Transition metal composite oxide powder, electrode obtained using same, and non-aqueous electrolyte power storage device

Abstract

Provided is a transition metal composite oxide powder which contains at least zinc and niobium, and which is characterized in that the molar ratio (MNb / MZn) of niobium relative to zinc is such that 8≤MNb / MZn≤40, and the D50 value of primary particles, which corresponds to a cumulative volume of 50% in a volume-based particle size distribution determined using a laser diffraction scattering method, is 0.25-2.8 μm.

Description

Transition metal composite oxide powder, electrode using the same, and non-aqueous electrolyte storage device

[0001] The present invention relates to a transition metal composite oxide powder suitable as an electrode material for an electricity storage device, an electrode using the same, and an electricity storage device.

[0002] Energy storage devices for electric vehicles require high energy density to improve fuel economy and power consumption. Lithium-ion batteries, in particular, are widely used as power sources for electric vehicles and power storage. Various materials have been studied as electrode materials for lithium-ion batteries. While lithium titanate has excellent input / output characteristics, its energy density remains at 175 mAh / g, leaving challenges for further energy enhancement. Therefore, there has been a movement to use niobium-containing oxides, primarily niobium titanate, which has a high energy density of 380 mAh / g, as an alternative anode material.

[0003] Furthermore, because currently available lithium-ion batteries use electrolytes containing flammable organic solvents, they require the installation of safety devices to suppress temperature rises in the event of a short circuit, as well as short-circuit prevention structures. Under these circumstances, all-solid-state secondary batteries using inorganic solid electrolytes instead of organic electrolytes are attracting attention. Because the positive and negative electrodes and electrolytes of all-solid-state secondary batteries are all solid, they have the potential to significantly improve the safety and reliability issues associated with batteries using organic electrolytes. Furthermore, because safety devices can be simplified, high energy density is possible, making them promising for applications in electric vehicles, large-scale storage batteries, and more.

[0004] Patent Document 1 describes a niobium-containing oxide, Zn, having a particle size range of 3 to 5 μm, produced by a solid phase method. ２ Nb ３４ O ８７ It has been reported that when used as an electrode material for an electricity storage device, excellent battery characteristics can be obtained. In addition, Patent Document 2 discloses a zinc niobium oxide having a D50 of 5 μm or more and containing at least one element. ２ Nb ３４ O ８７ is disclosed, and the element is not substituted Zn ２Nb ３４ O ８７ It has been reported that the rate characteristics are superior.

[0005] U.S. Patent No. 11,380,881 Patent Publication No. 2023-534759

[0006] However, when the zinc niobium oxide having a relatively large particle size of 3 μm or more as described in Patent Document 1 is used as a negative electrode material, it is not possible to obtain a sufficiently satisfactory battery capacity and rate characteristics. ２ Nb ３４ O ８７ is Zn where the element is not substituted. ２ Nb ３４ O ８７ Although the rate characteristics improved, satisfactory rate characteristics were still not achieved. After various investigations into the cause, it was found that zinc niobium oxide has lower electronic conductivity than other niobium composite oxides. It was also found that when zinc niobium oxide with low electronic conductivity is used as a negative electrode material, contact with the conductive additive in the electrode is extremely important. It was found that the zinc niobium oxides of 3 μm or more described in Patent Documents 1 and 2 undergo large volume changes during battery charging and discharging, making it impossible to maintain contact with the conductive additive, resulting in reduced rate characteristics. Furthermore, it was also found that the molar ratio of niobium to zinc among zinc niobium oxides affects volume change. The benefit of increasing battery capacity is that it leads to improved energy density per unit weight or unit area (unit volume), which can extend the driving range of electric vehicles and secure installation space for storage batteries.

[0007] For the above reasons, the discharge capacity, discharge rate characteristics, charge rate characteristics, and electrode thickness change due to charge and discharge of the electricity storage devices using the negative electrode active materials of Patent Document 1 and Patent Document 2 are not fully satisfactory, and further improvements are required.

[0008] Therefore, an object of the present invention is to provide a transition metal composite oxide powder that can be used as an electrode material for a non-aqueous electrolyte electricity storage device, and that can maintain the initial discharge capacity in a liquid-based lithium-ion secondary battery while exhibiting excellent rate characteristics and suppressing the rate of change in electrode thickness during charge and discharge; an electrode for an electricity storage device using the same; and a non-aqueous electrolyte electricity storage device.

[0009] As a result of extensive investigations to achieve the above-mentioned object, the present inventors discovered that by using a transition metal composite oxide powder as an electrode material, in which the molar ratio of niobium to zinc in zinc niobium oxide and the D50 of primary particles corresponding to 50% cumulative volume in a volume-based particle size distribution measured by laser diffraction scattering method are controlled within appropriate ranges, it is possible to obtain an electricity storage device that is excellent in initial discharge capacity and rate characteristics and that also has a small rate of change in electrode thickness with charge and discharge, and thus completed the present invention. Such effects, particularly the effect of being able to reduce change in electrode thickness with charge and discharge, are not described or suggested at all in Patent Documents 1 and 2. That is, the present invention relates to the following matters.

[0010] [1] A transition metal composite oxide containing at least zinc and niobium, wherein the molar ratio of niobium to zinc is M Nb / M Zn is 8≦M Nb / M Zn [2] The transition metal composite oxide powder according to [1], wherein the D50 of primary particles corresponding to a volume cumulative 50% in a volume-based particle size distribution determined by a laser diffraction scattering method is 0.25 μm or more and 2.8 μm or less, and wherein the D50 of primary particles corresponding to a volume cumulative 50% in a volume-based particle size distribution determined by a laser diffraction scattering method is 0.25 μm or more and 2.8 μm or less. １０ (D ９０ ) -log １０ (D ５０ ) < 0.6 (I) (Note: D ５０ indicates the particle size at which the cumulative volume distribution of particle sizes of primary particles is 50% in the particle size distribution, and D ９０ indicates the particle size at which the cumulative volume distribution of particle sizes of primary particles in the particle size distribution is 90%.) [3] The specific surface area of ​​the transition metal composite oxide is 1.2 m ２ / g or more 10m ２[4] The transition metal composite oxide powder according to [1] or [2], characterized in that the transition metal composite oxide has a ZnNb ８ O ２１ , Zn ２ Nb ３４ O ８７ , ZnNb ２０ O ５１ , ZnNb ４０ O １０１ The transition metal composite oxide powder according to any one of [1] to [3], which satisfies any one of the following general formulae (II) to (VII): a Zn １－ｘ M ＩＩＩ １．５ｘ＋ｖ Nb １４－０．５ｘ＋ｖ O ３６±ｚ (II) A a Zn １－ｙ M ＩＶ ３ｙ＋ｗ Nb １４－２ｙ＋ｗ O ３６±ｚ (III) A a Zn １－ｐ M ＩＩ ｐ＋ｖ Nb １４－ｑ M Ｖ ｑ＋ｗ O ３６±ｚ (IV) A a ZnM ＩＩ ０．２５ｒ＋ｗ Nb １４－ｒ M ＶＩ ０．７５ｒ＋ｗ O ３６±ｚ (V) A a ZnM ＩＩＩ ０．３３ｓ＋ｗ Nb １４－ｓ M ＶＩ ０．６７ｓ＋ｗ O ３６±ｚ (VI) A a ZnM ＩＶ ０．５ｔ＋ｗ Nb １４－ｔ M ＶＩ ０．５ｔ＋ｗ O ３６±ｚ (VII) (wherein A is at least one element selected from Li and Na, and M ＩＩare each independently at least one divalent metal element selected from the group consisting of Mg, Ca, and Cu, and M ＩＩＩ are each independently at least one element selected from Al, Ga, Fe, and Cr, and M ＩＶ are each independently at least one element selected from Ti, Zr, Ge, and Sn, and M Ｖ are each independently at least one pentavalent metal element selected from the group consisting of V and Ta, and M ＶＩ is at least one hexavalent metal element selected from the group consisting of Mo and W, and 0≦a≦6, −0.05≦v≦0.05, −0.05≦w≦0.05, 0<x<0.1, 0<y<0.1, 0≦p<0.1, 0≦q<6, 0<r<6, 0<s<6, 0<t<6, 0≦z≦1). [5] An electrode for a non-aqueous electrolyte electricity storage device, comprising the transition metal composite oxide powder according to any one of [1] to [4]. [6] A negative electrode active material composition for a non-aqueous electrolyte electricity storage device, comprising the transition metal composite oxide powder according to any one of [1] to [4] and an inorganic solid electrolyte. [7] A non-aqueous electrolyte electricity storage device, comprising the electrode according to [5]. [8] An all-solid-state secondary battery comprising a positive electrode layer, a negative electrode layer, and a solid electrolyte layer, wherein the negative electrode layer is a layer comprising the negative electrode active material composition according to [6].

[0011] The present invention can provide a transition metal composite oxide powder that, in a non-aqueous electrolyte electricity storage device, maintains initial discharge capacity while exhibiting excellent rate characteristics and is capable of suppressing the rate of change in electrode thickness associated with charge and discharge; an electrode for an electricity storage device using the same; and a non-aqueous electrolyte electricity storage device.

[0012] [Transition metal composite oxide powder of the present invention] The transition metal composite oxide powder of the present invention is a transition metal composite oxide powder containing at least zinc and niobium, and has a molar ratio M of niobium to zinc of 0.1 to 0.2. Nb / M Zn is 8≦M Nb / M ZnThe transition metal composite oxide powder of the present invention satisfies the above condition: D50 of primary particles corresponding to 50% cumulative volume in a volume-based particle size distribution measured by a laser diffraction scattering method is 0.25 μm or more and 2.8 μm or less. The transition metal composite oxide powder of the present invention is suitably used for electrodes of non-aqueous electrolyte electricity storage devices. In other words, the transition metal composite oxide powder of the present invention is suitably used as a transition metal oxide powder for electrodes of non-aqueous electrolyte electricity storage devices. The non-aqueous electrolyte may be any other than an aqueous electrolyte, and is not particularly limited, but examples thereof include non-aqueous electrolytic solutions and solid electrolytes.

[0013] <Transition metal composite oxide powder containing zinc and niobium> The transition metal composite oxide powder of the present invention is a transition metal composite oxide containing at least zinc and niobium, and from the viewpoint of improving the rate characteristics and suppressing the rate of change in electrode thickness during charge and discharge, the molar ratio M of niobium to zinc is Nb / M Zn is 8≦M Nb / M Zn The transition metal composite oxide powder satisfies the condition M≦40. Nb / M Zn is 10≦M Nb / M Zn ≦30 is preferred, and 10≦M Nb / M Zn ≦20 is more preferable, and 10≦M Nb / M Zn ≦15 is particularly preferred.

[0014] The transition metal composite oxide containing zinc and niobium is ZnNb ８ O ２１ , Zn ２ Nb ３４ O ８７ , ZnNb ２０ O ５１ , ZnNb ４０ O １０１ When the compound is at least one selected from the compounds represented by the following general formulas (II) to (VII), it is preferable because it can maintain the initial discharge capacity, have better rate characteristics, and further suppress the rate of change in electrode thickness during charge and discharge. a Zn １－ｘ M ＩＩＩ１．５ｘ＋ｖ Nb １４－０．５ｘ＋ｖ O ３６±ｚ　　　　　　　 (II) A a Zn １－ｙ M ＩＶ ３ｙ＋ｗ Nb １４－２ｙ＋ｗ O ３６±ｚ (III) A a Zn １－ｐ M ＩＩ ｐ＋ｖ Nb １４－ｑ M Ｖ ｑ＋ｗ O ３６±ｚ (IV) A a ZnM ＩＩ ０．２５ｒ＋ｗ Nb １４－ｒ M ＶＩ ０．７５ｒ＋ｗ O ３６±ｚ (V) A a ZnM ＩＩＩ ０．３３ｓ＋ｗ Nb １４－ｓ M ＶＩ ０．６７ｓ＋ｗ O ３６±ｚ (VI) A a ZnM ＩＶ ０．５ｔ＋ｗ Nb １４－ｔ M ＶＩ ０．５ｔ＋ｗ O ３６±ｚ　　　　　　　　 (VII) (wherein A is at least one element selected from Li and Na, and M ＩＩ are each independently at least one divalent metal element selected from the group consisting of Mg, Ca, and Cu, and M ＩＩＩ are each independently at least one element selected from Al, Ga, Fe, and Cr, and M ＩＶ are each independently at least one element selected from Ti, Zr, Ge, and Sn, and M Ｖ are each independently at least one pentavalent metal element selected from the group consisting of V and Ta, and M ＶＩis at least one hexavalent metallic element selected from the group consisting of Mo and W, and 0≦a≦6, −0.05≦v≦0.05, −0.05≦w≦0.05, 0<x<0.1, 0<y<0.1, 0≦p<0.1, 0≦q<6, 0<r<6, 0<s<6, 0<t<6, 0≦z≦1)

[0015] In the general formulas (II) to (VII), A is not particularly limited as long as it is at least one element selected from Li and Na, but is preferably Li.

[0016] Said M ＩＩＩ is not particularly limited as long as it is at least one element selected from Al, Ga, Fe, and Cr, but is preferably Al, Fe, and Cr, more preferably Al and Fe, and even more preferably Al.

[0017] Said M ＩＶ is not particularly limited as long as it is at least one element selected from Ti, Zr, Ge, and Sn, but is preferably Ti, Zr, and Ge, more preferably Ti and Zr, and even more preferably Ti.

[0018] Said M ＩＩ is not particularly limited as long as it is at least one element selected from Mg, Ca, and Cu, but is preferably Mg and Cu.

[0019] Said M Ｖ is not particularly limited as long as it is at least one element selected from V and Ta, but is preferably Ta.

[0020] Said M ＶＩ is not particularly limited as long as it is at least one element selected from Mo and W, but is preferably W.

[0021] In general formulas (II) to (VII), it is preferable that 0≦a≦6, more preferably 0≦a≦2, even more preferably 0≦a≦0.5, and even more preferably a=0. It is also preferable that −0.05≦v≦0.05, more preferably −0.01≦v≦0.01, and even more preferably v=0. It is also preferable that −0.05≦w≦0.05, more preferably −0.01≦w≦0.01, and even more preferably w=0. It is also preferable that 0<x<0.1, more preferably 0<x<0.08, and even more preferably 0<x≦0.06. It is also preferable that 0<y<0.1, more preferably 0<y≦0.08, and even more preferably 0<y≦0.06. It is also preferable that 0≦p<0.1, more preferably 0≦p≦0.08, and even more preferably 0≦p≦0.06. Furthermore, it is preferable that 0≦q<6, more preferably 0≦q<3, and even more preferably 0≦q<1. It is preferable that 0<r<6, more preferably 0<r<3, and even more preferably 0<r<1. It is preferable that 0<s<6, more preferably 0<s<3, and even more preferably 0<s<1. It is preferable that 0<t<6, more preferably 0<t<3, and even more preferably 0<t<1. It is preferable that 0≦z≦1, more preferably 0≦z≦0.5, and even more preferably 0≦z≦0.2, and particularly preferably z=0.

[0022] <Containment of at least one metal element selected from the group consisting of Mo and Ce> The transition metal composite oxide powder of the present invention may contain at least one metal element selected from the group consisting of Mo and Ce. When at least one metal element selected from the group consisting of Mo and Ce is contained, it is preferably localized on the surface of the transition metal composite oxide particles constituting the powder. More specifically, it is preferable that at least one metal element selected from the group consisting of Mo and Ce is localized and present in greater amounts in the surface region than in the internal region of the transition metal composite oxide particles. Furthermore, by detecting at least one metal element selected from the group consisting of Mo and Ce in inductively coupled plasma atomic emission spectroscopy (ICP-AES) or X-ray fluorescence spectroscopy (XRF) of the transition metal composite oxide powder of the present invention, it is possible to confirm that the transition metal composite oxide powder is localized on the surface of the transition metal composite oxide particles. The lower limit of the amount detectable by inductively coupled plasma atomic emission spectroscopy is typically 0.001% by mass. Both Mo and Ce may be contained on the particle surface of the transition metal composite oxide powder. From the viewpoint of further improving the initial discharge capacity and rate characteristics, it is preferable that Mo be contained.

[0023] The content (mass%) of at least one metal element selected from the group consisting of Mo and Ce in the transition metal composite oxide powder of the present invention, as determined by X-ray fluorescence analysis (XRF), is preferably 0.01 to 2.0. When the content of at least one metal element selected from the group consisting of the metal elements Mo and Ce is within this range, a nonaqueous electrolyte electricity storage device with improved initial discharge capacity and rate characteristics can be obtained. The content (mass%) is preferably 0.01 to 1.7, and from the viewpoint of further improving rate characteristics, the content is more preferably 0.015 to 1.5, even more preferably 0.04 to 1.3, even more preferably 0.07 to 1.25, and particularly preferably 0.2 to 1.1. However, when Mo and Ce are simultaneously contained on the particle surfaces of the transition metal composite oxide powder, the content (mass%) refers to the combined content of the two metal elements.

[0024] As an example, when at least one metal element selected from the group consisting of Mo and Ce is contained, in a cross-sectional analysis of the transition metal composite oxide particles using a scanning transmission electron microscope, it is sufficient that at least one metal element selected from the group consisting of Mo and Ce is contained in a large amount in the so-called near-surface region up to a depth of about 20 nm from the surface of the transition metal composite oxide particles as measured by energy dispersive X-ray spectroscopy. It is preferable that at least one metal element selected from the group consisting of Mo and Ce is detected at a depth of 20 nm from the surface of the transition metal composite oxide particles, while Mo and Ce are not detected at a depth of 100 nm from the surface. In this state, it can be determined that at least one metal element selected from the group consisting of Mo and Ce is localized on the surface of the transition metal composite oxide particles. In other words, when measured by energy dispersive X-ray spectroscopy, it means that the amount is below the amount detected by the measurement. The lower limit of the amount detected by energy dispersive X-ray spectroscopy varies depending on the element and state being measured, but is usually 0.5 atm%. Other examples of surface analysis methods include X-ray photoelectron spectroscopy (XPS) and Auger electron spectroscopy (AES). In the present invention, the form of the at least one metal element selected from the group consisting of Mo and Ce that is localized on the surface of the transition metal composite oxide particles is not particularly limited, and it is sufficient that at least one metal element selected from the group consisting of Mo and Ce is localized on the surface, and the at least one metal element may be in a metallic state or in the form of a metal compound such as a metal oxide.

[0025] <D50> The D50 of the primary particles of the transition metal composite oxide powder of the present invention is an index of the volume median particle size. It means the particle size at which the cumulative volume frequency calculated from the volume fraction determined by laser diffraction / scattering particle size distribution measurement reaches 50% when calculated from the smallest particle size. The measurement method will be explained in the examples below.

[0026] The transition metal composite oxide powder of the present invention may be in the form of primary particles or secondary particles formed by agglomeration of primary particles. When the primary particles made of transition metal composite oxide particles contain secondary particles formed by agglomeration, some of the secondary particles may not form secondary particles and may be in the form of primary particles themselves.

[0027] When the transition metal composite oxide powder of the present invention is in the form of secondary particles, the lower limit of D50 of the secondary particles is preferably 5 μm or more, more preferably 7 μm or more, and even more preferably 9 μm or more, from the viewpoint of improving electrode density. Furthermore, the upper limit of D50 of the secondary particles is preferably 20 μm or less, more preferably 18 μm or less, and even more preferably 14 μm or less.

[0028] In a liquid-based lithium-ion secondary battery of a nonaqueous electrolyte electricity storage device, from the viewpoint of excellent rate characteristics and suppressing the rate of change in electrode thickness during charge and discharge, the lower limit of D50 of the primary particles of the transition metal composite oxide powder of the present invention is 0.25 μm or more, preferably 0.4 μm or more, and more preferably 0.6 μm or more. The upper limit of D50 of the primary particles is 2.8 μm or less, preferably 2.5 μm or less, more preferably 2.3 μm or less, even more preferably 2.2 μm or less, and even more preferably 2 μm or less. The transition metal composite oxide powder may contain primary particles having a size of less than 0.4 μm or may contain primary particles having a size of more than 2.5 μm.

[0029] <D90> From the viewpoint of improving the initial discharge capacity, rate characteristics, and electrode thickness change rate during charge and discharge in a liquid-based lithium-ion secondary battery of a nonaqueous electrolyte storage device, and improving the initial discharge capacity and rate characteristics in an all-solid-state battery, the D90 of the primary particles of the transition metal composite oxide powder of the present invention is preferably 0.8 μm or more, more preferably 1.0 μm or more, and even more preferably 1.2 μm or more. The upper limit of the D90 of the primary particles is preferably 15 μm or less, more preferably 10 μm or less, even more preferably 8 μm or less, even more preferably 5 μm or less, and particularly preferably 3 μm or less. The D90 of the primary particles of the transition metal composite oxide powder refers to the particle size at which the cumulative volume frequency calculated from the volume fraction determined by laser diffraction / scattering particle size distribution measurement is 90% when calculated from the smallest particle size. The measurement method will be described in the Examples below.

[0030] <D10> From the viewpoint of improving the initial discharge capacity, rate characteristics, and electrode thickness change rate during charge and discharge in a liquid-based lithium-ion secondary battery of a nonaqueous electrolyte storage device, and improving the initial discharge capacity and rate characteristics in an all-solid-state battery, the D10 of the primary particles of the transition metal composite oxide powder of the present invention is preferably 0.05 μm or more, more preferably 0.1 μm or more, and even more preferably 0.2 μm or more. The upper limit of the D10 of the primary particles is preferably 1.5 μm or less, more preferably 1.2 μm or less, even more preferably 1.0 μm or less, and even more preferably 0.8 μm or less. The D10 of the primary particles of the transition metal composite oxide powder refers to the particle size at which the cumulative volume frequency calculated from the volume fraction determined by laser diffraction / scattering particle size distribution measurement is 10% from the smallest particle size. The measurement method will be described in the Examples below.

[0031] The logarithm of the primary particles of the transition metal composite oxide powder of the present invention １０ (D ９０ ) -log １０ (D ５０) is preferably less than 0.6, more preferably 0.56 or less, even more preferably 0.53 or less, and even more preferably 0.5 or less, from the viewpoint of being able to suppress the rate of change in electrode thickness during charge and discharge in a lithium ion secondary battery of a nonaqueous electrolyte electricity storage device, and the value calculated by is preferably less than 0.6, more preferably 0.56 or less, even more preferably 0.53 or less, and even more preferably 0.5 or less. The lower limit is preferably 0.03 or more, more preferably 0.08 or more, even more preferably 0.1 or more, and particularly preferably 0.15 or more. By setting the value within this range, the possibility of coarse transition metal composite oxide particles inhibiting contact with the conductive material or ion conductor in the electrode mixture, or of the electrode as a whole being distorted during charge and discharge, thereby increasing the electrode thickness during charge and discharge, is reduced. Therefore, a lithium ion secondary battery of an aqueous electrolyte electricity storage device can be obtained that is excellent in initial discharge capacity and rate characteristics and that has a small rate of change in electrode thickness during charge and discharge. Note that D １０ , D ５０ , D ９０ , log １０ (D ９０ ) -log １０ (D ５０ ) can be adjusted, for example, by controlling the production conditions of the transition metal composite oxide powder. More specifically, it is preferable to adjust it by controlling the firing conditions and crushing treatment conditions when producing the transition metal composite oxide powder.

[0032] Also, log １０ (D ５０ ) is the D of the primary particle ５０ The logarithm of D50 is a logarithm of D50 with a base of 10, and its unit is μm. Therefore, for example, if D50=10 μm, then log １０ (D ５０ ) is 1, and D ５０ If = 1 μm, then log １０ (D ５０ ) is 0. Similarly, the value of log １０ (D １０ ) is the D of the primary particle １０ The logarithm of the logarithm is a logarithm with the base 10, and its unit is μm. １０ (D ９０) is the D of the primary particle ９０ The logarithm is a logarithm with the base 10, and its unit is μm.

[0033] <Specific Surface Area> The specific surface area of ​​the transition metal composite oxide powder of the present invention is the surface area per unit mass when nitrogen is used as an adsorption gas. The measurement method will be explained in the examples below.

[0034] The transition metal composite oxide powder of the present invention has an upper limit of the specific surface area of ​​10 m ２ / g or less, and ２ / g or less is more preferable, and 6.0m ２ / g or less is more preferable, and 4.0m ２ On the other hand, the lower limit of the specific surface area is 1.2 m ２ / g or more, and ２ / g or more, and 1.8m ２ / g or more is more preferable, and 2.0m ２ / g or more is even more preferable, and 2.1m ２ / g or more is particularly preferred, and 2.2m ２ When the content is within the above range, a nonaqueous electrolyte electricity storage device can be provided that is superior in terms of further improving the rate characteristics and further suppressing the rate of change in electrode thickness during charge and discharge.

[0035] The reason why remarkable effects were observed by using zinc niobium oxide in a transition metal composite oxide in which the molar ratio of niobium to zinc and the D50 of the primary particles, which corresponds to 50% cumulative volume in the volume-based particle size distribution measured by laser diffraction scattering, were controlled within appropriate ranges is unclear, but it is thought to be as follows. Generally, negative electrode active materials, such as transition metal composite oxide powders such as zinc niobium oxide, exhibit capacity by absorbing and releasing lithium ions via an electrolyte solution or solid electrolyte. Therefore, the contact area between the negative electrode active material and a non-aqueous electrolyte, such as an electrolyte solution or solid electrolyte, and the diffusion of lithium ions and electrons within the active material particles are extremely important. Furthermore, in electrodes using zinc niobium oxide active materials with low electronic conductivity, volume changes associated with charge and discharge of the active material in the negative electrode composite layer gradually cause the contact with the conductive additive to disappear, resulting in a significant decrease in rate characteristics. By controlling the molar ratio of niobium to zinc and the D50 of the primary particles within appropriate ranges, the transition metal composite oxide of the present invention is believed to be able to suppress the rate of change in electrode thickness during charge and discharge, and to maintain contact with the conductive additive and solid electrolyte in the negative electrode composite layer. Furthermore, by substituting a portion of the zinc and niobium in the zinc niobium oxide with another element, it is believed that the diffusion of lithium ions and electrons within the active material particles is improved. As a result, the niobium oxide of the present invention is superior to the zinc niobium oxides described in Patent Documents 1 and 2, which have a primary particle size of 3 μm or more and which have a large volume change during charge and discharge, and the zinc niobium oxides described in Patent Documents 1 and 2, which have a molar ratio of niobium to zinc that is too large. １／３ Nb ７４／３ O ６２ It is believed that this resulted in battery characteristics that could not be achieved with other elements. Furthermore, if part of the zinc or niobium is replaced with another element, the battery characteristics can be further improved.

[0036] [Method for producing transition metal composite oxide powder of the present invention] An example of a method for producing a transition metal composite oxide powder of the present invention will be described below, divided into a raw material preparation step, a calcination step, a surface treatment step, etc., but the method for producing a transition metal composite oxide powder of the present invention is not limited thereto.

[0037] <Raw Material Preparation Process> First, the starting materials are mixed. An oxide or salt containing Zn and Nb is used as the starting material. Furthermore, when the transition metal composite oxide contains other additive elements, an oxide or salt containing at least one element selected from the group consisting of Zr, Si, Ge, Sn, V, Ta, Al, Ga, Fe, Cr, Mg, Ca, Cu, Bi, Mo, and W is used as the starting material, in addition to the oxide containing Zn and Nb. These are mixed in a stoichiometric ratio to achieve the target composition of the present invention. The salt used is preferably a salt that decomposes at a relatively low melting point to produce an oxide, such as a hydroxide salt, carbonate salt, or nitrate salt. Furthermore, to reduce the primary particle size, it is preferable to use a powder as the starting material having an average primary particle size of 2 μm or less, preferably 0.5 μm or less.

[0038] The method for mixing the raw materials is not particularly limited, and either wet mixing or dry mixing may be used. For example, a Henschel mixer, an ultrasonic disperser, a homomixer, a mortar, a ball mill, a centrifugal ball mill, a planetary ball mill, a vibrating ball mill, an attritor-type high-speed ball mill, a bead mill, a roll mill, etc. may be used.

[0039] <Firing Step> Next, the mixture obtained above is fired. Firing is preferably carried out at a temperature range of 500 to 1250°C, more preferably 700 to 1250°C, and even more preferably 900 to 1250°C. By setting the firing temperature at 1250°C or less, general-purpose equipment can be used. When firing the mixture for a short period of time, it is preferable to prepare the mixed powder constituting the mixture before firing so that the D95 value in the particle size distribution curve measured with a laser diffraction / scattering particle size distribution analyzer is 5 μm or less. Here, D95 refers to the particle size at which the cumulative volume frequency calculated by volume fraction is 95% when calculated from the smallest particle size.

[0040] The calcination method is not particularly limited as long as it can be performed under the above conditions. Usable calcination methods include fixed-bed calcination furnaces, roller hearth calcination furnaces, mesh belt calcination furnaces, fluidized bed calcination furnaces, and rotary kiln calcination furnaces. However, for efficient calcination in a short time, roller hearth calcination furnaces, mesh belt calcination furnaces, and rotary kiln calcination furnaces are preferred. In particular, rotary kiln calcination furnaces are particularly preferred for producing the transition metal composite oxide powder of the present invention because they do not require a container to contain the mixture, can be used to calcinate the mixture while continuously adding it, and can impart a uniform thermal history to the calcined material, thereby enabling the production of a homogeneous oxide.

[0041] <Surface Treatment Step> The transition metal composite oxide obtained above may be subjected to a surface treatment. By localizing at least one metal element selected from the group consisting of Mo and Ce on the surface of the particles constituting the transition metal composite oxide powder of the present invention, when used as a battery anode material, a dense anode layer can be formed and excellent charge rate characteristics can be imparted. In the calcination step, a surface-treated transition metal composite oxide powder of the present invention can be produced by adding a compound containing at least one metal element selected from the group consisting of Mo and Ce (hereinafter, sometimes referred to as a treating agent). However, it is more preferable to produce a surface-treated transition metal composite oxide powder of the present invention by the following surface treatment step. In particular, by adopting the following surface treatment step, it is possible to appropriately and relatively simply bring at least one metal element selected from the group consisting of Mo and Ce into a state where it is present on the surface of the transition metal composite oxide particles.

[0042] There are no particular limitations on the method for mixing the transition metal composite oxide powder as the base material with the compound containing at least one metal element selected from the group consisting of Mo and Ce, and either wet mixing or dry mixing can be used. However, it is preferable to uniformly disperse the compound containing at least one metal element selected from the group consisting of Mo and Ce on the surfaces of the particles constituting the transition metal composite oxide powder as the base material, and in this respect, wet mixing is preferred.

[0043] In wet mixing, the treatment agent and the transition metal composite oxide powder of the substrate are placed in a water or alcohol solvent and mixed in a slurry state. As the alcohol solvent, those with a boiling point of 100°C or less, such as methanol, ethanol, and isopropyl alcohol, are preferred because they are easy to remove. Furthermore, from an industrial perspective, water solvents are preferred because of the ease of recovery and disposal.

[0044] The compound (treatment agent) containing at least one metal element selected from the group consisting of Mo and Ce is not particularly limited, and examples thereof include oxides, phosphates, hydroxides, sulfates, nitrates, fluorides, chlorides, organic compounds, and metal salt compounds such as ammonium salts and phosphates. Specific examples of Mo compounds include molybdenum oxide, molybdenum trioxide, molybdenum trioxide hydrate, molybdenum boride, molybdophosphoric acid, molybdenum disilicide, molybdenum chloride, molybdenum sulfide, molybdenum silicic acid hydrate, sodium molybdenum oxide, molybdenum carbide, molybdenum acetate dimer, lithium molybdate, sodium molybdate, potassium molybdate, calcium molybdate, magnesium molybdate, manganese molybdate, and ammonium molybdate. Among these, molybdenum trioxide, molybdenum trioxide hydrate, molybdenum chloride, molybdenum sulfide, and lithium molybdate are preferred. Examples of Ce compounds include cerium oxide, cerium hydroxide, cerium fluoride, cerium sulfate, cerium nitrate, cerium carbonate, cerium acetate, cerium oxalate, cerium chloride, cerium boride, and cerium phosphate, and among these, cerium sulfate and its hydrates are preferred.

[0045] The amount of the compound containing at least one metal element selected from the group consisting of Mo and Ce may be any amount as long as the amount of the at least one metal element selected from the group consisting of Mo and Ce in the transition metal composite oxide falls within the range of the present invention, but it may be added in a proportion of 0.03 mass% or more, preferably 0.05 mass% or more, relative to the transition metal composite oxide powder of the substrate, and may be added in a proportion of 12 mass% or less, preferably 10 mass% or less, more preferably 8 mass% or less, relative to the transition metal composite oxide powder of the substrate.

[0046] It is preferable to perform heat treatment after the surface treatment. The heat treatment temperature is a temperature at which the at least one metal element selected from the group consisting of Mo and Ce diffuses into at least the surface region of the transition metal composite oxide particles constituting the transition metal composite oxide powder of the substrate, and a temperature at which a significant decrease in specific surface area due to sintering of the transition metal composite oxide of the substrate does not occur. The upper limit of the heat treatment temperature is preferably 700°C or less, more preferably 600°C or less. The lower limit of the heat treatment temperature is preferably 300°C or more, more preferably 400°C or more. The heat treatment time is preferably 0.1 to 8 hours, more preferably 0.5 to 5 hours. The temperature and time at which the at least one metal element selected from the group consisting of Mo and Ce diffuses into at least the surface region of the transition metal composite oxide powder of the substrate should be set appropriately, as the reactivity varies depending on the compound containing the at least one metal element selected from the group consisting of Mo and Ce. The heating method for the heat treatment is not particularly limited. Usable heat treatment furnaces include fixed-bed firing furnaces, roller hearth firing furnaces, mesh belt firing furnaces, fluidized-bed firing furnaces, and rotary kiln firing furnaces. The atmosphere during the heat treatment may be either air or an inert atmosphere such as a nitrogen atmosphere. In particular, when a metal salt compound is used for the surface treatment, air is preferred because it facilitates the removal of anionic species from the particle surface.

[0047] The heat-treated transition metal composite oxide powder obtained as described above is preferably subjected to a crushing treatment as necessary to adjust the specific surface area to the above range. The crushing treatment can be carried out using, for example, a ball mill, and the conditions for the crushing treatment are not particularly limited as long as they allow the specific surface area to be within the above range. In addition to the crushing treatment, classification may also be carried out.

[0048] The transition metal composite oxide powder of the present invention may be granulated and heat-treated to form a powder containing secondary particles formed by aggregation of primary particles. Any method for granulation may be used as long as it can produce secondary particles, but a spray dryer is preferred because it can process large quantities.

[0049] In order to reduce the moisture content of the transition metal composite oxide powder of the present invention, dew point control may be performed during the heat treatment process. If the heat-treated powder is exposed to the atmosphere, moisture from the atmosphere will be adsorbed by the powder. Therefore, it is preferable to handle the powder in a dew point-controlled environment during cooling in the heat treatment furnace and after the heat treatment. The heat-treated powder may be classified as needed to adjust the particles to the desired maximum particle size range. When dew point control is performed during the heat treatment process, it is preferable to seal the transition metal composite oxide powder of the present invention in an aluminum laminate bag or the like and then place it in an environment outside of dew point control. Even under dew point control, pulverization of the heat-treated transition metal composite oxide powder makes it more likely to absorb moisture from the crushed surfaces, increasing the moisture content of the powder. Therefore, it is preferable not to pulverize the heat treatment. Regarding heat treatment conditions, the temperature and holding time within specific ranges significantly affect the secondary particle morphology and surface treatment process. The heat treatment temperature is preferably 450°C or higher, and preferably less than 550°C. This is because a heat treatment temperature exceeding 550°C significantly reduces the specific surface area, significantly degrading battery performance, particularly rate characteristics. The holding time is preferably 1 hour or more, because if the holding time is short, the amount of moisture contained in the powder increases and it is thought that this will also affect the state of the particle surfaces.

[0050] [Active Material] The active material of the present invention contains the transition metal composite oxide powder of the present invention. It may contain one or more substances other than the transition metal composite oxide powder of the present invention. Examples of other substances include carbon materials (pyrolytic carbons, cokes, graphites (artificial graphite, natural graphite, etc.), organic polymer compound combustion bodies, carbon fibers), tin and tin compounds, silicon and silicon compounds, and lithium-containing metal oxides. In particular, lithium-containing metal oxides include Li ４ Ti ５ O １２ Lithium titanate containing the above as its main component is exemplified.

[0051] [Electricity Storage Device] The electricity storage device of the present invention is a device that includes an electrode containing the active substance material of the present invention and stores and releases energy by utilizing intercalation and deintercalation of lithium ions into such an electrode, and examples thereof include a hybrid capacitor and a lithium battery.

[0052] [Hybrid Capacitor] The hybrid capacitor is a device that uses, as a positive electrode, an active material that generates capacitance by physical adsorption, such as activated carbon, similar to the electrode material of an electric double layer capacitor, an active material that generates capacitance by physical adsorption and intercalation / deintercalation, such as graphite, or an active material that generates capacitance by redox, such as a conductive polymer, and uses, as a negative electrode, the active material of the present invention. The active material of the present invention is usually used in the form of an electrode sheet for the hybrid capacitor.

[0053] [Lithium Battery] The lithium battery of the present invention is a general term for lithium primary batteries and lithium secondary batteries. In this specification, the term lithium secondary battery is used to conceptually include so-called non-aqueous electrolyte lithium ion secondary batteries and all-solid-state lithium ion secondary batteries.

[0054] The lithium battery is composed of a positive electrode, a negative electrode, and a non-aqueous electrolyte solution in which an electrolyte salt is dissolved in a non-aqueous solvent, or a solid electrolyte, and the active material of the present invention can be used as an electrode material. The active material of the present invention is usually used in the form of an electrode sheet for the lithium battery. This active material may be used as either a positive electrode active material or a negative electrode active material, but the following description will be given of its use as a negative electrode active material.

[0055] <Negative Electrode> The negative electrode has a negative electrode layer containing a negative electrode active material (the active material of the present invention), a conductive agent, and a binder on one or both sides of a negative electrode current collector. This negative electrode layer is usually in the form of an electrode sheet. In the case of a negative electrode current collector that is porous or the like and has pores, the negative electrode layer contains the negative electrode active material (the active material of the present invention), a conductive agent, and a binder in the pores.

[0056] The conductive agent for the negative electrode is not particularly limited as long as it is an electron-conductive material that does not undergo chemical change. Examples thereof include graphites such as natural graphite (e.g., flake graphite) and artificial graphite, carbon blacks such as acetylene black, ketjen black, channel black, furnace black, lamp black, and thermal black, and carbon nanotubes such as single-phase carbon nanotubes, multi-walled carbon nanotubes (graphite layers in a multi-layered concentric cylindrical shape) (non-fishbone-shaped), cup-stacked carbon nanotubes (fishbone-shaped), nodular carbon nanofibers (non-fishbone structure), and platelet-type carbon nanofibers (playing card-shaped).

[0057] The amount of conductive agent added varies depending on the specific surface area of ​​the active material and the type and combination of conductive agents, and therefore should be optimized. However, it is preferably 0.1% to 10% by mass, and more preferably 0.5% to 5% by mass, in the negative electrode layer. At less than 0.1% by mass, the conductivity of the negative electrode layer cannot be ensured. At more than 10% by mass, the active material ratio decreases, resulting in insufficient discharge capacity of the energy storage device per unit mass and unit volume of the negative electrode layer, making it unsuitable for achieving high capacity. The conductive agent may be added during electrode preparation or by coating the active material itself with the conductive agent. This is because coating with a conductive agent such as carbon fiber can further improve the conductivity of the negative electrode layer.

[0058] Examples of the binder for the negative electrode include polytetrafluoroethylene (PTFE), polyvinylidene fluoride (PVDF), polyvinylpyrrolidone (PVP), styrene-butadiene copolymer (SBR), acrylonitrile-butadiene copolymer (NBR), and carboxymethyl cellulose (CMC).

[0059] The amount of binder added varies depending on the specific surface area of ​​the active material and the type and combination of conductive agents, and therefore should be optimized, but is preferably 0.2% by mass to 15% by mass in the negative electrode layer. From the viewpoint of enhancing binding properties and ensuring the strength of the negative electrode layer, the amount is preferably 0.5% by mass or more, more preferably 1% by mass or more, and even more preferably 2% by mass or more. From the viewpoint of preventing a decrease in the active material ratio and a decrease in the discharge capacity of the power storage device per unit mass and unit volume of the negative electrode layer, the amount is preferably 10% by mass or less, and more preferably 5% by mass or less.

[0060] Examples of the negative electrode current collector include aluminum, stainless steel, nickel, copper, titanium, baked carbon, and those whose surfaces are coated with carbon, nickel, titanium, silver, etc. The surface of these materials may be oxidized, or the surface of the negative electrode current collector may be roughened by surface treatment.

[0061] The negative electrode can be produced by uniformly mixing a negative electrode active material (including the active material of the present invention), a conductive agent, and a binder in a solvent to form a paint, which is then applied to the negative electrode current collector, dried, and compressed. In the case of a negative electrode current collector that is porous or the like and has pores, the paint is pressurized into the pores of the current collector to fill the pores, or the current collector having pores is immersed in the paint to diffuse the pores, and then the paint is dried and compressed.

[0062] As a method for uniformly mixing the negative electrode active material (the active material of the present invention), the conductive agent, and the binder in a solvent to prepare a paint, for example, a kneader of the type in which a stirring rod revolves while rotating on its axis in a kneading container such as a planetary mixer, a twin-screw extrusion kneader, a planetary stirring degassing device, a bead mill, a high-speed rotary mixer, a powder suction continuous dissolution and dispersion device, etc. Alternatively, the manufacturing process may be divided into steps depending on the solid content concentration, and these devices may be used separately.

[0063] Uniform mixing of the negative electrode active material (the active material of the present invention), conductive agent, and binder in a solvent requires optimization, as it varies depending on the specific surface area of ​​the active material, the type of conductive agent, the type of binder, and the combination thereof. However, when using a kneader such as a planetary mixer in which the stirring rod revolves while rotating within a kneading vessel, a twin-screw extrusion kneader, or a planetary stirring and degassing device, it is preferable to divide the manufacturing process into steps based on the solid content concentration, knead the mixture at a high solid content concentration, and then gradually reduce the solid content concentration to adjust the viscosity of the paint. A high solid content concentration is preferably 60% to 90% by mass, more preferably 60% to 80% by mass. A concentration of 60% by mass or more is preferable because shear force can be obtained, and a concentration of 90% by mass or less is preferable because the load on the device is reduced, and a concentration of 80% by mass or less is even more preferable.

[0064] The mixing procedure is not particularly limited, but examples include a method of simultaneously mixing the negative electrode active material, the conductive agent, and the binder in a solvent, a method of previously mixing the conductive agent and the binder in a solvent and then adding and mixing the negative electrode active material, a method of previously preparing a negative electrode active material slurry, a conductive agent slurry, and a binder solution and then mixing them, etc. Among these, in order to achieve uniform dispersion, a method of previously mixing the conductive agent and the binder in a solvent and then adding and mixing the negative electrode active material, and a method of previously preparing a negative electrode active material slurry, a conductive agent slurry, and a binder solution and then mixing them are preferred.

[0065] As the solvent, an organic solvent can be used, and examples of the organic solvent include aprotic organic solvents such as 1-methyl-2-pyrrolidone, dimethylacetamide, and dimethylformamide, used alone or in combination of two or more kinds, and preferably 1-methyl-2-pyrrolidone.

[0066] When an organic solvent is used as the solvent, it is preferable to dissolve the binder in the organic solvent before use.

[0067] <Positive Electrode> The positive electrode has a positive electrode layer containing a positive electrode active material, a conductive agent, and a binder on one or both sides of a positive electrode current collector.

[0068] As the positive electrode active material, a material capable of absorbing and releasing lithium is used, and examples of the active material include composite metal oxides containing cobalt, manganese, and nickel with lithium, and lithium-containing olivine-type phosphates. These positive electrode active materials can be used alone or in combination of two or more. Examples of such composite metal oxides include LiCoO ２ , LiMn ２ O ４ , LiNiO ２ , LiCo １－ｘ Ni ｘ O ２ (0.01<x<1), LiCo １／３ Ni １／３ Mn １／３ O ２ , LiNi １／２ Mn ３／２ O ４ These lithium composite oxides may be partially substituted with other elements, such as by substituting a portion of the cobalt, manganese, or nickel with at least one element such as B, Nb, Sn, Mg, Fe, Ti, Al, Zr, Cr, V, Ga, Zn, Cu, Bi, Mo, or La, or by substituting a portion of the O with S or F, or by coating with a compound containing these other elements. Examples of lithium-containing olivine-type phosphates include LiFePO ４ , LiCoPO ４ , LiNiPO ４ , LiMnPO ４ , LiFe １－ｘ MxPO４ (M is at least one selected from Co, Ni, Mn, Cu, Zn, and Cd, and x is 0≦x≦0.5), etc.

[0069] The conductive agent and binder for the positive electrode may be the same as those for the negative electrode. Examples of the positive electrode current collector include aluminum, stainless steel, nickel, titanium, baked carbon, and aluminum or stainless steel surface-treated with carbon, nickel, titanium, or silver. The surface of these materials may be oxidized, or the positive electrode current collector surface may be roughened by surface treatment.

[0070] <Non-aqueous electrolyte> The non-aqueous electrolyte is a solution of an electrolyte salt dissolved in a non-aqueous solvent. There are no particular limitations on the non-aqueous electrolyte, and various types can be used.

[0071] The electrolyte salt used is one that dissolves in a non-aqueous electrolyte, such as LiPF ６ , LiBF ４ , LiPO ２ F ２ , LiN(SO ２ F) ２ , LiClO ４ Inorganic lithium salts such as LiN(SO ２ CF ３ ) ２ , LiN(SO ２ C ２ F ５ ) ２ , LiCF ３ SO ３ , LiC(SO ２ CF ３ ) ３ , LiPF ４ (CF ３ ) ２ , LiPF ３ (C ２ F ５ ) ３ , LiPF ３ (CF ３ ) ３ , LiPF ３ (iso-C ３ F ７ ) ３ , LiPF ５ (iso-C３ F ７ ) and lithium salts containing chain-like fluorinated alkyl groups such as (CF ２ ) ２ (SO ２ ) ２ NLi, (CF ２ ) ３ (SO ２ ) ２ Examples of the electrolyte salt include lithium salts containing a cyclic fluorinated alkylene chain, such as NLi, and lithium salts having an oxalate complex as the anion, such as lithium bis[oxalate-O,O']borate and lithium difluoro[oxalate-O,O']borate. Among these, a particularly preferred electrolyte salt is LiPF ６ , LiBF ４ , LiPO ２ F ２ , and LiN(SO ２ F) ２ and the most preferred electrolyte salt is LiPF ６ These electrolyte salts may be used singly or in combination of two or more.

[0072] The concentration of all of these electrolyte salts dissolved in the nonaqueous solvent is usually preferably 0.3 M or more, more preferably 0.5 M or more, and even more preferably 0.7 M or more. The upper limit is preferably 2.5 M or less, more preferably 2.0 M or less, and even more preferably 1.5 M or less.

[0073] On the other hand, examples of the non-aqueous solvent include cyclic carbonates, chain carbonates, chain esters, ethers, amides, phosphate esters, sulfones, lactones, nitriles, and S═O bond-containing compounds, and the non-aqueous solvent preferably contains a cyclic carbonate. Note that the term "chain ester" is used as a concept including chain carbonates and chain carboxylic acid esters.

[0074] Examples of the cyclic carbonate include one or more selected from ethylene carbonate (EC), propylene carbonate (PC), 1,2-butylene carbonate, 2,3-butylene carbonate, 4-fluoro-1,3-dioxolan-2-one (FEC), trans- or cis-4,5-difluoro-1,3-dioxolan-2-one (hereinafter, both are collectively referred to as "DFEC"), vinylene carbonate (VC), vinylethylene carbonate (VEC), and 4-ethynyl-1,3-dioxolan-2-one (EEC). , ethylene carbonate, propylene carbonate, 1,2-butylene carbonate, 2,3-butylene carbonate, 4-fluoro-1,3-dioxolan-2-one, and 4-ethynyl-1,3-dioxolan-2-one (EEC) are more preferred from the viewpoint of improving the charge rate characteristics of the electricity storage device and suppressing the amount of gas generation during high-temperature operation, and one or more cyclic carbonates having an alkylene chain selected from propylene carbonate, 1,2-butylene carbonate, and 2,3-butylene carbonate are even more preferred.

[0075] In particular, the concentration of the total electrolyte salt is 0.5M to 2.0M, and the electrolyte salt contains at least LiPF ６ and further comprising 0.001M to 1M LiBF ４ , LiPO ２ F ２ , and LiN(SO ２ F) ２ It is preferable to use a non-aqueous electrolyte containing at least one lithium salt selected from the group consisting of LiPF ６ When the proportion of lithium salts other than the lithium salts in the non-aqueous solvent is 0.001 M or more, the effect of improving the charge rate characteristics of the electricity storage device and suppressing the amount of gas generation during high-temperature operation is likely to be exerted, and when the proportion is 1.0 M or less, there is little concern that the effect of improving the charge rate characteristics of the electricity storage device and suppressing the amount of gas generation during high-temperature operation will be reduced, which is preferable.

[0076] In order to achieve suitable physical properties, the non-aqueous solvents are preferably used in combination, such as a combination of a cyclic carbonate and a chain carbonate, a combination of a cyclic carbonate, a chain carbonate and a lactone, a combination of a cyclic carbonate, a chain carbonate and an ether, a combination of a cyclic carbonate, a chain carbonate and a chain ester, a combination of a cyclic carbonate, a chain carbonate and a nitrile, or a combination of a cyclic carbonate, a chain carbonate and an S═O bond-containing compound.

[0077] Suitable examples of the chain ester include one or more asymmetric chain carbonates selected from methyl ethyl carbonate (MEC), methyl propyl carbonate (MPC), methyl isopropyl carbonate (MIPC), methyl butyl carbonate, and ethyl propyl carbonate; one or more symmetric chain carbonates selected from dimethyl carbonate (DMC), diethyl carbonate (DEC), dipropyl carbonate, and dibutyl carbonate; pivalic acid esters such as methyl pivalate, ethyl pivalate, and propyl pivalate; and one or more chain carboxylic acid esters selected from methyl propionate, ethyl propionate, propyl propionate, methyl acetate, and ethyl acetate (EA).

[0078] <Structure of Lithium Battery> The structure of the lithium battery of the present invention is not particularly limited, and examples include a coin battery having a positive electrode, a negative electrode, and a single-layer or multi-layer separator, and further, a cylindrical battery or a prismatic battery having a positive electrode, a negative electrode, and a roll-shaped separator.

[0079] The separator is an insulating thin film having high ion permeability and a predetermined mechanical strength. Examples include polyethylene, polypropylene, cellulose paper, glass fiber paper, polyethylene terephthalate, and polyimide microporous membranes. Multilayer membranes made by combining two or more types of materials can also be used. The surface of these separators can also be coated with resins such as PVDF, silicone resins, and rubber-based resins, or with particles of metal oxides such as aluminum oxide, silicon dioxide, and magnesium oxide.

[0080] <Negative Electrode Active Material Composition> The negative electrode active material composition of the present invention includes the transition metal composite oxide powder of the present invention and an inorganic solid electrolyte having conductivity for metal ions belonging to Group 1 of the periodic table. The content of the inorganic solid electrolyte in the active material composition is not particularly limited, but may be 1% by mass or more, preferably 5% by mass or more, more preferably 20% by mass or more, and even more preferably 30% by mass or more. A higher content of the inorganic solid electrolyte is preferable because it facilitates contact between the transition metal composite oxide powder and the solid electrolyte. Furthermore, since a too high content of the inorganic solid electrolyte reduces the battery capacity of the all-solid-state secondary battery, the content is preferably 70% by mass or less, and more preferably 60% by mass or less. Generally, a low content of the inorganic solid electrolyte is preferable to increase the battery capacity of the all-solid-state secondary battery. However, a low content of the inorganic solid electrolyte makes it difficult to achieve contact between the transition metal composite oxide powder and the solid electrolyte. By using the transition metal composite oxide powder used in the negative electrode active material composition of the present invention, satisfactory contact between the transition metal composite oxide powder and the solid electrolyte can be achieved even when the content of the inorganic solid electrolyte is low. The transition metal composite oxide powder and inorganic solid electrolyte of the present invention may contain one or more substances other than the transition metal composite oxide powder and inorganic solid electrolyte. Examples of the other substances include carbon materials (pyrolytic carbons, cokes, graphites (artificial graphite, natural graphite, etc.), organic polymer compound combustion bodies, carbon fibers), tin and tin compounds, silicon and silicon compounds, and lithium-containing metal oxides. In particular, lithium-containing metal oxides include Li ４ Ti ５ O １２Lithium titanate containing the above as its main component is exemplified.

[0081] <Periodic Table> The periodic table in this specification refers to a long-period periodic table of elements based on the provisions of IUPAC (International Union of Pure and Applied Chemistry).

[0082] <Solid Electrolyte> A solid electrolyte is a solid electrolyte capable of transferring ions therein. In particular, inorganic solid electrolytes are solid in a steady state and are not usually dissociated or liberated into cations and anions. The inorganic solid electrolyte is not particularly limited as long as it has the conductivity of metal ions belonging to Group 1 of the periodic table, and generally has almost no electronic conductivity. Representative examples of inorganic solid electrolytes include (A) sulfide inorganic solid electrolytes, (B) oxide inorganic solid electrolytes, and (C) chloride inorganic solid electrolytes. In particular, sulfide inorganic solid electrolytes are preferably used because they have high ionic conductivity and can be formed into a dense molded body with few grain boundaries simply by applying pressure at room temperature.

[0083] The sulfide inorganic solid electrolyte may be amorphous glass, crystallized glass, or a crystalline material. Specific examples of the sulfide inorganic solid electrolyte include, but are not limited to, the following combinations: Li ２ S-P ２ S ５ , Li ２ S-P ２ S ５ -Al ２ S ３ , Li ２ S-GeS ２ , Li ２ S-Ga ２ S ３ , Li ２ S-GeS ２ -Ga ２ S ３ , Li ２ S-GeS ２ -P ２ S ５ , Li ２ S-GeS ２ -Sb ２ S ５ , Li ２ S-GeS ２ -Al２ S ３ , Li ２ S-SiS ２ , Li ２ S-Al ２ S ３ , Li ２ S-SiS ２ -Al ２ S ３ , Li ２ S-SiS ２ -P ２ S ５ , Li １０ GeP ２ S １２ .

[0084] Among the above combinations, Li ２ S-P ２ S ５ In addition, as the sulfide inorganic solid electrolyte other than the above, Li ６ P.S. ５ Cl and Li ６ P.S. ５ Argerodite-type solid electrolytes such as Br are also suitable.

[0085] The oxide inorganic solid electrolyte preferably contains oxygen atoms, has ion conductivity of a metal belonging to Group 1 of the periodic table, and has electronic insulation properties.

[0086] Examples of oxide inorganic solid electrolytes include Lithium super ionic conductor (LISICON)-type crystalline structures. ３．５ Zn ０．２５ GeO ４ , La having a perovskite crystal structure ０．５５ Li ０．３５ TiO ３ , LiTi having a NASICON (sodium super ionic conductor) type crystal structure ２ P ３ O １２ , Li having a garnet-type crystal structure ７ La ３ Zr ２ O １２ (LLZ), lithium phosphate (Li３ P.O. ４ ), LiPON, in which some of the oxygen in lithium phosphate is replaced with nitrogen, Li ３ BO ３ -Li ２ SO ４ , Li ２ Alumni ２ O ３ -P ２ O ５ , Li ２ O—SiO ２ , and Li ６ BaLa ２ Ta ２ O １２ Suitable examples include:

[0087] The chloride inorganic solid electrolyte is Li ３ ScCl ６ , LiAlCl ４ , Ln １－Ｘ A Ｘ OCl １－Ｘ (wherein Ln represents any rare earth element, A represents an alkaline earth metal, and X is 0<X<1) and the like are preferred.

[0088] The volume average particle size of the inorganic solid electrolyte is not particularly limited, but is preferably 0.01 μm or more, more preferably 0.1 μm or more, and the upper limit is preferably 100 μm or less, more preferably 50 μm or less.

[0089] Next, the present invention will be explained in more detail with reference to examples and comparative examples, but the present invention is not limited to the following examples and includes various combinations that can be easily inferred from the gist of the invention.

[0090] (Liquid-type lithium-ion secondary battery) [Example 1-1] <Material preparation step> Nb ２ O ５(average particle size 0.2 μm) and ZnO were weighed out to a molar ratio of 4:1 and mixed. This mixed powder was subjected to a calcination treatment at 1200°C for 12 hours. Powder X-ray diffraction measurement was performed on the obtained calcined powder sample under conditions of a sampling interval of 0.01° and a scan rate of 2° / min. No peaks derived from the starting materials were observed, confirming that the reaction had proceeded completely. The results of crystal structure analysis of the synthesized sample and X-ray fluorescence analysis (XRF) using an X-ray fluorescence analyzer (manufactured by SII Technology Inc., product name "SPS5100") confirmed that the synthesized sample was the target transition metal composite oxide (ZnNb ８ O ２１ ) was confirmed.

[0091] <Crushing Treatment Step> Zirconia beads of φ2.0 mm were added to the obtained fired powder sample, and crushing treatment was carried out using a ball mill to produce the transition metal composite oxide powder of Example 1-1 in which the particle size distribution of the primary particles was adjusted.

[0092] [Examples 1-2 to 1-8] Transition metal composite oxide powders according to Examples 1-2 to 1-8 were produced in the same manner as in Example 1-1, except that the raw materials and mixing ratios in the raw material preparation step were changed to obtain the composition formulas shown in Table 1.

[0093] [Examples 1-9 to 1-26] The same procedure as in Example 1-2 was carried out to produce transition metal composite oxide powders according to Examples 1-9 to 1-26, except that one of the following oxides was added in the raw material preparation step, so that the composition formula shown in Table 2 was achieved. ２ O ３ (Examples 1-9 to 1-11, and 1-25), TiO ２ (Examples 1-14 to 1-15, 1-19, and 1-26), Fe ２ O ３ (Examples 1-12), Ga ２ O ３ (Examples 1-13), ZrO ２ (Examples 1-16), GeO ２ (Examples 1-17), SiO ２(Example 1-18), CuO (Example 1-20), MgO (Example 1-21), Ta ２ O ５ (Examples 1-22), V ２ O ５ (Examples 1-23), WO ３ (Example 1-24 to Example 1-26) were used.

[0094] [Comparative Example 1-1 and Comparative Example 1-2] Nb ２ O ５ and ZnO were weighed and mixed to obtain the composition shown in Table 1. This mixed powder was simply subjected to a firing treatment at 1200°C for 12 hours, and transition metal composite oxide powders according to Comparative Examples 1-1 and 1-2 were produced in which the crushing treatment step was not carried out as in Patent Document 1.

[0095] [Comparative Example 1-3] Nb ２ O ５ A transition metal composite oxide powder according to Comparative Example 1-3 was produced in the same manner as in Example 1-1, except that the molar ratio of ZnO to ZnO was changed to 37:1.

[0096] [Measurement of Powder Physical Properties] Various physical properties of the transition metal composite oxide powders of each Example and Comparative Example were measured as follows.

[0097] <Measurement of specific surface area> The specific surface area (m ２ / g) was measured using a fully automatic BET specific surface area measuring device (manufactured by Mountec Co., Ltd., product name "Macsorb HM model-1208"), and nitrogen gas was used as the adsorption gas. 0.5 g of the measurement sample powder was weighed out and placed in a φ12 standard cell (HM1201-031), and after degassing under vacuum at 100°C for 0.5 hours, it was measured by the BET single-point method.

[0098] <Calculation of D10, D50, and D90: Dry Laser Diffraction Scattering Method> The D50 of the primary particles of the transition metal composite oxide powder in each Example and Comparative Example was calculated from a particle size distribution curve measured using a laser diffraction / scattering particle size distribution analyzer (Microtrac MT3300EXII, manufactured by Nikkiso Co., Ltd.). 50 mg of a sample was placed in a container containing 50 ml of ion-exchanged water as a measurement solvent, and the measurement solvent was added until the transmittance of the slurry fell within the appropriate range (the range displayed by the green bar on the device), and particle size distribution measurement was performed. From the obtained particle size distribution curve, the D10, D50, and D90 of the primary particles of the powder were calculated. In addition, log １０ (D ９０ ) -log １０ (D ５０ ) was calculated.

[0099] [Evaluation of Battery Characteristics] Coin-type batteries were fabricated using the transition metal composite oxide powders of each Example and Comparative Example, and their battery characteristics were evaluated. The evaluation results are shown in Tables 1 and 2.

[0100] <Preparation of Negative Electrode Sheet> A negative electrode sheet was prepared as follows in a room maintained at a room temperature of 25°C and a dew point of −20°C or lower. The transition metal composite oxide powder of each Example and Comparative Example was removed from an aluminum laminate bag in a room maintained at a temperature of 25°C and a dew point of −20°C or lower. A coating material was prepared by mixing 85% by mass of the removed transition metal composite oxide powder of each Example and Comparative Example as an active material, 10% by mass of acetylene black as a conductive agent, and 5% by mass of polyvinylidene fluoride as a binder. The obtained coating material was applied to aluminum foil and dried to prepare a single-sided negative electrode sheet for use in a coin battery described below.

[0101] <Preparation of Electrolyte> The electrolyte used in the battery for characteristic evaluation was prepared as follows: In an argon glove box controlled at a temperature of 25°C and a dew point of -70°C or less, a non-aqueous solvent of ethylene carbonate (EC):dimethyl carbonate (DMC) = 1:2 (volume ratio) was prepared, and LiPF 6 was added as an electrolyte salt to the non-aqueous solvent. ６ was dissolved to a concentration of 1 M to prepare an electrolyte solution for a coin battery, which will be described later.

[0102] <Preparation of Coin Battery> The negative electrode single-sided sheet prepared by the method described above was punched into a circle with a diameter of 14 mm, and ２ An evaluation electrode was prepared by pressing the electrode at a pressure of 1000 kJ / cm2 and then vacuum drying at 120° C. for 5 hours. The evaluation electrode was placed opposite metallic lithium (molded into a circle with a thickness of 0.5 mm and a diameter of 16 mm) via glass filters (one each of GA-100 manufactured by ADVANTEC and GF / C manufactured by Whatman), and the nonaqueous electrolyte prepared by the method described above in <Preparation of Electrolyte> was added and sealed to prepare a 2032-type coin battery.

[0103] <Initial Battery Characteristics: Initial Discharge Capacity> A coin battery prepared by the method described above in <Preparation of Coin Battery> was placed in a thermostatic chamber at 25°C and charged at 0.2 mA / cm in the direction in which Li was absorbed into the evaluation electrode. ２ The battery was charged to 1 V at a current density of 0.05 mA / cm ２ After constant current and constant voltage charging was performed until the current density reached 0.2 mA / cm ２ The battery was subjected to constant current discharge at a current density of 0.1 V to 3 V. The obtained discharge capacity (mAh) was divided by the mass of the transition metal composite oxide to determine the initial discharge capacity (mAh / g).

[0104] <Measurement of 10C Rate Charge / Discharge Rate> The battery was charged to 1 V at a current equivalent to 10C of the initial discharge capacity, and then subjected to constant-current / constant-voltage charging at 1 V until the charging current reached a current density of 0.05C. This was followed by constant-current discharging at 10C to 3 V. The 10C rate charge rate (%) was calculated by dividing the capacity obtained from the 10C constant-current charge by the initial discharge capacity, and the 10C rate discharge rate (%) was calculated by dividing the capacity obtained from the 10C constant-current discharge by the initial discharge capacity. The results are shown in Tables 1 and 2. If a transition metal composite oxide has high 10C rate characteristics, when it is used as an electrode material for an energy storage device, improved discharge rate characteristics of the energy storage device can be expected. The "C" in 1C refers to the current value during charging and discharging. For example, 1C refers to the current value at which the theoretical capacity can be fully discharged (or fully charged) in 1 / 1 hour, while 0.1C refers to the current value at which the theoretical capacity can be fully discharged (or fully charged) in 1 / 0.1 hour.

[0105] <Measurement of electrode thickness change rate due to charge and discharge> A coin battery prepared by the method described above in <Preparation of coin battery> was placed in a thermostatic chamber at 25°C and charged at 0.2 mA / cm ２ The battery was charged to 0.8 V at a current density of 0.05 mA / cm. ２ After constant current and constant voltage charging was performed until the current density reached 0.2 mA / cm ２ A constant current discharge was performed by discharging the battery to 2 V at a current density of 0.2 mA / cm. ２ The battery was charged to 0.8 V at a current density of 0.05 mA / cm. ２ After constant-current, constant-voltage charging (charging until a current density of 0.8 V was reached), the coin battery was disassembled, and the charged negative electrode sheet was removed and measured for thickness. The thickness of the negative electrode sheet after charging to 0.8 V was divided by the thickness of the negative electrode sheet before fabrication of the coin battery to calculate the rate of change in electrode thickness during charge and discharge. The results are shown in Tables 1 and 2.

[0106]

[0107]

[0108] <Evaluation Results> D50 of primary particles and molar ratio M of niobium to zinc Ｎｂ / M Ｚｎ The electrodes using the transition metal composite oxide powders of Examples 1-1 to 1-26 in which the particle size (D50) was controlled within a certain range were compared with Comparative Examples 1-1 and 1-2, which were electrodes using transition metal composite oxide powders having a particle size (D50) of 3 μm or more as described in Patent Document 1, and the molar ratio M Nb / M Zn It was found that the electrode had a smaller thickness change rate, a better 10C rate charge rate and a better 10C rate discharge rate, and better rate characteristics than Comparative Example 1-3, which was an electrode using a transition metal composite oxide powder with a molecular weight of 74.

[0109] [Example 1-27] <Surface Treatment Step> Ion-exchanged water was added to the transition metal composite oxide of Example 1-4 so that the solid content concentration of the slurry was 30 mass %, and the mixture was stirred to disintegrate the particles. ２ MoO ４ ) was added at 0.8% by mass to 100 g of the crushed fired powder to prepare a mixed slurry. This mixed slurry was mixed for 3 hours using a paint shaker, dried at a temperature of 100°C, and then heat-treated for 1 hour at 500°C using a muffle furnace to produce the transition metal composite oxide powder of Example 1-27. A secondary battery of Example 1-27 was fabricated in the same manner as in Example 1-1, except that the obtained transition metal composite oxide was used, and the battery characteristics of the secondary battery of Example 1-27 were evaluated. The results are shown in Table 3.

[0110]

[0111] (All-Solid State Secondary Battery) [Example 2-1] In a glove box under an argon atmosphere, the transition metal composite oxide and sulfide solid electrolyte Li ６ P.S. ５ Cl powder (volume average particle size measured using a laser diffraction / scattering particle size distribution analyzer: 1 μm) and a conductive agent were added to a transition metal composite oxide: Li ６ P.S. ５ The materials were weighed out so as to have a mass ratio of Cl:conductive agent = 60:40:6, and stirred and mixed in an agate mortar and a planetary ball mill to obtain a negative electrode active material composition of Example 2-1. The obtained negative electrode active material composition was pressed (360 MPa) at room temperature for 10 minutes to produce pellets (molded bodies) with a diameter of 10 mm and a thickness of approximately 0.7 mm. A pellet-shaped electrode containing this negative electrode active material composition and a pellet-shaped solid electrolyte layer (Li ２ S:P ２ S ５ An all-solid-state secondary battery was fabricated by stacking a lithium-indium alloy foil (LPS glass with a molar ratio of 75:25) and a lithium-indium alloy foil as a counter electrode in this order and sandwiching the stack between stainless steel current collectors. The battery characteristics of the resulting all-solid-state secondary battery were evaluated. The evaluation results are shown in Table 4.

[0112] Examples 2-2 to 2-5 All solid state secondary batteries according to Examples 2-2 to 2-5 were fabricated in the same manner as in Example 2-1, except that the transition metal composite oxides were changed to those of Examples 1-4, 1-5, 1-10, and 1-27.

[0113] The battery characteristics of the all-solid-state secondary batteries according to Examples 2-1 to 2-5 were evaluated. The evaluation results are shown in Table 4.

[0114] Comparative Examples 2-1 and 2-2 All-solid-state secondary batteries according to Comparative Examples 2-1 and 2-2 were fabricated in the same manner as in Example 2-1, except that the transition metal composite oxides were changed to those of Comparative Examples 1-1 and 1-3.

[0115] The battery characteristics of the all-solid-state secondary batteries according to Comparative Examples 2-1 and 2-2 were evaluated. The evaluation results are shown in Table 4.

[0116] <Measurement of 0.4C Charge / Discharge Rate Characteristics> In a thermostatic chamber at 25°C, the all-solid-state secondary battery prepared by the above method was charged to 0.5V at a current equivalent to 0.05C of the theoretical capacity of the transition metal composite oxide, with charging in the direction in which Li was absorbed into the evaluation electrode. Further, constant current / constant voltage charging was performed in which charging was performed at 0.5V until the charging current reached a current equivalent to 0.01C. The initial charge capacity (mAh / g) was calculated by dividing the charge capacity (mAh) by the mass of the transition metal composite oxide. Subsequently, a constant current discharge was performed in which the battery was discharged to 2V at a current equivalent to 0.05C. The initial discharge capacity (mAh / g) was calculated by dividing the discharge capacity (mAh) by the mass of the transition metal composite oxide. Next, the battery was charged to 0.5V at a current equivalent to 0.4C of the theoretical capacity of the transition metal composite oxide, and the 0.4C charge capacity was calculated. The 0.4C rate charge rate (%) was calculated by dividing the 0.4C charge capacity by the initial charge capacity. Thereafter, the battery was discharged to 2 V at a current equivalent to 0.4 C of the theoretical capacity of the transition metal composite oxide, and the 0.4 C discharge capacity was determined. The 0.4 C discharge capacity was divided by the initial discharge capacity to calculate the 0.4 C rate discharge ratio (%).

[0117]

[0118] <Evaluation Results> In all-solid-state batteries, the D50 of the primary particles and the molar ratio M of niobium to zinc Ｎｂ / M ＺｎIt was found that the electrodes using the transition metal composite oxide powders of Examples 2-1 to 2-4, in which the content of the transition metal composite oxide powder was controlled within a certain range, and the electrode using the surface-treated transition metal composite oxide powder of Example 2-5, were excellent in initial discharge capacity and 0.4 C rate characteristics. It was also found that the 0.4 C rate characteristics were further improved by performing the surface treatment.

[0119] The transition metal composite oxide powder obtained by the present invention is useful as an electrode active material for lithium-ion batteries because it exhibits a small change in electrode thickness during charge and discharge and improves rate characteristics. Energy storage devices using this transition metal composite oxide powder as an electrode active material are useful as secondary batteries for driving or backing up various devices, such as automobiles and electronic devices, and for storing power overnight in homes and offices. Providing electrode materials for lithium-ion batteries, such as nonaqueous electrolyte secondary batteries, to society can contribute to the achievement of Goal 12 (Ensure sustainable consumption and production patterns), Goal 3 (Ensure healthy lives and promote well-being for all at all ages), Goal 7 (Ensure access to affordable, reliable, sustainable, and modern energy for all), and Goal 11 (Make cities and human settlements inclusive, safe, resilient, and sustainable) out of the 17 Sustainable Development Goals (SDGs) established by the United Nations.

Claims

1. A transition metal composite oxide containing at least zinc and niobium, wherein the molar ratio of niobium to zinc is M Nb / M Zn 8≦M Nb / M Zn ≦40, and D50 of primary particles corresponding to a volume cumulative 50% in a volume-based particle size distribution measured by a laser diffraction scattering method is 0.25 μm or more and 2.8 μm or less.

2. The transition metal composite oxide powder according to claim 1, which satisfies the following formula (I): log １０ (D ９０ ) -log １０ (D ５０ ) < 0.6 (I) (Note that D ５０ D indicates the particle size at the point where the cumulative volume distribution of the particle size of the primary particles is 50% in the particle size distribution, ９０ indicates the particle size at the point where the cumulative volume distribution of the particle size of primary particles is 90% in the particle size distribution.) 3. The specific surface area of ​​the transition metal composite oxide powder is 1.2 m ２ / g or more 10m ２ The transition metal composite oxide powder according to claim 1, wherein the transition metal composite oxide powder has a molecular weight of 1000 or less.

4. The transition metal composite oxide is ZnNb ８ O ２１ , Zn ２ Nb ３４ O ８７ , ZnNb ２０ O ５１ , ZnNb ４０ O １０１ The transition metal composite oxide powder according to claim 1, which satisfies any one of the following general formulas (II) to (VII). a Zinc １－ｘ M ＩＩＩ １．５ｘ＋ｖ Nb １４－０．５ｘ＋ｖ O ３６±ｚ (II) A a Zinc １－ｙ M ＩＶ ３ｙ＋ｗ Nb １４－２ｙ＋ｗ O ３６±ｚ (III) A a Zinc １－ｐ M ＩＩ ｐ＋ｖ Nb １４－ｑ M Ｖ ｑ＋ｗ O ３６±ｚ (IV) A a ZnM ＩＩ ０．２５ｒ＋ｗ Nb １４－ｒ M ＶＩ ０．７５ｒ＋ｗ O ３６±ｚ (V) A a ZnM ＩＩＩ ０．３３ｓ＋ｗ Nb １４－ｓ M ＶＩ ０．６７ｓ＋ｗ O ３６±ｚ (VI) A a ZnM ＩＶ ０．５ｔ＋ｗ Nb １４－ｔ M ＶＩ ０．５ｔ＋ｗ O ３６±ｚ (VII) (wherein A is at least one element selected from Li and Na, and M ＩＩ are each independently at least one divalent metal element selected from the group consisting of Mg, Ca, and Cu, and M ＩＩＩ are each independently at least one element selected from Al, Ga, Fe, and Cr; M ＩＶ are each independently at least one element selected from Ti, Zr, Ge, and Sn; M Ｖ are each independently at least one pentavalent metal element selected from the group consisting of V and Ta, M ＶＩ is at least one hexavalent metallic element selected from the group consisting of Mo and W, and 0≦a≦6, −0.05≦v≦0.05, −0.05≦w≦0.05, 0<x<0.1, 0<y<0.1, 0≦p<0.1, 0≦q<6, 0<r<6, 0<s<6, 0<t<6, 0≦z≦1) 5. An electrode for a non-aqueous electrolyte electricity storage device, comprising the transition metal composite oxide powder according to any one of claims 1 to 4 as an active material.

6. A negative electrode active material composition for a non-aqueous electrolyte storage device, comprising the transition metal composite oxide powder according to any one of claims 1 to 4 and an inorganic solid electrolyte.

7. A non-aqueous electrolyte electricity storage device comprising the electrode according to claim 5.

8. An all-solid-state secondary battery comprising a positive electrode layer, a negative electrode layer and a solid electrolyte layer, the negative electrode layer being a layer containing the negative electrode active material composition according to claim 6.