E ₀ was measured, Δ and δ were fixed, and g was changed by 10 points or more in the range of 0.2 (T / m) to Ln (E / E ₀ ) ≦ −3. The peak intensity (E) is measured, and the vertical axis is Ln (E / E ₀ ) and the horizontal axis is γ ² δ ² g ² (Δ−δ / 3). A plot of the diffusion coefficient D ( m ² / s) was calculated using the following formula (2).
Ln (E / E ₀ ) = − D × γ ² δ ² g ² (Δ−δ / 3) (2)

[Composition analysis method]
Take 30 mg of a lithium ion conductor sample in a 30 cc platinum crucible, add 3 g of sodium potassium carbonate and 1 g of sodium tetraborate, heat and melt with a burner flame, dissolve completely with hydrochloric acid, and add pure water. Using the sample for measurement, the element concentration was measured by the ICP-AES method. When the lithium ion conductor sample contains potassium and / or sodium, the composition is quantified by thermally decomposing the sample into aqua regia, precipitating insoluble matter, and adding pure water to the supernatant to obtain a measurement sample. -Element concentration was measured by AES method.

[X-ray diffraction (XRD)]
X-ray diffraction (XRD) was measured using a D8 ADVANCE type X-ray diffractometer manufactured by Bruker AXS. The lithium ion conductor sample was pulverized in an agate mortar and then placed on an XRD measurement cell, and the surface was flattened for measurement. X-ray source is CuKα1 + CuKα2, tube voltage is 40 kV, tube current is 40 mA, divergence slit (DS): 0.3 °, step width: 0.02 ° / step, counting time: 0.5 sec, measurement range: 2θ = 5 The angle was set to ° to 70 °.

  In the case where the diffraction angle 2θ = 32.5 ± 1.0 °, 46.8 ± 1.0 °, and 57.8 ± 1.0 ° have peaks, “◯” is shown in the column of Table 1. If not detected, “x” is indicated. Also, when diffraction angles 2θ = 40.3 ± 0.5 °, 22.6 ± 0.5 °, 11.3 ± 0.5 °, and 67.7 ° ± 1.0 ° have peaks. In the column of Table 1, “◯” is described, and “X” is described when it is not detected.

[Heating test]
After pulverizing the powder in an agate mortar, 1 g of the powder is placed in a 12 cc container made of zirconia together with 4.5 g of isopropanol solvent and 50 zirconia beads having a diameter of 5 mm, and 320 rpm in a Fritsch planetary ball mill P-5. Milled for 1 hour. Thereafter, the IPA solvent was removed with an evaporator. This operation was repeated to obtain a molding powder. 1.5 g of the molding powder was formed into a tablet using a pellet die having a diameter of 19 mm to obtain a pellet having a thickness of about 2.0 mm. The pellet was vacuum laminated with a resin film, and then pressed with a CIP apparatus at 100 MPa for 1 minute, and the pellet was taken out from the resin film to obtain a test specimen for a heat test.

After calculating the bulk density of the specimen from the diameter, thickness, and weight of the specimen, the temperature was raised to 1100 ° C. at a rate of temperature rise of 2 ° C./min using an electric furnace and then heated at 1100 ° C. for 1 hour. After that, after heating was stopped and the electric furnace was gradually cooled to room temperature, the specimen was taken out, the bulk density was measured in the same manner, and the volume reduction rate, which is the ratio of the volume reduction in the test to the sample volume before the test, was as follows. Was calculated.
Volume reduction rate = 100 − ((1 / bulk density after test) / (1 / bulk density before test)) * 100
Here, it is shown that the larger the volume reduction rate in the heating test, the denser the specimen after sintering and the easier the sintering.

[Measurement of average primary particle size]
Using a FE-SEM apparatus S-4700 (trade name, manufactured by Hitachi High-Tech Fielding Co., Ltd.), the ferret diameter of 1000 primary particles of the lithium ion conductor powder was determined, and the average value was taken as the average value of the primary particle diameter. .

[Preparation of niobium raw material liquid]
To 94 g of pure water, 8 g of niobic acid containing 76% by mass in terms of Nb ₂ O ₅ and 15.58 g of oxalic acid dihydrate [H ₂ C ₂ O ₄ .2H ₂ O] were added, and the mixture was stirred under 60%. After heating to 0 ° C. to dissolve, the solution was cooled to 30 ° C. to obtain a niobium raw material liquid.

[Example 1]
In a 100 cc alumina crucible, 5.10 g of a titanium tetrachloride aqueous solution having a Ti concentration of 16.9%, 36.0 g of pure water, 0.683 g of lithium nitrate [LiNO ₃ ], and lithium tetraborate trihydrate 200g was added, further added lanthanum nitrate hexahydrate _{[La (NO 3) 3 ·} 6H 2 O] 3.90g. After evaporating and drying the precipitate on a hot stirrer at 150 ° C., the dried precipitate was baked in an electric furnace at 1100 ° C. for 1 hour to obtain 3.19 g of the lithium ion conductor powder of Example 1. Obtained.

As a result of composition analysis, the lithium ion conductor of Example 1 was Li 2.35 mass%, B 1.22 mass%, La 39.2 mass%, Ti 27.0 mass%, the balance being oxygen, and the composition formula was Li ₁ It was _.2 LaB _0.4 Ti ₂ O _6.7.

  As a result of XRD measurement, peaks were observed at 2θ = 11.4 °, 22.9 °, 32.7 °, 40.3 °, 46.9 °, 58.3 °, and 68.4 °. .

As a result of measuring a lithium ion diffusion coefficient, it was 6.2 × 10 ⁻¹¹ m ² / s.

As a result of the heating test, the bulk density of the specimen before the heating test was 2.6 g / cm ³ , the bulk density of the specimen after the heating test was 4.5 g / cm ³ , and the volume reduction rate was 42%. .

  The average primary particle size was 20 μm.

[Example 2]
To a 100 cc alumina crucible, 46.3 g of niobium raw material liquid, 0.341 g of lithium nitrate [LiNO ₃ ] and 0.211 g of lithium tetraborate trihydrate were added, and further dissolved in 12.0 g of pure water. lanthanum nitrate hexahydrate _{[La (NO 3) 3 ·} 6H 2 O] were added and 1.95 g, yield a precipitate. After the precipitate was evaporated to dryness on a hot stirrer at 150 ° C., the dried precipitate was baked in an electric furnace at 1100 ° C. for 1 hour, and the obtained baked product was pulverized to obtain lithium of Example 2. 3.35 g of ion conductor powder was obtained.

As a result of the compositional analysis, the lithium ion conductor of Example 2 was Li1.32 mass%, B1.22 mass%, La18.6 mass%, Nb49.9 mass%, the balance being oxygen, and the composition formula was Li _{0 0.71} La _0.5 B _0.42 Nb ₂ O _6.74 .

  As a result of XRD measurement, peaks were observed at 2θ = 11.2 °, 22.7 °, 32.2 °, 46.4 °, 57.7 °, and 67.5 °.

As a result of measuring the lithium ion diffusion coefficient, it was 5.5 × 10 ⁻¹⁰ m ² / s.

As a result of the heating test, the bulk density of the specimen before the heating test was 2.7 g / cm ³ , the bulk density of the specimen after the heating test was 4.5 g / cm ³ , and the volume reduction rate was 40%. .

  The average primary particle diameter was 90 μm.

[Comparative Example 1]
In 100cc alumina crucible of pure water 24.0 g, lithium nitrate _[LiNO 3] 0.683 g, lanthanum nitrate hexahydrate _{[La (NO 3) 3 ·} 6H 2 O] 3.90g, fumes 1.44g Dotitania (made by Nippon Aerosil Co., Ltd., trade name AEROXIDE P25) was added. After the precipitate was evaporated to dryness on a hot stirrer at 150 ° C., the dried precipitate was baked in an electric furnace at 1100 ° C. for 1 hour, and the obtained baked product was pulverized. As a result, 3.04 g of ion conductor powder was obtained.

As a result of the compositional analysis, the lithium ion conductor of Comparative Example 1 was Li 2.06 mass%, La 41.4 mass%, Ti 28.4 mass%, the balance being oxygen, and the composition formula was LiLaTi ₂ O ₆ .

  As a result of XRD measurement, peaks were observed at 2θ = 11.4 °, 32.7 °, 40.3 °, 46.9 °, 58.4 °, and 68.5 °.

As a result of measuring the lithium ion diffusion coefficient, it was 5.7 × 10 ⁻¹¹ m ² / s.

As a result of the heating test, the bulk density of the specimen before the heating test was 2.8 g / cm ³ , the bulk density of the specimen after the heating test was 3.6 g / cm ³ , and the volume reduction rate was 26%. .

  The average primary particle diameter was 0.5 μm.

[Comparative Example 2]
In Example 2, it carried out similarly except not having added lithium tetraborate trihydrate, and 3.19 g of lithium ion conductor powders of Comparative Example 2 were obtained.

As a result of the compositional analysis, the lithium ion conductor of Comparative Example 2 is Li0.98 mass%, La 19.6 mass%, Nb 52.4 mass%, the balance is oxygen, and the composition formula is Li _0.5 La _0.5 Nb ₂ O ₆ .

  As a result of XRD measurement, peaks were observed at 2θ = 11.3 °, 22.8 °, 32.3 °, 46.5 °, 57.8 °, and 67.7 °.

As a result of measuring the lithium ion diffusion coefficient, it was 4.8 × 10 ⁻¹⁰ m ² / s.

As a result of the heating test, the bulk density of the specimen before the heating test was 2.8 g / cm ³ , the bulk density of the specimen after the heating test was 3.9 g / cm ³ , and the volume reduction rate was 28%. .

  The average primary particle size was 2 μm.

  It was found that the lithium ion conductor of the present invention had a high volume reduction rate in the heating test and was easily sintered as compared with the lithium ion conductor of the comparative example. The reason why the lithium ion conductor of the present invention is easily sintered is not limited to theory, but it is considered that B (boron) acts as a flux that lowers the melting point of glass.

Claims (7)

The following general formula (1):
Li _x A _y B _z MO _{3 + α} (1)
{In Formula (1), A is H, Na, K, Rb, Cs, Ca, Sr, Ba, Y, La, Ce, Pr, Nd, Pm, Sm, Gd, Tb, Dy, Ho, and Er. Represents at least one element selected from the group consisting of: B represents boron; M represents Mg, Al, Si, P, Sc, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zn; Represents at least one element selected from the group consisting of Ga, Ge, Zr, Nb, Mo, Ru, In, Sn, Sb, Bi, Te, Hf, Ta, W, Eu, Tm, Yb, and Lu , X represents the composition ratio of Li to M element, y represents the composition ratio of A element to M element, 0 <x ≦ 2.5, 0 ≦ y <2.5, and 0 <x + y ≦ 2.5 Z represents the composition ratio of boron to M element, 0 <z ≦ 0.5, and (3 + α) is It represents a composition ratio of oxygen atoms to the element and is -1 ≦ α ≦ 3. }, The metal oxide has a diffraction angle 2θ in X-ray diffraction = 32.5 ± 1.0 °, 46.8 ± 1.0 °, and 57.8 ± 1. A lithium ion conductor having a peak in the range of 0 °.   2. The lithium ion conductor according to claim 1, wherein the metal oxide further has a peak at a diffraction angle 2θ = 22.6 ± 0.5 ° in X-ray diffraction.   The lithium ion conductor according to claim 1, wherein the metal oxide further has a peak at a diffraction angle 2θ = 40.3 ± 0.5 ° in X-ray diffraction.   The lithium ion conductor according to claim 1, wherein the metal oxide further has a peak at a diffraction angle 2θ = 11.3 ± 0.5 ° in X-ray diffraction.   5. The lithium ion conductor according to claim 1, wherein the composition ratio of the metal oxide satisfies x−3z + y ≦ 1. A lithium ion battery having a positive electrode layer, a negative electrode layer, and a separator between the positive electrode layer and the negative electrode layer,
The lithium ion battery which has a lithium ion conductor as described in any one of Claims 1-5 in at least any one of the said positive electrode layer, the said negative electrode layer, or the said separator. An all-solid lithium ion battery having a positive electrode layer, a negative electrode layer, and a solid electrolyte layer between the positive electrode layer and the negative electrode layer,
The all-solid-state lithium ion battery which has a lithium ion conductor as described in any one of Claims 1-5 in at least any one of the said positive electrode layer, the said negative electrode layer, or the said solid electrolyte layer.