JP7259703B2 - Non-aqueous electrolyte battery - Google Patents

Description

The present disclosure relates to non-aqueous electrolyte batteries.

2. Description of the Related Art In recent years, with the rapid spread of information-related equipment and communication equipment such as personal computers, video cameras, and mobile phones, the development of batteries used as power sources for these devices has been emphasized. In addition, in the automobile industry and the like, development of high-output and high-capacity batteries for electric vehicles or hybrid vehicles is underway.
Among batteries, lithium-ion secondary batteries are attracting attention because of their high output voltage.

Patent Document 1 discloses a negative electrode for a lithium ion secondary battery containing carbon material particles mixed with LTO (lithium titanate).

Further, Patent Document 2 describes using a positive electrode active material containing titanium oxide and a metal oxide that discharges at a voltage higher than that of the titanium oxide at the initial stage of discharge.

Further, Patent Document 3 discloses a secondary battery using, as a positive electrode active material, a substrate having a highly oriented thin film obtained by lithiating a niobium pentoxide film on a metal substrate or a silicon substrate.

Patent Document 4 discloses a non-aqueous electrolyte battery including a negative electrode containing a monoclinic composite oxide containing titanium and niobium.

JP 2019-106271 A Japanese Patent Application Laid-Open No. 2007-080680 JP-A-1995-142054 WO2015/040709

When an internal short circuit occurs during a nail penetration test or the like, the battery generates heat due to the generation of a short circuit current, and the temperature inside the battery rises.
As a method for suppressing heat generation, there is an increase in battery resistance during a short circuit. As one of them, there is a technique of including lithium titanate (LTO) in the negative electrode layer. Due to its structure, LTO has the property of increasing its resistance in a Li desorption state, that is, in a discharged state. When an internal short circuit occurs in the battery, LTO is in a discharged state and can suppress short-circuit current. However, since LTO has a small capacity per unit mass, it is necessary to increase the content of LTO in the negative electrode layer in order to sufficiently suppress the short-circuit current. Therefore, it is difficult to achieve both of securing the temperature and suppressing the temperature rise inside the battery.
In view of the above circumstances, an object of the present disclosure is to provide a non-aqueous electrolyte battery capable of ensuring a desired battery capacity and suppressing a temperature rise inside the battery.

The present disclosure provides a non-aqueous electrolyte battery comprising a positive electrode layer, a negative electrode layer, and an electrolyte layer disposed between the positive electrode layer and the negative electrode layer,
The negative electrode layer includes a titanium-niobium oxide containing an amorphous phase and a negative electrode active material having a lower Li absorption and release potential than the titanium-niobium oxide,
The negative electrode layer contains 2.0% by mass or more of the titanium-niobium oxide when the total of the negative electrode active material and the titanium-niobium oxide is 100% by mass,
The titanium-niobium oxide has a spectrum obtained by X-ray diffraction measurement using CuKα rays, and the full width at half maximum of the strongest diffraction peak observed at a diffraction angle of 2θ = 26° ± 0.5° is 0.17°. Provided is a non-aqueous electrolyte battery characterized in that the angle is not less than 0.20° and not more than 0.20°.

INDUSTRIAL APPLICABILITY The present disclosure can provide a non-aqueous electrolyte battery capable of ensuring a desired battery capacity and suppressing a temperature rise inside the battery.

1 is a cross-sectional schematic diagram showing an example of a non-aqueous electrolyte battery of the present disclosure; FIG. 1 is a diagram showing an XRD pattern of titanium-niobium oxide of Example 1. FIG. 3 is a diagram showing an XRD pattern of titanium-niobium oxide of Comparative Example 1. FIG.

The present disclosure provides a non-aqueous electrolyte battery comprising a positive electrode layer, a negative electrode layer, and an electrolyte layer disposed between the positive electrode layer and the negative electrode layer,
The negative electrode layer includes a titanium-niobium oxide containing an amorphous phase and a negative electrode active material having a lower Li absorption and release potential than the titanium-niobium oxide,
The negative electrode layer contains 2.0% by mass or more of the titanium-niobium oxide when the total of the negative electrode active material and the titanium-niobium oxide is 100% by mass,
The titanium-niobium oxide has a spectrum obtained by X-ray diffraction measurement using CuKα rays, and the full width at half maximum of the strongest diffraction peak observed at a diffraction angle of 2θ = 26° ± 0.5° is 0.17°. Provided is a non-aqueous electrolyte battery characterized in that the angle is not less than 0.20° and not more than 0.20°.

Like LTO, titanium-niobium oxide has the property of increasing its resistance when an internal short circuit occurs in the battery. , a desired battery capacity can be ensured even if the content of titanium-niobium oxide in the negative electrode layer is reduced. In addition, the crystal of titanium-niobium oxide has a lower resistance than LTO, but by partially including an amorphous phase, it is possible to increase the resistance of the titanium-niobium oxide when an internal short circuit occurs in the battery. Therefore, according to the present disclosure, it is possible to ensure both the desired capacity of the battery and the suppression of the temperature rise of the battery.

FIG. 1 is a cross-sectional schematic diagram showing an example of the non-aqueous electrolyte battery of the present disclosure.
As shown in FIG. 1, the nonaqueous electrolyte battery 100 includes a positive electrode 16 including a positive electrode layer 12 and a positive electrode current collector 14, a negative electrode 17 including a negative electrode layer 13 and a negative electrode current collector 15, a positive electrode layer 12 and a negative electrode layer. and an electrolyte layer 11 disposed between 13 .

[Negative electrode]
The negative electrode includes at least a negative electrode layer and, if necessary, a negative electrode current collector.

[Negative electrode layer]
The negative electrode layer includes a titanium-niobium oxide containing an amorphous phase and a negative electrode active material having a Li absorption/discharge potential lower than that of the titanium-niobium oxide. Incidentally, the Li absorption/desorption potential of titanium-niobium oxide is about 1.5 V (vs. Li/Li ⁺ ).
The type of the negative electrode active material is not particularly limited as long as it has a lower Li absorption and release potential than titanium-niobium oxide, and examples thereof include Li simple substance, lithium alloys, carbon, Si simple substances, and Si alloys. , Li-Au, Li-Mg, Li-Sn, Li-Si, Li-Al, Li-B, Li-C, Li-Ca, Li-Ga, Li-Ge, Li-As, Li-Se, Li -Ru, Li-Rh, Li-Pd, Li-Ag, Li-Cd, Li-In, Li-Sb, Li-Ir, Li-Pt, Li-Hg, Li-Pb, Li-Bi, Li-Zn , Li—Tl, Li—Te, and Li—At. Examples of Si alloys include alloys with metals such as Li, and may be alloys with at least one metal selected from the group consisting of Sn, Ge, and Al.

Titanium-niobium oxide may contain elements other than titanium and niobium, such as Mg, Sr, Mo, W, Ta, and V, as long as it contains titanium and niobium. .
Titanium-niobium oxide has a spectrum obtained by X-ray diffraction measurement using CuKα rays, and the full width at half maximum of the strongest diffraction peak observed at a diffraction angle 2θ = 26° ± 0.5° is 0.17° or more. 0.20° or less. The peak appearing at 2θ=26°±0.5° is considered to be mainly the peak of the (003) plane.
Titanium-niobium oxides include, for example, TiNb ₂ O ₇ and the like.
The titanium-niobium oxide may have a monoclinic crystal structure.
The titanium-niobium oxide crystals may belong to the space group C2/m.
Titanium-niobium oxide contains an amorphous phase. That is, in the titanium-niobium oxide of the present disclosure, some of the crystals are amorphized, and both crystal and amorphous phases are mixed. Whether the titanium-niobium oxide contains an amorphous phase can be confirmed by subjecting the titanium-niobium oxide to powder X-ray diffraction measurement using CuKα rays.

A method for making part of the crystals of the titanium-niobium oxide amorphous is not particularly limited, but examples thereof include mechanical milling.
Mechanical milling is not particularly limited as long as it is a method of mixing titanium-niobium oxide while applying mechanical energy. A planetary ball mill may be employed.

The mechanical milling may be dry mechanical milling or wet mechanical milling. Liquids used in wet mechanical milling include, for example, aprotic liquids such as polar aprotic liquids and non-polar aprotic liquids.

The mechanical milling conditions are appropriately set so as to obtain a desired amorphous phase. For example, when a planetary ball mill is used, titanium-niobium oxide crystals and grinding balls are added to a vessel and processed at a predetermined table rotation speed and time. The table rotation speed may be, for example, 200 rpm or more. On the other hand, the table rotation speed may be, for example, 800 rpm or less. Moreover, the treatment time of the planetary ball mill may be, for example, 30 minutes or longer. On the other hand, the processing time of the planetary ball mill is, for example, 24 hours or less, and may be 12 hours or less. Examples of materials for containers and grinding balls used in planetary ball mills include ZrO ₂ and Al ₂ O ₃ . The diameter of the grinding balls is, for example, 0.7 mm or more and 20 mm or less. Mechanical milling is preferably performed in an inert gas atmosphere (for example, an Ar gas atmosphere).

The negative electrode layer contains titanium-niobium oxide with a lower limit of 2.0% by mass or more, and an upper limit of 3.0% by mass, when the total of the negative electrode active material and titanium-niobium oxide is 100% by mass. % or less.

A mixture of the negative electrode active material and titanium-niobium oxide may be used, or a negative electrode active material coated with titanium-niobium oxide may be used. The mixing method and coating method are not particularly limited, and conventionally known methods can be employed.

The thickness of the negative electrode layer is not particularly limited, but may be 30 nm or more and 5000 nm or less.

[Negative electrode current collector]
Examples of materials for the negative electrode current collector include SUS, copper, and nickel. Examples of the shape of the negative electrode current collector include a foil shape and a plate shape. The shape of the negative electrode current collector in a plan view is not particularly limited, but examples thereof include a circular shape, an elliptical shape, a rectangular shape, and an arbitrary polygonal shape. Also, the thickness of the negative electrode current collector varies depending on the shape, but may be, for example, within the range of 1 μm to 50 μm.

[Electrolyte layer]
The electrolyte layer contains at least an electrolyte.
A non-aqueous electrolytic solution, a gel electrolyte, a solid electrolyte, or the like can be used as the electrolyte. These may be used singly or in combination of two or more.

As the non-aqueous electrolytic solution, one containing a lithium salt and a non-aqueous solvent is usually used.
Examples of lithium salts _include inorganic lithium salts _{such as LiPF 6} , LiBF _{4 ,} LiClO _{4 and LiAsF 6 ;} ) ₂ and organic lithium salts such as LiC(SO ₂ CF ₃ ) ₃ and the like.
Examples of non-aqueous solvents include ethylene carbonate (EC), propylene carbonate (PC), butylene carbonate (BC), dimethyl carbonate (DMC), diethyl carbonate (DEC), ethylmethyl carbonate (EMC), γ-butyrolactone, sulfolane, Acetonitrile (AcN), dimethoxymethane, 1,2-dimethoxyethane (DME), 1,3-dimethoxypropane, diethyl ether, tetraethylene glycol dimethyl ether (TEGDME), tetrahydrofuran, 2-methyltetrahydrofuran, dimethylsulfoxide (DMSO) and these From the viewpoint of ensuring a high dielectric constant and a low viscosity, a cyclic carbonate compound such as EC, PC, and BC having a high dielectric constant and a high viscosity, and a DMC having a low dielectric constant and a low viscosity , DEC, and EMC are preferred, and mixtures of EC and DEC are more preferred.
The concentration of the lithium salt in the non-aqueous electrolyte may be, for example, 0.3-5M.

A gel electrolyte is generally obtained by adding a polymer to a non-aqueous electrolytic solution to form a gel.
Specifically, as the gel electrolyte, a polymer such as polyethylene oxide, polypropylene oxide, polyacrylonitrile, polyvinylidene fluoride (PVdF), polyurethane, polyacrylate, and cellulose is added to the non-aqueous electrolytic solution described above to form a gel. obtained by converting

Solid electrolytes contained in the electrolyte layer include sulfide-based solid electrolytes, oxide-based solid electrolytes, polymer electrolytes, and the like.
The sulfide-based solid electrolyte may contain Li element, A element (A is at least one of P, Ge, Si, Sn, B and Al), and S element. The sulfide-based solid electrolyte may further contain a halogen element. Halogen elements include, for example, F element, Cl element, Br element, and I element. Moreover, the sulfide-based solid electrolyte may further have an O element.
Examples of sulfide-based solid electrolytes include Li ₂ SP ₂ S ₅ , Li ₂ SP ₂ S ₅ -LiI, Li ₂ SP ₂ S ₅ -GeS ₂ , Li ₂ SP ₂ S _{5 -Li2O ,} Li2SP2S5 _{- Li2O} -LiI _{, Li2SP2S5} -LiI _- LiBr, _Li2S - _SiS2 , _Li2S - _{SiS2 -} LiI, Li _2S —SiS ₂ —LiBr, Li ₂ S—SiS ₂ —LiCl, Li ₂ S—SiS ₂ —B ₂ S ₃ —LiI, Li ₂ S—SiS ₂ —P ₂ S ₅ —LiI, Li ₂ S—B ₂ S ₃ , Li ₂ SP ₂ S ₅ -Z _m S _n (where m and n are positive numbers and Z is either Ge, Zn or Ga), Li ₂ S—GeS ₂ , Li _2S —SiS ₂ —Li ₃ PO ₄ , Li ₂ S—SiS ₂ —Li _x MO _y (where x and y are positive numbers and M is P, Si, Ge, B, Al, Ga or In). Either.). The above description of "Li ₂ SP ₂ S ₅ " means a material obtained by using a raw material composition containing Li ₂ S and P ₂ S ₅ , and the same applies to other descriptions.
The molar ratio of each element in the sulfide-based solid electrolyte can be controlled by adjusting the content of each element in the raw material. Also, the molar ratio and composition of each element in the sulfide-based solid electrolyte can be measured, for example, by ICP emission spectrometry.

The sulfide-based solid electrolyte may be sulfide glass, crystallized sulfide glass (glass ceramics), or a crystalline material obtained by solid-phase reaction treatment of a raw material composition. .
The crystalline state of the sulfide-based solid electrolyte can be confirmed, for example, by subjecting the sulfide-based solid electrolyte to powder X-ray diffraction measurement using CuKα rays.

Sulfide glass can be obtained by subjecting a raw material composition (for example, a mixture of Li ₂ S and P ₂ S ₅ ) to amorphous processing. Examples of amorphous processing include mechanical milling.

Glass-ceramics can be obtained, for example, by heat-treating sulfide glass.
The heat treatment temperature may be any temperature higher than the crystallization temperature (Tc) observed by thermal analysis measurement of sulfide glass, and is usually 195° C. or higher. On the other hand, the upper limit of the heat treatment temperature is not particularly limited.
The crystallization temperature (Tc) of sulfide glass can be measured by differential thermal analysis (DTA).
The heat treatment time is not particularly limited as long as the desired crystallinity of the glass-ceramics is obtained. are mentioned.
The method of heat treatment is not particularly limited, but for example, a method using a kiln can be mentioned.

Examples of oxide-based solid electrolytes include Li _6.25 La ₃ Zr ₂ Al _0.25 O ₁₂ , Li ₃ PO ₄ and Li _3+x PO _4-x N _x (1≦x≦3).

Polymer electrolytes typically contain a lithium salt and a polymer.
As the lithium salt, the above inorganic lithium salt, organic lithium salt and the like can be used. The polymer is not particularly limited as long as it forms a complex with a lithium salt, and examples thereof include polyethylene oxide.

The shape of the solid electrolyte may be particulate from the viewpoint of ease of handling.
Moreover, the average particle diameter (D50) of the particles of the solid electrolyte is not particularly limited, but the lower limit may be 0.5 μm or more and the upper limit may be 2 μm or less.

In the present disclosure, unless otherwise specified, the average particle diameter of particles is the volume-based median diameter (D50) measured by laser diffraction/scattering particle size distribution measurement. In the present disclosure, the median diameter (D50) is the diameter (volume average diameter) at which the cumulative volume of particles is half (50%) of the total volume when the particles are arranged in ascending order of particle size.

Solid electrolytes can be used singly or in combination of two or more. Moreover, when using two or more kinds of solid electrolytes, two or more kinds of solid electrolytes may be mixed, or two or more layers of each solid electrolyte may be formed to form a multilayer structure.
The ratio of the solid electrolyte in the electrolyte layer is not particularly limited, but is, for example, 50% by mass or more, may be in the range of 60% by mass or more and 100% by mass or less, or 70% by mass or more and 100% by mass. % or less, or 100% by mass.

The solid electrolyte layer may contain a binder from the viewpoint of exhibiting plasticity. Examples of such a binder include the materials exemplified as binders used in the positive electrode layer. However, in order to facilitate high output, it is contained in the solid electrolyte layer from the viewpoint of preventing excessive aggregation of the solid electrolyte and making it possible to form a solid electrolyte layer having a uniformly dispersed solid electrolyte. The binder may be 5% by mass or less.

The electrolyte layer may be a separator that is impregnated with an electrolyte such as the aqueous electrolyte described above and that prevents contact between the positive electrode layer and the negative electrode layer.
The material of the separator is not particularly limited as long as it is a porous film, and examples thereof include resins such as polyethylene (PE), polypropylene (PP), polyester, cellulose and polyamide, among which polyethylene and polypropylene are preferred. Moreover, the separator may have a single-layer structure or a multilayer structure. Examples of the separator having a multilayer structure include a separator having a two-layer structure of PE/PP, or a separator having a three-layer structure of PP/PE/PP or PE/PP/PE.
The separator may be a nonwoven fabric such as resin nonwoven fabric or glass fiber nonwoven fabric.

The thickness of the electrolyte layer is not particularly limited, and is usually 0.1 μm or more and 1 mm or less.

[Positive electrode]
The positive electrode includes at least a positive electrode layer and, if necessary, a positive electrode current collector.

[Positive electrode layer]
The positive electrode layer contains a positive electrode active material, and may contain a solid electrolyte, a conductive material, a binder, and the like as optional components.

The type of positive electrode active material is not particularly limited, and any material that can be used as an active material for non-aqueous electrolyte batteries can be used. When the non-aqueous electrolyte battery is a lithium battery, the positive electrode active material is, for example, lithium simple substance, lithium alloy, LiCoO ₂ , LiNi _x Co _1-x O ₂ (0<x<1), LiNi _1/3 Co _{1/ 3Mn 1/3} O ₂ , LiNi _1/3 Co _1/3 Al _1/3 O ₂ , LiMnO ₂ , heteroelement-substituted Li—Mn spinels (eg LiMn _1.5 Ni _0.5 O ₄ , LiMn _{1.5 Al0.5O4 , LiMn1.5Mg0.5O4 , LiMn1.5Co0.5O4 , LiMn1.5Fe0.5O4 , and LiMn1.5Zn0.5O _ _ _ 4} etc.), lithium _titanates ( _{e.g. Li4Ti5O12} ), lithium metal phosphates _{( e.g. LiFePO4} , _LiMnPO4 , _LiCoPO4 and _LiNiPO4 etc.), LiCoN, _Li2SiO3 and _Li4SiO4 transition metal oxides (such as V ₂ O ₅ and MoO ₃ ), TiS ₂ , Si, SiO ₂ , and lithium storage intermetallic compounds (such as Mg ₂ Sn, Mg ₂ Ge, Mg ₂ Sb , and Cu ₃ Sb, etc.). Examples of lithium alloys include the lithium alloys exemplified as the lithium alloys used for the negative electrode active material.
Although the shape of the positive electrode active material is not particularly limited, it may be particulate.
A coat layer containing a Li ion conductive oxide may be formed on the surface of the positive electrode active material. This is because the reaction between the positive electrode active material and the solid electrolyte can be suppressed.
Li ion conductive oxides include, for example, LiNbO ₃ , Li ₄ Ti ₅ O ₁₂ , Li ₃ PO ₄ and the like. The thickness of the coat layer is, for example, 0.1 nm or more, and may be 1 nm or more. On the other hand, the thickness of the coat layer is, for example, 100 nm or less, and may be 20 nm or less. The coverage of the coat layer on the surface of the positive electrode active material is, for example, 70% or more, and may be 90% or more.

Examples of the solid electrolyte include solid electrolytes that can be contained in the electrolyte layer described above.
The content of the solid electrolyte in the positive electrode layer is not particularly limited, but may be in the range of, for example, 1% by mass to 80% by mass when the total mass of the positive electrode layer is 100% by mass.

As the conductive material, a known material can be used, and examples thereof include carbon materials, metal particles, and the like. Examples of the carbon material include at least one selected from the group consisting of carbon black such as acetylene black and furnace black, VGCF, carbon nanotubes, and carbon nanofibers. At least one selected from the group consisting of VGCF, carbon nanotubes, and carbon nanofibers may be used. Metal particles include particles of Ni, Cu, Fe, SUS, and the like.
The content of the conductive material in the positive electrode layer is not particularly limited.

Examples of binders include rubber-based binders such as butadiene rubber, hydrogenated butadiene rubber, styrene-butadiene rubber (SBR), hydrogenated styrene-butadiene rubber, nitrile-butadiene rubber, hydrogenated nitrile-butadiene rubber, ethylene-propylene rubber, polyvinylidene fluoride (PVDF ), polyvinylidene fluoride-polyhexafluoropropylene copolymer (PVDF-HFP), polytetrafluoroethylene, fluoride-based binders such as fluororubber, polyolefin-based thermoplastic resins such as polyethylene, polypropylene, polystyrene, polyimide, polyamideimide imide resins such as polyimide, amide resins such as polyamide, acrylic resins such as polymethyl acrylate and polyethyl acrylate, and methacrylic resins such as polymethyl methacrylate and polyethyl methacrylate. The content of the binder in the positive electrode layer is not particularly limited.

The thickness of the positive electrode layer is not particularly limited.

The positive electrode layer can be formed by a conventionally known method.
For example, the positive electrode active material and, if necessary, other components are put into a solvent and stirred to prepare a positive electrode layer slurry. The positive electrode layer is obtained by coating on top and drying.
Solvents include, for example, methyl isobutyl ketone, n-decane, butyl acetate, butyl butyrate, heptane, and N-methyl-2-pyrrolidone.
The method for applying the positive electrode layer slurry onto one surface of a support such as a positive electrode current collector is not particularly limited, and may be a doctor blade method, a metal mask printing method, an electrostatic coating method, a dip coating method, a spray coating method, a roll coating method, or the like. Examples include a coating method, a gravure coating method, and a screen printing method.
As the support, one having self-supporting properties can be appropriately selected and used, and there is no particular limitation. For example, metal foils such as Cu and Al can be used.

As another method of forming the positive electrode layer, the positive electrode layer may be formed by pressure-molding a powder of a positive electrode mixture containing the positive electrode active material and, if necessary, other components. When the powder of the positive electrode mixture is pressure-molded, a press pressure of about 1 MPa to 600 MPa is normally applied.
The pressurizing method is not particularly limited, but examples thereof include a method of applying pressure using a flat plate press, a roll press, and the like.

[Positive collector]
The positive electrode current collector contains one or more elements selected from the group consisting of Cu, Ni, Al, V, Au, Pt, Mg, Fe, Ti, Co, Cr, Zn, Ge, and In. A metal material can be exemplified.
The shape of the positive electrode current collector is not particularly limited, and various shapes such as a foil shape and a mesh shape can be used.

A non-aqueous electrolyte battery is provided with an outer package housing a positive electrode layer, a negative electrode layer, an electrolyte layer, and the like, if necessary.
The material of the exterior body is not particularly limited as long as it is stable in the electrolyte, and examples thereof include polypropylene, polyethylene, and resins such as acrylic resins.

The non-aqueous electrolyte battery may be a primary battery, a secondary battery, or a secondary battery. This is because they can be repeatedly charged and discharged, and are useful, for example, as batteries for vehicles. Also, the non-aqueous electrolyte battery may be a non-aqueous electrolyte battery, an all-solid battery, or the like, and the all-solid battery may be an all-solid lithium battery, an all-solid lithium ion battery, or the like.
Examples of the shape of the non-aqueous electrolyte battery include coin type, laminate type, cylindrical type, rectangular type, and the like.

In the manufacturing method of the non-aqueous electrolyte battery of the present disclosure, for example, a solid electrolyte layer is first formed by pressure-molding powder of a solid electrolyte material. Then, the positive electrode layer is obtained by pressure-molding the powder of the positive electrode mixture containing the positive electrode active material on one surface of the solid electrolyte layer. Thereafter, a slurry containing a negative electrode layer material containing titanium-niobium oxide is applied to the other surface of the solid electrolyte layer and dried to form a negative electrode layer. The non-aqueous electrolyte battery of the present disclosure may be obtained by attaching the positive electrode current collector on the opposite side and attaching the negative electrode current collector on the side of the negative electrode layer opposite to the solid electrolyte layer.
In this case, the press pressure when the powder of the solid electrolyte material and the powder of the positive electrode material mixture is pressure-molded is usually about 1 MPa or more and 600 MPa or less.
The pressurization method is not particularly limited, but includes the pressurization method exemplified in the formation of the positive electrode layer.

• Synthesis of TNO Titanium oxide (anatase type, manufactured by Wako Pure Chemical Industries) and niobium oxide (manufactured by Kishida Chemical Co., Ltd.) were weighed so that the molar ratio of Ti and Nb was 1:2. These raw materials, zirconia beads with a diameter of 10 mm, and ethanol were placed in a planetary ball mill (manufactured by Fritsche) and mixed for 2 hours at a rotation speed of 200 rpm. The dried product obtained by mixing was fired in air at 1100° C. for 12 hours to obtain a powder of TiNb ₂ O ₇ which is a crystal of titanium-niobium oxide (TNO).

(Example 1)
Partial amorphization treatment of TNO The obtained TNO powder, φ1 mm zirconia beads and ethanol are placed in a planetary ball mill, wet-ground at a rotation speed of 400 rpm for 12 hours, dried, and part of the crystals are non-crystallized. A crystallized titanium-niobium oxide powder was obtained.

・X-ray diffraction measurement of TNO TNO powder partially amorphized is subjected to X-ray diffraction measurement using CuKα rays using an X-ray diffractometer (RINT-TTR-III type manufactured by Rigaku Co., Ltd.). gone. The full width at half maximum of the diffraction peak with the highest intensity observed at the diffraction angle 2θ=26°±0.5° was calculated from the obtained XRD spectrum. Table 1 shows the results. FIG. 2 shows the XRD spectrum obtained by the XRD measurement of the partially amorphized titanium-niobium oxide of Example 1. As shown in FIG.

Measurement of powder resistance of TNO The powder resistance (volume resistance, Ωcm) of the partially amorphized TNO powder was measured. As for the powder resistance, an EZGraph, ADC Digital ultra-high resistance/micro current meter 5450 manufactured by Shimadzu Corporation was used to measure the resistance value under a load of 14.1 MPa. Table 1 shows the results.

- Production of Negative Electrode Artificial graphite and partially amorphized TiNb ₂ O ₇ were used as negative electrode active materials.
When the total mass of artificial graphite and TiNb ₂ O ₇ is 100% by mass, the mass ratio of artificial graphite and TiNb ₂ O ₇ is artificial graphite:TiNb ₂ O ₇ =97:3.
The mass ratio of the sulfide-based solid electrolyte (10LiI-15LiBr-75 (0.75Li ₂ S-0.25P ₂ S ₅ ), synthesized in-house) is negative electrode material: sulfide-based solid electrolyte = 65:35. A sulfide-based solid electrolyte was weighed as follows.
A PVDF-HFP binder (Soref (registered trademark); 21510 manufactured by Solvay) was weighed to 1.5 parts by mass with respect to 100 parts by mass of the negative electrode material.
Furthermore, the volume ratio of the main solvent (methyl isobutyl ketone (dehydrated grade), manufactured by Nacalai Tesque Co., Ltd.) and the secondary solvent (n-decane, manufactured by Tokyo Chemical Industry Co., Ltd.) dehydrated with molecular sieves is the main solvent: The solvents were mixed so that the co-solvents were 90:10.
Then, the negative electrode material, the sulfide-based solid electrolyte, the PVDF-HFP binder, and the solvent were kneaded for 1 minute using an ultrasonic homogenizer to prepare a slurry negative electrode composition.
After that, a slurry negative electrode composition was applied to one surface of a nickel current collector as a negative electrode current collector using a doctor blade, dried naturally for 30 minutes, and then dried at 100 ° C. for 30 minutes. A negative electrode layer was obtained by heating and drying by heating to obtain a negative electrode including a nickel current collector and a negative electrode layer.

・Preparation of positive electrode LiNi _1/3 Co _1/3 Mn _1/3 O ₂ (manufactured by Nichia Corporation) as a positive electrode active material and 10LiI-15LiBr-75 (0.75Li ₂ S- 0.25P ₂ S ₅ ) (synthesized in-house) was weighed so that the mass ratio of positive electrode active material: sulfide-based solid electrolyte = 75:25, and PVDF-HFP was added to 100 parts by mass of the positive electrode active material. 1.5 parts by mass of a binder (Soref (registered trademark); 21510 manufactured by Solvay), and 3.0 parts of vapor growth carbon fiber (manufactured by Showa Denko K.K.) as a conductive material with respect to 100 parts by mass of the positive electrode active material. It was weighed so as to be parts by mass.
Furthermore, the volume ratio of the main solvent (methyl isobutyl ketone (dehydrated grade), manufactured by Nacalai Tesque Co., Ltd.) and the secondary solvent (n-decane, manufactured by Tokyo Chemical Industry Co., Ltd.) dehydrated with molecular sieves is the main solvent: The solvents were mixed so that the co-solvents were 90:10.
Then, the positive electrode active material, the sulfide-based solid electrolyte, the PVDF-HFP binder, the conductive material, and the solvent were kneaded for 1 minute using an ultrasonic homogenizer to prepare a slurry positive electrode composition.
After that, a slurry-like positive electrode composition was applied to one side of an aluminum foil (manufactured by Showa Denko KK) as a positive electrode current collector using a doctor blade, dried naturally for 30 minutes, and then heated to 100°C. The positive electrode layer was obtained by heating and drying for 30 minutes, and the positive electrode including the aluminum foil and the positive electrode layer was obtained.

- Preparation of All-Solid Metal Lithium Counter Electrode Cell In a glove box in an Ar atmosphere, a compact press cell (φ11.28 mm evaluation battery) was prepared as an all-solid metal lithium counter electrode cell by the following method.
65.0 mg of the powder of the sulfide-based solid electrolyte (10LiI-15LiBr-75 (0.75Li ₂ S-0.25P ₂ S ₅ ) (manufactured product)) was put into a cylinder made by Macor, and 1 ton/cm ² was applied. A solid electrolyte layer is formed by pressing, and the negative electrode (φ11.28 mm) prepared above is placed thereon so that the negative electrode layer of the negative electrode faces the solid electrolyte layer. cm ² , then a Li—In alloy was placed on the surface of the solid electrolyte layer opposite to the negative electrode layer, and pressed at 4.3 ton/cm ² . Thereafter, the resulting Li—In alloy-solid electrolyte layer-negative electrode laminate was fastened with three bolts at a torque of 6 N·m and placed in a sealed container to prepare an all-solid metallic lithium counter electrode cell.

・Evaluation method of all-solid metal lithium counter electrode cell The all-solid metal lithium counter electrode cell prepared was charged at 0.1 C, discharged at 0.1 C, and discharged at 0.1 C in a voltage range of 0.7 V to 2.5 V. After measuring the capacity, the battery was charged at 0.1C and discharged at 2.0C to measure the 2.0C discharge capacity.
Then, a discharge capacity retention rate [(0.1C discharge capacity/2.0C discharge capacity)×100(%)] was calculated from the measured discharge capacity. Table 1 shows the results.
It can be determined that the higher the discharge capacity retention rate, the faster the battery changes to the discharged state when an internal short circuit occurs in the battery, and the higher the safety of the battery. Note that the discharge maintenance rate may be 80% or more.

・Preparation of all-solid-state laminated battery In a glove box in an Ar atmosphere, 100 mass of the sulfide-based solid electrolyte (10LiI-15LiBr-75 (0.75Li ₂ S-0.25P _{2 S} ) (in-house synthesized product)) 1 part by mass of PVDF-HFP binder (Soref (registered trademark); 21510 manufactured by Solvay) is added to the parts, and methyl isobutyl ketone (dehydrated grade, manufactured by Nacalai Tesque Co., Ltd.) is added as a solvent to form the solid electrolyte layer obtained. A solid electrolyte layer-forming slurry was obtained by kneading the slurry with an ultrasonic homogenizer so that the solid content in the slurry was 35% by mass.
A solid electrolyte layer-forming slurry was applied to one surface of an aluminum foil using a doctor blade and dried to obtain a solid electrolyte layer.
The positive electrode layer side of the positive electrode was opposed to the solid electrolyte layer and pressed at room temperature at 2.0 ton/cm ² to peel off the aluminum foil of the solid electrolyte layer and transfer the solid electrolyte layer to the positive electrode layer.
Furthermore, the negative electrode layer side of the negative electrode is opposed to the solid electrolyte layer, and pressed at 135° C. and 4.3 tons/cm ² , and the positive electrode current collector, positive electrode layer, solid electrolyte layer, negative electrode layer, and negative electrode current collector are pressed in this order. A stacked unit cell was obtained. An all-solid-state laminated battery was obtained by laminating 10 unit batteries and sealing the obtained laminated body in a laminate. In the unit battery, A/B was set to 1.15, where A was the capacity of the positive electrode and B was the capacity of the negative electrode. The capacity of the all-solid-state laminated battery is 2.5 Ah.

・Nail penetration test of all-solid-state laminated battery Charge the all-solid-state laminated battery at 0.1C, and insert a Φ3mm iron nail at the center of the upper part of the all-solid-state laminated battery in a charged state at room temperature at a speed of 3mm/sec. , and the maximum temperature reached by the all-solid-state laminated battery was confirmed by a thermocouple attached to the negative electrode tab of the all-solid-state laminated battery. The nail penetration test was repeated 5 times, and the average maximum temperature was calculated. Table 1 shows the results. Note that the maximum temperature reached at the time of nail penetration may be less than 150°C.

(Example 2)
Example 1 except that in the partial amorphization treatment of TNO, the obtained TNO powder, φ1 mm zirconia beads, and ethanol were placed in a planetary ball mill, wet-ground at a rotation speed of 500 rpm for 12 hours, and dried. A partially amorphized titanium-niobium oxide powder of Example 2 was obtained in the same manner as above. Then, in the same manner as in Example 1, XRD measurement and powder resistance measurement of the partially amorphized titanium-niobium oxide of Example 2, preparation and evaluation of an all-solid metallic lithium counter electrode cell, and An all-solid-state laminated battery was fabricated and a nail penetration test was performed. Table 1 shows the results.

(Example 3)
In the partial amorphization treatment of TNO, the obtained TNO powder, zirconia beads of φ0.7 mm, and ethanol were placed in a planetary ball mill, wet-ground at a rotation speed of 400 rpm for 12 hours, and dried. A partially amorphized titanium-niobium oxide powder of Example 3 was obtained in the same manner as in Example 1. Then, in the same manner as in Example 1, XRD measurement and powder resistance measurement of the titanium-niobium oxide partially amorphized in Example 3, preparation and evaluation of an all-solid metallic lithium counter electrode cell, and An all-solid-state laminated battery was fabricated and a nail penetration test was performed. Table 1 shows the results.

(Example 4)
In the partial amorphization treatment of TNO, the obtained TNO powder, zirconia beads of φ0.7 mm, and ethanol were placed in a planetary ball mill, wet-ground at a rotation speed of 500 rpm for 12 hours, and dried. A partially amorphized titanium-niobium oxide powder of Example 4 was obtained in the same manner as in Example 1. Then, in the same manner as in Example 1, XRD measurement and powder resistance measurement of the partially amorphized titanium-niobium oxide of Example 4, preparation and evaluation of an all-solid metallic lithium counter electrode cell, and An all-solid-state laminated battery was fabricated and a nail penetration test was performed. Table 1 shows the results.

(Example 5)
In the partial amorphization treatment of TNO, the obtained TNO powder, zirconia beads of φ0.7 mm, and ethanol were placed in a planetary ball mill, wet-ground at a rotation speed of 500 rpm for 12 hours, and dried. A partially amorphized titanium-niobium oxide powder of Example 5 was obtained in the same manner as in Example 1. Then, XRD measurement and powder resistance measurement of the partially amorphized titanium-niobium oxide of Example 5 were performed in the same manner as in Example 1. Further, in the production of the negative electrode, when the total mass of artificial graphite and TiNb ₂ O ₇ is 100% by mass, the mass ratio of artificial graphite and TiNb ₂ O ₇ is artificial graphite:TiNb ₂ O ₇ =98:2. An all-solid metallic lithium counter electrode cell of Example 5 was produced and evaluated, and an all-solid laminated battery was produced and a nail penetration test was performed in the same manner as in Example 1 except that the method was the same as in Example 1. Table 1 shows the results.

(Comparative example 1)
XRD measurement and powder resistance of Li ₄ Ti ₅ O ₁₂ of Comparative Example 1 were performed in the same manner as in Example 1 except that Li ₄ Ti ₅ O ₁₂ (average particle size 4 μm) was used instead of TiNb ₂ O ₇ . was measured, an all-solid metallic lithium counter electrode cell was produced and evaluated, and an all-solid-state laminated battery was produced and a nail penetration test was performed. Table 1 shows the results. Moreover, the XRD spectrum obtained by the XRD measurement of Li ₄ Ti ₅ O ₁₂ of Comparative Example 1 is shown in FIG.

(Comparative example 2)
Example 1 except that in the partial amorphization treatment of TNO, the obtained TNO powder, φ3 mm zirconia beads, and ethanol were placed in a planetary ball mill, wet-ground at a rotation speed of 200 rpm for 3 hours, and dried. A partially amorphized titanium-niobium oxide powder of Comparative Example 2 was obtained in the same manner as above. Then, in the same manner as in Example 1, the XRD measurement and powder resistance measurement of the partially amorphized titanium-niobium oxide of Comparative Example 2, the production and evaluation of an all-solid metallic lithium counter electrode cell, and An all-solid-state laminated battery was fabricated and a nail penetration test was performed. Table 1 shows the results.

(Comparative Example 3)
Example 1 except that in the partial amorphization treatment of TNO, the obtained TNO powder, φ3 mm zirconia beads, and ethanol were placed in a planetary ball mill, wet-ground at a rotation speed of 300 rpm for 3 hours, and dried. A partially amorphized titanium-niobium oxide powder of Comparative Example 3 was obtained in the same manner as above. Then, in the same manner as in Example 1, the XRD measurement and powder resistance measurement of the partially amorphized titanium-niobium oxide of Comparative Example 3, the production and evaluation of an all-solid metallic lithium counter electrode cell, and An all-solid-state laminated battery was fabricated and a nail penetration test was performed. Table 1 shows the results.

(Comparative Example 4)
Example 1 except that in the partial amorphization treatment of TNO, the obtained TNO powder, φ3 mm zirconia beads, and ethanol were placed in a planetary ball mill, wet-ground at a rotation speed of 300 rpm for 3 hours, and dried. A partially amorphized titanium-niobium oxide powder of Comparative Example 4 was obtained in the same manner as above. Then, XRD measurement and powder resistance measurement of the partially amorphized titanium-niobium oxide of Comparative Example 4 were performed in the same manner as in Example 1. Further, in the production of the negative electrode, when the total mass of artificial graphite and TiNb ₂ O ₇ is 100% by mass, the mass ratio of artificial graphite and TiNb ₂ O ₇ is artificial graphite:TiNb ₂ O ₇ =90:10. An all-solid metallic lithium counter electrode cell of Comparative Example 4 was produced and evaluated, and an all-solid laminated battery was produced and a nail penetration test was performed in the same manner as in Example 1 except that the method was the same as in Example 1. Table 1 shows the results.

(Comparative Example 5)
Example 1 except that in the partial amorphization treatment of TNO, the obtained TNO powder, φ3 mm zirconia beads, and ethanol were placed in a planetary ball mill, wet-ground at a rotation speed of 400 rpm for 3 hours, and dried. A partially amorphized titanium-niobium oxide powder of Comparative Example 5 was obtained in the same manner as above. Then, in the same manner as in Example 1, the XRD measurement and powder resistance measurement of the partially amorphized titanium-niobium oxide of Comparative Example 5, the production and evaluation of an all-solid metallic lithium counter electrode cell, and An all-solid-state laminated battery was fabricated and a nail penetration test was performed. Table 1 shows the results.

(Comparative Example 6)
In the partial amorphization treatment of TNO, the obtained TNO powder, zirconia beads of φ0.5 mm, and ethanol were placed in a planetary ball mill, wet-ground at a rotation speed of 500 rpm for 24 hours, and dried. A partially amorphized titanium-niobium oxide powder of Comparative Example 6 was obtained in the same manner as in Example 1. Then, in the same manner as in Example 1, the XRD measurement and powder resistance measurement of the partially amorphized titanium-niobium oxide of Comparative Example 6, the production and evaluation of an all-solid metallic lithium counter electrode cell, and An all-solid-state laminated battery was fabricated and a nail penetration test was performed. Table 1 shows the results.

[XRD and powder resistance evaluation results]
From the results of observing the particles of each partially amorphized TNO powder with an XRD measurement and a transmission electron microscope, the partially amorphized TNO of Examples 1 to 5 and Comparative Examples 2 to 6 has a monoclinic crystal structure and could be assigned to the C2/m space group.
A halo peak was observed in the partially amorphized TNO powders of Examples 1 to 5 in the XRD spectrum, confirming that part of the TNO was amorphous.
In addition, as in Examples 1 to 5, the powder obtained by pulverizing TNO for 12 hours in the partial amorphization treatment of TNO was partially amorphous as in Comparative Examples 2 to 5. Compared to the powder obtained by pulverizing TNO for 3 hours in the hardening treatment, the full width at half maximum of the strongest diffraction peak observed at the diffraction angle 2θ = 26 ° ± 0.5 ° obtained from the XRD spectrum increased. Body resistance increased. This is probably because the 12-hour pulverization caused greater damage to the particle surfaces, and part of the crystals became amorphous at the desired rate. In the partially amorphized TNO of Examples 1 to 5 in this way, since the amorphous phase is partially present, the highest intensity observed at the diffraction angle 2θ = 26 ° ± 0.5 ° It is believed that the full width at half maximum of the strong diffraction peaks increased.

[Discharge capacity maintenance rate evaluation result]
Compared with the all-solid metal lithium counter electrode cells of Comparative Examples 2-3 and 5, the all-solid metal lithium counter electrode cells of Examples 1-4 showed no significant change in discharge capacity retention rate.
As in Comparative Example 6, TNO that was partially amorphized under the pulverization condition of 24 hours increased the powder resistance, but the discharge capacity retention rate of the all-solid metallic lithium counter electrode cell decreased. This is probably because the TNO was excessively pulverized to excessively increase the proportion of the amorphous portion of the TNO, resulting in a significant decrease in the ability of the TNO to diffuse Li ions.

[Nail penetration test evaluation results]
Compared with the all-solid-state laminated batteries of Comparative Examples 1-6, the all-solid-state laminated batteries of Examples 1-5 had a lower average maximum temperature at the time of nail penetration of 142° C. or less.
This is because, in the case of Examples 1 to 5, when an internal short circuit occurs in the battery, it is easy to shift to a discharged state (insulated state), and the powder resistance of TNO partially subjected to amorphization treatment is high, so heat generation occurs in the battery. It is considered that it has become difficult to
In the case of Examples 1 to 4, since TNO partially subjected to amorphization treatment is included and the discharge capacity retention rate of the all-solid metal lithium counter electrode cell is high, the TNO content in the negative electrode layer is the same as that of LTO. It is possible to suppress the heat generation of the battery even if it is , and since TNO has a larger capacity per mass than LTO, it is considered that the decrease in battery capacity is small.
From the results of Example 5, it can be seen that heat generation of the battery can be suppressed even when the content of partially amorphized TNO is lower than that of Example 4.
On the other hand, in the case of Comparative Examples 2, 3 and 5, since the powder resistance of TNO was low, suppression of the short-circuit current was insufficient, and the heat generation temperature of the battery increased.
In the case of Comparative Example 4, the powder resistance of TNO was low, but the TNO content was higher than that of Comparative Example 3, so the heat generation temperature of the battery was able to be reduced compared to Comparative Example 3. However, it is considered that the content of natural graphite is relatively low, resulting in a decrease in battery capacity.
In the case of Comparative Example 6, the powder resistance of TNO is high, but the discharge capacity retention rate of the all-solid metal lithium counter electrode cell is low, so it takes time to become an insulator (discharged state) when a short circuit occurs in the battery. , the amount of heat generated by the battery is considered to have increased compared to the cases of Examples 1-5.

From the above results, it can be seen that the batteries of Examples 1 to 5 contain titanium-niobium oxide (TNO) containing an amorphous phase whose resistance increases in the discharged state. It is possible to suppress heat generation when a short circuit occurs in a battery during a puncture test or the like, and since TNO has a larger capacity per mass than LTO, it is considered possible to secure a desired battery capacity.
Therefore, according to the present disclosure, it was demonstrated that it is possible to provide a non-aqueous electrolyte battery capable of ensuring a desired battery capacity and suppressing a temperature rise inside the battery.

11 Electrolyte layer 12 Positive electrode layer 13 Negative electrode layer 14 Positive electrode current collector 15 Negative electrode current collector 16 Positive electrode 17 Negative electrode 100 Non-aqueous electrolyte battery

Claims (1)

A nonaqueous electrolyte battery comprising a positive electrode layer, a negative electrode layer, and an electrolyte layer disposed between the positive electrode layer and the negative electrode layer,
The negative electrode layer includes a titanium-niobium oxide containing an amorphous phase and a negative electrode active material having a lower Li absorption and release potential than the titanium-niobium oxide,
The negative electrode active material is at least one selected from the group consisting of Li simple substance, lithium alloy, carbon, Si simple substance, and Si alloy,
The negative electrode layer contains 2.0 % by mass or more and 3.0% by mass or less of the titanium-niobium oxide when the total of the negative electrode active material and the titanium-niobium oxide is 100% by mass,
The titanium-niobium oxide has a spectrum obtained by X-ray diffraction measurement using CuKα rays, and the full width at half maximum of the strongest diffraction peak observed at a diffraction angle of 2θ = 26° ± 0.5° is 0.17°. A non-aqueous electrolyte battery characterized in that the angle is not less than 0.20° and not more than 0.20°.

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