JP2010123401A - Electrode material for nonaqueous electrolyte secondary battery, electrode for nonaqueous electrolyte secondary battery, and nonaqueous electrolyte secondary battery using it - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an electrode material for a nonaqueous electrolyte secondary battery with high discharge capacity and excellent cycle characteristics, and an electrode for a nonaqueous electrolyte secondary battery using the same, as well as a nonaqueous electrolyte secondary battery using the same. <P>SOLUTION: The electrode material for a nonaqueous electrolyte secondary battery contains TiO<SB>2</SB>(B) and/or its element substitute, and satisfies following requirements (1), (2). (1) When a half-value width of a diffraction peak 'a' in which a diffraction angle 2θ in powder X-ray diffraction measurement using CuKα<SB>1</SB>rays exists around 22 to 27° is FWHMa, an FWHMa value is to be 0.6 or more. (2) When a half-value width of a diffraction peak b in which a diffraction angle 2θ in powder X-ray diffraction measurement using CuKα<SB>1</SB>rays exists around 43.5° is FWHMb, an X-ray half-width value ratio XFab value stipulated in a formula (1) below is to be 1 or less. Formula (1): XFab value=FWHMb/FWHMa. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to an electrode material for a nonaqueous electrolyte secondary battery, an electrode for a nonaqueous electrolyte secondary battery, and a nonaqueous electrolyte secondary battery using the same.

  In recent years, there has been a demand for large-sized secondary batteries as power sources for electric vehicles and road labeling, and in particular, non-aqueous solvent lithium secondary batteries with higher energy density compared to nickel-cadmium and nickel-hydrogen batteries. Has attracted attention.

As a negative electrode material for a lithium secondary battery, graphite and the like have been studied so far. Graphite has been used because of its excellent cycle characteristics, small electrode expansion, and low cost. However, a negative electrode material made of graphite has a problem of low high input / output characteristics, which is one of the important characteristics of large secondary batteries. Therefore, in recent years, lithium titanate having a spinel structure excellent in input / output characteristics (hereinafter sometimes abbreviated as “Li ₄ Ti ₅ O ₁₂ ”, etc.) has been studied in place of the graphite negative electrode. In particular, since lithium titanate is excellent in rate characteristics (input / output characteristics) and cycle characteristics, many studies have been made as negative electrodes. However, the theoretical capacity of lithium titanate is 175 mAh / g, which is smaller than the theoretical capacity of 372 mAh / g of the current graphite-based negative electrode, and the development of a higher capacity, higher input / output titanium oxide negative electrode material is desired. ing.

Under these circumstances, Non-Patent Document 1 discloses a TiO ₂ (B) negative electrode material that is a titanium oxide having a layered structure by subjecting anatase-type titanium oxide particles to hydrothermal treatment in a sodium hydroxide aqueous solution and then ion exchange. It is described that a negative electrode material having excellent rate characteristics can be obtained as a powder.

In Patent Document 1, as in Non-Patent Document 1, anatase-type titanium oxide particles are subjected to sodium hydroxide hydrothermal treatment and then ion-exchanged, or TiO ₂ particles are mixed with cesium carbonate or potassium nitrate and fired. Thus, it is described that a negative electrode material powder having a TiO ₂ (B) structure is obtained and a negative electrode material having excellent rate characteristics is obtained.

In Patent Document 2, TiO ₂ particles are mixed with cesium carbonate or potassium nitrate and fired to obtain a TiO ₂ (B) negative electrode material powder having an isotropic shape of micron size and excellent initial efficiency. It is described that a negative electrode material is obtained.

G. Armstrong and P.M. G. Bruce, Electrochem. Solid-State Lett. 9, A139-A143 (2006) WO2006 / 033069 JP 2008-117625 A

As mentioned above, due to the recent need for higher input / output for batteries, utilization of titanium oxide-based negative electrode materials with high capacity and high input / output is desired. The titanium oxide negative electrode material having a simple layered structure has a problem that the developed capacity is small relative to the theoretical capacity, and the cycle characteristics are liable to deteriorate. Therefore, for example, in order to further increase the capacity of the lithium secondary battery, improve the cycle characteristics, etc., there is a strong demand for a device for improving the efficiency of lithium ion migration in the titanium oxide particles.

However, in the electrode material using TiO ₂ (B) described in the above-mentioned known document, the characteristics of the battery, in particular, the discharge capacity is improved by suppressing the crystallite growth in a specific axial direction as in the present invention. It was not considered to make it. For example, in TiO ₂ (B) described in Non-Patent Document 1, as can be seen from the described XRD chart, the suppression of crystallite growth in a specific axial direction is not sufficient.

Further, TiO ₂ (B) described in Patent Document 1 has an insufficient discharge capacity (see Comparative Example 3 described later). In the electrode using TiO ₂ (B), it is considered that the suppression of crystallite growth in a specific axial direction is not necessarily sufficient.

Further, TiO ₂ (B) described in Patent Document 2 has a problem that the discharge capacity is insufficient. As can be seen from the described XRD pattern, the peak due to the (110) plane is sharp, and the suppression of crystallite growth in a specific axial direction is not sufficient.

  The present invention has been made in view of the above, and an electrode material for a non-aqueous electrolyte secondary battery that can provide a non-aqueous electrolyte secondary battery having a high discharge capacity and excellent cycle characteristics, and a non-aqueous electrolyte using the same It aims at providing the electrode for secondary batteries, and the nonaqueous electrolyte secondary battery using these.

  As a result of intensive studies on specific titanium oxides, the present inventors have reduced the lithium ion diffusion distance by reducing the crystallite growth in the specific axial direction of the titanium oxide particles, thereby reducing the discharge capacity and cycle. A titanium oxide with good characteristics was found and the present invention was completed.

That is, the gist of the present invention is as follows.
(1) An electrode material for TiO ₂ (B) and / or an element substitution product thereof, which satisfies the following requirements (A) and (B): A nonaqueous electrolyte secondary battery electrode material.
(A) The FWHMa value is 0.6 or more when the half-value width of the diffraction peak a having a diffraction angle 2θ in the vicinity of 22 to 27 ° in powder X-ray diffraction measurement using CuKα ₁ line is FWHMa.
(B) X defined by the following formula (1) when the half-value width of the diffraction peak b where the diffraction angle 2θ exists in the vicinity of 43.5 ° in the powder X-ray diffraction measurement using CuKα ₁ line is FWHMb The line half width ratio XFab value is 1 or less.
XFab value = FWHMb / FWHMa (1)
(2) The electrode material for a nonaqueous electrolyte secondary battery according to (1), wherein the following requirement (c) is satisfied.
(C) Using an electrode material containing TiO ₂ (B) and / or its element substitution product, a diffraction peak a having a diffraction angle 2θ in the vicinity of 22 to 27 ° in powder X-ray diffraction measurement using CuKα ₁ line When the area is Aa and the area of the diffraction peak b existing in the vicinity of 43.5 ° is Ab, the X-ray peak area ratio XAab value defined by the following formula (2) is 0.27 or less.
XAab value = Ab / Aa (2)
(3) An electrode for a nonaqueous electrolyte secondary battery comprising the electrode material according to (1) or (2) as an electrode active material.
(4) A nonaqueous electrolyte secondary battery comprising a positive electrode and a negative electrode capable of inserting and extracting lithium ions and an electrolyte, wherein the electrode is the electrode for a nonaqueous electrolyte secondary battery according to (3). Non-aqueous electrolyte secondary battery.

  According to the present invention, it is possible to stably and efficiently realize a high-performance nonaqueous electrolyte secondary battery having a high discharge capacity, high initial discharge efficiency during cycles and high cycle characteristics, and excellent cycle characteristics.

  Hereinafter, the present invention will be described in detail, but the present invention is not limited to the following description, and can be arbitrarily modified and implemented without departing from the gist of the present invention.

[1] Electrode Material for Nonaqueous Electrolyte Secondary Battery The electrode material for nonaqueous secondary battery of the present invention is an electrode material containing TiO ₂ (B) and / or an element substitution product thereof, and has the following requirements ( ) And (b). An electrode material for a non-aqueous electrolyte secondary battery.
(A) The FWHMa value is 0.6 or more when the half-value width of the diffraction peak a having a diffraction angle 2θ in the vicinity of 22 to 27 ° in powder X-ray diffraction measurement using CuKα ₁ line is FWHMa.
(B) X defined by the following formula (1) when the half-value width of the diffraction peak b where the diffraction angle 2θ exists in the vicinity of 43.5 ° in the powder X-ray diffraction measurement using CuKα ₁ line is FWHMb The line half width ratio XFab value is 1 or less.
XFab value = FWHMb / FWHMa (1)

<TiO ₂ (B)>
In the present invention, “TiO ₂ (B)” means TiO ₂ having a crystal structure belonging to the space group C2 / m, and TiO ₂ (B) is a kind of TiO ₂ having a layered structure. Moreover, sometimes referred to as beta-TiO _2. TiO ₂ (B) has diffraction peaks in the vicinity of 14.2 °, 15.2 °, 24.9 °, and 28.6 ° in the X-ray diffraction pattern of CuKα.

<Element substitution of TiO ₂ (B)>
The “element-substituted product of TiO ₂ (B)” in the present invention refers to a compound in which Ti is partially substituted with another element M, and is composed of at least Ti, O, and element M, and has a B phase structure. It is what has. Here, the “B phase structure” refers to a similar crystal structure having an atomic arrangement similar to that of TiO ₂ (B), and includes those whose space group is changed to other than C2 / m.

  “Atomic ratio M / Ti of element Ti and element M” defined by the following method is usually 0.01 or more, preferably 0.03 or more, more preferably 0.05 or more, and particularly preferably 0.08 or more. In addition, it is usually 0.5 or less, preferably 0.45 or less, more preferably 0.40 or less, and particularly preferably 0.35 or less.

  The atomic ratio M / Ti of the electrode material of the present invention is determined from the following energy dispersive X-ray analysis (EDX), induction plasma emission spectroscopic analysis (ICP-AES), atomic absorption analysis, etc., and is defined as follows: Is done. It is preferable if the value measured by any one of them is within the above range.

[Method to obtain from EDX measurement]
Using an energy dispersive X-ray analyzer (for example, “NORAN VANTAGE” manufactured by Thermo Fisher Scientific), the electrode material of the present invention is placed on a sample stage, and a peak corresponding to the element M detected at an acceleration voltage of 20 KeV ( For example, the ratio of the element M and the ratio of the Ti element are calculated from the peak (Ti-Kα) corresponding to the Ti element (Na-Kα, K-Kα, Cs-Lα, Rb-Lα), and the atomic ratio M / Ti is calculated. Ask. At this time, when a plurality of elements M are detected, the ratios of the respective elements are calculated and added to obtain the atomic ratio M / Ti as the ratio of the elements M.

[Method determined from ICP-AES measurement and atomic absorption analysis]
(Inductive plasma emission spectroscopy)
As the induction plasma emission spectroscopic measurement, ICP-AES measurement is performed using an inductively coupled plasma emission spectroscopic analyzer (for example, “Utima 2C” manufactured by JOBIN YVON). Here, as a pretreatment for measurement, the anode material powder is added to sulfuric acid for decomposition, then nitric acid is added for thermal decomposition, hydrogen peroxide is further added for thermal decomposition, and the concentration is adjusted and used as a measurement solution.

(Atomic absorption spectrometry)
As atomic absorption spectrometry, atomic absorption spectrometry is performed using an atomic absorption spectrophotometer (“SpectraAA 220” manufactured by Varian Technologies Japan Limited) using a measurement solution that has been subjected to the same pretreatment as ICP measurement.

  From the peak detected using the above-mentioned ICP-AES measurement or atomic absorption spectrometry, the concentration of element M or Ti element is calculated using a calibration curve, and the atomic ratio M / Ti is obtained. At this time, when a plurality of elements M are detected, the ratios of the respective elements are calculated and added to obtain the atomic ratio M / Ti as the ratio of the elements M.

<Element M>
The element M is not particularly limited, but H, P, B, Zr, Hf, V, Nb or Ta is preferable. Here, the “element M” in the present invention is an element present in the titanium oxide, and includes, for example, elements such as salts (NaCl, KCl, etc.) adhering to the titanium oxide surface. I can't. The salt adhering to the titanium oxide surface can be easily removed by washing in an aqueous solution, for example.

Here, the half width FWHMa value of the present invention will be described.
The half-value width FWHMa value can be determined by using an X-ray diffraction measurement method, and in the powder X-ray diffraction measurement using CuKα ₁ line, the half-value width of a diffraction peak a having a diffraction angle 2θ of around 22 to 27 °. Is defined as FWHMa. Here, the diffraction peak a indicates a peak having the maximum intensity among peaks appearing in the vicinity of 22 to 27 °.

Next, the half width ratio XFab value of the present invention will be described.
The half-value width ratio XFab value can be determined using X-ray diffraction measurement, and the half-value width of diffraction peak a having a diffraction angle 2θ of around 22 to 27 ° in powder X-ray diffraction measurement using CuKα ₁ line. Where FWHMMa is the full width at half maximum of the diffraction peak b existing in the vicinity of 43.5 °, and the X-ray half width ratio XFab value is defined by the following formula (1). The diffraction peak b indicates a peak having the maximum intensity in the range of 43.2 to 44.2, and the value derived from the CuKα ₁ line is used for FWHMb. When the diffraction peak b overlaps with other peaks, FWHMb needs to be obtained by peak separation analysis.
XFab value = FWHMb / FWHMMa (1)

Next, the X peak area ratio XAab value of the present invention will be described.
The X peak area ratio can be determined using X-ray diffraction measurement, and the area of the diffraction peak a having a diffraction angle 2θ in the vicinity of 22 to 27 ° in powder X-ray diffraction measurement using the XAab value CuKα ₁ line is defined as Aa The X-ray peak area ratio XAab value is defined as the following formula (2), where Ab is the area of the diffraction peak present near 43.5 °.
XAab value = Ab / Aa (2)

<X-ray diffraction measurement>
As an X-ray diffraction measurement, for example, an electrode material powder sample is packed in a glass sample holder and set on an irradiation surface, and a powder X-ray diffractometer (for example, “X'Pert Pro MPD made by Panalical)
The measurement conditions are as shown in the examples described later.

Here, the peak a is a peak mainly derived from the (110) plane of TiO ₂ (B). The half width of the X-ray diffraction peak is generally used as an index of crystallite size, and the half width becomes smaller as the crystallite size increases. Accordingly, the half width FWHMa value of the peak a is a value reflecting the crystallite size in the direction orthogonal to the (110) plane of the crystallite of TiO ₂ (B), and the half value of the peak derived from the (110) plane. The width is a good index for crystal growth in the a-axis or b-axis direction. In addition, a weak peak derived from the (201) plane of TiO ₂ (B) and the (101) plane of TiO ₂ (anatase) as an impurity may appear in the region of peak a, but the crystallinity is low. In this case, it is difficult to clearly separate these from the peak derived from the (110) plane of TiO ₂ (B). In such a case, the peak is treated as one peak.
Peak b is a peak derived from the (003) plane of TiO ₂ (B), and the half width of peak b indicates the degree of crystal growth in the c-axis direction. Therefore, the half-value width ratio XFab value between the peak a and the peak b is in the c-axis direction orthogonal to the (003) plane with respect to the degree of growth of the TiO ₂ (B) crystallite in the a-axis or b-axis direction. Indicates the rate of growth. For example, if the growth in the a-axis or b-axis direction is significantly inhibited with respect to the c-axis, the half-value width ratio XFab value is small.
Similarly, the X-ray peak area ratio XAab similarly indicates the ratio of the degree of growth in the c-axis direction to the degree of growth of the TiO ₂ (B) crystallites in the a-axis or b-axis direction. For example, if the growth in the a-axis or b-axis direction is significantly inhibited with respect to the c-axis, the X-ray peak area ratio XAab value becomes a small value.

  The electrode of the present invention is extremely useful as an electrode active material in a non-aqueous electrolyte secondary battery such as a lithium secondary battery including a positive electrode and a negative electrode capable of inserting and extracting lithium ions, and an electrolyte. For example, a non-aqueous electrolyte secondary battery composed of a combination of a metal chalcogenide-based positive electrode for a lithium secondary battery that is normally used and an organic electrolyte mainly composed of a carbonate-based solvent, using the electrode of the present invention as a negative electrode, It has a large capacity, excellent cycle characteristics, and is extremely excellent as a large-sized battery or a vehicle-mounted battery.

<Half Width FWHMa Value of Electrode Material Containing TiO ₂ (B) or its Element Substitute>
The half width FWHMa value measured by the powder X-ray diffraction measurement method using CuKα ₁ line for the powder of the electrode material containing TiO ₂ (B) or an element substitution product thereof of the present invention is usually 0.6 or more, preferably It is 0.7 or more, more preferably 0.8 or more, and still more preferably 0.9 or more. If the FWHMa value is lower than this value, crystal growth proceeds in the a-axis or b-axis direction and the Li diffusion path becomes longer, so that it is difficult to obtain an excellent expression capacity and good cycle characteristics. The upper limit of the FWHMa value is usually 5 or less, preferably 4.5 or less, more preferably 4. When the FWHMa value exceeds this value, it becomes difficult to obtain an excellent expression capacity and good cycle characteristics.

<Half Width Ratio XFab Value of Electrode Material Containing TiO ₂ (B) or its Element Substitute>
The half-value width ratio XFab value measured by the powder X-ray diffraction measurement method using CuKα ₁ line for the powder of the electrode material containing TiO ₂ (B) or its element substitution product of the present invention is usually 1 or less, preferably 0. .95 or less, more preferably 0.9 or less, and still more preferably 0.85 or less. When the XFab value exceeds this value, the crystal growth in the a-axis or b-axis direction advances with respect to the crystal growth in the c-axis direction, and it is difficult to obtain excellent expression capacity and cycle characteristics by extending the Li diffusion path. Become. The lower limit of the XFab value is usually 0 or more, preferably 0.03, and more preferably 0.06. When the XFab value is lower than this value, it is difficult to obtain excellent expression capacity and good cycle characteristics.

<X-ray peak area ratio XAab value of electrode material containing TiO ₂ (B) or its element substitution product>
The X-ray peak area ratio XAab value measured by the powder X-ray diffraction measurement method using CuKα ₁ line for the powder of the electrode material containing TiO ₂ (B) or its element substitution product of the present invention is usually 0.27 or less, preferably Is 0.25 or less, more preferably 0.23 or less, and still more preferably 0.21 or less. When the XAab value exceeds this value, the crystal growth in the a-axis or b-axis direction advances with respect to the crystal growth in the c-axis direction, and it is difficult to obtain excellent expression capacity and cycle characteristics by extending the Li diffusion path. Become. The lower limit value of the XAab value is usually 0 or more, preferably 0.03 or more, more preferably 0.06 or more. When the XAab value is lower than this value, it is difficult to obtain excellent expression capacity and good cycle characteristics.

  The half-value width FWHMa value, the half-value width ratio XFab value, and the X-ray peak area ratio XAab value can be obtained by, for example, the X-ray diffraction measurement method under the conditions described above.

  In the following, an “electrode” is a material in which the electrode material of the present invention is used as an active material and a layer containing the active material is provided on a current collector. The electrode material of the present invention can be used for both the negative electrode and the positive electrode, but is preferably used for the negative electrode. A “negative electrode” is a material in which the electrode material of the present invention is used as a negative electrode active material and a layer containing the negative electrode active material is provided on a current collector.

[Other physical properties]
<BET specific surface area>
BET specific surface area of the electrode material of the present invention is not particularly limited, usually 0.5 m ² / g or more, preferably ^{1 m} 2 / g or more, more preferably ^2m 2 / g or more, and usually 300 meters ² / g or less, preferably 280 m ² / g or less, more preferably 260 m ² / g or less. If the value of the BET specific surface area is within this range, it is preferable because lithium can be taken in and out quickly and the rate characteristics are excellent in high-speed charge / discharge of the battery.

  The BET specific surface area is determined by using a surface area meter (for example, a fully automatic surface area measuring device manufactured by Ritsu Okura), preliminarily drying the electrode material at 300 ° C. for 15 minutes under nitrogen flow, and then relative pressure of nitrogen with respect to atmospheric pressure. A value measured by a nitrogen adsorption BET one-point method using a gas flow method is used, using a nitrogen-helium mixed gas that has been accurately adjusted so that the value of is 0.3.

<Volume standard average particle size>
The volume-based average particle diameter of the electrode material of the present invention is not particularly limited, but is usually 0.1 μm or more, preferably 1 μm or more, more preferably 3 μm or more, and usually 60 μm or less, preferably 55 μm or less, more preferably 50 μm or less. It is. If the volume-based average particle size of the electrode material is below this range, the particle size is too small, and it is difficult to take a conductive path between the electrode material powder and a conductive path between the electrode material powder and the conductive agent described later. In some cases, the cycle characteristics may deteriorate. On the other hand, if it exceeds this range, unevenness may easily occur when an electrode active material layer is produced on the current collector by coating as described later.

  The volume-based average particle size is measured by mixing a 2% by volume aqueous solution (about 1 mL) of polyoxyethylene (20) sorbitan monolaurate, which is a surfactant, and laser diffraction particle size distribution using ion-exchanged water as a dispersion medium. A value obtained by measuring a volume-based average particle diameter (median diameter) with a meter (for example, “LA-920” manufactured by Horiba, Ltd.) is used. In Examples described later, the volume-based average particle diameter was determined by this method.

<Average particle size of primary particles>
The average particle size of the primary particles of the electrode material of the present invention is not particularly limited, but is usually 5 nm or more, preferably 10 nm or more, more preferably 20 nm or more, and usually 20 μm or less, preferably 15 μm or less, more preferably The range is 10 μm or less. If the value of the average particle diameter of the primary particles is within this range, it is preferable because lithium can be taken in and out quickly and the rate characteristics are excellent in high-speed charge / discharge of the battery.

  The average particle size of the primary particles is obtained by observing three or more fields of view of the electrode material with an SEM and determining the average particle size of the primary particles from the average value. When the primary particles are fibrous, the fiber diameter direction is used as the average particle diameter, and when the primary particles are elliptical, the minor axis direction is used as the average particle diameter. In Examples described later, the average particle size of primary particles was determined by this method.

<Tap density>
The tap density of the electrode material of the present invention is not particularly limited, but is usually 0.1 g / cm ³ or more, preferably 0.4 g / cm ³ or more, more preferably 0.7 g / cm ³ or more, and usually 4. The range is 0 g / cm ³ or less, preferably 3.0 g / cm ³ or less. When the tap density is within this range, it is easy to increase the packing density of the electrode active material layer, and it is easy to obtain a high-capacity battery excellent in rate characteristics.

The tap density is measured using a sieve having a mesh opening of 300 μm, dropping the electrode material onto a 20 cm ³ tapping cell to fill the cell, and then using a powder density measuring device (eg, tap denser manufactured by Seishin Enterprise Co., Ltd.). Then, tapping with a stroke length of 10 mm is performed 1000 times, and a value obtained by measuring the tapping density at that time is used.

[Production method]
Although there is no restriction | limiting in particular in the manufacturing method of the electrode material used for the electrode of this invention, For example, it can manufacture by the manufacturing method etc. which are mentioned below.

<Raw material>
Among the raw materials for electrode materials (hereinafter sometimes referred to as “raw materials” as appropriate), as Ti raw materials, for example, metal titanium, titanium oxide (anatase type, rutile type, etc.), titanium complexes (titanium glycolate complex, etc.), Titanium alkoxide (titanium isopropoxide, etc.), titanium salt (titanium sulfate, etc.), titanium chloride (titanium tetrachloride, etc.), etc. can be used.

  As the element M raw material, H, P, B, Zr, Hf, V, Nb, and Ta can be used. For example, phosphoric acid, boric acid, zirconium metal, zirconium oxide sol, zirconium oxide, zirconium tetrabromide, zirconium tetrachloride, zirconium boride, zirconium oxychloride, zirconium hydroxychloride, sodium zirconium tetraoxalate, ammonium zirconium citrate, etc. Zirconium complex salts of zirconium hydroxide, zirconium carbonate, metal hafnium, hafnium oxide, hafnium tetrachloride, hafnium boride, metal vanadium, vanadium pentoxide, vanadium boride, ammonium metavanadate, vanadyl oxalate. Examples thereof include vanadium oxide sol, metal niobium, niobium oxide sol, niobium pentoxide, niobium pentachloride, niobium boride, niobium oxalate, metal tantalum, tantalum pentoxide, tantalum pentachloride, tantalum boride, and tantalum oxalate.

  As an oxygen source, oxygen-containing gas (air, oxygen, etc.), Ti, oxygen in oxide as element M source, oxygen in carbonate, etc. can be used.

  As a raw material for Ti, element M, and oxygen, a single compound (or element) combining Ti, element M, and oxygen may be used, or a plurality of compounds may be used.

  Moreover, the form of these Ti, the element M, and oxygen raw material can be used as a powder form, a granular form, a pellet form, a lump shape, a plate shape etc., for example.

<Method>
As an electrode material manufacturing method,
(1) Method using hydrothermal synthesis treatment
(2) Method using solid-phase reaction treatment
(3) Method using complex polymerization reaction treatment
(4) Method of hydrothermal synthesis treatment of complex
Etc.
Below, the manufacturing method of (1), (2), (3), (4) is demonstrated.

(1) Method using hydrothermal synthesis treatment
The method using the hydrothermal synthesis process in the present invention includes a hydrothermal synthesis process, an ion exchange process, and a firing process.

(Hydrothermal synthesis treatment)
Hydrothermal synthesis generally refers to a method for synthesizing a substance and crystal growth performed in the presence of high-temperature water, particularly high-temperature and high-pressure water. It is a step of reacting a Ti raw material and an aqueous solution of alkali or a mixed solution of an aqueous solution of alkali and alcohol at a temperature of 100 ° C. or higher in a pressure vessel such as an autoclave.

  As the alkali raw material of the alkali aqueous solution, alkali metal hydroxides such as sodium hydroxide, potassium hydroxide, cesium hydroxide and the like can be used. The concentration of the aqueous alkaline solution is not particularly limited, but is usually about 7 to 13M, preferably about 10M.

  Although it can set suitably according to the electrode material to synthesize | combine as a temperature of a hydrothermal synthesis process, it is 100 to 250 degreeC normally, Preferably it is 150 to 200 degreeC. In addition, the hydrothermal synthesis treatment pressure is, for example, about 0.1 MPa to 1.6 MPa, and the hydrothermal synthesis treatment time is, for example, about 1 hour to 10 days. Moreover, stirring may be performed during the hydrothermal synthesis process, or the stationary state may be maintained.

(Ion exchange treatment)
The ion exchange treatment is a step of neutralizing and ion-exchanging the above alkaline aqueous solution. Specifically, for example, the slurry obtained by the hydrothermal synthesis treatment is separated into a solid (powder) and an aqueous alkaline solution using a method such as filtration or centrifugation, and the obtained powder is put into an aqueous acid solution. , By performing a partial ion exchange treatment by holding, further repeating the filtration and centrifugation and the operation of this ion exchange treatment, until the pH of the filtrate and the supernatant is about 5-6, further washing with water, An ion-exchanged powder is obtained.

  As the aqueous solution for ion exchange, for example, an aqueous solution of hydrochloric acid, nitric acid or the like can be used.

(Baking process)
The firing treatment is a step of drying and firing the powder obtained by the ion exchange treatment. Specifically, for example, drying is performed at a temperature of about 60 to 120 ° C. for about 1 to 24 hours to obtain an electrode material. The atmosphere during drying may be a vacuum or an inert atmosphere or an air atmosphere. The apparatus used for drying is not particularly limited, and examples thereof include a hot air type box dryer, a tunnel dryer, a rotary dryer, a spray dryer, a conductive drum dryer, an infrared dryer, and the like. Further, for example, the baking is held at a temperature of about 250 ° C. to 600 ° C. for about 0.5 hours to 10 days. The atmosphere during firing may be a vacuum, an inert atmosphere, an air atmosphere, or the like, but an oxidizing atmosphere is preferable in order to stably produce titanium oxide. The apparatus used for firing is not particularly limited, and examples include a shuttle furnace, a tunnel furnace, an electric furnace, a lead hammer furnace, and a rotary kiln.

(Other processing)
After the baking treatment, further pulverization and classification treatment may be performed as necessary. The apparatus used for pulverization is not particularly limited. For example, examples of the coarse pulverizer include a jaw crusher, an impact crusher, and a cone crusher. Examples of the intermediate pulverizer include a roll crusher and a hammer mill. Examples of the pulverizer include a ball mill, a vibration mill, a pin mill, a stirring mill, and a jet mill.

  There are no particular restrictions on the apparatus used for the classification process. For example, in the case of dry sieving: rotary sieving, oscillating sieving, rotating sieving, vibrating sieving, etc. can be used. Cases: Gravity classifiers, inertial classifiers, centrifugal classifiers (classifiers, cyclones, etc.) can be used. In the case of wet sieving: mechanical wet classifiers, hydraulic classifiers, sedimentation classifiers A centrifugal wet classifier or the like can be used.

(2) Method using solid-phase reaction treatment
The method using the solid phase reaction treatment in the present invention comprises steps of a solid phase reaction treatment, an ion exchange treatment, and a baking treatment.

(Solid-phase reaction treatment)
The solid-phase reaction generally refers to a chemical reaction that occurs in or between solids. The solid-phase reaction treatment in the present invention is a mixture of the above-described Ti raw material and carbonate or nitrate, and heat treatment. It is the process of making it react.

  As the carbonate, alkali metal carbonates such as sodium carbonate, potassium carbonate, and cesium carbonate can be used, and as nitrates, alkali metal nitrates such as sodium nitrate, potassium nitrate, and cesium nitrate can be used.

  The heat treatment temperature of the solid phase reaction treatment is maintained at a temperature of about 700 to 1100 ° C. for about 1 to 48 hours to obtain a powder subjected to the solid phase reaction. The atmosphere during the heat treatment may be a vacuum, an inert atmosphere, an air atmosphere, or the like.

(Ion exchange treatment)
A method similar to the above-described ion exchange treatment can be used.

(Baking process)
A method similar to the above-described baking treatment can be used.

(Other processing)
A method similar to the other processing described above can be used.

(3) Method using complex polymerization reaction treatment
The method using the solid phase reaction treatment in the present invention comprises steps of a complex polymerization reaction treatment, an ion exchange treatment, and a baking treatment.

(Complex polymerization reaction treatment)
The complex polymerization reaction is a chemical reaction that first stabilizes a constituent metal element as a metal complex, and secondly fixes it in an organic polymer network to prevent decomposition or precipitation of the metal complex. The complex polymerization reaction treatment in the present invention is the above-mentioned Ti raw material, which is gelled by further melting and mixing the Ti complex and carbonate or nitrate Ti complex forming an acid or glycol solution, and evaporating the moisture, and further heat treatment. To carbonize. It is a step of decarboxylation by further heat treatment and crystallization by further heat treatment.

  As the carbonate, alkali metal carbonates such as sodium carbonate, potassium carbonate, and cesium carbonate can be used, and as nitrates, alkali metal nitrates such as sodium nitrate, potassium nitrate, and cesium nitrate can be used.

  The heat treatment temperature of the complex polymerization reaction treatment is maintained at a temperature of about 500 to 1100 ° C. for about 1 to 48 hours to obtain a powder that has undergone the complex polymerization reaction. The atmosphere during the heat treatment may be a vacuum, an inert atmosphere, an air atmosphere, or the like.

(Ion exchange treatment)
A method similar to the above-described ion exchange treatment can be used.

(Baking process)
A method similar to the above-described baking treatment can be used.

(Other processing)
A method similar to the other processing described above can be used.

(4) Method of hydrothermal synthesis treatment of complex
The method for hydrothermal synthesis treatment of the complex in the present invention comprises hydrothermal synthesis treatment of the complex raw material and a drying treatment step.

(Hydrothermal synthesis treatment of complex raw materials)
In the hydrothermal synthesis treatment of the complex raw material in the present invention, the titanium complex and the acid aqueous solution, or the acid aqueous solution and alcohol mixed solution and the element M raw material were mixed, and the pH was adjusted with acid or alkali. Then, it is the process made to react at the temperature of 100 degreeC or more within pressure vessels, such as an autoclave.

  As the acid raw material for the acid aqueous solution, sulfuric acid, hydrochloric acid, nitric acid and the like can be used.

  Moreover, as pH after the said pH adjustment, it is about pH = 0.1-7 normally, Preferably it is about pH = 0.25-5, More preferably, it is about pH = 0.5-3.

  Although it can set suitably according to the electrode material to synthesize | combine as a temperature of a hydrothermal synthesis process, it is 100 to 250 degreeC normally, Preferably it is 150 to 200 degreeC. In addition, the hydrothermal synthesis treatment pressure is, for example, about 0.1 MPa to 1.6 MPa, and the hydrothermal synthesis treatment time is, for example, about 1 hour to 10 days. Moreover, stirring may be performed during the hydrothermal synthesis process, or the stationary state may be maintained.

(Drying process)
A drying process is a process of drying after neutralizing and filtering the above-mentioned aqueous acid solution. Specifically, for example, the slurry obtained by the hydrothermal synthesis treatment is separated into a solid (powder) and an acid aqueous solution using a method such as filtration or centrifugation, and the obtained powder is put into an alkali or an aqueous solution. Then, neutralization is performed by holding, and filtration and centrifugation are repeated. The obtained powder is dried at a temperature of about 50 to 200 ° C. for 1 to 48 hours.

(Other processing)
A method similar to the other processing described above can be used.

[2] Electrode for non-aqueous electrolyte secondary battery
The electrode for a non-aqueous electrolyte secondary battery of the present invention uses the electrode material of the present invention as an electrode active material, and in general, an electrode active material layer containing the electrode material of the present invention on a current collector Is provided so as to ensure conductivity.

  Such an electrode of the present invention is extremely useful as an electrode (including a positive electrode and a negative electrode) in a non-aqueous electrolyte secondary battery such as a positive and negative electrodes capable of inserting and extracting lithium ions, and a lithium secondary battery equipped with an electrolyte. It is. In particular, using the electrode of the present invention as a negative electrode, a non-aqueous electrolyte secondary battery configured by combining a metal chalcogenide-based positive electrode for a lithium secondary battery that is normally used and an organic electrolyte mainly composed of a carbonate solvent, The discharge capacity is large, the rate characteristics are excellent, the cycle characteristics are excellent, and the electrode expansion after the cycle is suppressed.

[Electrode active material]
As the electrode active material of the present invention, the electrode material of the present invention is used. As long as the effect of the present invention is not hindered, the electrode material is an electrode material other than the electrode material of the present invention (hereinafter referred to as “electrode material A”). May be used in combination. When the electrode material A is used, the electrode material A may be anything as long as it can charge and discharge lithium ions. For example, when the electrode material is used as a negative electrode, the electrode material A is an amorphous material obtained by firing natural graphite (scaly graphite, spheroidized graphite, etc.), artificial graphite (mesocarbon microbeads, etc.), pitch, resin, etc. Examples include carbonaceous materials, multiphase structural materials obtained by combining graphite and amorphous carbon, metals such as aluminum and tin, and oxides such as SiO ₂ . These may be used individually by 1 type and may be used in combination of 2 or more type.

  The addition amount of the electrode material A is not particularly limited, but is usually 1% by mass or more, preferably 5% by mass or more, more preferably 20% by mass or more, and usually 80% by mass or less with respect to the electrode material of the present invention. Preferably, it is 70 mass% or less, More preferably, it is 60 mass% or less.

[Current collector]
As the current collector, for example, a metal cylinder, a metal coil, a metal plate, a metal foil film, a carbon plate, a carbon thin film, a carbon cylinder, or the like is used. Among these, a metal foil film is particularly preferable because it is currently used in industrialized products. The metal thin film may be used in a suitable mesh shape.

  The thickness of the metal foil film is not particularly limited, but is usually 1 μm or more, preferably 5 μm or more, more preferably 10 μm or more, and usually 100 μm or less, preferably 50 μm or less, more preferably 20 μm or less. In the case of a metal foil film thinner than the above range, the strength required as a current collector may be insufficient.

  Specific examples of the metal used for the current collector include copper, nickel, stainless steel, iron, titanium, aluminum, and an aluminum alloy.

[Physical properties]
<Filling density>
The packing density of the electrode is not particularly limited, but is usually 0.1 g / cm ³ or more, preferably 0.5 g / cm ³ or more, and usually 5.0 g / cm ³ or less, preferably 4.0 g / cm ³ or less. is there. If the electrode packing density is below this range, it may be difficult to obtain a high-capacity battery. On the other hand, if it exceeds this range, the amount of pores in the electrode may be reduced, and it may be difficult to obtain favorable battery characteristics. As the electrode packing density, a value obtained by dividing the electrode weight excluding the current collector by the electrode area and the electrode thickness is used.

<Porosity>
The porosity of the electrode is not particularly limited, but is usually 10% or more, preferably 20% or more, and usually 50% or less, preferably 40% or less. When the porosity of the electrode is below this range, there are few pores in the electrode, and the electrolyte does not easily penetrate, and it may be difficult to obtain preferable battery characteristics. On the other hand, if this range is exceeded, there may be many pores in the electrode, and the electrode strength becomes too weak, making it difficult to obtain favorable battery characteristics. As the porosity of the electrode, a percentage obtained by dividing the total pore volume obtained by measuring the pore distribution with the mercury porosimeter of the electrode by the apparent volume of the electrode material active material layer excluding the current collector is used.

<Conductive agent>
The electrode active material layer may contain a conductive agent. The conductive agent may be any electronic conductive material that does not cause a chemical change at the charge / discharge potential of the electrode active material to be used. For example, carbon blacks such as acetylene black, ketjen black, channel black, furnace black, lamp black and thermal black, carbon fibers, vapor grown carbon fibers (VGCF), conductive fibers such as metal fibers, fluorine Metal powders such as carbonized carbon and copper can be contained alone or as a mixture thereof. Of these conductive agents, acetylene black and VGCF are particularly preferable. These may be used individually by 1 type and may be used in combination of 2 or more type. Although the addition amount of a electrically conductive agent is not specifically limited, 1-30 mass% is preferable with respect to an electrode active material, and 1-15 mass% is especially preferable.

<Binder>
As the binder, a polymer that is stable against a liquid solvent described later is preferable. For example, resin polymers such as polyethylene, polypropylene, polyethylene terephthalate, aromatic polyamide, cellulose, rubbery polymers such as styrene / butadiene rubber, isoprene rubber, butadiene rubber or ethylene / propylene rubber, styrene / butadiene / styrene block Polymers, hydrogenated products thereof, styrene / ethylene / butadiene / styrene copolymers, styrene / isoprene / styrene block copolymers and thermoplastic elastomeric polymers such as hydrogenated products, syndiotactic 1,2-polybutadiene , Ethylene / vinyl acetate copolymer, or soft resinous polymer such as propylene / α-olefin (carbon number 2 to 12) copolymer, polyvinylidene fluoride, polytetrafluoroethylene, or polytetrafluoroethylene / ethylene The fluoropolymer of the polymer such as, a polymer composition or the like having an ionic conductivity of alkali metal ions (especially lithium ions) can be mentioned. These may be used individually by 1 type and may be used in combination of 2 or more type.

  Examples of the polymer composition having ion conductivity include polyether polymer compounds such as polyethylene oxide and polypropylene oxide, crosslinked polymers of polyether compounds, polyepichlorohydrin, polyphosphazene, polysiloxane, and polyvinylpyrrolidone. , A polymer in which a lithium salt or an alkali metal salt mainly composed of lithium is combined with a polymer compound such as polyvinylidene carbonate or polyacrylonitrile, or a high dielectric such as propylene carbonate, ethylene carbonate, or γ-butyrolactone. A polymer in which an organic compound having a rate or an ion-dipole interaction force is blended can be used.

Specifically, resin polymers such as polyethylene, polypropylene, polyethylene terephthalate, aromatic polyamide, or cellulose and derivatives thereof (for example, carboxymethylcellulose), styrene / butadiene rubber, isoprene rubber, butadiene rubber, or ethylene / propylene are usually used. Rubber-like polymers such as rubber, fluoropolymers such as polyvinylidene fluoride, polytetrafluoroethylene, or polytetrafluoroethylene / ethylene copolymers, polyether polymer compounds such as polyethylene oxide and polypropylene oxide, polyethers Examples include crosslinked polymers of the compound, preferably polyethylene, polypropylene, styrene / butadiene rubber, polyvinylidene fluoride, polytetrafluoroethylene, or polyethylene oxide. Is, more preferably, polyethylene, styrene-butadiene, polyvinylidene fluoride, or polytetrafluoroethylene. These are currently used industrially and are suitable because they are easy to handle.

  The structure of this electrode is that the electrode material of the present invention, electrode material A and / or a conductive agent, and a slurry in which a binder is dispersed in a dispersion liquid are thinly applied and dried on a current collector substrate. Followed by a pressing step of compacting to a predetermined thickness and density.

  An aqueous solvent or an organic solvent is used as a dispersion medium for preparing an electrode active material slurry when an electrode active material, a conductive agent and a binder used as necessary are mixed and applied onto a current collector. As the aqueous solvent, water is usually used, and additives such as alcohols such as ethanol and cyclic amides such as N-methylpyrrolidone may be added to water up to about 30% by mass or less. it can.

  As the organic solvent, usually, cyclic amides such as N-methylpyrrolidone, linear amides such as N, N-dimethylformamide and N, N-dimethylacetamide, and aromatic carbonization such as anisole, toluene and xylene Examples thereof include alcohols such as hydrogens, butanol and cyclohexanol, among which cyclic amides such as N-methylpyrrolidone, linear amides such as N, N-dimethylformamide and N, N-dimethylacetamide are preferable. .

  A negative electrode active material, a binder, and a conductive agent blended as necessary are mixed with these solvents to prepare a negative electrode active material slurry, and this is applied to the negative electrode current collector substrate so as to have a predetermined thickness. Thus, the negative electrode active material layer is formed. The upper limit of the concentration of the negative electrode active material in the negative electrode active material slurry is usually 70% by mass or less, preferably 55% by mass or less, and the lower limit is usually 30% by mass or more. , Preferably it is 40 mass% or more. When the concentration of the negative electrode active material exceeds this upper limit, the negative electrode active material in the negative electrode active material slurry tends to aggregate, and when the concentration is lower than the lower limit, the negative electrode active material tends to settle during storage of the negative electrode active material slurry.

  The upper limit of the binder concentration in the negative electrode active material slurry is usually 30% by mass or less, preferably 10% by mass or less, and the lower limit is usually 0.1% by mass or more, preferably 0.5% or more. . When the concentration of the binder exceeds this upper limit, the internal resistance of the negative electrode obtained increases, and when the concentration is lower than the lower limit, the binding property of the negative electrode active material layer becomes poor.

[3] Non-aqueous electrolyte secondary battery
The non-aqueous electrolyte secondary battery of the present invention uses the electrode of the present invention as an electrode in a non-aqueous electrolyte secondary battery including a positive electrode and a negative electrode capable of inserting and extracting lithium ions, and an electrolyte.

  There is no particular limitation on the selection of members other than the electrodes necessary for the battery configuration such as the positive electrode and the electrolyte constituting the nonaqueous electrolyte secondary battery of the present invention. In the following, materials of members other than the negative electrode constituting the nonaqueous electrolyte secondary battery when the electrode of the present invention is used as a negative electrode will be exemplified, but the materials that can be used are not limited to these specific examples. Absent.

[Positive electrode]
The positive electrode is formed by forming a positive electrode active material and an active material layer containing an organic substance (binder) having a binding and thickening effect on a current collector substrate. Usually, the positive electrode active material and the binder are used. The slurry is dispersed in water or an organic solvent, and is applied by a thin coating and drying process on a current collector substrate, followed by a pressing process for compacting to a predetermined thickness and density.

<Positive electrode active material>
The positive electrode active material is not particularly limited as long as it has a function capable of inserting and extracting lithium. For example, lithium transition metal composite oxide materials such as lithium cobalt oxide, lithium nickel oxide, and lithium manganese oxide Transition metal oxide materials such as manganese dioxide; carbonaceous materials such as graphite fluoride can be used. Specifically, LiFeO ₂ , LiCoO ₂ , LiNiO ₂ , LiMn ₂ O ₄ and their non-stoichiometric compounds, MnO ₂ , TiS ₂ , FeS ₂ , Nb ₃ S ₄ , Mo ₃ S ₄ , CoS ₂ , V ₂ O ₅ , P ₂ O ₅ , CrO ₃ , V ₃ O ₃ , TeO ₂ , GeO ₂ or the like can be used. These may be used individually by 1 type and may be used in combination of 2 or more type.

<Conductive agent>
A positive electrode conductive agent can be used for the positive electrode active material layer. The positive electrode conductive agent may be any electron conductive material that does not cause a chemical change at the charge / discharge potential of the positive electrode active material used. For example, graphite such as natural graphite (flaky graphite etc.), artificial graphite, etc .; carbon blacks such as acetylene black, ketjen black, channel black, furnace black, lamp black, thermal black; carbon fiber, metal fiber, etc. Conductive fibers of: carbon fluorides; metal powders such as aluminum; conductive whiskers such as zinc oxide and potassium titanate; conductive metal oxides such as titanium oxide; organic conductive materials such as polyphenylene derivatives; Etc. can be included alone or as a mixture thereof. Among these conductive agents, artificial graphite, acetylene black and the like are particularly preferable. These may be used individually by 1 type and may be used in combination of 2 or more type.

  Although the addition amount of a electrically conductive agent is not specifically limited, 1-50 mass% is preferable with respect to a positive electrode active material, and 1-30 mass% is especially preferable. In the case of carbon or graphite, 2 to 15% by mass is particularly preferable.

<Binder>
There is no restriction | limiting in particular as a binder used for formation of a positive electrode active material layer, Any of a thermoplastic resin and a thermosetting resin may be sufficient. For example, polyethylene, polypropylene, polytetrafluoroethylene (PTFE), polyvinylidene fluoride (PVDF), styrene butadiene rubber, tetrafluoroethylene-hexafluoroethylene copolymer, tetrafluoroethylene-hexafluoropropylene copolymer (FEP), Tetrafluoroethylene-perfluoroalkyl vinyl ether copolymer (PFA), vinylidene fluoride-hexafluoropropylene copolymer, vinylidene fluoride-chlorotrifluoroethylene copolymer, ethylene-tetrafluoroethylene copolymer (ETFE resin) , Polychlorotrifluoroethylene (PCTFE), vinylidene fluoride-pentafluoropropylene copolymer, propylene-tetrafluoroethylene copolymer, ethylene-chlorotrif Oroethylene copolymer (ECTFE), vinylidene fluoride-hexafluoropropylene-tetrafluoroethylene copolymer, vinylidene fluoride-perfluoromethyl vinyl ether-tetrafluoroethylene copolymer, ethylene-acrylic acid copolymer or (Na ⁺ ) ion crosslinked product, ethylene-methacrylic acid copolymer or (Na ⁺ ) ion crosslinked product of the material, ethylene-methyl acrylate copolymer, or (Na ⁺ ) ion crosslinked product of the material, ethylene-methacrylic acid Examples thereof include an acid methyl copolymer or a (Na ⁺ ) ion-crosslinked product of the above materials, and these materials can be used alone or as a mixture. Among these materials, more preferable materials are polyvinylidene fluoride (PVDF) and polytetrafluoroethylene (PTFE).

<Other additives>
In addition to the conductive agent described above, the positive electrode active material layer may further contain a filler, a dispersant, an ionic conductor, a pressure enhancer, and other various additives. Any filler can be used as long as it is a fibrous material that does not cause a chemical change in the constructed battery. Usually, olefin polymers such as polypropylene and polyethylene, and fibers such as glass and carbon are used. Although the addition amount of a filler is not specifically limited, 0-30 mass% is preferable as content in an active material layer.

<Solvent>
In preparing the positive electrode active material slurry, an aqueous solvent or an organic solvent is used as a dispersion medium. As the aqueous solvent, water is usually used, and additives such as alcohols such as ethanol and cyclic amides such as N-methylpyrrolidone may be added to water up to about 30% by mass or less. it can. As the organic solvent, usually, cyclic amides such as N-methylpyrrolidone, linear amides such as N, N-dimethylformamide and N, N-dimethylacetamide, and aromatic carbonization such as anisole, toluene and xylene Examples thereof include alcohols such as hydrogens, butanol and cyclohexanol, among which cyclic amides such as N-methylpyrrolidone, linear amides such as N, N-dimethylformamide and N, N-dimethylacetamide are preferable. .

  A positive electrode active material, a binder as a binder, an organic substance having a thickening effect, a positive electrode conductive agent blended as necessary, and other fillers are mixed in these solvents to prepare a positive electrode active material slurry, The positive electrode active material layer is formed by applying this to the positive electrode current collector substrate so as to have a predetermined thickness.

  The upper limit of the concentration of the positive electrode active material in the positive electrode active material slurry is usually 70% by mass or less, preferably 55% by mass or less, and the lower limit is usually 30% by mass or more, preferably 40% by mass or more. When the concentration of the positive electrode active material exceeds this upper limit, the positive electrode active material in the positive electrode active material slurry tends to aggregate, and when the concentration is lower than the lower limit, the positive electrode active material tends to settle during storage of the positive electrode active material slurry.

  Further, the upper limit of the concentration of the binder in the positive electrode active material slurry is usually 30% by mass or less, preferably 10% by mass or less, and the lower limit is usually 0.1% by mass or more, preferably 0.5% or more. . When the concentration of the binder exceeds this upper limit, the internal resistance of the positive electrode obtained increases, and when it falls below the lower limit, the binding property of the positive electrode active material layer may be inferior.

<Current collector>
As the positive electrode current collector, for example, it is preferable to use a valve metal or an alloy thereof that forms a passive film on the surface by anodic oxidation in an electrolytic solution. Examples of the valve metal include metals belonging to Groups 4, 5, and 13 of the periodic table and alloys thereof. Specifically, Al, Ti, Zr, Hf, Nb, Ta and alloys containing these metals can be exemplified, and Al, Ti, Ta and alloys containing these metals can be preferably used. . In particular, Al and its alloys are desirable because of their light weight and high energy density. The thickness of the positive electrode current collector is not particularly limited, but is usually about 1 to 50 μm.

[Electrolytes]
Any electrolyte such as an electrolytic solution or a solid electrolyte can be used as the electrolyte. Here, the electrolyte refers to all ionic conductors, and both the electrolytic solution and the solid electrolyte are included in the electrolyte.

As the electrolytic solution, for example, a solution obtained by dissolving a solute in a non-aqueous solvent can be used. As the solute, an alkali metal salt, a quaternary ammonium salt, or the like can be used. Specifically, LiClO ₄ , LiPF ₆ , LiBF ₄ , LiCF ₃ SO ₃ , LiN (CF ₃ SO ₂ )
₂ , LiN (CF ₃ CF ₂ SO ₂ ) ₂ , LiN (CF ₃ SO ₂ ) (C ₄ F ₉ SO ₂ ), LiC (CF ₃ SO ₂ ) _{3 and the} like are preferably used. One kind of these solutes may be selected and used, or two or more kinds may be mixed and used. The content of these solutes in the electrolytic solution is preferably 0.2 mol / L or more, particularly 0.5 mol / L or more, and 2 mol / L or less, particularly 1.5 mol / L or less.

Examples of the non-aqueous solvent include cyclic carbonates such as ethylene carbonate, propylene carbonate, butylene carbonate and vinylene carbonate, cyclic ester compounds such as γ-butyrolactone; chain ethers such as 1,2-dimethoxyethane; crown ethers, 2- Cyclic ethers such as methyltetrahydrofuran, 1,2-dimethyltetrahydrofuran, 1,3-dioxolane, and tetrahydrofuran; chain carbonates such as diethyl carbonate, ethyl methyl carbonate, and dimethyl carbonate can be used. Among these, a nonaqueous solvent containing a cyclic carbonate and a chain carbonate is preferable.
One type of these solvents may be selected and used, or two or more types may be mixed and used.

  The nonaqueous electrolytic solution according to the present invention may contain various auxiliary agents such as a cyclic carbonate having an unsaturated bond in the molecule, a conventionally known overcharge inhibitor, a deoxidizer, and a dehydrator.

Examples of the cyclic carbonate having an unsaturated bond in the molecule include vinylene carbonate compounds, vinyl ethylene carbonate compounds, methylene ethylene carbonate compounds, and the like.
Examples of the vinylene carbonate compounds include vinylene carbonate, methyl vinylene carbonate, ethyl vinylene carbonate, 4,5-dimethyl vinylene carbonate, 4,5-diethyl vinylene carbonate, fluoro vinylene carbonate, trifluoromethyl vinylene carbonate, and the like.
Examples of the vinyl ethylene carbonate compound include vinyl ethylene carbonate, 4-methyl-4-vinyl ethylene carbonate, 4-ethyl-4-vinyl ethylene carbonate, 4-n-propyl-4-vinyl ethylene carbonate, 5-methyl- Examples include 4-vinylethylene carbonate, 4,4-divinylethylene carbonate, 4,5-divinylethylene carbonate, and the like.
Examples of the methylene ethylene carbonate compound include methylene ethylene carbonate, 4,4-dimethyl-5-methylene ethylene carbonate, 4,4-diethyl-5-methylene ethylene carbonate, and the like.
Of these, vinylene carbonate and vinyl ethylene carbonate are preferable, and vinylene carbonate is particularly preferable.
These may be used individually by 1 type, or may use 2 or more types together.

When the non-aqueous electrolyte contains a cyclic carbonate compound having an unsaturated bond in the molecule, the proportion in the non-aqueous electrolyte is usually 0.01% by mass or more, preferably 0.1% by mass or more, particularly Preferably it is 0.3 mass% or more, Most preferably, it is 0.5 mass% or more, Usually 8 mass% or less, Preferably it is 4 mass% or less, Most preferably, it is 3 mass% or less.
By including in the electrolyte a cyclic carbonate having an unsaturated bond in the molecule, the cycle characteristics of the battery can be improved. Although the reason is not clear, it is presumed that a stable protective film can be formed on the surface of the negative electrode. However, when the content is small, this property is not sufficiently improved. However, if the content is too large, the gas generation amount tends to increase during high-temperature storage, so the content in the electrolyte is preferably in the above range.

Examples of the overcharge inhibitor include aromatic compounds such as biphenyl, alkylbiphenyl, terphenyl, partially hydrogenated terphenyl, cyclohexylbenzene, t-butylbenzene, t-amylbenzene, diphenyl ether, and dibenzofuran; 2-fluoro Partially fluorinated products of the above aromatic compounds such as biphenyl, o-cyclohexylfluorobenzene, p-cyclohexylfluorobenzene; fluorine-containing compounds such as 2,4-difluoroanisole and 2,5-difluoroanisole; Anisole compounds and the like can be mentioned.
These may be used alone or in combination of two or more.
The ratio of the overcharge inhibitor in the non-aqueous electrolyte is usually 0.1 to 5% by mass. By containing an overcharge preventing agent, rupture / ignition of the battery can be suppressed during overcharge or the like.

Other auxiliary agents include, for example, carbonate compounds such as fluoroethylene carbonate, trifluoropropylene carbonate, phenylethylene carbonate, erythritan carbonate, spiro-bis-dimethylene carbonate, methoxyethyl-methyl carbonate; succinic anhydride, anhydrous glutar Carboxylic acid anhydrides such as acid, maleic anhydride, citraconic anhydride, glutaconic anhydride, itaconic anhydride, diglycolic anhydride, cyclohexanedicarboxylic anhydride, cyclopentanetetracarboxylic dianhydride, phenylsuccinic anhydride; Ethylene sulfite, 1,3-propane sultone, 1,4-butane sultone, methyl methanesulfonate, busulfan, sulfolane, sulfolene, dimethyl sulfone, tetramethylthiuram monosulfide Sulfur-containing compounds such as N, N-dimethylmethanesulfonamide and N, N-diethylmethanesulfonamide; 1-methyl-2-pyrrolidinone, 1-methyl-2-piperidone, 3-methyl-2-oxazolidinone, 1,3 -Nitrogen-containing compounds such as dimethyl-2-imidazolidinone and N-methylsuccinimide; hydrocarbon compounds such as heptane, octane and cycloheptane; fluorine-containing compounds such as fluorobenzene, difluorobenzene, hexafluorobenzene and benzotrifluoride An aromatic compound etc. are mentioned.
These may be used alone or in combination of two or more.
The ratio of these auxiliaries in the nonaqueous electrolytic solution is usually 0.1 to 5% by mass. By containing these auxiliaries, capacity maintenance characteristics and cycle characteristics after high-temperature storage can be improved.

  Further, the non-aqueous electrolyte solution may include an organic polymer compound in the electrolyte solution, and may be a solid electrolyte such as a gel, rubber, or solid sheet. In this case, specific examples of the organic polymer compound include polyether polymer compounds such as polyethylene oxide and polypropylene oxide; crosslinked polymers of polyether polymer compounds; vinyl alcohol polymers such as polyvinyl alcohol and polyvinyl butyral. Compound; insolubilized product of vinyl alcohol polymer; polyepichlorohydrin; polyphosphazene; polysiloxane; vinyl polymer such as polyvinylpyrrolidone, polyvinylidene carbonate, polyacrylonitrile; poly (ω-methoxyoligooxyethylene methacrylate), Examples thereof include polymer copolymers such as poly (ω-methoxyoligooxyethylene methacrylate-co-methyl methacrylate).

[Other components]
In addition to the electrolyte, the negative electrode, and the positive electrode, an outer can, a separator, a gasket, a sealing plate, a cell case, and the like can be used for the non-aqueous electrolyte secondary battery as necessary.
The material and shape of the separator are not particularly limited. The separator is separated so that the positive electrode and the negative electrode do not come into physical contact with each other, and preferably has high ion permeability and low electrical resistance. The separator is preferably selected from materials that are stable with respect to the electrolyte and excellent in liquid retention. Specific examples include porous sheets or nonwoven fabrics made from polyolefins such as polyethylene and polypropylene.

[Shape of non-aqueous electrolyte secondary battery]
The shape of the nonaqueous electrolyte secondary battery of the present invention is not particularly limited. For example, a cylinder type in which a sheet electrode and a separator are spiral, a cylinder type having an inside-out structure in which a pellet electrode and a separator are combined, a pellet electrode and a separator It can be made into the coin type etc. which were laminated | stacked.

[Method for producing non-aqueous electrolyte secondary battery]
The method for producing the nonaqueous electrolyte secondary battery of the present invention having at least an electrolyte, a negative electrode, and a positive electrode is not particularly limited, and can be appropriately selected from commonly employed methods. An example of the method for producing the nonaqueous electrolyte secondary battery of the present invention is as follows: a negative electrode is placed on an outer can, an electrolytic solution and a separator are provided thereon, and a positive electrode is placed so as to face the negative electrode; A method of assembling the battery by caulking with a sealing plate is mentioned.

  Hereinafter, the present invention will be described in more detail with reference to examples. However, the present invention is not limited to these examples as long as the gist thereof is not exceeded. “%” Means “% by mass” unless otherwise specified.

[Example 1]
(Titanium complex synthesis treatment)
Ice-cooled ammonia and H ₂ O ₂ prepared by adjusting the metal titanium powder to have a molar ratio of Ti: NH ₃ : H ₂ O ₂ : H ₂ O = 0.03: 0.44: 1.06: 5.75 After throwing into the mixed aqueous solution and dissolution, glycolic acid was added so that the molar ratio of Ti: glycolic acid was 3: 8. The mixed aqueous solution was evaporated to dryness at 80 ° C. and then redissolved in water to obtain a titanium complex aqueous solution.

(Hydrothermal synthesis treatment)
The obtained aqueous solution of titanium complex was adjusted in pH with sulfuric acid (manufactured by Junsei Co., Ltd.) and then placed in a Teflon (registered trademark) container. The Teflon (registered trademark) container containing the titanium complex aqueous solution whose pH was adjusted was placed in a stainless steel pressure vessel together with the container, and hydrothermal synthesis treatment was performed at 200 ° C. The obtained slurry subjected to hydrothermal synthesis treatment was repeatedly centrifuged and washed. The obtained powder after washing was dried overnight at 100 ° C. using a dryer.

(Rehydrothermal treatment)
The obtained powder after drying was put into a hydrochloric acid aqueous solution in a Teflon (registered trademark) container and mixed to obtain a slurry. The Teflon (registered trademark) container containing the mixed slurry was placed in a stainless steel pressure vessel together with the container, and hydrothermal synthesis treatment was performed at 180 ° C. The obtained slurry after the rehydrothermal treatment was washed with water and suction filtered using a filter paper having retention particles of 0.2 μm to obtain a white powder. The obtained powder was dried overnight at 80 ° C. using a dryer to obtain an electrode material.

  From the SEM photograph of the electrode material obtained above, 10 primary electrode materials were selected at random, the length measured with a ruler, and the "primary particle diameter of the electrode material" determined by taking the arithmetic mean is 0.02 μm (= 20 nm).

When the volume-based average particle diameter and the BET specific surface area of the electrode material were determined according to the method described above, the volume-based average particle diameter was 20 μm and the BET specific surface area was 231 m ² / g. These measured values are shown in Table 1.

When the half-value width FWHMa value of the electrode material was determined by X-ray diffraction measurement according to the following method, it was 2.35, and when the half-value width ratio XFab value was determined, it was 0.24. Further, the half-value width FWHMb of the electrode material was 0.568 when determined in the same manner as the half-value width FWHMMa value. Further, the X-ray peak area ratio XAab value was determined to be 0.19. FIG. 2 shows the X-ray diffraction pattern used at that time, and Table 2 shows these measured values.

Further, from the X-ray diffraction pattern, the obtained electrode material was identified as a titanium oxide containing TiO ₂ (B) having a layered structure.

<Method for measuring X-ray diffraction of electrode material>
The powder of the electrode material containing TiO ₂ (B) or its element substitution product obtained above is packed in a sample holder, set on the irradiation surface, and measured under the following measurement conditions using the following powder X-ray diffractometer. did.

<X-ray diffraction measurement device and measurement conditions>
X-ray diffraction measurement was performed under the following conditions.
(Examples 1 and 2, Comparative Examples 1 and 2)
X-ray diffractometer Panalytic PW1700
Gonio radius: 173mm
Scanning axis: θ-2θ
Scanning range: 2θ = 5-60 °
[Incoming side]
Enclosed X-ray tube (CuKα, 40kV-30mA)
Solar slit diverging slit (1 °)
[Light receiving side]
Scattering slit (1 °)
Receiving slit (0.2mm)
Monochromator Solar Slit Scintillation Detector (Example 3)
X-ray diffractometer JEOL JDX-3500
Gonio radius: 250mm
Scanning axis: θ-2θ
Scanning range: 2θ = 5-60 °
[Incoming side]
Rotating anti-cathode X-ray tube (CuKα, 30 kV-200 mA)
Solar slit divergence slit (1/2 °)
[Light receiving side]
Scattering slit (1/2 °)
Receiving slit (0.2mm)
Monochromator Solar Slit Scintillation Detector (Comparative Example 3)
X-ray diffractometer panalical X'Pert Pro MPD
Gonio radius: 240mm
Scanning axis: θ-2θ
Scanning range: 2θ = 6-60 °
[Light receiving side]
Enclosed X-ray tube (CuKα, 45kV-40mA)
Solar slit (0.04 rad)
Divergent slit (1/2 °)
Incident side anti-scattering slit [receiving side]
Semiconductor detector (PIXcel)
Graphite Monochromator Solar Slit (0.04 rad)

The full width at half maximum FWHMa of the diffraction peak a existing in the vicinity of 22 to 27 ° is obtained by connecting the background correction with a straight line between 2θ = 21 to 24 ° and 26 to 29 ° as shown in FIG. The vertical line was dropped. A straight line parallel to the background was drawn so as to pass through the midpoint of the perpendicular, and 2θ at the intersection of the straight line and the peak was read to obtain the half width. The area Aa of the diffraction peak a is measured by Materials Data Inc. Calculation was performed using a peak area tool of analysis software JADE5J. The half width FWHMb and the peak area Ab of the diffraction peak b existing around 43.5 ° are obtained by separating the −601 peak adjacent to the 003 peak using the peak separation tool (fitting function: Pearson VII) of JADE5J. Calculated.

<Method for producing lithium secondary battery>
The obtained negative electrode was transferred to a glove box under an argon atmosphere, and 1 mol / L-LiPF ₆ electrolysis using a mixed liquid of ethylene carbonate (EC) / diethyl carbonate (EMC) = 3/7 (weight ratio) as a solvent as an electrolytic solution. A coin battery (lithium secondary battery) was manufactured using the liquid, a polyethylene separator as a separator, and a lithium metal counter electrode as a counter electrode.

<Evaluation of discharge capacity>
After charging to 1.0 V with respect to the lithium counter electrode at a current density of 0.15 mA / cm ² , and further charging until the current value becomes 0.02 mA at a constant voltage of 10 mV, after doping lithium into the negative electrode, A charge / discharge cycle of discharging to a lithium counter electrode up to 2.5 V at a current density of 0.15 mA / cm ² was repeated 5 times, and the average value of the discharge in the third cycle was defined as the discharge capacity. Further, when the discharge capacity per weight was determined, the weight of the active material was obtained by subtracting the weight of the conductive additive, the binder, and the stainless mesh from the weight of the negative electrode, and calculated according to the following.
Discharge capacity (mAh / g)
= Average discharge capacity (mAh) at the third cycle / Weight of active material (g)
Active material weight (g)
= Negative electrode weight (g)-(Binder weight (g) + Conductive auxiliary agent weight (g) + Stainless steel mesh weight (g))

<Cycle characteristic evaluation>
This charge / discharge cycle was repeated 50 times in accordance with the above-described discharge capacity measurement method, and the cycle retention rate was calculated as follows.
Cycle maintenance rate (%)
= {Discharge capacity after 50 cycles (mAh) / 3 to 5 cycles average discharge capacity (mAh)} × 100

  Table 3 shows the battery evaluation results of this electrode material.

[Example 2]
(Titanium complex synthesis treatment)
Titanium metal powder in molar ratio Ti: NH ₃ : H ₂ O ₂ : H ₂ O = 0.03: 0.44:
It was added to an ice-cold ammonia and H ₂ O ₂ mixed aqueous solution adjusted to 1.06: 5.75, and after dissolution, glycolic acid was added in a molar ratio of Ti: glycolic acid = 3: 8. . The mixed aqueous solution was evaporated to dryness at 80 ° C. and then redissolved in water to obtain a titanium complex aqueous solution.

(Hydrothermal synthesis treatment)
The obtained aqueous solution of titanium complex was adjusted in pH with sulfuric acid (manufactured by Junsei Co., Ltd.) and then placed in a Teflon (registered trademark) container. The Teflon (registered trademark) container containing the titanium complex aqueous solution whose pH was adjusted was placed in a stainless steel pressure vessel together with the container, and hydrothermal synthesis treatment was performed at 200 ° C. The obtained slurry subjected to hydrothermal synthesis treatment was repeatedly centrifuged and washed. The obtained powder after washing was dried overnight at 100 ° C. using a dryer.

(Rehydrothermal treatment)
The obtained powder after drying was put into a hydrochloric acid aqueous solution in a Teflon (registered trademark) container and mixed to obtain a slurry. The Teflon (registered trademark) container containing the mixed slurry was placed in a stainless steel pressure resistant container together with the container, and hydrothermal synthesis treatment was performed at 200 ° C. The obtained slurry after the rehydrothermal treatment was washed with water and suction filtered using a filter paper having retention particles of 0.2 μm to obtain a white powder. The obtained powder was dried overnight at 80 ° C. using a dryer to obtain an electrode material.

From the SEM photograph of the obtained electrode material, the primary particle diameter of the electrode material was about 0.06 μm (= about 60 nm). It was 31 micrometers when the volume reference | standard average particle diameter of the electrode material was measured similarly to Example 1. FIG. Moreover, it was 244 m < ² > / g when the specific surface area value of the electrode material was calculated | required like Example 1. FIG. These measured values are shown in Table 1.

  When the half-value width FWHMa value of the electrode material was determined by X-ray diffraction measurement, it was 2.03, and when the half-value width ratio XFab value was determined, it was 0.29. Further, the half-value width FWHMb of the electrode material was 0.596 when determined in the same manner as the half-value width FWHMMa value. Further, the X-ray peak area ratio XAab value was determined to be 0.17. The X-ray diffraction pattern used at that time is shown in FIG. 3, and these measured values are shown in Table 2.

Further, from the X-ray diffraction pattern, the obtained electrode material was identified as a titanium oxide containing TiO ₂ (B) having a layered structure.

  Using this electrode material, a negative electrode and a coin battery were produced and evaluated in the same manner as in Example 1, and the results are shown in Table 3.

[Example 3]
(Hydrothermal synthesis treatment)
An ethanol solution of Ti isopropoxide was added dropwise to an aqueous boric acid solution. After removing water and ethanol from the resulting slurry solution with an evaporator, the powder dried overnight at 100 ° C. is put into 70 ml of 10 molar aqueous sodium hydroxide solution in a Teflon (registered trademark) container, and mixed with the slurry. did.
The Teflon (registered trademark) container containing the mixed slurry was placed in a stainless steel pressure resistant container together with the container, rotated at 15 rpm, and subjected to hydrothermal synthesis at 200 ° C.
(Ion exchange treatment)
The obtained hydrothermal synthesis-treated slurry was subjected to suction filtration using a filter paper with 1 μm retained particles to obtain a white powder. Next, this powder was put into 100 ml of 0.05 M hydrochloric acid aqueous solution, stirred, ion exchanged for 30 minutes, and further subjected to suction filtration as described above to obtain a partially ion exchanged powder. This hydrochloric acid ion exchange and filtration operation was repeated three times.
(Baking process)
The obtained ion-exchanged powder was dried at 100 ° C. for 12 hours using a drier, and then fired at 400 ° C. for 5 hours in an air atmosphere using an electric furnace to obtain an electrode material powder.

From the SEM photograph of the obtained electrode material, the primary particle diameter of the electrode material was about 2 μm. It was 41 micrometers when the volume reference | standard average particle diameter of the electrode material was measured similarly to Example 1. FIG. Moreover, it was 51 m < ² > / g when the specific surface area value of the electrode material was calculated | required like Example 1. FIG. These measured values are shown in Table 1.

  When the half-value width FWHMa value of the electrode material was determined by X-ray diffraction measurement, it was 0.92, and when the half-value width ratio XFab value was determined, it was 0.97. Further, the half-value width FWHMb of the electrode material was 0.896 as determined in the same manner as the half-value width FWHMMa value. Further, the X-ray peak area ratio XAab value was determined to be 0.18. FIG. 4 shows the X-ray diffraction pattern used at that time, and Table 2 shows the measured values.

Further, from the X-ray diffraction pattern, the obtained electrode material was identified as a titanium oxide containing TiO ₂ (B) having a layered structure.

  Using this electrode material, a negative electrode and a coin battery were produced and evaluated in the same manner as in Example 1, and the results are shown in Table 3.

[Comparative Example 1]
(Preparation of titanium complex aqueous solution)
Ice-cooled ammonia, H ₂ O, in which the metal titanium powder was adjusted to have a molar ratio of Ti: NH ₃ : H ₂ O ₂ : H ₂ O = 0.03: 0.44: 1.1: 5.8 _The mixture was poured into a mixed aqueous solution and dissolved, and citric acid was added at a molar ratio of Ti: citric acid = 1: 1. The mixed aqueous solution was evaporated to dryness at 80 ° C. and then redissolved in water to obtain an aqueous titanium complex solution.

(Synthesis of precursor K ₂ Ti ₄ O ₉ )
In the titanium complex aqueous solution obtained above, 10 times the amount of citric acid added above and citric acid at a molar ratio of K: Ti = 2: 3.7 were added and dissolved, Moisture was evaporated by performing heat treatment on a hot plate, gelled, and further carbonized by heating to obtain a black powder.

The obtained black powder was put into a ceramic crucible and fired at 500 ° C. in an air atmosphere using an electric furnace. Further, after naturally cooling, the mixture was pulverized and mixed again in a mortar, and baked at 1023 ° C. in an air atmosphere using an electric furnace to obtain a precursor K ₂ Ti ₄ O ₉ .

(Ion exchange treatment)
The pulverized product of K ₂ Ti ₄ O ₉ synthesized above was immersed in an aqueous hydrochloric acid solution and subjected to ion exchange treatment. Then, it washed with water and the obtained slurry was suction-filtered using the filter paper of a retention particle 0.2 micrometer, and white powder was obtained.

(Baking process)
The obtained ion-exchanged white powder was dried at 100 ° C. overnight using a dryer and then baked at 325 ° C. in an air atmosphere using an electric furnace to obtain a powder of an electrode material.

From the SEM photograph of the obtained electrode material, the primary particle diameter of the electrode material was about 8 nm. It was 3 micrometers when the volume reference | standard average particle diameter of the electrode material was measured similarly to Example 1. FIG. Moreover, it was 12 m < ² > / g when the specific surface area value of the electrode material was calculated | required similarly to Example 1. FIG. These measured values are shown in Table 1.

  When the half-value width FWHMa value of the electrode material was determined by X-ray diffraction measurement, it was 0.57, and when the half-value width ratio XFab value was determined, it was 1.25. Further, the half-value width FWHMb of the electrode material was 0.710 when determined in the same manner as the half-value width FWHMMa value. Further, the X-ray peak area ratio XAab value was determined to be 0.30. The X-ray diffraction pattern used at that time is shown in FIG. 5, and the measured values are shown in Table 2.

Further, from the X-ray diffraction pattern, the obtained electrode material was identified as a titanium oxide containing TiO ₂ (B) having a layered structure.

  Using this electrode material, a negative electrode and a coin battery were produced and evaluated in the same manner as in Example 1, and the results are shown in Table 3.

[Comparative Example 2]
(Preparation of titanium complex aqueous solution)
In the same manner as in Comparative Example 1, a titanium complex aqueous solution was prepared.

(Synthesis of precursor K ₂ Ti ₄ O ₉ )
The precursor K ₂ Ti ₄ O ₉ was synthesized in the same manner as in Comparative Example 1.

(Ion exchange treatment)
Ion exchange treatment was performed in the same manner as in Comparative Example 1.

(Baking process)
The obtained ion-exchanged white powder was dried at 100 ° C. overnight using a dryer, and then fired at 350 ° C. in an air atmosphere using an electric furnace to obtain an electrode material powder.

From the SEM photograph of the obtained electrode material, the primary particle diameter of the electrode material was about 9 μm. It was 3 micrometers when the volume reference | standard average particle diameter of the electrode material was measured similarly to Example 1. FIG. Moreover, it was 12 m < ² > / g when the specific surface area value of the electrode material was calculated | required similarly to Example 1. FIG. These measured values are shown in Table 1.

  When the half-value width FWHMa value of the electrode material was determined by X-ray diffraction measurement, it was 0.47, and when the half-value width ratio XFab value was determined, it was 1.26. Further, the half-value width FWHMb of the electrode material was also found to be 0.590 in the same manner as the half-value width FWHMMa value. Further, the X-ray peak area ratio XAab value was determined to be 0.28. FIG. 6 shows the X-ray diffraction pattern used at that time, and Table 2 shows the measured values.

Further, from the X-ray diffraction pattern, the obtained electrode material was identified as a titanium oxide containing TiO ₂ (B) having a layered structure.

  Using this electrode material, a negative electrode and a coin battery were produced and evaluated in the same manner as in Example 1, and the results are shown in Table 3.

[Comparative Example 3]
(Synthesis treatment of precursor Na ₂ Ti ₃ O ₇ )
Anatase type titanium oxide powder (“Titanium (IV) oxide, anatase type” manufactured by Wako Pure Chemical Industries, Ltd.) and sodium carbonate (sodium carbonate [sodium carbonate (made by Wako Pure Chemical Industries, Ltd.) as titanium raw materials) Anhydrous)]]) was weighed so that the molar ratio was Na: Ti = 2: 3. These were mixed in a mortar, pelletized, placed in a ceramic crucible, and fired at 800 ° C. in an air atmosphere using an electric furnace. Further, after naturally cooling, the mixture is pulverized and mixed again in a mortar, pelletized, and fired at 800 ° C. in an air atmosphere using an electric furnace to obtain a precursor Na ₂ Ti ₃ O ₇ . It was.

(Ion exchange treatment)
Ion exchange treatment was performed in the same manner as in Comparative Example 1.

(Baking process)
The obtained ion-exchanged white powder was dried at 100 ° C. overnight using a dryer, and then fired at 300 ° C. in an air atmosphere using an electric furnace to obtain a powder of an electrode material.

From the SEM photograph of the obtained electrode material, the primary particle diameter of the electrode material was about 1 μm. It was 2 micrometers when the volume reference | standard average particle diameter of the electrode material was measured similarly to Example 1. As shown in FIG. Moreover, it was 5 m < ² > / g when the specific surface area value of the electrode material was calculated | required like Example 1. FIG.

When the half-value width FWHMa value of the electrode material was determined by X-ray diffraction measurement, it was 0.22, and when the half-value width ratio XFab value was determined, it was 1.6. Further, the half-value width FWHMb of the electrode material was found to be 0.352 in the same manner as the half-value width FWHMMa value. Further, the X-ray peak area ratio XAab value was determined to be 0.54. FIG. 7 shows the X-ray diffraction pattern used at that time, and Table 2 shows these measured values.

Further, from the X-ray diffraction pattern, the obtained electrode material was identified as a titanium oxide containing TiO ₂ (B) having a layered structure.

  Using this electrode material, a negative electrode and a coin battery were produced and evaluated in the same manner as in Example 1, and the results are shown in Table 3.

  As can be seen from the results in Table 3, the nonaqueous electrolyte secondary batteries of Examples 1 to 3 using the electrode material of the present invention had high discharge capacity and excellent cycle characteristics. On the other hand, the nonaqueous electrolyte secondary batteries using the electrode materials of Comparative Examples 1 to 3 had low discharge capacity and poor cycle characteristics.

  The non-aqueous electrolyte secondary battery using the electrode material of the present invention has a high discharge capacity and is excellent in rate characteristics and cycle characteristics. Therefore, secondary batteries such as power sources for electric vehicles and road labeling are used. It is widely used in all fields.

It is a figure which shows the correction method of the half value width FWHMa of the diffraction peak a. 2 is an X-ray diffraction pattern of an electrode material obtained in Example 1. FIG. 3 is an X-ray diffraction pattern of an electrode material obtained in Example 2. FIG. 3 is an X-ray diffraction pattern of an electrode material obtained in Example 3. FIG. 2 is an X-ray diffraction pattern of an electrode material obtained in Comparative Example 1. FIG. 3 is an X-ray diffraction pattern of an electrode material obtained in Comparative Example 2. FIG. 4 is an X-ray diffraction pattern of an electrode material obtained in Comparative Example 3.

Claims (4)

An electrode material containing TiO ₂ (B) and / or an element substitution product thereof, which satisfies the following requirements (A) and (B): An electrode material for a nonaqueous electrolyte secondary battery.
(A) The FWHMa value is 0.6 or more when the half-value width of the diffraction peak a having a diffraction angle 2θ in the vicinity of 22 to 27 ° in powder X-ray diffraction measurement using CuKα ₁ line is FWHMa.
(B) X defined by the following formula (1) when the half-value width of the diffraction peak b where the diffraction angle 2θ exists in the vicinity of 43.5 ° in the powder X-ray diffraction measurement using CuKα ₁ line is FWHMb The line half width ratio XFab value is 1 or less.
XFab value = FWHMb / FWHMa (1) The electrode material for a nonaqueous electrolyte secondary battery according to claim 1, wherein the following requirement (c) is satisfied.
(C) Using an electrode material containing TiO ₂ (B) and / or its element substitution product, a diffraction peak a having a diffraction angle 2θ in the vicinity of 22 to 27 ° in powder X-ray diffraction measurement using CuKα ₁ line When the area is Aa and the area of the diffraction peak b existing in the vicinity of 43.5 ° is Ab, the X-ray peak area ratio XAab value defined by the following formula (2) is 0.27 or less.
XAab value = Ab / Aa (2)   A nonaqueous electrolyte secondary battery electrode comprising the electrode material according to claim 1 or 2 as an electrode active material.   A nonaqueous electrolyte secondary battery comprising a positive electrode and a negative electrode capable of inserting and extracting lithium ions and an electrolyte, wherein the electrode is the electrode for a nonaqueous electrolyte secondary battery according to claim 3. Secondary battery.

Images