JP2014026984A - Electrode material, battery electrode, method for manufacturing these, nonaqueous electrolyte battery and battery pack - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide: a nonaqueous electrolyte battery improved in cycle life; an electrode material used for the battery, an electrode and methods for manufacturing these; and a battery pack.SOLUTION: According to one embodiment, there is provided an electrode material including: an active material including a titanium oxide compound having a crystal structure of a monoclinic titanium dioxide; and a compound present on the surface of the active material and having a trialkylsilyl group represented by formula (I). In the formula, R, Rand Rare the same or different and represent a 1-10C alkyl group.

Description

  Embodiments described herein relate generally to an electrode material, a battery electrode, a manufacturing method thereof, a nonaqueous electrolyte battery, and a battery pack.

Non-aqueous electrolyte batteries using titanium oxide as a negative electrode can generate lithium dendrites compared to batteries using carbonaceous materials because the lithium storage and release potential of titanium oxide is higher than that of carbonaceous materials. The nature is low. In addition, since titanium oxide is a ceramic, it is unlikely to cause thermal runaway. Therefore, a nonaqueous electrolyte battery using titanium oxide for the negative electrode has high safety. Among them, spinel type lithium titanate is promising as a negative electrode active material having excellent cycle characteristics and high safety because there is no volume change accompanying charge / discharge reaction. However, non-aqueous electrolyte batteries using titanium oxide have a problem of low energy density. For example, the theoretical capacity of titanium dioxide having an anatase structure is about 160 mAh / g, and the theoretical capacity of a lithium titanium composite oxide having a spinel structure such as Li ₄ Ti ₅ O ₁₂ is about 170 mAh / g.

  Therefore, in recent years, a titanium oxide compound having a crystal structure of monoclinic titanium dioxide has attracted attention. The reversible capacity of a titanium oxide compound having a monoclinic titanium dioxide crystal structure is about 240 mAh / g, which is a significantly higher capacity than other titanate compounds.

  However, when a titanium oxide compound having a monoclinic titanium dioxide crystal structure is used for the negative electrode, there is a problem that the cycle life is reduced.

JP 2008-91327 A

T. Ohzuku, T. Kodama, T. Hirai, J. Power Sources 1985, 14, 153. R. Marchand, L. Brohan, M. Tournoux, Material Research Bulletin 15, 1129 (1980).

  Provided are a nonaqueous electrolyte battery with improved cycle life, an electrode material used for the battery, an electrode, a method for producing the same, and a battery pack.

According to one embodiment, an active material comprising a titanium oxide compound having a monoclinic titanium dioxide crystal structure, and a compound having a trialkylsilyl group of formula (I) present on the surface of the active material, An electrode material comprising is provided.

Here, R ¹ , R ² and R ³ are the same or different and represent an alkyl group having 1 to 10 carbon atoms.

  According to another embodiment, particles of a titanium oxide compound having a monoclinic titanium dioxide crystal structure are immersed in a solution of a compound having a trialkylsilyl group of the above formula (I); There is provided a method for producing an electrode material comprising separating a titanium oxide compound to which a compound having an alkylsilyl group is attached.

  According to another embodiment, there is provided a battery electrode comprising an active material comprising a titanium oxide compound having a monoclinic titanium dioxide crystal structure and a compound having a trialkylsilyl group of the above formula (I). The

  According to another embodiment, a slurry in which an active material containing a titanium oxide compound having a monoclinic titanium dioxide crystal structure and a compound having a trialkylsilyl group of the above formula (I) is dispersed in a solvent. A method for producing a battery electrode is provided.

  According to another embodiment, a negative electrode including an active material including a titanium oxide compound having a monoclinic titanium dioxide crystal structure, a positive electrode, and a nonaqueous electrolyte battery including a nonaqueous electrolyte are provided. The non-aqueous electrolyte includes a compound having a trialkylsilyl group of the above formula (I).

  According to another embodiment, a battery pack including the nonaqueous electrolyte battery is provided.

The cross-sectional schematic diagram of the thin nonaqueous electrolyte battery of embodiment. The expanded sectional view of the A section of FIG. The disassembled perspective view of the battery pack of embodiment. The block diagram which shows the electric circuit of the battery pack of FIG. The graph which shows the resistance increase rate of Examples 1-3 and Comparative Examples 1-4.

The crystal structure of monoclinic titanium dioxide belongs mainly to the space group C2 / m and exhibits a tunnel structure. Here, the crystal structure of monoclinic titanium dioxide is referred to as TiO ₂ (B). A titanium oxide compound having a monoclinic titanium dioxide crystal structure is referred to as a TiO ₂ (B) structure titanium oxide compound. The detailed crystal structure of TiO ₂ (B) is described in Non-Patent Document 2. A titanium oxide compound having a TiO ₂ (B) structure can be represented by a general formula Li _x TiO ₂ (0 ≦ x ≦ 1). Note that x in the above equation varies in the range of 0 to 1 depending on the charge / discharge reaction.

Since the titanium oxide compound having a TiO ₂ (B) structure has a high theoretical capacity, it is considered that the theoretical capacity of the battery can be increased by using it as an active material.

However, a titanium oxide compound having a TiO ₂ (B) structure is a solid acid and has a solid acid point, a hydroxyl group, and the like on the surface, and thus has high reactivity with a non-aqueous electrolyte. Therefore, in a battery using a titanium oxide compound having a TiO ₂ (B) structure as a negative electrode active material, the nonaqueous electrolyte is decomposed along with charge and discharge, and excessive inorganic and organic coatings are formed on the negative electrode. As a result, resistance increases and cycle life decreases.

In a battery using a carbonaceous material or spinel type lithium titanate as the negative electrode active material, it is possible to suppress side reactions between the negative electrode and the nonaqueous electrolyte by adding vinylene carbonate to the nonaqueous electrolyte. In such a battery, vinylene carbonate is reduced and decomposed on the negative electrode to form a stable film on the negative electrode, whereby excessive film formation can be suppressed. However, in a battery using a titanium oxide compound having a TiO ₂ (B) structure as a negative electrode active material, even if vinylene carbonate is added, side reaction between the negative electrode and the nonaqueous electrolyte is not suppressed, and formation of a film is not suppressed. Therefore, there exists a problem that resistance increases and a cycle life falls.

  The present inventors have found that an increase in battery resistance can be suppressed by including a compound having a trialkylsilyl group in any of the active material, the electrode, and the nonaqueous electrolyte. This is presumably because excessive film formation is suppressed by the formation of a stable film containing a trialkylsilyl group. Hereinafter, each embodiment will be described in detail.

(First embodiment)
According to this embodiment, an electrode material comprising an active material containing a titanium oxide compound having a TiO ₂ (B) structure and a compound having a trialkylsilyl group of formula (I) present on the surface of the active material is provided. Provided.

In the formula (I), R ¹ , R ² and R ³ are the same or different and represent an alkyl group having 1 to 10 carbon atoms.

  In such an electrode material, the compound having a trialkylsilyl group is preferably contained on the surface of the primary particles of the titanium oxide compound. Here, the surface of the primary particle of the titanium oxide compound includes the inner surface of the hole existing on the surface of the primary particle.

The electrode material according to the present embodiment is contained in the electrode of the battery as an active material. In such a battery, with the initial charge and subsequent charge / discharge, the nonaqueous electrolyte is decomposed and a film is formed on the surface of the electrode material. However, the presence of a compound having a trialkylsilyl group in the electrode material forms a film containing a trialkylsilyl group. The coating film containing the trialkylsilyl group is stable, can suppress side reactions between the titanium oxide compound having a TiO ₂ (B) structure and the non-aqueous electrolyte, and can suppress subsequent decomposition of the non-aqueous electrolyte. Thereby, formation of an excessive film can be suppressed, and an increase in resistance of the battery can be suppressed, and as a result, cycle life can be improved. Such an effect can be obtained by using an alkyl group having 10 or less carbon atoms as the alkyl group of the trialkylsilyl group. The alkyl group of the trialkylsilyl group is more preferably an alkyl group having 1 to 3 carbon atoms.

  The presence of a trialkylsilyl group on the surface of the electrode material can be detected by time-of-flight secondary ion mass spectrometry. It is also possible to detect that a trialkylsilyl group is contained in the coating formed on the surface of the electrode material by analyzing the surface of the electrode material after charging / discharging by time-of-flight secondary ion mass spectrometry. it can.

In time-of-flight secondary ion mass spectrometry, for example, a primary ion (eg, Bi ₃ ⁺⁺ ) is irradiated on a sample surface in a vacuum. Then, secondary ions having a positive or negative charge are released from the sample surface. The emitted secondary ions are detected by a detector separated by a certain distance. At this time, the time for the secondary ions accelerated with the same energy to reach the detector is a function of mass. Therefore, in the time-of-flight secondary ion mass spectrometry, it is possible to identify the mass distribution of secondary ions and the organic and inorganic substances present on the sample surface. It is also possible to compare the abundance from the peak intensity.

When the surface of the electrode material in this embodiment is measured by time-of-flight secondary ion mass spectrometry, the peak intensity (I ₁ ) of the Si (CH ₃ ) ₃ ⁺ peak and the peak of the Ti ⁺ peak are measured. The intensity (I ₂ ) ratio (I ₁ / I ₂ ) is preferably 1 or more. Due to the presence of the trialkylsilyl group in the electrode material, the peak intensity ratio (I ₁ / I ₂ ) becomes 1 or more. In addition, the peak intensity ratio (I ₁ / I ₂ ) becomes 1 or more due to the presence of a trialkylsilyl group in the film formed after charging and discharging. An electrode material having a peak intensity ratio (I ₁ / I ₂ ) of 1 or more can further increase the resistance of the battery and further improve the cycle life. Note that the peak intensity ratio (I ₁ / I ₂ ) is preferably 10 or less because an excess of trialkylsilyl groups causes an increase in resistance.

  The compound containing a trialkylsilyl group is not limited to this, but is preferably at least one compound selected from a phosphoric acid compound containing a trialkylsilyl group or a boric acid compound containing a trialkylsilyl group. Examples of such compounds include tris (trimethylsilyl) borate, tris (trimethylsilyl) phosphate, tris (triethylsilyl) borate, tris (triethylsilyl) phosphate, tris (triisopropylsilyl) borate, phosphoric acid Tris (triisopropylsilyl), tris (dimethylethylsilyl) borate, tris (dimethylethylsilyl) phosphate, tris (butyldimethylsilyl) borate, and tris (butyldimethylsilyl) phosphate are included. Preferably, tris (trimethylsilyl) phosphate is used.

(Time-of-flight secondary ion mass spectrometry)
A measurement method of time-of-flight secondary ion mass spectrometry will be described. Measurement conditions were as follows. Primary ion species: Bi ₃ ⁺⁺ , primary ion energy: 25 kV, pulse width: 4.7 ns, bunching: yes, charge neutralization: no, measurement vacuum was 4x10-7 Pa. In the case of measuring only the active material, the active material is embedded in a resin, subjected to cross-sectional processing with an argon ion milling apparatus, and used for measurement. When measuring an electrode, the electrode can be used as a sample. When measuring the electrode, disassemble the battery, take out the electrode, and avoid exposure to the atmosphere as much as possible.

(Specific surface area)
The specific surface area of the titanium oxide compound having a TiO ₂ (B) structure is preferably 5 m ² / g or more and 100 m ² / g or less. When the specific surface area is 5 m ² / g or more, sufficient lithium ion storage / release sites can be secured, and the battery capacity can be increased. When the specific surface area is 100 m ² / g or less, the Coulomb efficiency during charging and discharging can be improved.

(Powder X-ray diffraction)
Titanium oxide compounds of TiO ₂ (B) structure has a crystalline structure of TiO ₂ (B) can be measured by powder X-ray diffraction of the Cu-K [alpha as a radiation source.

The powder X-ray diffraction measurement can be performed as follows. First, the target sample is pulverized until the average particle size becomes about 5 μm. The average particle diameter can be determined by a laser diffraction method. The crushed sample is filled in a holder portion having a depth of 0.2 mm formed on a glass sample plate. At this time, care should be taken so that the sample is sufficiently filled in the holder portion. Also, be careful that there are no cracks or voids due to insufficient filling of the sample. Next, using another glass plate from the outside, it is sufficiently pressed and smoothed. Be careful not to cause unevenness from the reference surface of the holder due to excessive or insufficient filling amount. Next, the glass plate filled with the sample is placed in a powder X-ray diffractometer, and a diffraction pattern is obtained using Cu-Kα rays. In general, since TiO ₂ (B) has low crystallinity, depending on the sample, the peak intensity of the X-ray diffraction pattern is weak in powder X-ray measurement, and it is difficult to observe the intensity of either peak. A peak derived from monoclinic titanium dioxide belonging to the space group C2 / m may be observed.

  According to the above embodiment, the electrode material which can implement | achieve the nonaqueous electrolyte battery by which resistance increase was suppressed and the cycle life was improved can be provided.

(Second Embodiment)
Next, the manufacturing method of the electrode material described in the first embodiment will be described. In this method, particles of a titanium oxide compound having a TiO ₂ (B) structure are immersed in a solution of a compound having a trialkylsilyl group of formula (I), and the compound having the trialkylsilyl group is attached. Separating the titanium oxide compound.

Here, R ¹ , R ² and R ³ are the same or different and represent an alkyl group having 1 to 10 carbon atoms.

More specifically, the particles of titanium oxide compound having a TiO ₂ (B) structure are immersed in a solution of a compound having a trialkylsilyl group, whereby the particles of titanium oxide compound are impregnated with the solution. At this time, in order to promote the impregnation of the solution into the pores of the titanium oxide compound, the pressure may be reduced. Next, the titanium oxide compound is separated and dried, for example, by filtration. Alternatively, the solution may be volatilized and separated using a hot plate or the like. Thereby, titanium oxide compound particles to which a compound having a trialkylsilyl group is attached can be obtained.

  As the compound having a trialkylsilyl group, those described in the first embodiment can be used. The content of the compound having a trialkylsilyl group can be adjusted by changing the concentration of the solution of the compound having a trialkylsilyl group and the impregnation time.

  According to the above embodiment, it is possible to provide a method for producing an electrode material capable of realizing a nonaqueous electrolyte battery in which an increase in resistance is suppressed and a cycle life is improved.

(Third embodiment)
According to this embodiment, there is provided a battery electrode including an active material containing a titanium oxide compound having a TiO ₂ (B) structure and a compound having a trialkylsilyl group of formula (I).

Here, R ¹ , R ² and R ³ are the same or different and represent an alkyl group having 1 to 10 carbon atoms.

In such an electrode, for example, an active material layer containing an active material containing a titanium oxide compound having a TiO ₂ (B) structure can be formed on a current collector described later. The compound having a trialkylsilyl group can be contained in the active material layer, and is preferably dispersed in the active material layer.

With the initial charge of the battery and subsequent charge / discharge, the nonaqueous electrolyte is decomposed to form a film on the surface of the electrode. However, the presence of a compound having a trialkylsilyl group in the electrode forms a film containing a trialkylsilyl group. The coating film containing the trialkylsilyl group is stable, can suppress side reactions between the titanium oxide compound having a TiO ₂ (B) structure and the non-aqueous electrolyte, and can suppress subsequent decomposition of the non-aqueous electrolyte. Thereby, formation of an excessive film can be suppressed, and an increase in resistance of the battery can be suppressed, and as a result, cycle life can be improved.

  In addition, in the electrode in this embodiment, it is not limited to the film formed in the surface of an electrode, A trialkylsilyl group can also be contained in the film formed in the surface of the active material contained in an electrode.

  The inclusion of a trialkylsilyl group in the electrode can be detected by time-of-flight secondary ion mass spectrometry. Further, by analyzing the surface of the electrode after charging / discharging by time-of-flight secondary ion mass spectrometry, it can be detected that a trialkylsilyl group is contained in the coating formed on the surface of the electrode.

When the surface of the electrode in this embodiment is measured by time-of-flight secondary ion mass spectrometry, the peak intensity (I ₁ ) of the Si (CH ₃ ) ₃ ⁺ peak and the peak intensity of the Ti ⁺ peak the ratio of _{(I 2) (I 1 /} I 2) is preferably 1 or more. Due to the presence of the trialkylsilyl group in the electrode, the peak intensity ratio (I ₁ / I ₂ ) becomes 1 or more. In addition, the peak intensity ratio (I ₁ / I ₂ ) becomes 1 or more due to the presence of a trialkylsilyl group in the film formed after charging and discharging. Therefore, an electrode having a peak intensity ratio (I ₁ / I ₂ ) of 1 or more can suppress an increase in battery resistance and improve cycle life. Note that the peak intensity ratio (I ₁ / I ₂ ) is preferably 10 or less because an excess of trialkylsilyl groups causes an increase in resistance.

  As the compound containing a trialkylsilyl group, those described in the first embodiment can be used.

  Although the electrode in this embodiment can be used for any of a positive electrode and a negative electrode, it is preferably used as a negative electrode.

  Moreover, you may use the electrode material described in 1st Embodiment as an active material contained in an electrode.

  According to the above embodiment, the electrode which can implement | achieve the nonaqueous electrolyte battery by which the increase in resistance was suppressed and the cycle life was improved can be provided.

(Fourth embodiment)
Next, a method for manufacturing the electrode described in the third embodiment will be described. The method includes preparing a slurry by dispersing an active material containing a titanium oxide compound having a TiO ₂ (B) structure and a compound having a trialkylsilyl group of formula (I) in a solvent.

Here, R ¹ , R ² and R ³ are the same or different and represent an alkyl group having 1 to 10 carbon atoms.

  Next, an electrode can be obtained by applying the obtained slurry to one or both sides of a current collector, drying, and pressing. In preparing the slurry, other components such as a conductive agent and a binder may be added to the solvent.

  For example, N-methylpyrrolidone (NMP) or water can be used as the solvent.

  As the compound containing a trialkylsilyl group, those described in the first embodiment can be used.

  For example, an aluminum foil or an aluminum alloy foil can be used as the current collector, but the current collector is not limited thereto.

  The electrode manufacturing method in the present embodiment can be used for manufacturing either the positive electrode or the negative electrode, but is preferably used for manufacturing the negative electrode. As the solvent, the compound having a trialkylsilyl group, the current collector, the conductive agent, and the binder, those suitable for the positive electrode and the negative electrode can be selected.

As an example of producing a negative electrode, for example, a powder of a titanium oxide compound having a TiO ₂ (B) structure, a tri (trimethylsilyl) phosphate solution, acetylene black, and polyvinylidene fluoride are added to an NMP solvent and mixed. A slurry is prepared. A negative electrode can be produced by applying this slurry onto a current collector and drying to remove NMP.

  According to the above embodiment, it is possible to provide an electrode manufacturing method capable of realizing a nonaqueous electrolyte battery in which increase in resistance is suppressed and cycle life is improved.

(Fifth embodiment)
In the fifth embodiment, a nonaqueous electrolyte battery including a negative electrode, a positive electrode, a nonaqueous electrolyte, a separator, and an exterior member is provided. In the present embodiment, the negative electrode includes a titanium oxide compound having a TiO ₂ (B) structure. The nonaqueous electrolyte includes a compound having a trialkylsilyl group of the formula (I).

Here, R ¹ , R ² and R ³ are the same or different and represent an alkyl group having 1 to 10 carbon atoms.

  Below, a negative electrode, a positive electrode, a nonaqueous electrolyte, a separator, and an exterior member are demonstrated in detail.

1) Negative electrode The negative electrode includes a current collector and a negative electrode layer (negative electrode active material-containing layer). The negative electrode layer is formed on one side or both sides of the current collector and includes an active material, a conductive agent, and a binder.

An active material containing a titanium oxide compound having a TiO ₂ (B) structure is used as the active material. The TiO ₂ (B) structure titanium oxide compound may be used alone, but mixed with other titanium-containing oxides such as lithium titanate having a spinel structure and titanium oxide having an anatase structure. It can also be used.

  The conductive agent improves current collection performance and suppresses contact resistance between the active material and the current collector. Examples of the conductive agent include acetylene black, carbon black, graphite, carbon nanofiber, and carbon nanotube.

  The binder binds the active material, the conductive agent, and the current collector. Examples of the binder include polytetrafluoroethylene (PTFE), polyvinylidene fluoride (PVdF), fluorine-based rubber, and styrene butadiene rubber.

  The active material, conductive agent and binder in the negative electrode layer are preferably blended in a proportion of 70% to 96% by weight, 2% to 28% by weight and 2% to 28% by weight, respectively. . By setting the amount of the conductive agent to 2% by mass or more, the current collecting performance of the negative electrode layer can be improved. Moreover, the binding property of a negative electrode layer and a collector can be improved by making the quantity of a binder into 2 mass% or more. On the other hand, the conductive agent and the binder are each preferably 28% by mass or less in order to increase the capacity.

  The current collector is preferably electrochemically stable in a potential range nobler than 1 V, and is one or more selected from aluminum foil or Mg, Ti, Zn, Mn, Fe, Cu, and Si It is preferable that it is an aluminum alloy foil containing these elements.

  The negative electrode is produced by, for example, preparing a slurry by suspending an active material, a conductive agent, and a binder in a suitable solvent, applying the slurry to a current collector, drying it, and then pressing it. The negative electrode may also be produced by forming an active material, a conductive agent, and a binder into a pellet shape to form a negative electrode layer on a current collector.

2) Positive electrode The positive electrode includes a current collector and a positive electrode layer (positive electrode active material-containing layer). The positive electrode layer is formed on one side or both sides of the current collector and includes an active material, a conductive agent, and a binder.

For example, an oxide or a sulfide can be used as the active material.
Examples of the oxide include lithium cobalt composite oxide (for example, Li _x CoO ₂ etc.), lithium nickel cobalt composite oxide (for example, Li _x Ni _1-y Co _y O ₂ ), lithium nickel manganese composite oxide ( for _{example, Li x Ni 1-y Mn} y O 2), and lithium-nickel-cobalt-manganese composite oxide (e.g., oxides having a _{Li x Ni 1-yz Co y} Mn z layered structure, such as O _2), lithium manganese Complex oxides (for example, Li _x Mn ₂ O ₄ ), and oxides having a spinel structure such as lithium manganese nickel complex oxide (for example, Li _x Mn _{2 -y} Ni _y O ₄ ), lithium iron phosphate ( for example, Li _x FePO _4), lithium iron phosphate manganese complex compound _{(e.g., Li x Fe 1-y Mn} y PO 4), lithium cobalt phosphate (e.g., a compound having an olivine structure such as Li _x CoPO ₄₎ Is included. In the above, 0 <x ≦ 1, 0 ≦ y ≦ 1, and 0 ≦ z ≦ 1 are preferable. As the active material, these compounds may be used alone, or a plurality of compounds may be used in combination.

The specific surface area of the positive electrode active material is preferably 0.1 m ² / g or more and 10 m ² / g or less. When it is 0.1 m ² / g or more, sufficient storage and release sites for lithium ions can be secured. It is easy to handle on industrial production as it is 10 m < ² > / g or less, and favorable charging / discharging cycle performance is securable.

  The conductive agent improves the current collecting performance and suppresses the contact resistance between the active material and the current collector. Examples of the conductive agent include carbonaceous materials such as acetylene black, carbon black, graphite, carbon nanofiber, and carbon nanotube.

  The binder binds the active material, the conductive agent, and the current collector. Examples of the binder include polytetrafluoroethylene (PTFE), polyvinylidene fluoride (PVdF), and fluorine-based rubber.

  The active material, the conductive agent, and the binder in the positive electrode layer may be blended at a ratio of 80% by mass to 95% by mass, 3% by mass to 18% by mass, and 2% by mass to 17% by mass, respectively. preferable. The conductive agent can exhibit the above-described effects by adjusting the amount to 3% by mass or more. By making the amount of the conductive agent 18% by mass or less, the decomposition of the nonaqueous electrolyte on the surface of the conductive agent under high temperature storage can be reduced. A sufficient positive electrode strength can be obtained by adjusting the amount of the binder to 2% by mass or more. By setting the binder to an amount of 17% by mass or less, the amount of the binder, which is an insulating material in the positive electrode, can be reduced, and the internal resistance can be reduced.

  The current collector is preferably an aluminum foil or an aluminum alloy foil containing one or more elements selected from Mg, Ti, Zn, Mn, Fe, Cu, and Si.

  For example, the positive electrode is prepared by suspending an active material, a conductive agent, and a binder in an appropriate solvent to prepare a slurry. The slurry is applied to a positive electrode current collector, dried to form a positive electrode layer, and then pressed. It is produced by this. The positive electrode may also be produced by forming an active material, a conductive agent and a binder in the form of a pellet to form a positive electrode layer, which is formed on a current collector.

3) Nonaqueous electrolyte As the nonaqueous electrolyte, for example, a liquid nonaqueous electrolyte prepared by dissolving an electrolyte in an organic solvent, or a gelled nonaqueous electrolyte obtained by combining a liquid nonaqueous electrolyte and a polymer material is used. In any case, a compound having a trialkylsilyl group of the formula (I) is included.

Examples of the electrolyte contained in the liquid non-aqueous electrolyte include lithium perchlorate (LiClO ₄ ), lithium hexafluorophosphate (LiPF ₆ ), lithium tetrafluoroborate (LiBF ₄ ), lithium arsenic hexafluoride ( LiAsF ₆ ), lithium trifluorometasulfonate (LiCF ₃ SO ₃ ), and lithium salts such as lithium bistrifluoromethylsulfonylimide [LiN (CF ₃ SO ₂ ) ₂ ] and mixtures thereof are included. The electrolyte is preferably one that is not easily oxidized even at a high potential, and LiPF ₆ is most preferred. The electrolyte is preferably dissolved in the organic solvent at a concentration of 0.5M or more and 2.5M or less.

  Examples of organic solvents include propylene carbonate (PC), ethylene carbonate (EC), cyclic carbonates such as vinylene carbonate; diethyl carbonate (DEC), dimethyl carbonate (DMC), chain like methyl ethyl carbonate (MEC) Carbonates; cyclic ethers such as tetrahydrofuran (THF), 2-methyltetrahydrofuran (2MeTHF), and dioxolane (DOX); chain ethers such as dimethoxyethane (DME) and dietoethane (DEE); or γ-butyrolactone (GBL), Acetonitrile (AN) and sulfolane (SL) are included. These organic solvents can be used alone or in the form of a mixed solvent.

  Examples of the polymer material include polyvinylidene fluoride (PVdF), polyacrylonitrile (PAN), and polyethylene oxide (PEO).

  As the compound having a trialkylsilyl group of the formula (I) contained in the nonaqueous electrolyte, those described in the first embodiment can be used.

  The content of the compound having a trialkylsilyl group in the nonaqueous electrolyte is preferably 0.02% by mass or more and 3% by mass or less with respect to the total mass of the nonaqueous electrolyte. By being 0.02 mass% or more, the compound containing a trialkylsilyl group is formed on an electrode, and the side reaction inhibitory effect is acquired.

When the content is 3% by mass or less, excessive film formation does not occur. The content is more preferably 0.5% by mass or more and 2% by mass or less.

As an example of a non-aqueous electrolyte, for example, LiPF ₆ is dissolved at a concentration of 1M in a solvent in which ethylene carbonate and diethyl carbonate are mixed at a volume ratio of 1: 2, and further, tri (trimethylsilyl) phosphate is a ratio of 1% by mass. And those dissolved in (1).

4) Separator The separator can be formed from, for example, a porous film containing polyethylene, polypropylene, cellulose, or polyvinylidene fluoride (PVdF), or a synthetic resin nonwoven fabric. Preferably, a porous film formed from polyethylene or polypropylene is used. Since these porous films can be melted at a constant temperature and cut off the current, safety can be improved.

5) Exterior member As the exterior member, a container made of a laminate film having a thickness of 0.2 mm or less or a metal container having a thickness of 0.5 mm or less can be used. The metal container is more preferably 0.2 mm or less in thickness.

  Examples of the shape of the exterior member include a flat type (thin type), a square type, a cylindrical type, a coin type, and a button type. The exterior member may be appropriately selected according to the battery size. For example, a small battery exterior member loaded on a portable electronic device or the like, or a large battery exterior member loaded on a two-wheel or four-wheel automobile or the like is used.

  As the laminate film, a multilayer film in which a metal layer is interposed between resin layers can be used. The metal layer is preferably an aluminum foil or an aluminum alloy foil for weight reduction. The resin layer is for reinforcing the metal layer, and for example, a polymer material such as polypropylene (PP), polyethylene (PE), nylon, and polyethylene terephthalate (PET) can be used. The laminate film can be formed into a desired shape by sealing by heat sealing.

  The metal container is made of aluminum or an aluminum alloy. The aluminum alloy is preferably an alloy containing one or more elements selected from magnesium, zinc, and silicon. When the alloy contains a transition metal such as iron, copper, nickel, or chromium, the amount is preferably 100 ppm or less.

In the nonaqueous electrolyte battery described above, by using a nonaqueous electrolyte containing a compound having a trialkylsilyl group, a film containing a trialkylsilyl group is formed on the surfaces of the electrode and the active material by initial charge and subsequent charge / discharge. It is formed. As described above, the coating containing a trialkylsilyl group is stable, suppresses side reactions between the titanium oxide compound having a TiO ₂ (B) structure and the nonaqueous electrolyte, and suppresses subsequent decomposition of the nonaqueous electrolyte. Can do. Thereby, formation of an excessive film can be suppressed, and an increase in resistance of the battery can be suppressed, and as a result, cycle life can be improved.

  The inclusion of a trialkylsilyl group in the film formed after charge / discharge can be detected by time-of-flight secondary ion mass spectrometry. The measurement may be performed for any of the coating formed on the electrode surface and the coating formed on the active material surface, but it is easier to measure the electrode surface. Therefore, hereinafter, a case where the electrode surface is measured will be described as an example, but the same applies to a film formed on the active material surface.

The nonaqueous electrolyte battery according to the present embodiment has a peak intensity (I ₁ ) of Si (CH ₃ ) ₃ ⁺ and Ti ⁺ when the surface of the electrode is measured by time-of-flight secondary ion mass spectrometry. The peak intensity (I ₂ ) ratio (I ₁ / I ₂ ) of the peaks is preferably 1 or more. The presence of trialkylsilyl groups in the film formed on the electrode surface results in a peak intensity ratio (I ₁ / I ₂ ) of 1 or more. The non-aqueous electrolyte battery having a peak intensity ratio (I ₁ / I ₂ ) of 1 or more on the electrode surface can further suppress an increase in resistance and have a more excellent cycle life. Note that the peak intensity ratio (I ₁ / I ₂ ) is preferably 10 or less because an excess of trialkylsilyl groups causes an increase in resistance.

  Next, as an example of the nonaqueous electrolyte battery according to the embodiment, a thin nonaqueous electrolyte battery whose exterior member is made of a laminate film will be described. FIG. 1 is a schematic cross-sectional view of a thin nonaqueous electrolyte battery, and FIG. 2 is an enlarged cross-sectional view of part A of FIG. Each figure is a schematic diagram for promoting explanation and understanding of the invention, and its shape, dimensions, ratio, etc. are different from the actual apparatus. The design can be changed as appropriate.

The flat wound electrode group 1 is housed in a bag-shaped exterior member 2 made of a laminate film in which an aluminum foil is interposed between two resin layers. The flat wound electrode group 1 is formed by winding a laminate of the negative electrode 3, the separator 4, the positive electrode 5, and the separator 4 in this order from the outside in a spiral shape and press-molding. As shown in FIG. 2, the outermost negative electrode 3 has a negative electrode layer 3b formed on one surface on the inner surface side of the negative electrode current collector 3a. In the other negative electrode 3, negative electrode layers 3b are formed on both surfaces of the negative electrode current collector 3a. The active material in the negative electrode layer 3b includes a titanium oxide compound having a TiO ₂ (B) structure. In the positive electrode 5, positive electrode layers 5b are formed on both surfaces of the positive electrode current collector 5a.

  In the vicinity of the outer peripheral end of the wound electrode group 1, the negative electrode terminal 6 is connected to the negative electrode current collector 3 a of the outermost negative electrode 3, and the positive electrode terminal 7 is connected to the positive electrode current collector 5 a of the inner positive electrode 5. . The negative electrode terminal 6 and the positive electrode terminal 7 are extended to the outside from the opening of the bag-shaped exterior member 2. The liquid non-aqueous electrolyte is injected from the opening of the bag-shaped exterior member 2. By heat-sealing the opening of the bag-shaped exterior member 2 with the negative electrode terminal 6 and the positive electrode terminal 7 extending to the outside, the wound electrode group 1 and the liquid nonaqueous electrolyte are completely sealed.

  The negative electrode terminal 6 is made of, for example, a material having electrical stability and conductivity in a range where the potential with respect to the lithium ion metal is 1 V or more and 3 V or less. Examples of the material include an aluminum alloy containing one or more elements selected from aluminum, Mg, Ti, Zn, Mn, Fe, Cu, and Si. The negative electrode terminal 6 is preferably formed of the same material as the negative electrode current collector 3a in order to reduce the contact resistance with the negative electrode current collector 3a.

  The positive electrode terminal 7 is made of a material having electrical stability and conductivity in a range of a potential with respect to the lithium ion metal of 3 to 4.5V. Examples of the material include an aluminum alloy containing one or more elements selected from aluminum, Mg, Ti, Zn, Mn, Fe, Cu, and Si. The positive electrode terminal 7 is preferably formed of the same material as the positive electrode current collector 5a in order to reduce the contact resistance with the positive electrode current collector 5a.

  According to these embodiments, it is possible to provide a nonaqueous electrolyte battery in which increase in resistance is suppressed and cycle life is improved.

  In the nonaqueous electrolyte battery according to the present embodiment, the electrode material of the first embodiment may be used as a negative electrode active material, and / or the electrode of the third embodiment may be used as a negative electrode. In such a nonaqueous electrolyte battery, the compound having a trialkylsilyl group of the formula (I) may be contained in the nonaqueous electrolyte, but it may not be contained. In any configuration, the increase in resistance is suppressed, and the cycle life of the nonaqueous electrolyte battery can be improved.

(Sixth embodiment)
Next, a battery pack according to a sixth embodiment will be described with reference to the drawings. The battery pack includes one or a plurality of nonaqueous electrolyte batteries (unit cells) according to the third embodiment. When a plurality of unit cells are included, each unit cell is electrically connected in series or in parallel.

  3 and 4 show an example of a battery pack including a plurality of flat batteries. FIG. 3 is an exploded perspective view of the battery pack. FIG. 4 is a block diagram showing an electric circuit of the battery pack of FIG.

  The plurality of single cells 8 are laminated so that the negative electrode terminal 6 and the positive electrode terminal 7 extending to the outside are aligned in the same direction, and are fastened with an adhesive tape 9 to constitute an assembled battery 10. These unit cells 8 are electrically connected to each other in series as shown in FIG.

  The printed wiring board 11 is disposed to face the side surface of the unit cell 8 from which the negative electrode terminal 6 and the positive electrode terminal 7 extend. As shown in FIG. 4, a thermistor 12, a protection circuit 13, and a terminal 14 for energizing external devices are mounted on the printed wiring board 11. An insulating plate (not shown) is attached to the surface of the printed wiring board 11 facing the assembled battery 10 in order to avoid unnecessary connection with the wiring of the assembled battery 10.

  The positive electrode side lead 15 is connected to the positive electrode terminal 7 located in the lowermost layer of the assembled battery 10, and the tip thereof is inserted into the positive electrode side connector 16 of the printed wiring board 11 and electrically connected thereto. The negative electrode side lead 17 is connected to the negative electrode terminal 6 located in the uppermost layer of the assembled battery 10, and the tip thereof is inserted into the negative electrode side connector 18 of the printed wiring board 11 and electrically connected thereto. These connectors 16 and 18 are connected to the protection circuit 13 through wirings 19 and 20 formed on the printed wiring board 11.

  The thermistor 12 is used to detect the temperature of the unit cell 8, and the detection signal is transmitted to the protection circuit 13. The protection circuit 13 can cut off the plus side wiring 21a and the minus side wiring 21b between the protection circuit 13 and the terminal 14 for energizing the external device under a predetermined condition. The predetermined condition is, for example, when the temperature detected by the thermistor 12 is equal to or higher than a predetermined temperature. The predetermined condition is when an overcharge, overdischarge, overcurrent, or the like of the cell 8 is detected. This detection of overcharge or the like is performed for each single cell 8 or the entire single cell 8. When detecting each single cell 8, the battery voltage may be detected, or the positive electrode potential or the negative electrode potential may be detected. In the latter case, a lithium electrode used as a reference electrode is inserted into each unit cell 8. In the case of FIGS. 3 and 4, the voltage detection wiring 25 is connected to each of the single cells 8, and the detection signal is transmitted to the protection circuit 13 through the wiring 25.

  Protective sheets 22 made of rubber or resin are disposed on the three side surfaces of the assembled battery 10 excluding the side surfaces from which the positive electrode terminal 7 and the negative electrode terminal 6 protrude.

  The assembled battery 10 is stored in the storage container 23 together with the protective sheets 22 and the printed wiring board 11. That is, the protective sheet 22 is disposed on each of the inner side surfaces of the storage container 23 in the long side direction and one inner side surface in the short side direction, and the printed wiring board 11 is disposed on the other inner side surface in the short side direction. The assembled battery 10 is located in a space surrounded by the protective sheet 22 and the printed wiring board 11. The lid 24 is attached to the upper surface of the storage container 23.

  In addition, instead of the adhesive tape 9, a heat shrink tape may be used for fixing the assembled battery 10. In this case, protective sheets are arranged on both side surfaces of the assembled battery, the heat shrinkable tape is circulated, and then the heat shrinkable tape is heat shrunk to bind the assembled battery.

  3 and 4 show the configuration in which the single cells 8 are connected in series, but in order to increase the battery capacity, they may be connected in parallel, or a combination of serial connection and parallel connection may be used. The assembled battery packs can be further connected in series and in parallel.

  Moreover, the aspect of a battery pack is changed suitably by a use. The battery pack is preferably one that exhibits excellent cycle characteristics when a large current is taken out. Specific examples include a power source for a digital camera, a vehicle for a two- to four-wheel hybrid electric vehicle, a two- to four-wheel electric vehicle, an assist bicycle, and the like. In particular, the vehicle-mounted one is suitable.

  According to these embodiments, it is possible to provide a battery pack having an improved cycle life by including a nonaqueous electrolyte battery having an excellent cycle life.

Example 1
<Production of negative electrode>
Particles of a titanium oxide compound (TiO ₂ ) having a TiO ₂ (B) structure were immersed in a tris (trimethylsilyl) phosphate solution, separated by filtration, and dried. Thereby, an electrode material was obtained. The specific surface area of the particles was 13.6 m ² / g.

  This electrode material, acetylene black, and PVdF were dissolved in NMP at a weight ratio of 100: 10: 10 to prepare a negative electrode slurry. This negative electrode slurry was applied on an aluminum foil and dried to obtain a negative electrode.

<Production of evaluation cell>
A cell was produced using the negative electrode produced above, lithium metal as the counter electrode, and a glass filter as the separator. In an atmosphere of dry argon, a negative electrode and a counter electrode were placed in a tripolar glass cell so as to face each other via a separator, and a reference electrode made of lithium metal was inserted so as not to contact the negative electrode and the counter electrode.

  Each of the negative electrode, the counter electrode, and the reference electrode was connected to the terminal of the glass cell, and a nonaqueous electrolyte was poured. The glass container was sealed while the separator and the electrode were sufficiently impregnated with the nonaqueous electrolyte.

As the non-aqueous electrolyte, a solution obtained by dissolving 1.0 mol / L of LiPF ₆ as an electrolyte in a mixed solvent in which ethylene carbonate (EC) and diethyl carbonate (DEC) were mixed at a volume ratio of 1: 2 was used.

(Example 2)
Except that a titanium oxide compound having a TiO ₂ (B) structure, acetylene black, PVdF, and tris (trimethylsilyl) phosphate were dissolved in NMP at a weight ratio of 100: 10: 10: 2 to prepare a negative electrode slurry. Produced an evaluation cell in the same manner as in Example 1.

(Example 3)
A titanium oxide compound having a TiO ₂ (B) structure, acetylene black, and PVdF were dissolved in NMP to prepare a negative electrode slurry. This negative electrode slurry was applied onto an aluminum foil and dried to prepare a negative electrode.

LiPF ₆ was dissolved at a concentration of 1.0 mol / L in a mixed solvent in which ethylene carbonate (EC) and diethyl carbonate (DEC) were mixed at a volume ratio of 1: 2, and further 2% by mass of tris (trimethylsilyl) phosphate. A non-aqueous electrolyte was prepared by dissolving at a concentration.

  An evaluation cell was prepared in the same manner as in Example 1 using the negative electrode prepared above and a nonaqueous electrolyte.

Example 4
An evaluation cell was prepared in the same manner as in Example 3 except that a nonaqueous electrolyte was prepared using tris (trimethylsilyl) borate instead of tris (trimethylsilyl) phosphate.

(Example 5)
An evaluation cell was prepared in the same manner as in Example 3 except that the nonaqueous electrolyte was prepared using tris (triethylsilyl) phosphate instead of tris (trimethylsilyl) phosphate.

(Example 6)
An evaluation cell was prepared in the same manner as in Example 3 except that a nonaqueous electrolyte was prepared using tris (triethylsilyl) borate instead of tris (trimethylsilyl) phosphate.

(Example 7)
An evaluation cell was prepared in the same manner as in Example 3 except that a non-aqueous electrolyte was prepared using tris (butyldimethylsilyl) phosphate instead of tris (trimethylsilyl) phosphate.

(Comparative Example 1)
A titanium oxide compound having a TiO ₂ (B) structure, acetylene black, and PVdF were dissolved in NMP to prepare a negative electrode slurry. This negative electrode slurry was applied onto an aluminum foil and dried to prepare a negative electrode.

A nonaqueous electrolyte was prepared by dissolving LiPF ₆ at a concentration of 1.0 mol / L in a mixed solvent in which ethylene carbonate (EC) and diethyl carbonate (DEC) were mixed at a volume ratio of 1: 2.

  An evaluation cell was prepared in the same manner as in Example 1 using the negative electrode prepared above and a nonaqueous electrolyte.

(Comparative Example 2)
LiPF ₆ is dissolved at a concentration of 1.0 mol / L in a mixed solvent in which ethylene carbonate (EC) and diethyl carbonate (DEC) are mixed at a volume ratio of 1: 2, and 2% by mass of vinylene carbonate is further dissolved. A water electrolyte was prepared.

  An evaluation cell was prepared in the same manner as in Comparative Example 1 except that this nonaqueous electrolyte was used.

(Comparative Example 3)
An evaluation cell was prepared in the same manner as in Comparative Example 2 except that a non-aqueous electrolyte was prepared using fluoroethylene carbonate instead of vinylene carbonate.

(Comparative Example 4)
An evaluation cell was prepared in the same manner as in Comparative Example 2 except that a non-aqueous electrolyte was prepared using vinyl ethylene carbonate instead of vinylene carbonate.

(Charge / discharge test)
Using the cells for evaluation of Examples 1 to 7 and Comparative Examples 1 to 4, charge and discharge were repeated 25 and 50 cycles (one cycle by charge / discharge), and the resistance increase rate was examined. Charging / discharging was performed under the conditions of a charging / discharging rate: 20 mA / g and 200 mA / g, and a voltage range: 1.0 to 3.0 V.

The battery was discharged at a current density of 20 mA / g and 200 mA / g from the fully charged state, and the DC resistance value (R ₁ ) was calculated from the cell voltage 10 seconds after the discharge. In addition, the resistance value after 25 cycles (R ₂₅ ) and the resistance value after 50 cycles (R ₅₀ ) were measured in the same manner, and the resistance increase rate (R ₂₅ / R ₁ and R ₅₀ / R ₁ ) was obtained. The results are shown in Table 1. Moreover, the graph of the resistance increase rate of Examples 1-3 and Comparative Examples 1-4 was shown in FIG.

(Time-of-flight secondary ion mass spectrometry)
The evaluation cells of Examples 1 to 7 and Comparative Examples 1 to 4 after 50 cycles of charge and discharge were subjected to time-of-flight secondary ion mass spectrometry. Example 1 measured the active material surface, and others measured the negative electrode surface. The results are shown in Table 1.

In all of Examples 1 to 7, the peak intensity ratio I ₁ / I ₂ was 1 or more. On the other hand, in Comparative Examples 1 to 4, the peak intensity ratio I ₁ / I ₂ was less than 1. From this, it was shown that the peak intensity ratio I ₁ / I ₂ was 1 or more by including a compound having a trialkylsilyl group in any of the electrode material, the electrode, and the nonaqueous electrolyte.

  Moreover, compared with Comparative Examples 1-4, Examples 1-7 have a low resistance increase rate, and by including the compound which has a trialkylsilyl group in any of electrode material, an electrode, and a nonaqueous electrolyte, after a cycle It was shown that the resistance increase was suppressed.

Comparative Example 2 contains vinylene carbonate, which is reported to have a film formation inhibitory effect when a carbonaceous material negative electrode is used, in a non-aqueous electrolyte. Since the rate of increase in resistance in Comparative Example 2 was higher than that in Comparative Example 1, in the battery using a titanium oxide compound having a TiO ₂ (B) structure as an active material, the effect of suppressing film formation by vinylene carbonate may not be obtained. Indicated.

  Comparative Example 3 contains fluoroethylene carbonate in a non-aqueous electrolyte. The resistance increase rate of Comparative Example 3 was significantly higher than Comparative Examples 1, 2, and 4. This suggests that fluorine contained in fluoroethylene carbonate acts and an inorganic coating containing LiF or the like was excessively formed.

  Comparative Example 4 contains vinyl ethylene carbonate in a non-aqueous electrolyte. Comparative Example 4 showed a resistance increase rate comparable to that of Comparative Example 2. From this, it was shown that the effect of inhibiting film formation cannot be obtained even with vinylethylene carbonate.

(Comparative Example 5)
An evaluation cell was prepared in the same manner as in Example 1 except that lithium titanate was used instead of the titanium oxide compound having the TiO ₂ (B) structure.

(Comparative Example 6)
An evaluation cell was prepared in the same manner as in Example 2 except that lithium titanate was used instead of the titanium oxide compound having the TiO ₂ (B) structure.

(Comparative Example 7)
An evaluation cell was prepared in the same manner as in Example 3 except that lithium titanate was used instead of the titanium oxide compound having the TiO ₂ (B) structure.

(Charge / discharge test)
Using the evaluation cells of Comparative Examples 5 to 7, a charge / discharge test was performed in the same manner as described above to obtain the resistance increase rate. The results are shown in Table 2.

  In each of Comparative Examples 5 to 7, the resistance increase rate after the cycle was extremely low.

(Time-of-flight secondary ion mass spectrometry)
The evaluation cells of Comparative Examples 5 to 7 after 50 cycles of charge and discharge were subjected to time-of-flight secondary ion mass spectrometry on the negative electrode surface. As a result, the peak intensity ratios I ₁ / I ₂ for Comparative Examples 5 to 7 were all less than 0.1.

  From Comparative Example 5 and Comparative Example 6, tris (trimethylsilyl) phosphate did not act on the lithium titanate surface, and no trialkylsilyl group was detected.

  In Comparative Example 7, since lithium titanate has low surface solid acidity, an excessive film is not formed. Moreover, since tri (trimethylsilyl) phosphate does not act on the lithium titanate surface, it is considered that a trialkylsilyl group was not detected.

Since the trialkylsilyl group was not detected in Comparative Examples 5 to 7, the reason why the resistance increase rate of Comparative Examples 5 to 7 was low was not due to the trialkylsilyl group. Therefore, it was shown that the effect of suppressing the increase in resistance by forming a film containing a trialkylsilyl group is obtained in a battery using a titanium oxide compound having a TiO ₂ (B) structure.

  Although several embodiments of the present invention have been described, these embodiments are presented by way of example and are not intended to limit the scope of the invention. These novel embodiments can be implemented in various other forms, and various omissions, replacements, and changes can be made without departing from the scope of the invention. These embodiments and modifications thereof are included in the scope and gist of the invention, and are included in the invention described in the claims and the equivalents thereof.

Supplementary Note [1] An active material containing a titanium oxide compound having a monoclinic titanium dioxide crystal structure and a compound having a trialkylsilyl group of formula (I) present on the surface of the active material Characteristic electrode material. In the formula (I), R ¹ , R ² and R ³ are the same or different and represent an alkyl group having 1 to 10 carbon atoms.
[2] The peak intensity ratio (I ₁ / I ₂ ) satisfies the formula (II) when the surface of the electrode material is measured by time-of-flight secondary ion mass spectrometry, [1] Electrode materials described in:
1 ≦ I ₁ / I ₂ (II)
Here, I ₁ is the peak intensity of Si (CH ₃ ) ₃ ⁺ , and I ₂ is the peak intensity of Ti ⁺ .
[3] Immersing particles of a titanium oxide compound having a monoclinic titanium dioxide crystal structure in a solution of a compound having a trialkylsilyl group of formula (I), and a compound having the trialkylsilyl group Separating the titanium oxide compound to which is attached, and a method for producing an electrode material. In the formula (I), R ¹ , R ² and R ³ are the same or different and represent an alkyl group having 1 to 10 carbon atoms.
[4] The compound containing a trialkylsilyl group is at least one compound selected from a phosphoric acid compound containing a trialkylsilyl group or a boric acid compound containing a trialkylsilyl group [3] The manufacturing method as described in.
[5] A battery electrode comprising an active material containing a titanium oxide compound having a monoclinic titanium dioxide crystal structure, and a compound having a trialkylsilyl group of formula (I). In the formula (I), R ¹ , R ² and R ³ are the same or different and represent an alkyl group having 1 to 10 carbon atoms.
[6] The peak intensity ratio (I ₁ / I ₂ ) satisfies the formula (II) when the surface of the battery electrode is measured by time-of-flight secondary ion mass spectrometry, [5] The battery electrode according to:
1 ≦ I ₁ / I ₂ (II)
Here, I ₁ is the peak intensity of Si (CH ₃ ) ₃ ⁺ , and I ₂ is the peak intensity of Ti ⁺ .
[7] preparing a slurry by dispersing an active material containing a titanium oxide compound having a monoclinic titanium dioxide crystal structure and a compound having a trialkylsilyl group of formula (I) in a solvent; The manufacturing method of the electrode for batteries. In the formula (I), R ¹ , R ² and R ³ are the same or different and represent an alkyl group having 1 to 10 carbon atoms.
[8] The compound containing a trialkylsilyl group is at least one compound selected from a phosphoric acid compound containing a trialkylsilyl group or a boric acid compound containing a trialkylsilyl group [7] The manufacturing method as described in.
[9] A negative electrode containing an active material containing a titanium oxide compound having a monoclinic titanium dioxide crystal structure, a positive electrode, and a non-aqueous electrolyte, wherein the non-aqueous electrolyte is a trialkylsilyl group of the formula (I) A non-aqueous electrolyte battery comprising a compound having: In the formula (I), R ¹ , R ² and R ³ are the same or different and represent an alkyl group having 1 to 10 carbon atoms.
[10] The peak intensity ratio (I ₁ / I ₂ ) satisfies the formula (II) when the surface of the negative electrode is measured by time-of-flight secondary ion mass spectrometry, [9] Non-aqueous electrolyte battery described:
1 ≦ I ₁ / I ₂ (II)
Here, I ₁ is the peak intensity of Si (CH ₃ ) ₃ ⁺ , and I ₂ is the peak intensity of Ti ⁺ .
[11] The compound containing a trialkylsilyl group is at least one compound selected from a phosphoric acid compound containing a trialkylsilyl group or a boric acid compound containing a trialkylsilyl group [9] Or the nonaqueous electrolyte battery as described in [10].
[12] A battery pack comprising the nonaqueous electrolyte battery according to any one of [9] to [11].

  DESCRIPTION OF SYMBOLS 1 ... Positive electrode terminal, 2 ... Negative electrode terminal, 3 ... Positive electrode, 3a ... Positive electrode collector, 3b ... Positive electrode layer, 4 ... Negative electrode, 4a ... Negative electrode collector, 4b ... Negative electrode layer, 5 ... Separator, 6 ... Winding Electrode, 7 ... exterior member, 11 ... single battery, 12 ... printed wiring board, 13 ... positive electrode terminal, 14 ... negative electrode terminal, 15 ... positive electrode side wiring, 16 ... positive electrode side connector, 17 ... negative electrode side wiring, 18 ... negative electrode side Connector, 19 ... adhesive tape, 20 ... battery laminate, 21 ... protective sheet, 22 ... protective block, 23 ... storage container, 24 ... lid.

Claims (8)

A battery electrode comprising: an active material containing a titanium oxide compound having a monoclinic titanium dioxide crystal structure; and a compound having a trialkylsilyl group of formula (I):
Here, R ¹ , R ² and R ³ are the same or different and represent an alkyl group having 1 to 10 carbon atoms. The peak intensity ratio (I ₁ / I ₂ ) satisfies the formula (II) when the surface of the battery electrode is measured by time-of-flight secondary ion mass spectrometry. Battery electrodes:
1 ≦ I ₁ / I ₂ (II)
Here, I ₁ is the peak intensity of Si (CH ₃ ) ₃ ⁺ , and I ₂ is the peak intensity of Ti ⁺ . For a battery, comprising preparing a slurry by dispersing an active material containing a titanium oxide compound having a crystal structure of monoclinic titanium dioxide and a compound having a trialkylsilyl group of formula (I) in a solvent Electrode manufacturing method:
Here, R ¹ , R ² and R ³ are the same or different and represent an alkyl group having 1 to 10 carbon atoms.   The compound containing a trialkylsilyl group is at least one compound selected from a phosphoric acid compound containing a trialkylsilyl group or a boric acid compound containing a trialkylsilyl group. Production method. A negative electrode including an active material including a titanium oxide compound having a monoclinic titanium dioxide crystal structure;
A positive electrode;
Including non-aqueous electrolytes,
Nonaqueous electrolyte battery characterized in that the nonaqueous electrolyte contains a compound having a trialkylsilyl group of the formula (I):
Here, R ¹ , R ² and R ³ are the same or different and represent an alkyl group having 1 to 10 carbon atoms. The non-polarity according to claim 5, wherein the peak intensity ratio (I ₁ / I ₂ ) satisfies the formula (II) when the surface of the negative electrode is measured by time-of-flight secondary ion mass spectrometry. Water electrolyte battery:
1 ≦ I ₁ / I ₂ (II)
Here, I ₁ is the peak intensity of Si (CH ₃ ) ₃ ⁺ , and I ₂ is the peak intensity of Ti ⁺ .   The compound containing a trialkylsilyl group is at least one compound selected from a phosphoric acid compound containing a trialkylsilyl group or a boric acid compound containing a trialkylsilyl group. The nonaqueous electrolyte battery described.   A battery pack comprising the nonaqueous electrolyte battery according to claim 1.