JP6652534B2 - Electrodes, non-aqueous electrolyte batteries, battery packs and vehicles - Google Patents

Description

  Embodiments of the present invention relate to an electrode, a nonaqueous electrolyte battery, a battery pack, and a vehicle.

  Non-aqueous electrolyte batteries in which charging and discharging are performed by moving lithium ions between a negative electrode and a positive electrode are being actively studied as high energy density batteries.

  This nonaqueous electrolyte battery is expected to be used not only as a power source for small electronic devices, but also as a medium-large power source for in-vehicle use and stationary use. In such medium and large-sized applications, the non-aqueous electrolyte battery is required to have a long life characteristic and high safety. Further, non-aqueous electrolyte batteries also require high input / output characteristics.

As an example of a non-aqueous electrolyte battery having long life characteristics and high safety, a non-aqueous electrolyte battery using lithium titanate having a spinel-type crystal structure in a negative electrode is known. Lithium titanate having a spinel type crystal structure has a high lithium storage / release potential of about 1.55 V (vs. Li / Li ⁺ ). Therefore, a nonaqueous electrolyte battery using lithium titanate having a spinel-type crystal structure for the negative electrode has a low battery voltage. In addition, lithium titanate having a spinel-type crystal structure has a feature in that a change in potential due to a change in a charged state is extremely small in a range of lithium occlusion and release potential. That is, the charge / discharge curve of the spinel-type lithium titanate includes a flat portion of the potential in the range of lithium storage and release potential.

  In such a non-aqueous electrolyte battery, further improvement in life characteristics is required.

JP 2015-79742 A JP-A-2006-35902 JP-A-2006-103325 JP-A-2006-171071 JP-A-2006-146359 International Patent Publication No. WO 2013/022034

The Japan Society for Analytical Chemistry, X-ray Analysis Research Roundtable, edited by Izumi Nakai and Fujio Izumi, "Practical Practice of Powder X-Ray Analysis", 2nd edition, Asakura Shoten, published July 10, 2009, p. 97-115

  An object is to provide an electrode capable of obtaining excellent life characteristics, a non-aqueous electrolyte battery capable of exhibiting excellent life characteristics, a battery pack including the non-aqueous electrolyte battery, and a vehicle including the battery pack. And

According to an embodiment, an electrode is provided. This electrode has an active material containing layer. The active material-containing layer contains a Na-containing niobium titanium composite oxide having an orthorhombic crystal structure. The active material containing layer satisfies I ₂ / I ₁ ≧ 1. I ₁ is a peak P ₁ that appears in a binding energy range of 289 to 292 eV in an X-ray photoelectron spectroscopy (XPS) obtained by X-ray photoelectron spectroscopy (XPS) of the active material-containing layer. The strength of I ₂ is the intensity of the peak P ₂ appearing in the binding energy range of 283 to 285 eV in the X-ray photoelectron spectroscopy spectrum of the active material containing layer.

According to an embodiment, a non-aqueous electrolyte battery is provided. This non-aqueous electrolyte battery includes a negative electrode, a positive electrode, and a non-aqueous electrolyte. The negative electrode includes a negative electrode active material containing layer. The negative electrode active material-containing layer contains a Na-containing niobium titanium composite oxide having an orthorhombic crystal structure. The negative electrode active material-containing layer satisfies I ₂ / I ₁ ≧ 1. I ₁ is a peak P appearing in a binding energy range of 289 to 292 eV in an X-ray photoelectron spectroscopy (XPS) obtained by X-ray Photoelectron Spectroscopy (XPS) of the negative electrode active material-containing layer. ₁ strength. I ₂ is the intensity of the peak P ₂ that appears in the binding energy range of 283 to 285 eV in the X-ray photoelectron spectrum of the negative electrode active material-containing layer.

  According to an embodiment, a battery pack is provided. This battery pack includes the nonaqueous electrolyte battery according to the embodiment.

  According to an embodiment, a vehicle is provided. This vehicle is equipped with the battery pack according to the embodiment.

3 is a part of an XPS spectrum of each of a surface of a negative electrode included in a nonaqueous electrolyte battery of an example according to the embodiment and a surface of a negative electrode included in a battery of a reference example. FIG. 1 is a cross-sectional view illustrating an example of a nonaqueous electrolyte battery according to an embodiment. The enlarged sectional view of the A section of FIG. FIG. 4 is a partially cutaway perspective view schematically showing another example of the nonaqueous electrolyte battery according to the embodiment. FIG. 5 is an enlarged sectional view of a portion B in FIG. FIG. 1 is an exploded perspective view illustrating an example of a battery pack according to an embodiment. FIG. 7 is a block diagram showing an electric circuit of the battery pack in FIG. 6. FIG. 1 is a schematic sectional view of an example of a vehicle according to an embodiment. The figure which shows the structure of the vehicle of another example which concerns on embodiment. FIG. 2 is a schematic view showing a part of the procedure for manufacturing the nonaqueous electrolyte battery of Example 1. FIG. 2 is a schematic view showing a part of the procedure for manufacturing the nonaqueous electrolyte battery of Example 1. FIG. 2 is a schematic view showing a part of the procedure for manufacturing the nonaqueous electrolyte battery of Example 1. FIG. 2 is a schematic view showing a part of the procedure for manufacturing the nonaqueous electrolyte battery of Example 1. FIG. 2 is a schematic view showing a part of the procedure for manufacturing the nonaqueous electrolyte battery of Example 1. FIG. 2 is a schematic view showing a part of the procedure for manufacturing the nonaqueous electrolyte battery of Example 1. 4 is a part of each XPS spectrum on the surface of the negative electrode included in each of the nonaqueous electrolyte batteries of Example 1 and Comparative Example 1.

  Hereinafter, embodiments will be described with reference to the drawings. Note that the same reference numerals are given to the same components throughout the embodiments, and redundant description will be omitted. In addition, each drawing is a schematic diagram for promoting the explanation and understanding of the embodiment, and the shape, dimensions, ratio, and the like are different from those of an actual device. In consideration of the above, the design can be appropriately changed.

(First embodiment)
According to a first embodiment, an electrode and a non-aqueous electrolyte battery are provided. This non-aqueous electrolyte battery includes the electrode as a negative electrode, a positive electrode, and a non-aqueous electrolyte. The negative electrode includes a negative electrode active material containing layer. The negative electrode active material-containing layer contains a Na-containing niobium titanium composite oxide having an orthorhombic crystal structure. The negative electrode active material-containing layer satisfies I ₂ / I ₁ ≧ 1. I ₁ is the intensity of the peak P ₁ appearing in the binding energy range of 289 to 292 eV in the X-ray photoelectron spectroscopy spectrum obtained by the X-ray photoelectron spectroscopy on the negative electrode active material containing layer. I ₂ is the intensity of the peak P ₂ that appears in the binding energy range of 283 to 285 eV in the X-ray photoelectron spectrum of the negative electrode active material-containing layer.

The Na-containing niobium titanium composite oxide having an orthorhombic crystal structure included in the negative electrode of the nonaqueous electrolyte battery according to the first embodiment can occlude or release Li at a low potential among titanium-containing oxides. It is a composite oxide. For example, has the crystal structure of orthorhombic Akiragata and general formula _{Li 2 + v Na 2-w} M1 x Ti 6-yz Nb y M2 z O 14 + Na -containing niobium titanium composite oxide represented by _δ, the 1 Lithium occlusion and release potential in the range of 0.2 to 1.4 V (vs. Li / Li ⁺ ), that is, an operating potential. In the above general formula, M1 is at least one selected from the group consisting of Cs, K, Mg, Sr, Ba and Ca, and M2 is Zr, Sn, V, Ta, Mo, W, Fe, Co , Mn and Al, at least one selected from the group consisting of 0 ≦ v ≦ 4, 0 <w <2, 0 ≦ x <2, 0 <y <2, 0 ≦ z <3, −0. 5 ≦ δ ≦ 0.5.

  Further, for example, the Na-containing niobium titanium composite oxide having an orthorhombic crystal structure and represented by the above general formula may show a large potential change with a change in the state of charge in the operating potential range. it can.

  Therefore, the non-aqueous electrolyte battery using the Na-containing niobium titanium composite oxide having the orthorhombic crystal structure in the negative electrode shows a higher battery voltage than the non-aqueous electrolyte battery using lithium titanate in the negative electrode. And the state of charge can be easily grasped based on the change in potential.

  However, as a result of earnest studies, the inventors have found that the orthorhombic Na-containing niobium titanium composite oxide has a high reactivity, and thus has a problem that a side reaction easily occurs with the nonaqueous electrolyte. . And it turned out that the non-aqueous electrolyte battery using the orthorhombic-type Na-containing niobium titanium composite oxide has a problem that the life characteristics are inferior due to this side reaction. As a result of intensive studies to solve this problem, the inventors have realized a nonaqueous electrolyte battery according to the first embodiment.

The non-aqueous electrolyte battery according to the first embodiment includes a Na-containing niobium titanium composite oxide having an orthorhombic crystal structure and is subjected to X-ray photoelectron spectroscopy (X-ray Photoelectron Spectroscopy: XPS). intensity ratio I ₂ / I ₁ is provided with a negative electrode active material-containing layer which is 1 or more in the spectrum (XPS spectrum). In such a nonaqueous electrolyte battery, a film containing a CC portion and / or a CH _α portion (here, α is 1 or more and 3 or less) is sufficiently formed on a negative electrode active material-containing layer. Can be said. The detailed reason will be described below with reference to FIG. In the non-aqueous electrolyte battery according to the first embodiment, the negative electrode active material-containing layer contains the Na-containing niobium titanium composite oxide having the orthorhombic crystal structure. Can prevent a side reaction between the Na-containing niobium titanium composite oxide and the non-aqueous electrolyte. As a result, the nonaqueous electrolyte battery according to the first embodiment can exhibit excellent life characteristics.

  Next, the reason why a sufficient film is formed on the surface of the negative electrode active material-containing layer in the nonaqueous electrolyte battery according to the first embodiment will be described with reference to FIG.

  FIG. 1 shows a part of each of the XPS spectra of the surface of the negative electrode included in the nonaqueous electrolyte battery of the example according to the first embodiment and the surface of the negative electrode included in the battery of the reference example.

  The spectrum (1) indicated by the solid line in FIG. 1 is an XPS spectrum related to the C1s orbit on the surface of the negative electrode included in the nonaqueous electrolyte battery of the first example according to the first embodiment. The spectrum (2) indicated by a broken line in FIG. 1 shows the non-aqueous electrolyte of Reference Example 1 produced in the same manner as the non-aqueous electrolyte battery of the first example except that the aging treatment described in detail below was not performed. 5 is an XPS spectrum related to a C1s orbit on a surface of a negative electrode included in an electrolyte battery. The spectrum (3) indicated by the dotted line in FIG. 1 is included in the nonaqueous electrolyte battery of Reference Example 2 manufactured in the same manner as the nonaqueous electrolyte battery of the first example except that the composition of the nonaqueous electrolyte was changed. 5 is an XPS spectrum related to a C1s orbit on a surface of a negative electrode to be measured. In Reference Example 2, the non-aqueous electrolyte contained in the battery unit subjected to aging did not contain ethylene carbonate.

In three spectra shown in FIG. 1 (1) to (3), a peak P ₁ having a peak top in the binding energy range of 289~292eV appears to XPS spectra for the surface of the front of the negative electrode incorporated in the battery. Thus, the peak P ₁ may be the constituent material of the anode active material-containing layer, that is specifically a peak derived from a conductive agent and a binder.

Comparing the three spectra (1) to (3) shown in FIG. 1, the intensity I ₁ of the peak P ₁ is the most in the spectrum (1) relating to the battery of the first example according to the first embodiment. It turns out to be small. On the other hand, it can be seen that the peak P ₁ shows the same intensity in the spectra (2) and (3) for the batteries of Reference Examples 1 and 2.

On the other hand, in the three spectra shown in FIG. 1 (1) to (3), a peak P ₂ have a peak top in the binding energy range of 283~285eV may behave differently than the peak P _1. Specifically, as apparent from FIG. 1, the intensity I ₂ of the peak P ₂ in the spectrum (1) is larger than those in the spectra (2) and (3). Also, it can be seen that the intensity I ₂ of the peak P ₂ is the smallest in the spectrum (2) of the battery of Reference Example 1 in which aging was not performed. From this fact, it can be seen that the peak P ₂ is a peak derived from a substance generated by aging described in detail below.

In summary, from the behavior of the peak P _{1, in} the negative electrode showing the XPS spectrum (1), since any substance, that is, a surface film is formed on the surface of the negative electrode active material containing layer, the negative electrode active material contains intensity I ₁ of the derived peak P ₁ is considered small. Further, from the behavior of the peak P _2, the surface coating is formed on the surface of the negative electrode active material-containing layer of the negative electrode showing the XPS spectra (1) may be seen to be a substance produced by aging, described in detail below .

The peak P ₁ can be attributed to C constituting the COO moiety and / or CO ₃ ^2- moiety. The peak P ₂ is (are alpha, where in is 1 to 3) C-C section and / or CH _alpha moiety may be attributed to C constituting the.

Furthermore, the peak P ₃ showing a peak top in the binding energy range 284~286eV of the spectrum (3), as the peak P _2, can be attributed to C constituting the C-C section and / or CH _alpha moiety. It is considered that the peak P ₃ has a peak top in a higher energy region than the peak P ₂ because a film due to aging is not sufficiently formed.

The prominent peaks P ₄ in the spectrum (2) shows a peak top in the binding energy range 286～287EV. The peak P ₄ can be attributed to C constituting the C-O moiety and / or C-N moiety.

  The coating formed on the surface of the negative electrode active material-containing layer can suppress a side reaction between the Na-containing niobium titanium composite oxide contained in the negative electrode active material-containing layer and the nonaqueous electrolyte.

Intensity ratio I ₂ / I ₁ is the intensity of peak P ₂ derived from the components of the surface coating is the ratio to the intensity of the peak P ₁ derived from the component of the constituent material of the anode active material-containing layer. In the non-aqueous electrolyte battery according to the first embodiment in which the intensity ratio I ₂ / I ₁ is 1 or more, as described above, a sufficient film is formed on the surface of the negative electrode active material-containing layer, A side reaction between the Na-containing niobium titanium composite oxide contained in the negative electrode active material-containing layer and the nonaqueous electrolyte can be suppressed. As a result, the nonaqueous electrolyte battery according to the first embodiment can exhibit excellent life characteristics.

On the other hand, in a non-aqueous electrolyte battery having a strength ratio I ₂ / I ₁ of less than 1, a sufficient film is not formed on the surface of the negative electrode active material-containing layer. Such a non-aqueous electrolyte battery cannot sufficiently suppress the side reaction between the Na-containing niobium titanium composite oxide contained in the negative electrode active material-containing layer and the non-aqueous electrolyte, and cannot exhibit excellent life characteristics.

The intensity ratio I ₂ / I ₁ is preferably 5 or less. When the intensity ratio I ₂ / I ₁ is 1 or more and 5 or less, the coating is more appropriately formed. The intensity ratio I ₂ / I ₁ is more preferably 1 or more and 3 or less.

Note that, for example, lithium titanate having a spinel type crystal structure (eg, Li ₄ Ti ₅ O ₁₂ ) has a higher reactivity with a nonaqueous electrolyte than a Na-containing niobium titanium composite oxide having an orthorhombic type crystal structure. Low. Therefore, a non-aqueous electrolyte battery including a negative electrode that does not include a Na-containing niobium titanium composite oxide having an orthorhombic crystal structure and instead includes a lithium titanate having a spinel crystal structure has an intensity ratio of I ₂ No improvement in life characteristics can be expected by setting / I ₁ to 1 or more. This is presumably because lithium titanate has a higher operating potential than a Na-containing niobium titanium composite oxide having an orthorhombic crystal structure, and thus it is difficult to form a film on the surface of the negative electrode. Further, lithium titanate, regardless of the value of the intensity ratio I ₂ / I _1, it is possible to exhibit excellent cycle characteristics.

Hereinafter, the nonaqueous electrolyte battery according to the first embodiment will be described in more detail.
The non-aqueous electrolyte battery according to the first embodiment includes a negative electrode, a positive electrode, and a non-aqueous electrolyte.

  The negative electrode includes a negative electrode active material containing layer. The negative electrode may further include a negative electrode current collector. The negative electrode current collector can have two surfaces facing in opposite directions. The negative electrode current collector has, for example, a band shape. The negative electrode active material-containing layer can be supported on both surfaces or one surface of the negative electrode current collector. The negative electrode current collector may include a portion that does not support the negative electrode active material-containing layer. This portion can serve, for example, as a negative electrode tab. Alternatively, the negative electrode may include a negative electrode tab separate from the negative electrode current collector.

  The negative electrode active material containing layer can include a negative electrode active material. The Na-containing niobium titanium composite oxide having an orthorhombic crystal structure may be included in the negative electrode active material-containing layer as the negative electrode active material or as a part of the negative electrode active material. The negative electrode active material-containing layer may further include a conductive agent and a binder.

  The negative electrode active material containing layer can constitute the surface of the negative electrode. That is, it can be said that the X-ray photoelectron spectrum of the negative electrode is the X-ray photoelectron spectrum of the surface of the negative electrode active material-containing layer.

As described above, in the nonaqueous electrolyte battery according to the first embodiment, a film is formed on the surface of the negative electrode active material-containing layer. However, this film is extremely thin compared to the thickness of the negative electrode active material-containing layer, and it is difficult to confirm its existence as an image not only with the naked eye but also with, for example, a scanning electron microscope. However, if the intensity ratio I ₂ / I _{1 of} the negative electrode active material-containing layer obtained by the X-ray photoelectron spectroscopy spectrum is 1 or more, a sufficient film is formed on the surface of the negative electrode active material-containing layer for the reason described above. It can be said that it is formed. In addition, although the presence of the coating and the origin thereof can be confirmed from the XPS results, it is difficult to confirm the composition of the coating itself.

  The positive electrode can include a positive electrode current collector and a positive electrode active material-containing layer. The positive electrode current collector can have two surfaces facing in opposite directions. The positive electrode current collector has, for example, a belt shape. The positive electrode active material-containing layer can be supported on both surfaces or one surface of the positive electrode current collector. The positive electrode current collector may include a portion that does not support the positive electrode active material-containing layer. This portion can serve, for example, as a positive electrode tab. Alternatively, the positive electrode may include a positive electrode tab separate from the positive electrode current collector. The positive electrode active material-containing layer can include, for example, a positive electrode active material, a conductive agent, and a binder.

  The nonaqueous electrolyte battery according to the first embodiment may further include a separator, an exterior member, a positive electrode terminal, and a negative electrode terminal.

  The positive electrode and the negative electrode can form an electrode group with a separator interposed therebetween. The non-aqueous electrolyte can be retained on the electrode group. The electrode group can take various modes. For example, the electrode group may be of a stack type. The stacked electrode group can be obtained, for example, by laminating a plurality of positive electrodes and a plurality of negative electrodes with a separator interposed between the positive electrode and the negative electrode. Alternatively, the electrode group may be of a wound type. The wound electrode group can be obtained, for example, by winding a laminate obtained by laminating a positive electrode and a negative electrode with a separator interposed therebetween. The wound body may be subjected to a press. The electrode group may have a structure other than the above structure.

  The exterior member can accommodate the electrode group and the non-aqueous electrolyte. The positive electrode terminal can be electrically connected to the positive electrode. The negative electrode terminal can be electrically connected to the negative electrode.

  Hereinafter, the positive electrode, the negative electrode, the nonaqueous electrolyte, the separator, the exterior member, the positive electrode terminal, and the negative electrode terminal will be described in detail.

1) Positive electrode The positive electrode current collector is preferably an aluminum foil or an aluminum alloy foil containing at least one element selected from Mg, Ti, Zn, Mn, Fe, Cu and Si.

  The thickness of the aluminum foil and the aluminum alloy foil is, for example, 20 μm or less, and more preferably 15 μm or less. The purity of the aluminum foil is preferably 99% by mass or more. As the aluminum alloy, an alloy containing elements such as magnesium, zinc, and silicon is preferable. On the other hand, the content of transition metals such as iron, copper, nickel, and chromium is preferably 1% or less.

As the positive electrode active material, for example, manganese dioxide (MnO ₂ ), iron oxide, copper oxide, nickel oxide, and lithium manganese composite oxide (for example, Li _x Mn _2-y M) capable of inserting and extracting lithium can be used. _y O ₄ or _{Li x Mn 1-y M y} O 2), lithium nickel composite oxides (e.g., _{Li x Ni 1-x M y} O 2), lithium cobalt composite oxide (e.g., Li _x Co _1-y M y O _2), lithium nickel cobalt composite oxide (e.g., _{Li x Ni 1-yz Co y} M z O 2), lithium manganese cobalt composite oxides (e.g., _{Li x Mn 1-yz Co y} M z O 2), lithium nickel cobalt-manganese composite oxide _{(e.g., Li x Ni 1-yz Co} y Mn z O 2), lithium-nickel-cobalt-aluminum composite oxide _{(e.g., Li x Ni 1-yz Co} y Al z O 2), spinel Lithium manganese nickel complex oxide having a crystal structure (e.g., _{Li x Mn 2-y Ni y} O 4), lithium phosphorus oxides having the crystal structure of olivine _{(e.g., Li x FePO 4, Li x} MnPO 4, Li x Mn _1-y Fe _y PO ₄ , Li _x CoPO _4, Li _x Mn _1-yz F _y M _z PO ₄ ), iron sulfate (Fe ₂ (SO ₄ ) ₃ ), and vanadium oxide (for example, V ₂ O ₅₎ ) Can be used. In the above, 0 <x ≦ 1, 0 ≦ y ≦ 1, and preferably 0 ≦ z ≦ 1. In the above, M is at least one element selected from the group consisting of Mg, Ca, Al, Ti, Zn and Zr.

Among them, lithium-manganese composite oxide _{(Li x Mn 2-y M} y O 4), lithium cobalt composite oxide _{(Li x Co 1-y M} y O 2), lithium nickel cobalt composite oxide (e.g. Li _{x Ni 1-yz Co y M z} O 2), lithium manganese cobalt composite oxides (e.g., _{Li x Mn 1-yz Co y} M z O 2), lithium-nickel-cobalt-manganese composite oxide (e.g., Li _x Ni _1-yz Co _y Mn _z O ₂ ) and a lithium phosphate having an olivine structure (eg, Li _x FePO ₄ , Li _x MnPO ₄ , Li _x Mn _1-y Fe _y PO ₄ , Li _x CoPO _4, Li _x Mn ₁ it is preferred to use at least one selected from _{-yz Fe y M z PO 4)} . In the above, 0 <x ≦ 1, 0 ≦ y ≦ 1, and preferably 0 ≦ z ≦ 1.

  A positive electrode containing a lithium-cobalt composite oxide is preferable because it can exhibit excellent rate characteristics. In addition, a positive electrode containing a lithium nickel cobalt manganese composite oxide is preferable because a high energy density can be realized and further excellent life characteristics can be exhibited. Further, a positive electrode containing a spinel-type lithium manganese composite oxide is preferable because it can realize excellent life characteristics and excellent rate characteristics. A positive electrode containing the olivine-type lithium-manganese-iron composite phosphate compound is preferable because it can realize excellent life characteristics, particularly, excellent life characteristics at high temperatures.

  The positive electrode active material can have, for example, a particle shape. The particles of the positive electrode active material may be primary particles, or may include secondary particles formed by aggregation of the primary particles. The particles of the positive electrode active material may be a mixture of primary particles and secondary particles. The average primary particle size of the primary particles is preferably from 10 nm to 10 μm, more preferably from 50 nm to 5 μm. The average secondary particle diameter of the secondary particles is preferably 500 nm or more and 50 μm or less, more preferably 1 μm or more and 20 μm or less.

  The conductive agent is added as necessary to enhance current collection performance and to reduce contact resistance between the active material and the current collector. Examples of the conductive agent include carbonaceous materials such as acetylene black, Ketjen black, graphite and / or coke. As the conductive agent, one of these carbonaceous materials may be used alone, or a plurality of carbonaceous materials may be used in combination.

  The binder can have an action of binding the active material, the conductive agent, and the current collector. Examples of the binder include polytetrafluoroethylene (PTFE), polyvinylidene fluoride (PVdF), cellulose compounds such as sodium carboxymethylcellulose (Na salt of CMC), fluorine rubber, styrene butadiene rubber, acrylic resin and the like. At least one selected from the group consisting of a copolymer, polyacrylic acid, and polyacrylonitrile can be used, but is not limited thereto.

  It is preferable that the positive electrode active material, the conductive agent, and the binder are mixed in proportions of 80% by mass to 95% by mass, 3% by mass to 18% by mass, and 2% by mass to 17% by mass, respectively. When the amount of the conductive agent is 3% by mass or more, the above-described effect can be exhibited. By setting the amount of the conductive agent to 18% by mass or less, the decomposition of the non-aqueous electrolyte on the surface of the conductive agent during storage at a high temperature can be reduced. When the amount of the binder is 2% by mass or more, sufficient electrode strength can be obtained. By setting the amount of the binder to 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 positive electrode can be manufactured, for example, as follows. First, the above-described positive electrode active material, conductive agent, and binder are prepared. Next, these are suspended in an appropriate solvent, and this suspension is applied to one or both surfaces of a current collector such as an aluminum foil and dried. By pressing the current collector after drying the suspension, a positive electrode is obtained. The obtained positive electrode is, for example, a band-shaped electrode. The positive electrode may also be manufactured by forming a positive electrode active material, a conductive agent, and a binder into a pellet to form a positive electrode active material-containing layer, and forming the layer on a current collector.

2) Negative electrode The negative electrode current collector is preferably an aluminum foil or an aluminum alloy foil containing at least one element selected from Mg, Ti, Zn, Mn, Fe, Cu and Si.

  The thickness of the aluminum foil and the aluminum alloy foil is 20 μm or less, more preferably 15 μm or less. The purity of the aluminum foil is preferably 99% by mass or more. As the aluminum alloy, an alloy containing an element such as magnesium, zinc, or silicon is preferable. On the other hand, the content of transition metals such as iron, copper, nickel, and chromium is preferably 1% by mass or less.

  As described above, the Na-containing niobium titanium composite oxide having an orthorhombic crystal structure can be included in the negative electrode active material-containing layer as the negative electrode active material or as a part of the negative electrode active material. That is, the negative electrode active material may include another negative electrode active material other than the Na-containing niobium titanium composite oxide having the orthorhombic crystal structure. Other negative electrode active materials will be described later.

  The Na-containing niobium titanium composite oxide having an orthorhombic crystal structure preferably accounts for 70% by mass or more of the mass of the negative electrode active material contained in the negative electrode active material-containing layer, and accounts for 80% or more. Is more preferred. More preferably, the negative electrode active material does not contain any other negative electrode active material other than the Na-containing niobium titanium composite oxide having an orthorhombic crystal structure.

Na-containing niobium titanium composite oxide having a crystal structure of orthorhombic Akiragata, for example, can be represented by the general formula _{Li 2 + v Na 2-w} M1 x Ti 6-yz Nb y M2 z O 14 + δ.

  In the above general formula, the subscript v changes in a range of 0 ≦ v <4 according to the state of charge of the orthorhombic Na-containing niobium titanium composite oxide. The orthorhombic Na-containing niobium titanium composite oxide can have a value of 0 ≦ v ≦ 0.2 in a discharged state.

  In the above general formula, the subscript w takes a value greater than 0 and less than 2. The subscript w is an index of the amount of Na in the orthorhombic Na-containing niobium titanium composite oxide. In the orthorhombic Na-containing niobium titanium composite oxide, the occlusion and release potential of Li can be adjusted by the amount of Na contained therein. That is, by changing the value of the subscript w in the above general formula, the operating potential of the orthorhombic Na-containing niobium titanium composite oxide can be appropriately changed.

  In the above general formula, M1 is at least one selected from the group consisting of Cs, K, Mg, Sr, Ba and Ca. M1 may be one selected from the group consisting of Cs, K, Mg, Sr, Ba and Ca, or a combination of two or more of these. The orthorhombic Na-containing niobium titanium composite oxide can realize more excellent cycle characteristics by containing Cs. The orthorhombic Na-containing niobium titanium composite oxide can realize more excellent cycle characteristics by containing K. The orthorhombic Na-containing niobium titanium composite oxide can realize excellent cycle characteristics by containing Mg. The orthorhombic Na-containing niobium titanium composite oxide can realize more excellent rate characteristics by containing Sr. The orthorhombic Na-containing niobium titanium composite oxide can realize more excellent rate characteristics by containing Ba. The orthorhombic Na-containing niobium titanium composite oxide can realize more excellent rate characteristics by containing Ca. M1 more preferably contains at least one of Sr and Ba.

  In the above general formula, the subscript x can take a value of 0 ≦ x <2, for example. When the orthorhombic Na-containing niobium titanium composite oxide contains M1 so that the subscript x satisfies 0 ≦ x <2, it becomes easy to become a single-phase crystal phase. Further, in such a composite oxide, Li diffusibility in a solid is sufficient, and sufficient input / output characteristics can be obtained. It is preferable that the subscript x has a value of 0.05 or more and 0.2 or less. The orthorhombic Na-containing niobium titanium composite oxide having the subscript x in this range can exhibit more excellent rate characteristics. Alternatively, the orthorhombic Na-containing niobium titanium composite oxide may not include M1.

  In the above general formula, the subscript y can take a value of 0 <y <2. The orthorhombic Na-containing niobium titanium composite oxide represented by the above general formula in which the value of the subscript y is larger than 0 can realize higher reversible capacity. In addition, the orthorhombic Na-containing niobium titanium composite oxide represented by the above general formula in which the value of the subscript y is less than 2 tends to be a single-phase crystal phase. Further, in such a composite oxide, Li diffusibility in a solid is sufficient, and sufficient input / output characteristics can be obtained. Preferably, 0.1 ≦ y ≦ 0.8. Further, the orthorhombic Na-containing niobium titanium composite oxide represented by the above general formula in which the value of the subscript y is 0.1 or more and 0.8 or less can sufficiently provide reversible charge / discharge capacity. At the same time, sufficient input / output characteristics can be realized. The subscript y preferably has a value of 0.1 or more and 1 or less. The orthorhombic Na-containing niobium titanium composite oxide represented by the above general formula in which the value of the subscript y is within this range can exhibit more excellent rate characteristics.

  In the above general formula, M2 is at least one selected from the group consisting of Zr, Sn, V, Ta, Mo, W, Fe, Co, Mn and Al. M2 may be one selected from the group consisting of Zr, Sn, V, Ta, Mo, W, Fe, Co, Mn, and Al, or a combination of two or more of these. The orthorhombic Na-containing niobium titanium composite oxide can realize more excellent cycle characteristics by containing Zr. The orthorhombic Na-containing niobium titanium composite oxide can realize more excellent rate characteristics by containing Sn. V and Ta can exhibit similar physical and chemical properties as Nb. The orthorhombic Na-containing niobium titanium composite oxide can realize more excellent rate characteristics by containing Mo. By including W, the rhombic Na-containing niobium titanium composite oxide can realize more excellent rate characteristics. The orthorhombic Na-containing niobium titanium composite oxide can realize more excellent cycle characteristics by containing Fe. The orthorhombic Na-containing niobium titanium composite oxide can realize more excellent cycle characteristics by containing Co. The orthorhombic Na-containing niobium titanium composite oxide can realize more excellent cycle characteristics by containing Mn. The orthorhombic Na-containing niobium titanium composite oxide can realize more excellent rate characteristics by containing Al. M2 more preferably contains at least one selected from the group consisting of Al, Zr, Sn and V. In another preferred embodiment, M2 is at least one selected from the group consisting of Sn, V, Ta, Mo, W, Fe, Co, and Mn. Alternatively, the orthorhombic Na-containing niobium titanium composite oxide may not contain M2.

  In the above general formula, the subscript z can take a value of, for example, 0 ≦ z <3. When the orthorhombic Na-containing niobium titanium composite oxide contains M2 so that the value of the subscript z is less than 3, it becomes easy to become a single-phase crystal phase. Further, in such a composite oxide, Li diffusibility in a solid is sufficient, and sufficient input / output characteristics can be obtained. It is preferable that the subscript z has a value of 0.1 or more and 0.3 or less. The orthorhombic Na-containing niobium titanium composite oxide represented by the above general formula having the subscript z in this range can exhibit more excellent rate characteristics.

  The subscript δ can take, for example, a value of −0.5 ≦ δ ≦ 0.5. The orthorhombic Na-containing niobium titanium composite oxide represented by the above general formula having the subscript δ within this range can exhibit excellent charge / discharge cycle characteristics. Further, such a composite oxide can be in a single crystal phase state, and the amount of generated impurities can be suppressed. The subscript δ preferably has a value of −0.1 ≦ δ ≦ 0.1. The orthorhombic Na-containing niobium titanium composite oxide represented by the above general formula having the subscript δ within this range can exhibit more excellent rate characteristics and more excellent cycle characteristics.

  The subscripts v, w, x, y, z, and δ in the above general formula can take values within the ranges described above, but the complex oxide represented by the general formula has a charge neutrality. As can be shown, the value of each subscript can be selected in combination.

  The orthorhombic Na-containing niobium titanium composite oxide can have, for example, a particle shape. The particles of the orthorhombic Na-containing niobium titanium composite oxide may be primary particles or secondary particles as an aggregate of the primary particles. Alternatively, the particles of the orthorhombic Na-containing niobium titanium composite oxide may be a mixture of primary particles and secondary particles. Further, the particles of the orthorhombic Na-containing niobium titanium composite oxide may have carbon attached to the surface. The carbon may be attached to the surface of the primary particles, or may be attached to the surface of the secondary particles. Alternatively, the particles of the orthorhombic Na-containing niobium titanium composite oxide may include secondary particles formed by aggregating primary particles having carbon attached to the surface. Such secondary particles can exhibit excellent conductivity because carbon exists between the primary particles. An embodiment including such secondary particles is preferable because the negative electrode active material-containing layer can exhibit lower resistance.

  The average primary particle diameter of the orthorhombic Na-containing niobium titanium composite oxide particles is preferably 0.5 μm or more and 3 μm or less, more preferably 0.9 μm or more and 2 μm or less. The average secondary particle diameter of the particles of the orthorhombic Na-containing niobium titanium composite oxide is preferably 5 μm or more and 20 μm or less, more preferably 8 μm or more and 12 μm or less. These preferred particle diameters are those of carbon-free particles. The average primary particle diameter of the carbon-containing particles is preferably 0.8 μm or more and 3 μm or less, more preferably 1 μm or more and 2 μm or less. The average secondary particle size is preferably 5 μm or more and 25 μm or less, more preferably 8 μm or more and 15 μm or less.

  When the particles of the orthorhombic Na-containing niobium titanium composite oxide are a mixture of primary particles and secondary particles, the average particle diameter is preferably 3 μm or more and 10 μm or less, more preferably 4 μm or more and 7 μm or less. .

  The smaller the average primary particle diameter of the particles contained in the negative electrode active material-containing layer, the smaller the pore diameter of the negative electrode active material-containing layer can be. The same applies to the secondary particles. The smaller the average secondary particle diameter of the particles contained in the negative electrode active material-containing layer, the smaller the pore diameter in the negative electrode active material-containing layer. Further, by adjusting the particle size distribution of the primary particles and / or the secondary particles, the porosity of the negative electrode active material-containing layer can be adjusted. For example, by including particles having an average particle diameter of about 1 μm and particles having an average particle diameter of about 10 μm in the negative electrode active material-containing layer, the voids formed by the particles having the larger particle diameter, Particles having a particle size can be filled. Thereby, the porosity of the negative electrode active material containing layer can be reduced. From the above viewpoint, the orthorhombic Na-containing niobium titanium composite oxide contained in the negative electrode active material-containing layer is preferably a mixture of primary particles and secondary particles. In the electrode of such a preferred embodiment, since the negative electrode active material-containing layer contains small primary particles and large secondary particles, the negative electrode active material-containing layer can have a smaller porosity, and can be further orthorhombic. Higher contact between particles of the Na-containing niobium titanium composite oxide can be realized.

As the other negative electrode active material other than the Na-containing niobium titanium composite oxide having an orthorhombic crystal structure, for example, titanium oxide can be used. The titanium oxide is not particularly limited as long as it can occlude and release lithium, but, for example, has a crystal structure other than a spinel type lithium titanate, a ramsdellite type lithium titanate, and an orthorhombic type. Niobium-titanium composite oxide containing no or Na, titanium-containing metal composite oxide, niobium oxide and its composite oxide, titanium dioxide having a monoclinic crystal structure (TiO ₂ (B)), and anatase-type titanium dioxide Etc. can be used.

The Spinel type lithium _{titanate, Li 4 + x1 Ti 5 O} 12 (x1 varies from -1 ≦ x1 ≦ 3 by charge-discharge reaction), and the like. The ramsdellite type lithium _{titanate, Li 2 + y1 Ti 3 O} 7 (y1 varies from -1 ≦ y1 ≦ 3 by charge-discharge reaction), and the like. Examples of TiO ₂ (B) and anatase type titanium dioxide include Li _{1 + z1} TiO ₂ (z1 changes in the range of −1 ≦ z1 ≦ 0 due to charge / discharge reaction) and the like.

Examples of the niobium titanium composite oxide having a crystal structure other than the orthorhombic type or containing no Na include, for example, a compound group represented by Li _x2 Ti _1-y2 Mα _y2 Nb _2-z2 Mβ _z2 O _7. included. Here, x2 is a value that changes within the range of 0 ≦ x2 ≦ 5 due to the charge / discharge reaction. Mα is at least one selected from the group consisting of Zr, Si and Sn, Mβ is at least one selected from the group consisting of V, Ta and Bi, and y2 is a value satisfying 0 ≦ y2 <1. And z2 is a value satisfying 0 ≦ z2 ≦ 2. This compound group includes, for example, a niobium titanium composite oxide having a monoclinic crystal structure (eg, Li _x2 TiNb ₂ O ₇ (0 ≦ x ≦ 5)). In the above general formula, Mα may be one kind selected from the group consisting of Zr, Si and Sn, or a combination of two or more kinds selected from the group consisting of Zr, Si and Sn. Mβ may be one selected from the group consisting of V, Ta and Bi, or a combination of two or more selected from the group consisting of V, Ta and Bi.

Examples of the titanium-containing metal composite oxide include a metal composite oxide containing Ti and at least one element selected from the group consisting of P, V, Sn, Cu, Ni, and Fe. Examples of the metal composite oxide containing at least one element selected from the group consisting of Ti and P, V, Sn, Cu, Ni, and Fe include, for example, TiO ₂ -P ₂ O ₅ and TiO ₂ -V ₂ O ₅ , TiO ₂ —P ₂ O ₅ —SnO ₂ , TiO ₂ —P ₂ O ₅ —MeO (Me is at least one element selected from the group consisting of Cu, Ni and Fe), etc. .

Another example of the titanium-containing metal composite oxide further includes a composite oxide having a composition represented by Li ₂ Na ₂ Ti ₆ O ₁₄ or Li ₂ SrTi ₆ O ₁₄ .

  Such a metal composite oxide preferably has low crystallinity and has a microstructure in which a crystalline phase and an amorphous phase coexist or an amorphous phase exists alone. Due to the microstructure, the cycle performance can be further improved.

  The other negative electrode active materials described above can also have a particle shape similar to the Na-containing niobium titanium composite oxide having an orthorhombic crystal structure. The particles may be primary particles, secondary particles, or a mixture of primary and secondary particles. The average primary particle diameter of the primary particles of the negative electrode active material particles including the Na-containing niobium titanium composite oxide having the orthorhombic crystal structure and the other negative electrode active materials may be 10 nm or more and 10 μm or less. More preferably, it is 50 nm or more and 5 μm or less. The average secondary particle diameter of the secondary particles is preferably 500 nm or more and 50 μm or less, more preferably 1 μm or more and 20 μm or less.

  The conductive agent can exhibit a function of improving current collection performance and suppressing contact resistance between the active material and the current collector. Examples of conductive agents include acetylene black, carbon black, graphite, carbon nanofibers, carbon nanotubes, and carbonaceous materials such as coke. Among these, graphite and carbon nanofibers are preferred. Graphite and carbon nanofibers can easily enter between the particles of the orthorhombic Na-containing niobium titanium composite oxide as compared with acetylene black and carbon black, and can reduce the gap of the electrode active material-containing layer. Further, as the conductive agent, it is more preferable to use carbon material particles having a large aspect ratio. The carbon material particles here may be particles containing a carbon material, or may be fibers containing a carbon material. A preferred aspect ratio is 15 or more, more preferably 50 or more. Carbon material particles having a large aspect ratio can impart conductivity in the thickness direction of the negative electrode active material-containing layer, and can achieve higher input / output characteristics. As the conductive agent, one of the carbonaceous materials described above may be used alone, or a plurality of carbonaceous materials may be used.

  The binder can have an action of binding the active material, the conductive agent, and the current collector. Examples of the binder include polytetrafluoroethylene (PTFE), polyvinylidene fluoride (PVdF), cellulose compounds such as sodium carboxymethylcellulose (Na salt of CMC), fluorine rubber, styrene butadiene rubber, acrylic resin and the like. At least one selected from the group consisting of a copolymer, polyacrylic acid, and polyacrylonitrile can be used, but is not limited thereto.

  In the negative electrode active material-containing layer, the negative electrode active material, the conductive agent, and the binder are contained in proportions of 70% by mass to 96% by mass, 2% by mass to 28% by mass, and 2% by mass to 28% by mass, respectively. It is preferable to mix them. The negative electrode active material is preferably contained in an amount of 85% by mass or more and 93% by mass or less. By including the conductive agent in an amount of 2% by mass or more, a sufficient current collecting performance can be provided to the negative electrode active material-containing layer, whereby excellent large current characteristics can be realized. In addition, by including the binder in an amount of 2% by mass or more, excellent binding properties can be provided between the negative electrode active material-containing layer and the negative electrode current collector, thereby providing an excellent cycle. Characteristics can be realized. From the viewpoint of increasing the capacity, the amounts of the conductive agent and the binder are preferably 28% by mass or less. More preferably, the negative electrode active material, the conductive agent, and the binder are blended in proportions of 85% by mass or more and 96% by mass or less, 2% by mass or more and 13% by mass or less, and 2% by mass or more and 13% by mass or less.

The density of the negative electrode active material-containing layer is preferably not more than 2.4 g / cm ³ or more 2.7 g / cm ^3, more preferably not more than 2.5 g / cm ³ or more 2.6 g / cm ^3. An electrode having a negative electrode active material-containing layer having a density within a preferable range has more sufficient contact between particles of the orthorhombic Na-containing niobium titanium composite oxide, and therefore, the negative electrode active material-containing layer has a more excellent electronic conductivity. Sex can be shown. Further, a space in which the nonaqueous electrolyte is impregnated can be more sufficiently secured.
The negative electrode can be manufactured, for example, by producing a battery unit using the negative electrode intermediate member produced by the following procedure, and subjecting the battery unit to aging as described later.

  The negative electrode intermediate member can be manufactured, for example, by the following procedure. First, the above-described negative electrode active material, conductive agent, and binder are prepared. A method for synthesizing a Na-containing niobium titanium composite oxide having an orthorhombic crystal structure will be described later. Next, these are suspended in a suitable solvent. At this time, if the stirring speed is excessively high, the secondary particles may be disintegrated. Therefore, the stirring speed is preferably relatively low. This suspension is applied to one or both surfaces of a current collector such as an aluminum foil, and the coating film is dried. Next, the dried coating film is pressed together with the current collector. Thus, a negative electrode intermediate member including the negative electrode current collector and the negative electrode active material-containing layer supported on the negative electrode current collector can be obtained. The obtained negative electrode intermediate member has, for example, a belt shape. The negative electrode may also be manufactured by forming a negative electrode active material, a conductive agent, and a binder into a pellet to form a negative electrode active material-containing layer, and forming this on a current collector.

3) Non-aqueous electrolyte The non-aqueous electrolyte may be, for example, a liquid non-aqueous electrolyte prepared by dissolving the electrolyte in an organic solvent, or a gel non-aqueous electrolyte obtained by combining a liquid electrolyte and a polymer material. . The non-aqueous electrolyte may include an additive.

  The liquid non-aqueous electrolyte preferably dissolves the electrolyte in an organic solvent at a concentration of 0.5 mol / L or more and 2.5 mol / L or less.

Examples of the electrolyte include lithium perchlorate (LiClO ₄ ), lithium hexafluorophosphate (LiPF ₆ ), lithium tetrafluoroborate (LiBF ₄ ), lithium arsenic hexafluoride (LiAsF ₆ ), and trifluoromethane sulfone. Lithium salts such as lithium acid (LiCF ₃ SO ₃ ), lithium bistrifluoromethylsulfonylimide [LiN (CF ₃ SO ₂ ) ₂ ], or a mixture thereof are included. The electrolyte is preferably hardly oxidized even at a high potential, and LiPF ₆ is most preferred.

  Examples of the organic solvent include cyclic carbonates such as propylene carbonate (PC), ethylene carbonate (EC) and vinylene carbonate, and linear chains such as diethyl carbonate (DEC), dimethyl carbonate (DMC) and methyl ethyl carbonate (MEC). Carbonates, cyclic ethers such as tetrahydrofuran (THF), 2-methyltetrahydrofuran (2MeTHF), dioxolane (DOX), linear ethers such as dimethoxyethane (DME), diethoxyethane (DEE), acetonitrile (AN), and sulfolane (SL). These organic solvents can be used alone or in the form of a mixed solvent.

  The organic solvent is a mixed solvent obtained by mixing at least two or more selected from the group consisting of propylene carbonate (PC), ethylene carbonate (EC), diethyl carbonate (DEC), dimethyl carbonate (DMC), and methyl ethyl carbonate (MEC). Preferably, there is. Cyclic carbonate is preferable because the degree of dissociation of the lithium salt is high, and chain carbonate is preferable because the viscosity of the electrolytic solution is low and lithium is easily diffused. It is preferable to use a mixed solvent because these characteristics can be compatible.

  The organic solvent preferably contains ethylene carbonate (EC). The organic solvent preferably contains ethylene carbonate at a rate of 1% by volume or more based on the volume of the organic solvent, more preferably 5% by volume or more. In another preferred embodiment, the organic solvent preferably contains ethylene carbonate at a ratio of 1% by volume or more and 80% by volume or less, preferably 5% by volume or more and 50% by volume or less based on the volume of the organic solvent. More preferably, it is included.

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

  Alternatively, the non-aqueous electrolyte may be a room-temperature molten salt (ionic melt) containing lithium ions, a solid polymer electrolyte, an inorganic solid electrolyte, or the like.

  Room temperature molten salt (ionic melt) refers to a compound that can exist as a liquid at room temperature (15 to 25 ° C.) among organic salts composed of a combination of organic cations and anions. The room-temperature molten salt includes a room-temperature molten salt that exists alone as a liquid, a room-temperature molten salt that becomes a liquid when mixed with an electrolyte, and a room-temperature molten salt that becomes a liquid when dissolved in an organic solvent. Generally, the melting point of the room temperature molten salt used for the nonaqueous electrolyte battery is 25 ° C. or less. The organic cation generally has a quaternary ammonium skeleton.

The polymer solid electrolyte is prepared by dissolving the electrolyte in a polymer material and solidifying it.
The inorganic solid electrolyte is a solid substance having lithium ion conductivity.

  In addition, some components of the non-aqueous electrolyte may be decomposed by aging of the battery unit described in detail below. Therefore, the composition of the nonaqueous electrolyte included in the nonaqueous electrolyte battery completed by aging may be different from the composition of the nonaqueous electrolyte prepared before being included in the battery unit.

4) Separator The separator is disposed between the positive electrode and the negative electrode.
As the separator, for example, a porous film or a nonwoven fabric made of synthetic resin containing at least one selected from the group consisting of polyethylene, polypropylene, polyethylene terephthalate, cellulose, and polyvinylidene fluoride (PVdF) can be used. Alternatively, a separator in which an inorganic compound is applied to a porous film can be used.

5) Exterior Member As the exterior member, for example, a laminate film or a metal container can be used.

  Examples of the shape of the exterior member include a flat type (thin type), a square type, a cylindrical type, a coin type, a button type, a sheet type, and a laminated type. The exterior member may have a size corresponding to the battery size. The exterior member has a size used for, for example, a small battery mounted on a portable electronic device or the like, or a large battery mounted on a two-wheel or four-wheel automobile.

  As the laminate film, a multilayer film in which a metal layer is interposed between resin films is used. The thickness of the laminate film is preferably 0.2 mm or less. The metal layer is preferably an aluminum foil or an aluminum alloy foil for weight reduction. For the resin film, for example, a polymer material such as polypropylene (PP), polyethylene (PE), nylon, or polyethylene terephthalate (PET) can be used. The laminate film can be formed into a shape of an exterior member by performing sealing by heat fusion.

  The wall thickness of the metal container is preferably 0.5 mm or less, more preferably 0.2 mm or less.

  The metal container is formed from, for example, aluminum or an aluminum alloy. The aluminum alloy preferably contains elements such as magnesium, zinc, and silicon. When a transition metal such as iron, copper, nickel, and chromium is contained in the alloy, the content is preferably 100 ppm or less. Thereby, long-term reliability and heat dissipation under a high-temperature environment can be dramatically improved.

6) Positive electrode terminal The positive electrode terminal is made of, for example, a material having electrical stability and conductivity at a potential of 3 V to 4.5 V (vs Li / Li ⁺ ) with respect to the oxidation-reduction potential of lithium. Can be. Specifically, aluminum alloys and aluminum containing elements such as Mg, Ti, Zn, Mn, Fe, Cu, and Si can be used. To reduce the contact resistance, a material similar to that of the positive electrode current collector is preferable.

7) Negative electrode terminal The negative electrode terminal is formed of, for example, a material having electrical stability and conductivity at a potential of 0.4 V to 3 V (vs Li / Li ⁺ ) with respect to the oxidation-reduction potential of lithium. Can be. Specifically, aluminum alloys and aluminum containing elements such as Mg, Ti, Zn, Mn, Fe, Cu, and Si can be used. In order to reduce the contact resistance, a material similar to that of the negative electrode current collector is preferable.

[Synthesis method of Na-containing niobium titanium composite oxide having orthorhombic crystal structure]
The Na-containing niobium titanium composite oxide having an orthorhombic crystal structure can be synthesized, for example, by the following procedure.

When synthesizing a Na-containing niobium titanium composite oxide having an orthorhombic crystal structure, if the mixing ratio of the raw materials is such that each element is included in the stoichiometric amount of the target composition, the single-phase orthorhombic In addition to the type Na-containing niobium titanium composite oxide, impurities such as TiO ₂ can be synthesized. This is considered to be because lithium and sodium are vaporized and lost by the heat treatment. In particular, lithium has a great influence on battery characteristics due to its loss.
One way to solve this problem is to increase the amount of lithium or the like mixed as a raw material above the stoichiometric ratio. However, in such a method, there is a possibility that lithium which does not contribute to the synthesis remains even after heat treatment. Excess lithium that has not contributed to the synthesis may not be taken into the crystal phase of the target composition, and may exist on the particle surface as an impurity. If surplus lithium is present on the particle surface as an impurity, the lithium may cause an electrolyte decomposition reaction on the particle surface, thereby increasing the interface resistance between the electrode and the electrolyte.

  To solve this problem, as described below, the non-aqueous electrolyte decomposition reaction can be suppressed by removing excess lithium existing on the surface of the active material particles after the heat treatment. The suppression of this side reaction improves the life characteristics and reduces the resistance, thereby improving the rate characteristics.

  Although the case where the mixing ratio of the raw materials is set to be larger than the stoichiometric ratio of the target composition has been described above, the mixing ratio of the raw materials may be the same as the stoichiometric ratio of the target composition. Also in this case, after heat treatment, there may be lithium not taken into the crystal phase of the target composition, and thus, the life characteristics are improved by removing such lithium.

  The orthorhombic Na-containing niobium titanium composite oxide can be synthesized by, for example, a solid phase method. Alternatively, it can be synthesized by a wet synthesis method such as a sol-gel method or a hydrothermal method. According to the wet synthesis, fine particles can be obtained more easily than by the solid phase method.

  Hereinafter, an example of a method for synthesizing an orthorhombic Na-containing niobium titanium composite oxide by a solid phase method will be described.

  First, necessary raw materials among a Ti source, a Li source, a Na source, a Nb source, a metal element M1 source, and a metal element M2 source are prepared according to a target composition. These raw materials can be, for example, compounds such as oxides or salts. Preferably, the salts are salts that decompose at relatively low temperatures to form oxides, such as carbonates and nitrates.

Next, the prepared raw materials are mixed at an appropriate stoichiometric ratio to obtain a mixture. For example, when synthesizing a Na-containing niobium titanium composite oxide represented by the composition formula Li ₂ Na _1.7 Ti _5.7 Nb _0.3 O ₁₄ and having an orthorhombic crystal structure, titanium oxide TiO ₂ and lithium carbonate Li ₂ CO ₃ And sodium carbonate Na ₂ CO ₃ and niobium hydroxide Nb (V) (OH) ₅ at a molar ratio of Li: Na: Ti: Nb of 2: 1.7: 5.7: 0.3 in the mixture. Mix so that However, since Li and Na may be lost by the heat treatment as described above, they may be mixed more than the stoichiometric ratio of the target composition. In particular, since Li is likely to be lost during the heat treatment, Li may be mixed in a larger amount than the stoichiometric ratio of the target composition.

  In mixing the raw materials, it is preferable that these raw materials are sufficiently pulverized and then mixed. By mixing the sufficiently pulverized raw materials, the raw materials easily react with each other, and generation of impurities can be suppressed.

  Next, the mixture obtained by the above mixing is subjected to a heat treatment in an air atmosphere at a temperature of 800 ° C. or more and 1000 ° C. or less for a time of 1 hour or more and 24 hours or less. If the temperature is lower than 800 ° C., crystallization may not be sufficiently performed. If the temperature is higher than 1000 ° C., the grain growth is excessively advanced, which may result in coarse particles. If the heat treatment time is less than 1 hour, crystallization may not be sufficiently performed. If the heat treatment time is longer than 24 hours, it is not preferable because the grain growth may progress excessively and become coarse particles.

  This heat treatment is preferably performed at a temperature of 850 ° C. to 950 ° C. for a time of 2 hours to 5 hours. Thus, an orthorhombic Na-containing niobium titanium composite oxide can be obtained. After the obtained orthorhombic Na-containing niobium titanium composite oxide is recovered, an annealing treatment may be performed.

For example, in the case of the orthorhombic Na-containing niobium titanium composite oxide represented by the composition formula Li ₂ Na _1.7 Ti _5.7 Nb _0.3 O ₁₄ , the mixture obtained by mixing the raw materials as described above is treated in an air atmosphere. , At 900 ° C. for 3 hours.

  Next, the orthorhombic Na-containing niobium titanium composite oxide obtained by the heat treatment is subjected to, for example, pulverization by a wet ball mill using an aqueous solution to wash the surface of the active material particles. By this washing, surplus lithium adhering to the surface of the active material particles can be washed away. As the aqueous solution, for example, an acidic aqueous solution can be used. The acidic aqueous solution is, for example, an aqueous solution containing hydrochloric acid and sulfuric acid. Water may be used instead of the aqueous solution. Since the pH rises due to excess lithium on the surface of the particles, it is preferable to use an acidic aqueous solution for sufficient washing.

  The washing can also be performed by pulverization using a dry mill without using an aqueous solution. The washing can be performed without crushing by immersing the orthorhombic Na-containing niobium titanium composite oxide in an aqueous solution.

  Subsequently, the washed active material particles are subjected to a reheat treatment. By the reheat treatment, the composition near the surface of the active material particles can be crystallized. The temperature of the reheat treatment is, for example, 500 ° C. or more and 900 ° C. or less, and preferably 600 ° C. or more and 700 ° C. or less. If the temperature of the reheat treatment is lower than 500 ° C., the crystallinity of the particle surface may be poor. If the temperature of the reheat treatment is higher than 900 ° C., there is a possibility of grain growth.

  Through the above procedure, an example of a Na-containing niobium titanium composite oxide having an orthorhombic crystal structure can be synthesized.

[Production method]
The nonaqueous electrolyte battery according to the first embodiment can be manufactured, for example, by the following method.

  First, a positive electrode and a negative electrode intermediate member are manufactured by the procedure described above. Next, an electrode group is produced using the produced positive and negative electrode intermediate members and the separator. Next, the positive electrode of the electrode group is electrically connected to the positive electrode terminal. On the other hand, the negative electrode of the electrode group is electrically connected to the negative electrode terminal.

  Next, the electrode group is housed in the exterior member. Next, the non-aqueous electrolyte is accommodated in the exterior member. Thus, the non-aqueous electrolyte is held in the electrode group. Next, the exterior member is closed, and the electrode group and the non-aqueous electrolyte are sealed in the exterior member. Thus, a battery unit is obtained.

  This battery unit is subjected to aging including first aging and second aging. The first aging is performed before the second aging. The temperature in the first aging is lower than that in the second aging. The battery voltage of the battery unit used for the first aging is set lower than that of the battery unit used for the second aging.

  Specifically, the first aging temperature is preferably 35 ° C. or more and 95 ° C. or less, and more preferably 50 ° C. or more and 70 ° C. In addition, the first aging is preferably performed for 0.5 hours to 48 hours, and more preferably for 5 hours to 24 hours. Further, the battery voltage of the battery unit subjected to the first aging is preferably 1.8 V or more and 2.65 V or less, more preferably 2.4 V or more and 2.6 V or less.

  The temperature of the second aging is preferably from 40 ° C to 120 ° C, more preferably from 70 ° C to 100 ° C. The second aging is preferably performed for 1 hour to 48 hours, more preferably for 5 hours to 24 hours. Further, the battery voltage of the battery unit subjected to the second aging is preferably 2.7 V or more and 3.0 V or less, more preferably 2.7 V or more and 2.9 V or less. However, as described above, the second aging temperature is higher than the first aging temperature. Further, the battery voltage of the battery unit subjected to the second aging is higher than that of the battery unit subjected to the first aging.

  The first aging is preferably performed on the battery unit in a state where the internal gas can be released. Alternatively, after the first aging and / or the second aging, the gas inside the battery unit may be vented.

  The battery voltage of the battery unit subjected to the first aging is adjusted as follows. First, a battery unit is manufactured according to the procedure described above. Next, the produced battery unit is charged with a constant current of 5 C or less until the battery voltage reaches a predetermined voltage. Thus, a battery unit for the first aging can be prepared.

  Further, the SOC of the battery unit to be subjected to the second aging is adjusted as follows. After the first aging and optional degassing, the battery unit is discharged at a constant current until the battery voltage reaches 1.8V. Next, the battery unit is charged with a constant current of 5 C or less until the battery voltage reaches a predetermined voltage.

By subjecting the battery unit to the first and second aging described above, for unknown reasons, a film can be formed on the surface of the negative electrode active material-containing layer included in the negative electrode intermediate member, and the negative electrode active material can be formed. The containing layer satisfies I ₂ / I ₁ ≧ 1 described above. That is, the nonaqueous electrolyte battery according to the first embodiment can be obtained by subjecting the battery unit to the first and second aging described above. As a specific example, an example will be described later in this specification.

On the other hand, when only the first aging is performed or when only the second aging is performed, I ₂ / I ₁ is less than ₁ , as shown in the comparative example. Also, when the first aging is performed after the second aging, I ₂ / I ₁ is less than ₁ , as shown in the comparative example.

Furthermore, even if the first aging and the second aging are performed, depending on the composition of the non-aqueous electrolyte, for example, I ₂ / I ₁ becomes less than ₁ , as shown in the comparative example. However, again, according to the procedure given in the examples, the nonaqueous electrolyte battery according to the first embodiment can be obtained.

  After the first aging and the second aging, further aging may be performed.

[Various analysis methods]
Hereinafter, a method for analyzing the negative electrode active material-containing layer included in the negative electrode included in the nonaqueous electrolyte battery and a method for analyzing the active material included in the negative electrode active material will be described.

(Preparation of measurement sample)
First, a measurement sample is prepared according to the following procedure.
Prepare a non-aqueous electrolyte battery to be analyzed. The battery to be analyzed has a capacity of 80% or more of the nominal capacity.

  Next, the non-aqueous electrolyte battery is placed in a discharged state. For example, a non-aqueous electrolyte battery can be brought into a discharged state by discharging at a constant current of 5 C or less until the battery voltage reaches 1.8 V.

  Next, the nonaqueous electrolyte battery is transported into a glove box filled with argon, and disassembled here. Next, the negative electrode is taken out of the disassembled battery. The negative electrode taken out is washed with, for example, ethyl methyl carbonate (EMC). By this washing, the Li salt attached to the surface of the negative electrode can be removed. Next, the washed negative electrode is dried. Thus, a negative electrode sample as a measurement sample can be obtained.

(Analysis of negative electrode active material containing layer by XPS)
The XPS measurement can be performed, for example, according to the method described below.
As the apparatus, for example, Quantara SXM manufactured by PHI is used. Single crystal spectroscopy Al-Kα (1486.6 eV) is used for the excitation X-ray source, and the photoelectron detection angle is 45 °.

  The negative electrode sample prepared as described above is mounted on the sample holder of the XPS analyzer. The loading of the sample is performed in an inert atmosphere, for example, an argon atmosphere.

<Quantification of elements contained in negative electrode active material>
The elements contained in the negative electrode active material are inductively coupled plasma (ICP) emission spectroscopy, scanning electron microscope (SEM) observation, and energy dispersive X-ray spectroscopy (Energy Dispersive X-ray spectroscopy). -ray Spectrometry (EDX) can be used in combination.

(ICP analysis procedure)
A part of the negative electrode sample prepared as described above is placed in an appropriate solvent and irradiated with ultrasonic waves. For example, the negative electrode active material-containing layer can be separated from the current collector by placing the electrode body in ethyl methyl carbonate placed in a glass beaker and vibrating in an ultrasonic cleaner. Next, the separated negative electrode active material-containing layer is dried by drying under reduced pressure. The obtained negative electrode active material-containing layer is pulverized in a mortar or the like to form a powder containing the negative electrode active material, the conductive agent, the binder, the components of the coating, and the like. By dissolving this powder with an acid, a liquid sample containing the negative electrode active material can be prepared. At this time, hydrochloric acid, nitric acid, sulfuric acid, hydrogen fluoride and the like can be used as the acid. By subjecting this liquid sample to ICP emission spectroscopy, the amount of metal element contained in the negative electrode active material can be determined.

(SEM-EDX analysis procedure)
The negative electrode sample prepared as described above is cut out with an ion milling device to obtain a sample cross section. The cross section of the cut sample is observed with a scanning electron microscope. The sampling of the sample is also performed in an inert atmosphere such as argon or nitrogen without being exposed to the air.

  Some particles are randomly selected in a 3000 times SEM observation image. If it is difficult to obtain a particle diameter at 3000 times the particle size, the magnification may be increased. At this time, the particles are selected so that the particle size distribution of the selected particles is as wide as possible.

  Next, the selected particles are subjected to elemental analysis by an energy dispersive X-ray spectrometer attached to a scanning electron microscope. Thereby, the type and amount of elements other than Li among the elements contained in each selected particle can be specified. As for Li, information on the Li content in the active material contained in the electrode can be obtained by the above-described ICP emission spectroscopy.

  The composition of the negative electrode active material contained in the negative electrode active material-containing layer can be known by using the results of each analysis of ICP and SEM-EDX described above. Also, when the negative electrode active material is a mixture of a plurality of types of active materials, the composition of each active material element (other than Li) can be known by SEM-EDX, and the ICP analysis result is included in each active material. Since it can be regarded as the total of the metal elements, the composition of each negative electrode active material and the mass ratio of each active material in the negative electrode active material are known by using the respective analysis results of ICP and SEM-EDX. be able to.

<Specification of crystal structure of active material by XRD>
The crystal structure of the active material contained in each particle selected by SEM can be specified by X-ray diffraction (X-ray Diffraction: XRD) measurement.

  The XRD measurement of the electrode can be performed by cutting out the electrode to be measured to the same extent as the area of the holder of the wide-angle X-ray diffractometer, and directly attaching it to a glass holder for measurement. At this time, the XRD is measured in advance according to the type of the metal foil of the electrode current collector, and it is grasped at which position the peak derived from the current collector appears. In addition, the presence or absence of a peak of a material that can be included in the active material-containing layer such as a conductive agent and a binder is also grasped in advance. When the peak of the current collector and the peak of the active material overlap with each other, it is desirable that the active material be separated from the current collector and measured. This is to separate overlapping peaks when quantitatively measuring peak intensity. Of course, if these can be grasped in advance, this operation can be omitted. The electrode may be physically peeled off, but is easily peeled off when ultrasonic waves are applied in a solvent. By measuring the electrodes collected in this way, wide-angle X-ray diffraction measurement of the active material can be performed.

  An X-ray diffraction pattern can be obtained by performing the measurement in a measurement range of 2θ = 10 to 90 ° using CuKα radiation as a radiation source.

  As a device for powder X-ray diffraction measurement, Rigaku SmartLab is used. The measurement conditions are as follows: Cu target; 45 kV, 200 mA; solar slit: both incident and light receiving at 5 °; step width: 0.02 deg; scan speed: 20 deg / min; semiconductor detector: D / teX Ultra 250; Plate holder: flat glass sample plate holder (thickness: 0.5 mm); measurement range: 10 ° ≦ 2θ ≦ 90 °. When using other devices, perform measurement using a standard Si powder for powder X-ray diffraction, and find a condition under which a measurement result of a peak intensity and a peak top position equivalent to the result obtained by the above device is obtained. The sample is measured under the conditions.

  The X-ray diffraction (XRD) pattern obtained here must be applicable to Rietveld analysis. To collect Rietveld data, the step width is set to be 1/3 to 1/5 of the minimum half width of the diffraction peak, and the measurement is appropriately performed so that the intensity at the peak position of the strongest reflection is 5000 cps or more. Adjust time or X-ray intensity.

The XRD pattern obtained as described above is analyzed by the Rietveld method. In the Rietveld method, a diffraction pattern is calculated from a crystal structure model estimated in advance. The estimation of the crystal structure model here is performed based on the analysis results by EDX described above and ICP described above. By fitting all of the calculated values and the actually measured values, parameters (lattice constant, atomic coordinates, occupancy, etc.) relating to the crystal structure can be accurately analyzed. Thereby, the characteristics of the crystal structure of the composite oxide can be examined. In addition, it is possible to check the occupancy of each element in each site. The fitting parameter S is used as a scale for estimating the degree of coincidence between the observed intensity and the calculated intensity in Rietveld analysis. It is necessary to perform analysis so that S is smaller than 1.8. In determining the occupancy of each site, the standard deviation σ _j must be taken into account. The fitting parameter S and the standard deviation σ _j defined here are the mathematical formulas described in “Actual powder X-ray analysis” (edited by Izumi Nakai and Fujio Izumi, edited by the Japan Society for Analytical Chemistry, X-ray Analysis Research Council (Asakura Shoten)). It is assumed that

  Through the XRD analysis described above, information on the crystal structure of the active material can be obtained.

<Method of measuring BET specific surface area of active material>
The BET specific surface area of the negative electrode active material can be measured, for example, by a method described below.

  First, a powder containing components such as a negative electrode active material, a conductive agent, and a binder is taken out from the negative electrode sample prepared as described above by the same procedure as in the ICP analysis. Subsequently, this powder is heated at 600 ° C. for 1 hour to isolate the active material. This powder of the active material is used as a measurement sample.

  The active material mass is 4 g. As the evaluation cell, for example, a 1 / 2-inch cell is used. As a pretreatment method, degassing is performed by drying the evaluation cell under reduced pressure at a temperature of about 100 ° C. or higher for 15 hours. As a measuring device, for example, Tristar II3020 manufactured by Shimadzu-Micromeritics Co., Ltd. is used. Nitrogen gas is adsorbed while changing the pressure, and an adsorption isotherm with the relative pressure on the horizontal axis and the N2 gas adsorption amount on the vertical axis is determined. Assuming that this curve follows the BET theory, the specific surface area of the active material powder can be calculated by applying the BET equation.

<Method of measuring average primary particle diameter and average secondary particle diameter of negative electrode active material particles>
The negative electrode sample prepared as described above is cut out with an ion milling device to obtain a sample cross section. The cross section of the cut sample is observed with a scanning electron microscope, and an image of the active material particles is obtained at a magnification of 3000 times. In the obtained visual field, a group of particles that can confirm that the primary particles are in contact is referred to as secondary particles. Note that sampling of a sample is performed in an inert atmosphere such as argon or nitrogen without being exposed to the air.

  The size of the primary particle is determined from the diameter of the smallest circle corresponding to the primary particle. Specifically, the particle size is measured ten times in a SEM image at a magnification of 3000 times, and the average of the diameters of the smallest circles obtained in each case is defined as the primary particle size. For the calculation of the average, the maximum value and the minimum value of the particle diameter are not used among the ten measurements.

  The secondary particle size is measured in the same manner as the primary particle size. That is, the diameter of the smallest circle corresponding to the secondary particles is determined. Specifically, the particle size is measured ten times in an SEM image at a magnification of 3000 times, and the average of the diameters of the smallest circles obtained in each case is defined as the secondary particle size. For calculating the average, the maximum value and the minimum value of the particle size are not used among the 10 measurements.

  In the above, the analysis method for the negative electrode active material has been described. However, the analysis for the positive electrode active material can be performed in the same procedure.

  Next, some examples of the nonaqueous electrolyte battery according to the present embodiment will be described with reference to the drawings.

  First, a flat nonaqueous electrolyte battery, which is an example of the nonaqueous electrolyte battery according to the present embodiment, will be described with reference to FIGS. 2 and 3.

  FIG. 2 is a schematic cross-sectional view illustrating an example of the flat nonaqueous electrolyte battery according to the first embodiment. FIG. 3 is an enlarged sectional view of a portion A in FIG.

  The nonaqueous electrolyte battery 10 shown in FIGS. 2 and 3 includes a flat wound electrode group 1.

  The flat wound electrode group 1 includes a negative electrode 3, a separator 4, and a positive electrode 5, as shown in FIG. The separator 4 is interposed between the negative electrode 3 and the positive electrode 5. Such a flat wound electrode group 1 is formed by laminating a laminate formed by laminating the negative electrode 3, the separator 4, and the positive electrode 5 with the negative electrode 3 outside as shown in FIG. It can be formed by molding. This laminate is laminated such that the separator 4 is interposed between the negative electrode 3 and the positive electrode 5.

  The negative electrode 3 includes a negative electrode current collector 3a and a negative electrode active material containing layer 3b. The outermost portion of the negative electrode 3 has a configuration in which the negative electrode active material-containing layer 3b is formed only on one surface on the inner side of the negative electrode current collector 3a as shown in FIG. In other portions of the negative electrode 3, negative electrode active material-containing layers 3b are formed on both surfaces of a negative electrode current collector 3a.

  A coating is formed on the surface of the negative electrode active material-containing layer 3b that is not in contact with the current collector. However, as described above, this coating has a thickness much smaller than the thickness of the negative electrode active material containing layer 3b, and is not shown in FIG.

  The positive electrode 5 has a positive electrode active material-containing layer 5b formed on both surfaces of a positive electrode current collector 5a.

  As shown in FIG. 2, near 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 of the inner positive electrode 5. It is connected to the body 5a.

  The wound electrode group 1 is housed in a bag-like container 2 made of a laminate film having a metal layer interposed between two resin layers.

  A part of each of the negative electrode terminal 6 and the positive electrode terminal 7 is located outside the bag-shaped container 2. This state can be obtained, for example, by heat sealing the periphery of the bag-shaped container 2 with the negative electrode terminal 6 and the positive electrode terminal 7 interposed therebetween.

  The liquid non-aqueous electrolyte is stored in the bag-shaped container 2. The liquid non-aqueous electrolyte is held by the electrode group 1. The liquid non-aqueous electrolyte can be injected into the bag-shaped container 2 through the opening, for example, by providing an opening in the peripheral portion of the bag-shaped container 2. This opening can be formed, for example, by leaving a part of the peripheral portion of the bag-shaped container 2 without heat fusion at the time of heat sealing. After the injection of the nonaqueous electrolyte, the wound electrode group 1 and the liquid nonaqueous electrolyte can be sealed in the container 2 by heat sealing the opening.

  Next, another example of the nonaqueous electrolyte battery according to the first embodiment will be described with reference to FIGS. 4 and 5.

  FIG. 4 is a partially cutaway perspective view schematically illustrating another example of the nonaqueous electrolyte battery according to the first embodiment. FIG. 5 is a schematic cross-sectional view of a portion B in FIG.

  The nonaqueous electrolyte battery 10 shown in FIGS. 4 and 5 includes a stacked electrode group 11. As shown in FIG. 4, the laminated electrode group 11 is housed in an exterior member 12 made of a laminated film having a metal layer interposed between two resin films. As shown in FIG. 5, the stacked electrode group 11 has a structure in which a positive electrode 13 and a negative electrode 14 are alternately stacked with a separator 15 interposed therebetween. There are a plurality of positive electrodes 13 each including a positive electrode current collector 13a and a positive electrode active material-containing layer 13b supported on both surfaces of the positive electrode current collector 13a. The negative electrode 14 includes a plurality of negative electrodes 14 each including a negative electrode current collector 14a and a negative electrode active material-containing layer 14b supported on both surfaces of the negative electrode current collector 14a. A coating is formed on the surface of the negative electrode active material-containing layer 14b that is not in contact with the current collector. However, as described above, this coating has a thickness much smaller than the thickness of the negative electrode active material containing layer 14b, and is not shown in FIG.

  Part of the negative electrode current collector 14 a of each negative electrode 14 protrudes from the positive electrode 13. The protruding portion of the negative electrode current collector 14a is electrically connected to the strip-shaped negative electrode terminal 16. The tip of the strip-shaped negative electrode terminal 16 is drawn out of the exterior member 12 to the outside. Although not shown, a portion of the positive electrode current collector 13a of the positive electrode 13 that is located on a side opposite to a protruding portion of each negative electrode current collector 14a protrudes from the negative electrode 14. Although not shown, the protruding portion of each positive electrode current collector 13a is electrically connected to a belt-shaped positive terminal 17. The tip of the band-shaped positive electrode terminal 17 is located on the opposite side to the negative electrode terminal 16, and is drawn out from the side of the exterior member 12.

According to the first embodiment described above, an electrode and a nonaqueous electrolyte battery are provided. This non-aqueous electrolyte battery includes the electrode as a negative electrode, a positive electrode, and a non-aqueous electrolyte. The negative electrode includes a negative electrode active material containing layer. The negative electrode active material-containing layer contains a Na-containing niobium titanium composite oxide having an orthorhombic crystal structure. In the negative electrode active material-containing layer, the intensity ratio I ₂ / I _{1 determined} by X-ray photoelectron spectroscopy satisfies I ₂ / I ₁ ≧ 1. This nonaqueous electrolyte battery can suppress a side reaction between the Na-containing niobium titanium composite oxide contained in the negative electrode active material containing layer and the nonaqueous electrolyte. As a result, the electrode and the non-aqueous electrolyte battery according to the first embodiment can exhibit excellent life characteristics.

(Second embodiment)
According to the second embodiment, a battery pack is provided. This battery pack includes the nonaqueous electrolyte battery according to the first embodiment.

  The battery pack according to the present embodiment may include one nonaqueous electrolyte battery, or may include a plurality of nonaqueous electrolyte batteries. A plurality of non-aqueous electrolyte batteries that can be included in a battery pack can be electrically connected in series, parallel, or a combination of series and parallel. A plurality of non-aqueous electrolyte batteries can be electrically connected to form a battery pack. The battery pack may include a plurality of assembled batteries.

  The battery pack may further include a protection circuit. The protection circuit controls charging and discharging of the non-aqueous electrolyte battery. Further, a circuit included in a device (for example, an electronic device, an automobile, or the like) that uses the battery pack as a power supply can be used as a protection circuit for the battery pack.

  In addition, the battery pack may further include an external terminal for energization. The external terminals for energization are for outputting current from the non-aqueous electrolyte battery to the outside and for inputting current to the non-aqueous electrolyte battery. In other words, when the battery pack is used as a power source, a current is supplied to the outside through the external terminals for conduction. When charging the battery pack, a charging current (including regenerative energy for driving the vehicle) is supplied to the battery pack through an external terminal for power supply.

  Next, an example of the battery pack according to the present embodiment will be described with reference to the drawings.

  FIG. 6 is an exploded perspective view illustrating an example of the battery pack according to the present embodiment. FIG. 7 is a block diagram showing an electric circuit of the battery pack shown in FIG.

  The battery pack 20 shown in FIGS. 6 and 7 includes a plurality of flat cells 21 having the structure shown in FIGS.

  The plurality of cells 21 are stacked so that the negative electrode terminal 6 and the positive electrode terminal 7 extending to the outside are arranged in the same direction, and are fastened with the adhesive tape 22, thereby forming an assembled battery 23. I have. These cells 21 are electrically connected to each other in series as shown in FIG.

  The printed wiring board 24 is disposed so as to face the side surfaces of the plurality of unit cells 21 from which the negative electrode terminal 6 and the positive electrode terminal 7 extend. The printed wiring board 24 is provided with a thermistor 25, a protection circuit 26, and a terminal 27 for energizing an external device shown in FIG. An insulating plate (not shown) is attached to the surface of the printed wiring board 24 facing the battery pack 23 to avoid unnecessary connection with the wiring of the battery pack 23.

  The positive electrode lead 28 is connected to the positive electrode terminal 7 of the unit cell 21 located at the lowermost layer of the assembled battery 23, and the tip is inserted into the positive electrode connector 29 of the printed wiring board 24 and electrically connected. I have. A negative electrode lead 30 is connected to the negative electrode terminal 6 of the unit cell 21 located on the uppermost layer of the assembled battery 23, and the tip is inserted into the negative electrode connector 31 of the printed wiring board 24 and electrically connected. I have. These connectors 29 and 31 are connected to the protection circuit 26 through wirings 32 and 33 formed on the printed wiring board 24, respectively.

  The thermistor 25 detects the temperature of each of the cells 21 and sends a detection signal to the protection circuit 26. The protection circuit 26 can cut off the plus side wiring 34a and the minus side wiring 34b between the protection circuit 26 and the terminal 27 for energizing the external device under predetermined conditions. An example of the predetermined condition is when a signal indicating that the temperature of the cell 21 is equal to or higher than the predetermined temperature is received from the thermistor 25. Another example of the predetermined condition is when overcharge, overdischarge, overcurrent, or the like of the cell 21 is detected. The detection of the overcharge or the like is performed on each of the unit cells 21 or the assembled battery 23. When detecting the individual cells 21, the battery voltage may be detected, and 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 21. In the battery packs of FIGS. 6 and 7, wirings 35 for voltage detection are connected to the respective cells 21, and a detection signal is transmitted to the protection circuit 26 through these wirings 35.

  Protective sheets 36 made of rubber or resin are respectively disposed on three sides of the four side faces of the battery pack 23 except for the side faces from which the positive electrode terminal 7 and the negative electrode terminal 6 protrude.

  The battery pack 23 is stored in a storage container 37 together with each protective sheet 36 and the printed wiring board 24. The protective sheet 36 is disposed on both inner side surfaces in the long side direction of the storage container 37 and one inner side surface in the short side direction. The printed wiring board 24 is arranged on one inner surface in the short side direction different from the inner surface on which the protection sheet 36 is arranged. The battery pack 23 is located in a space surrounded by the protection sheet 36 and the printed wiring board 24. The lid 38 is attached to the upper surface of the storage container 37.

  Note that a heat-shrinkable tape may be used for fixing the battery pack 23 instead of the adhesive tape 22. In this case, the protective sheets are arranged on both side surfaces of the battery pack, and after the heat shrink tape is circulated, the heat shrink tape is heat shrunk to bind the battery pack.

  Although the battery pack 20 shown in FIGS. 6 and 7 has a form in which a plurality of unit cells 21 are connected in series, the battery pack may be connected to a plurality of unit cells 21 in parallel in order to increase the battery capacity. Good. Alternatively, the battery pack may include a plurality of cells 21 connected in combination of a series connection and a parallel connection. The battery packs 20 can be further electrically connected in series or in parallel.

  Although the battery pack 20 shown in FIGS. 6 and 7 includes a plurality of cells 21, the battery pack may include one cell 21.

  Further, the embodiment of the battery pack is appropriately changed depending on the application. The battery pack according to the present embodiment is suitably used for applications that require excellent cycle characteristics when a large current is taken out. Specifically, for example, as a power supply of a digital camera, as a vehicle-mounted battery of a two-wheel or four-wheel hybrid electric vehicle, a two-wheel or four-wheel electric vehicle, an assist bicycle, or the like, as a stationary battery, or as a railway vehicle Used as a battery for In particular, it is suitably used as a vehicle-mounted battery.

  In a vehicle such as an automobile equipped with the battery pack according to the present embodiment, the battery pack collects, for example, regenerative energy of the power of the vehicle.

  The battery pack according to the second embodiment includes the nonaqueous electrolyte battery according to the first embodiment. This nonaqueous electrolyte battery can suppress a side reaction between the Na-containing niobium titanium composite oxide contained in the negative electrode active material containing layer and the nonaqueous electrolyte. Therefore, the battery pack according to the second embodiment can exhibit excellent life characteristics.

(Third embodiment)
According to a third embodiment, a vehicle is provided. This vehicle mounts the battery pack according to the second embodiment.

  In the vehicle according to the third embodiment, the battery pack collects, for example, regenerative energy of the power of the vehicle.

  Examples of the vehicle according to the third embodiment include, for example, two-wheel or four-wheel hybrid electric vehicles, two-wheel or four-wheel electric vehicles, and assist bicycles and railway vehicles (for example, trains).

  The mounting position of the battery pack in the vehicle according to the third embodiment is not particularly limited. For example, when the battery pack is mounted on an automobile, the battery pack can be mounted on an engine room of the vehicle, behind the vehicle body, or under a seat.

  Next, an example of a vehicle according to a third embodiment will be described with reference to the drawings.

  FIG. 8 is a schematic cross-sectional view of an example vehicle according to the third embodiment.

  The vehicle 41 shown in FIG. 8 is an automobile. The vehicle 41 has a battery pack 42 mounted in an engine room in front of the vehicle body.

  Next, the configuration of another example of the vehicle according to the third embodiment will be described with reference to FIG.

  FIG. 9 shows a configuration of another example of the vehicle according to the third embodiment. The vehicle 300 shown in FIG. 9 is an electric vehicle.

  The vehicle 300 shown in FIG. 9 includes a vehicle power supply 301, a vehicle ECU (Electric Control Unit) 380 which is a higher-level control unit of the vehicle power supply 301, an external terminal 370, an inverter 340, and a drive motor 345. Have.

  The vehicle 300 has a vehicle power supply 301 mounted, for example, in an engine room, behind a vehicle body, or under a seat. However, FIG. 9 schematically shows the mounting location of the nonaqueous electrolyte battery on the vehicle 300.

  The vehicle power supply 301 includes a plurality (for example, three) of battery packs 312a, 312b, and 312c, a battery management unit (BMU: Battery Management Unit) 311 and a communication bus 310.

  The three battery packs 312a, 312b and 312c are electrically connected in series. The battery pack 312a includes an assembled battery 314a and an assembled battery monitoring device (VTM: Voltage Temperature Monitoring) 313a. The battery pack 312b includes an assembled battery 314b and an assembled battery monitoring device 313b. The battery pack 312c includes an assembled battery 314c and an assembled battery monitoring device 313c. Battery packs 312a, 312b, and 312c can be detached independently, and can be replaced with another battery pack.

  Each of the assembled batteries 314a to 314c includes a plurality of nonaqueous electrolyte batteries connected in series. Each of the non-aqueous electrolyte batteries is the non-aqueous electrolyte battery according to the first embodiment. The assembled batteries 314a to 314c perform charging and discharging through the positive terminal 316 and the negative terminal 317, respectively. That is, the battery packs 312a, 312b, and 312c are the battery packs according to the second embodiment.

  The battery management device 311 collects information such as the voltage and temperature of the non-aqueous electrolyte batteries of the assembled batteries 314a to 314c included in the vehicle power supply 301 in order to collect information on the maintenance of the vehicle power supply 301. It communicates with the 313c and collects them.

  A communication bus 310 is connected between the battery management device 311 and the battery pack monitoring devices 313a to 313c. The communication bus 310 is configured to share one set of communication lines by a plurality of nodes (a battery management device and one or more assembled battery monitoring devices). The communication bus 310 is a communication bus configured based on, for example, a CAN (Control Area Network) standard.

  The assembled battery monitoring devices 313a to 313c measure the voltages and temperatures of the individual non-aqueous electrolyte batteries constituting the assembled batteries 314a to 314c based on a command from the battery management device 311 through communication. However, the temperature can be measured at only a few locations per battery pack, and the temperature of all non-aqueous electrolyte batteries does not need to be measured.

  The vehicle power supply 301 can also include an electromagnetic contactor (for example, a switch device 333 shown in FIG. 9) for turning on and off the connection between the positive terminal and the negative terminal. The switch device 333 includes a precharge switch (not shown) that is turned on when the assembled batteries 314a to 314c are charged, and a main switch (not shown) that is turned on when the battery output is supplied to the load. . The precharge switch and the main switch each include a relay circuit (not shown) that is turned on and off by a signal supplied to a coil disposed near the switch element.

  Inverter 340 converts the input DC voltage into a three-phase alternating current (AC) high voltage for driving the motor. The output voltage of inverter 340 is controlled based on a control signal from battery management device 311 or vehicle ECU 380 for controlling the entire operation of the vehicle. The three-phase output terminals of the inverter 340 are connected to the three-phase input terminals of the drive motor 345.

  The drive motor 345 is rotated by electric power supplied from the inverter 340, and transmits the rotation to the axle and the drive wheels W via, for example, a differential gear unit.

  Although not shown, the vehicle 300 includes a regenerative brake mechanism that rotates the drive motor 345 when the vehicle 300 is braked and converts kinetic energy into regenerative energy as electric energy. The regenerative energy collected by the regenerative braking mechanism is input to the inverter 340 and is converted into a DC current. The DC current is input to the vehicle power supply 301.

  One terminal of a connection line L1 is connected to the negative terminal 317 of the vehicle power supply 301 via a current detection unit (not shown) in the battery management device 311. The other terminal of the connection line L1 is connected to a negative input terminal of the inverter 340.

  One terminal of a connection line L2 is connected to a positive terminal 316 of the vehicle power supply 301 via a switch device 333. The other terminal of the connection line L2 is connected to a positive input terminal of the inverter 340.

  The external terminal 370 is connected to the battery management device 311. The external terminal 370 can be connected to, for example, an external power supply.

  The vehicle ECU 380 controls the battery management device 311 in cooperation with other devices in response to an operation input by a driver or the like, and manages the entire vehicle. Between the battery management device 311 and the vehicle ECU 380, data related to the maintenance of the vehicle power supply 301 such as the remaining capacity of the vehicle power supply 301 is transferred via a communication line.

  Since the vehicle according to the third embodiment includes the battery pack according to the third embodiment, excellent vehicle life characteristics can be exhibited.

[Example]
Examples will be described below, but the embodiments are not limited to the examples described below.

(Example 1)
In Example 1, the nonaqueous electrolyte battery of Example 1 was manufactured according to the following procedure.

<Production of negative electrode active material>
The following procedure was synthesized _{Li 2.0 Na 1.5 Ti 5. 5 Nb} 0.5 O 14 as orthorhombic Akiragata Na-containing niobium titanium composite oxide.
First, titanium oxide TiO ₂ , lithium carbonate Li ₂ CO ₃ , sodium carbonate Na ₂ CO _3, and niobium (V) Nb (OH) ₅ were prepared as raw materials. These raw materials were mixed such that the molar ratio of Li: Na: Ti: Nb in the mixture was 2.0: 1.5: 5.5: 0.5. Prior to mixing, the raw materials were thoroughly ground.

  The mixed raw material was subjected to a heat treatment in an air atmosphere at 1000 ° C. for 10 hours. Thus, a product powder was obtained. The obtained product powder was subjected to a wet ball mill treatment in pure water for 5 hours, filtered, and then heat-treated again. The condition of the reheat treatment was 600 ° C. for 3 hours. Thus, a powder of the negative electrode active material was obtained.

The obtained negative electrode active material was analyzed by ICP, SEM-EDX and XRD described above. As a result, it was found that the obtained negative electrode active material was an orthorhombic Na-containing niobium titanium composite oxide powder having a composition represented by the formula: Li _2.0 Na _1.5 Ti _5.5 Nb _0.5 O ₁₄ .

<Preparation of negative electrode intermediate member>
The active material, acetylene black and polyvinylidene fluoride (PVdF) prepared above were dispersed in N-methylpyrrolidone (NMP) at a blending ratio of 90% by mass: 5% by mass: 5% by mass, and mixed. Obtained. This mixture was further stirred using a rotation and revolution mixer to prepare a slurry. This slurry was applied to both surfaces of a current collector made of aluminum foil having a thickness of 15 μm, and the coating film was dried. Next, the dried coating film is pressed to form a current collector and a negative electrode active material-containing layer formed on the current collector and having an electrode density (not including the current collector) of 2.3 g / cm ^3. A negative electrode intermediate member containing the same was produced.

  When the slurry was applied, an uncoated portion of the slurry was left on a part of the current collector. This portion was used as a negative electrode tab. The negative electrode terminal was ultrasonically bonded to the negative electrode tab.

<Preparation of positive electrode>
LiMn ₂ O ₄ was synthesized as spinel-type lithium manganate by the following procedure.
First, lithium carbonate Li ₂ CO ₃ and manganese carbonate MnCO ₃ were prepared as raw materials. These raw materials were mixed such that the molar ratio of Li: Mn of the mixture was 1.0: 2.0. Prior to mixing, the raw materials were thoroughly ground.

  The mixed raw material was subjected to a heat treatment at 700 ° C. for 10 hours in an air atmosphere. Thus, a product powder was obtained.

The obtained product was analyzed by ICP, SEM-EDX and XRD as described above. As a result, it was found that the obtained negative electrode active material was a spinel-type lithium manganate powder having a composition represented by the formula LiMn ₂ O ₄ .

The active material, acetylene black and polyvinylidene fluoride (PVdF) prepared above were dispersed and mixed in N-methylpyrrolidone (NMP) at a blending ratio of 90% by mass: 5% by mass: 5% by mass to obtain a mixture. . This mixture was further stirred using a rotation and revolution mixer to prepare a slurry. This slurry was applied to both surfaces of a current collector made of aluminum foil having a thickness of 15 μm, and the coating film was dried. Next, the dried coating film is pressed to form a current collector and a positive electrode active material-containing layer formed on the current collector and having an electrode density (not including the current collector) of 2.9 g / cm ^3. A positive electrode was prepared.

  When the slurry was applied, an uncoated portion of the slurry was left on a part of the current collector. This portion was used as a positive electrode tab. The positive electrode terminal was ultrasonically bonded to the positive electrode tab.

<Preparation of electrode group>
Two separators made of a polyethylene porous film having a thickness of 25 μm were prepared. Next, the previously manufactured positive electrode, one separator, the previously manufactured negative electrode intermediate member, and another separator were laminated in this order to obtain a laminate. This laminate was spirally wound to obtain a wound body. Next, the winding core was removed from the wound body, and the wound body was subjected to a heating press at 90 ° C. Thus, a flat electrode group having a width of 30 mm and a thickness of 3.0 mm was produced.

<Accommodation of electrode group in exterior member>
The obtained electrode group was wrapped with a laminate film. The laminated film was formed by forming a polypropylene layer on both sides of an aluminum foil having a thickness of 40 μm and having a total thickness of 0.1 mm. At this time, at one end of the laminate film, a part of the negative electrode terminal was sandwiched between two opposing portions of the polypropylene layer. Then, another part of the negative electrode terminal was made to come out of the laminate film. Similarly, at one end of the laminate film, a part of the positive electrode terminal was sandwiched between two opposing parts of the polypropylene layer. Then, another part of the positive electrode terminal was made to come out of the laminate film.

Next, the end portion sandwiching a part of the negative electrode terminal was heat-sealed. Similarly, an end portion sandwiching a part of the positive electrode terminal was heat-sealed. Thus, the electrode group was housed in an exterior member made of a laminate film.
Next, the electrode group was subjected to vacuum drying in an exterior member at 80 ° C. for 24 hours.

<Preparation of liquid non-aqueous electrolyte>
Ethylene carbonate (EC), propylene carbonate (PC) and ethyl methyl carbonate (EMC) were prepared as non-aqueous solvents. These were mixed so that the volume ratio of EC: PC: EMC became 1: 1: 4 to prepare a mixed solvent.

In this mixed solvent, lithium hexafluorophosphate (LiPF ₆ ) was dissolved at a concentration of 1.2M. Thus, a liquid non-aqueous electrolyte was prepared.

<Preparation of battery unit>
A battery unit was fabricated in a dry argon environment as described below with reference to FIGS. 10A to 10F.

  10A to 10F are schematic diagrams showing a part of the procedure for manufacturing the nonaqueous electrolyte battery of Example 1.

  First, as shown in FIG. 10A, the previously prepared liquid non-aqueous electrolyte 8 was injected into the exterior member 2 of the laminated film containing the electrode group 1. Next, as shown in FIG. 10B, the end 2a of the exterior member 2 was heat-sealed. Thus, the electrode group 1 and the liquid nonaqueous electrolyte 8 were completely sealed in the exterior member 2. At this time, as shown in FIG. 10B, a distance was provided between the heat seal portion 2a and the portion where the electrode group 1 was accommodated.

  Thus, the battery unit 10 'of Example 1 was manufactured.

<Aging process>
The prepared battery unit 10 ′ of Example 1 was subjected to a first aging process and then a second aging process in the following procedure.

  First, the voltage of the battery unit 10 'was adjusted to 2.5 V according to the procedure described above. This battery unit was subjected to a first aging treatment. The first aging treatment was performed in a 60 ° C. temperature environment for 10 hours. Next, the exterior member 2 was cut open along the cut line 2A shown in FIG. 10B as shown in FIG. 10C. Thus, the gas inside the exterior member 2 was released.

  Next, as shown in FIG. 10D, the end 2b of the exterior member 2 was heat-sealed. Thus, the electrode group 1 and the liquid nonaqueous electrolyte 8 were completely sealed in the exterior member 2.

  Next, the voltage of the battery unit 10 'was adjusted to 2.8 V by the procedure described above. This battery unit 10 'was subjected to a second aging treatment. The second aging treatment was performed in a temperature environment of 80 ° C. for 10 hours. Next, the exterior member 2 was cut open along the cut line 2B shown in FIG. 10D as shown in FIG. 10E. Thus, the gas inside the exterior member 2 was released.

  Next, as shown in FIG. 10F, the end 2c of the exterior member 2 was heat-sealed. Thus, the electrode group 1 and the liquid nonaqueous electrolyte 8 were completely sealed in the exterior member 2.

  Thus, it has the same structure as that of the example non-aqueous electrolyte battery 10 shown in FIGS. 2 and 3 described above, specifically, the width is 35 mm, the thickness is 3.2 mm, and the height is A non-aqueous electrolyte battery 10 of Example 1 having a size of 65 mm was obtained.

<Charge / discharge cycle test of test cell>
The nonaqueous electrolyte battery 10 of Example 1 was subjected to a high-temperature charge / discharge cycle test according to the following procedure.

  The test temperature environment was 60 ° C. In charging, the battery 10 was charged at a constant current value of 0.2 C until the voltage reached 3.0 V, and then the battery was charged at a constant voltage of 3.0 V. Charging was stopped when the current value reached 1 / 20C. The discharge was performed at a constant current value of 0.2C. The discharge was stopped when the voltage of the battery 10 reached 1.8V. A one-minute pause in the same temperature environment was performed between charging and discharging. Charging, resting, discharging and resting were defined as one cycle. The number of cycles performed in this test was 500. By dividing the discharge capacity at the 500th cycle of the nonaqueous electrolyte battery by the discharge capacity at the first cycle, the capacity retention after 500 cycles at a high temperature was evaluated. This capacity retention ratio is an index of the cycle characteristics of the electrode.

<X-ray photoelectron spectroscopy (XPS) measurement>
After performing the cycle test, the XPS measurement was performed according to the following procedure. As a device, Quantera SXM manufactured by PHI was used. Single crystal spectroscopy Al-Kα (1486.6 eV) was used as the excitation X-ray source, and the photoelectron detection angle was 45 °. By this measurement, the intensity I ₁ of the peak P ₁ appearing at 289 to 292 eV and the intensity I _{2 of the} peak P ₂ appearing at 283 to 285 eV on the negative electrode surface were measured.

(Examples 2 to 22)
In Examples 2 to 22, the same procedures as in Example 1 were performed except that the conditions of the first aging treatment and / or the second aging treatment were changed to the conditions shown in Table 1 below. Twenty-two nonaqueous electrolyte batteries were produced.

(Example 23)
In Example 23, the same as Example 1 except that an orthorhombic Na-containing niobium titanium composite oxide having a composition represented by the formula Li ₂ Na _1.75 Ti _5.75 Nb _0.25 O ₁₄ was used as the negative electrode active material. By the procedure, the nonaqueous electrolyte battery of Example 23 was produced.

An orthorhombic Na-containing niobium titanium composite oxide having a composition represented by the formula Li ₂ Na _1.75 Ti _5.75 Nb _0.25 O ₁₄ was synthesized by the following procedure.
First, titanium oxide TiO ₂ , lithium carbonate Li ₂ CO ₃ , sodium carbonate Na ₂ CO _3, and niobium (V) Nb (OH) ₅ were prepared as raw materials. These raw materials were mixed such that the molar ratio of Li: Na: Ti: Nb in the mixture was 2.0: 1.75: 5.75: 0.25. Prior to mixing, the raw materials were thoroughly ground.

  The mixed raw material was subjected to a heat treatment in an air atmosphere at 1000 ° C. for 10 hours. Thus, a product powder was obtained. The obtained product powder was subjected to a wet ball mill treatment in pure water for 5 hours, filtered, and then heat-treated again. The condition of the reheat treatment was 600 ° C. for 3 hours. Thus, a powder of the negative electrode active material was obtained.

The obtained negative electrode active material was analyzed by ICP, SEM-EDX and XRD described above. As a result, it was found that the obtained negative electrode active material was an orthorhombic Na-containing niobium titanium composite oxide powder having a composition represented by the formula: Li _2.0 Na _1.75 Ti _5.75 Nb _0.25 O ₁₄ .

Using the active material obtained as described above, a negative electrode intermediate member was produced in the following procedure.
The active material, acetylene black and polyvinylidene fluoride (PVdF) prepared above were dispersed in N-methylpyrrolidone (NMP) at a blending ratio of 90% by mass: 5% by mass: 5% by mass, and mixed. Obtained. This mixture was further stirred using a rotation and revolution mixer to prepare a slurry. This slurry was applied to both surfaces of a current collector made of aluminum foil having a thickness of 15 μm, and the coating film was dried. Next, the dried coating film is pressed to form a current collector and a negative electrode active material-containing layer formed on the current collector and having an electrode density (not including the current collector) of 2.3 g / cm ^3. A negative electrode intermediate member containing the same was produced.

  When the slurry was applied, an uncoated portion of the slurry was left on a part of the current collector. This portion was used as a negative electrode tab. The negative electrode terminal was ultrasonically bonded to the negative electrode tab.

(Examples 24 to 44)
In Examples 24 to 44, the procedure was the same as that in Example 23 except that the conditions of the first aging treatment and / or the second aging treatment were changed to the conditions shown in Table 1 or Table 2 below. The non-aqueous electrolyte batteries of Examples 24 to 44 were produced.

(Example 45)
In Example 45, the same as Example 1 except that an orthorhombic Na-containing niobium titanium composite oxide having a composition represented by the formula Li ₂ Na _1.8 Ti _5.8 Nb _0.2 O ₁₄ was used as the negative electrode active material. According to the procedure, a nonaqueous electrolyte battery of Example 45 was produced.

An orthorhombic Na-containing niobium titanium composite oxide having a composition represented by the formula Li ₂ Na _1.8 Ti _5.8 Nb _0.2 O ₁₄ was synthesized by the following procedure.

An orthorhombic Na-containing niobium titanium composite oxide having a composition represented by the formula Li _2.0 Na _1.8 Ti _5.8 Nb _0.2 O ₁₄ was synthesized by the following procedure.
First, titanium oxide TiO ₂ , lithium carbonate Li ₂ CO ₃ , sodium carbonate Na ₂ CO _3, and niobium (V) Nb (OH) ₅ were prepared as raw materials. These raw materials were mixed such that the molar ratio of Li: Na: Ti: Nb in the mixture was 2.0: 1.8: 5.8: 0.2. Prior to mixing, the raw materials were thoroughly ground.

  The mixed raw material was subjected to a heat treatment in an air atmosphere at 1000 ° C. for 10 hours. Thus, a product powder was obtained. The obtained product powder was subjected to a wet ball mill treatment in pure water for 5 hours, filtered, and then heat-treated again. The condition of the reheat treatment was 600 ° C. for 3 hours. Thus, a powder of the negative electrode active material was obtained.

The obtained negative electrode active material was analyzed by ICP, SEM-EDX and XRD described above. As a result, it was found that the obtained negative electrode active material was an orthorhombic Na-containing niobium titanium composite oxide powder having a composition represented by the formula: Li _2.0 Na _1.8 Ti _5.8 Nb _0.2 O ₁₄ .

Using the active material obtained as described above, a negative electrode intermediate member was produced in the following procedure.
The active material, acetylene black and polyvinylidene fluoride (PVdF) prepared above were dispersed and mixed in N-methylpyrrolidone (NMP) at a blending ratio of 90% by mass: 5% by mass: 5% by mass to obtain a mixture. Was. This mixture was further stirred using a rotation and revolution mixer to prepare a slurry. This slurry was applied to both surfaces of a current collector made of aluminum foil having a thickness of 15 μm, and the coating film was dried. Next, the dried coating film is pressed to form a current collector and a negative electrode active material-containing layer formed on the current collector and having an electrode density (not including the current collector) of 2.3 g / cm ^3. A negative electrode intermediate member containing the same was produced.

  When the slurry was applied, an uncoated portion of the slurry was left on a part of the current collector. This portion was used as a negative electrode tab. The negative electrode terminal was ultrasonically bonded to the negative electrode tab.

(Example 46)
Example 46 was performed in the same manner as in Example 1 except that as the negative electrode active material, an orthorhombic Na-containing niobium titanium composite oxide having a composition represented by the formula Li ₂ Na _1.4 K _0.1 Ti _5.5 Nb _0.5 O ₁₄ was used. The nonaqueous electrolyte battery of Example 46 was manufactured in the same procedure.

An orthorhombic Na-containing niobium titanium composite oxide having a composition represented by the formula Li ₂ Na _1.4 K _0.1 Ti _5.5 Nb _0.5 O ₁₄ was synthesized by the following procedure.

First, titanium oxide TiO ₂ , lithium carbonate Li ₂ CO ₃ , sodium carbonate Na ₂ CO ₃ , potassium carbonate K ₂ CO _3, and niobium (V) Nb (OH) ₅ were prepared as raw materials. . These raw materials were mixed such that the molar ratio of Li: Na: K: Ti: Nb in the mixture was 2.0: 1.4: 0.1: 5.5: 0.5. Prior to mixing, the raw materials were thoroughly ground.

  The mixed raw material was subjected to a heat treatment in an air atmosphere at 1000 ° C. for 10 hours. Thus, a product powder was obtained. The obtained product powder was subjected to a wet ball mill treatment in pure water for 5 hours, filtered, and then heat-treated again. The condition of the reheat treatment was 600 ° C. for 3 hours. Thus, a powder of the negative electrode active material was obtained.

The obtained negative electrode active material was analyzed by ICP, SEM-EDX and XRD described above. As a result, it was found that the obtained negative electrode active material was a powder of an orthorhombic Na-containing niobium titanium composite oxide having a composition represented by the formula Li _2.0 Na _1.4 K _0.1 Ti _5.5 Nb _0.5 O ₁₄ .

Using the active material obtained as described above, a negative electrode intermediate member was produced in the following procedure.
90% by mass of the active material prepared above, 5% by mass of acetylene black and 5% by mass of polyvinylidene fluoride (PVdF) were dispersed in N-methylpyrrolidone (NMP) and mixed to obtain a mixture. This mixture was further stirred using a rotation and revolution mixer to prepare a slurry. This slurry was applied to both surfaces of a current collector made of aluminum foil having a thickness of 15 μm, and the coating film was dried. Next, the dried coating film is pressed to form a current collector and a negative electrode active material-containing layer formed on the current collector and having an electrode density (not including the current collector) of 2.3 g / cm ^3. A negative electrode intermediate member containing the same was produced.

  When the slurry was applied, an uncoated portion of the slurry was left on a part of the current collector. This portion was used as a negative electrode tab. The negative electrode terminal was ultrasonically bonded to the negative electrode tab.

(Example 47)
Example 47 was the same as Example 1 except that as the negative electrode active material, an orthorhombic Na-containing niobium titanium composite oxide having a composition represented by the formula Li ₂ Na _1.6 Ti _5.5 Nb _0.4 Zr _0.1 O ₁₄ was used. The nonaqueous electrolyte battery of Example 47 was manufactured in the same procedure.

An orthorhombic Na-containing niobium titanium composite oxide having a composition represented by the formula Li ₂ Na _1.6 Ti _5.5 Nb _0.4 Zr _0.1 O ₁₄ was synthesized by the following procedure.

First, titanium oxide TiO ₂ , lithium carbonate Li ₂ CO ₃ , sodium carbonate Na ₂ CO ₃ , niobium (V) Nb (OH) _5, and zirconium hydroxide Zr (OH) ₄ were used as raw materials. Got ready. These raw materials were mixed so that the molar ratio of Li: Na: Ti: Nb: Zr in the mixture was 2.0: 1.6: 5.5: 0.4: 0.1. Prior to mixing, the raw materials were thoroughly ground.

  The mixed raw material was subjected to a heat treatment in an air atmosphere at 1000 ° C. for 10 hours. Thus, a product powder was obtained. The obtained product powder was subjected to a wet ball mill treatment in pure water for 5 hours, filtered, and then heat-treated again. The condition of the reheat treatment was 600 ° C. for 3 hours. Thus, a powder of the negative electrode active material was obtained.

The obtained negative electrode active material was analyzed by ICP, SEM-EDX and XRD described above. As a result, it was found that the obtained negative electrode active material was an orthorhombic Na-containing niobium titanium composite oxide powder having a composition represented by the formula: Li ₂ Na _1.6 Ti _5.5 Nb _0.4 Zr _0.1 O ₁₄ .

Using the active material obtained as described above, a negative electrode intermediate member was produced in the following procedure.
The active material, acetylene black and polyvinylidene fluoride (PVdF) prepared above were dispersed and mixed in N-methylpyrrolidone (NMP) at a blending ratio of 90% by mass: 5% by mass: 5% by mass to obtain a mixture. Was. This mixture was further stirred using a rotation and revolution mixer to prepare a slurry. This slurry was applied to both surfaces of a current collector made of aluminum foil having a thickness of 15 μm, and the coating film was dried. Next, the dried coating film is pressed to include a current collector and a negative electrode active material-containing layer formed on the current collector and having an electrode density (not including the current collector) of 2.3 g / cm 3. A negative electrode intermediate member was produced.

  When the slurry was applied, an uncoated portion of the slurry was left on a part of the current collector. This portion was used as a negative electrode tab. The negative electrode terminal was ultrasonically bonded to the negative electrode tab.

(Comparative Example 1)
In Comparative Example 1, a nonaqueous electrolyte battery of Comparative Example 1 was produced in the same procedure as in Example 1 except that the liquid nonaqueous electrolyte was changed.

The liquid non-aqueous electrolyte used in Comparative Example 1 was prepared according to the following procedure. First, propylene carbonate (PC) and ethyl methyl carbonate (EMC) were prepared as non-aqueous solvents. These were mixed so that the volume ratio of PC: EMC would be 1: 2 to prepare a mixed solvent. In this mixed solvent, lithium hexafluorophosphate (LiPF ₆ ) was dissolved at a concentration of 1.2M. Thus, a liquid non-aqueous electrolyte was prepared.

(Comparative Example 2)
In Comparative Example 2, the non-aqueous electrolyte battery of Comparative Example 2 was manufactured in the same procedure as in Example 1 except that the first aging condition and the second aging condition of the battery unit were changed as shown in Table 2 below. Was prepared.

(Comparative Examples 3 to 6)
In Comparative Examples 3 to 6, the non-aqueous electrolyte batteries of Comparative Examples 3 to 6 were manufactured by the same procedure as in Example 1 except that the aging of the battery unit was performed only once under the conditions shown in Table 2 below. did.

  Each of the nonaqueous electrolyte batteries of Examples 2 to 47 and Comparative Examples 1 to 6 was subjected to a test in the same manner as the nonaqueous electrolyte battery of Example 1. The results are shown in Tables 3 and 4 below.

(result)
FIG. 11 shows a part of the XPS spectrum on the surface of the negative electrode included in the nonaqueous electrolyte battery of Example 1 (solid line) and a part of the XPS spectrum on the surface of the negative electrode included in the battery of Comparative Example 1 (dotted line). Show.

First, as it is clear from FIG. 11, the spectrum of the negative electrode surface comprising a non-aqueous electrolyte battery of Example 1 has a peak P ₁ having a peak top at a binding energy of 291eV. Intensity I ₁ of the peak P ₁ is smaller than ₁ 'intensity I _1' peak P nonaqueous electrolyte battery which appeared in the same binding energy in the spectrum of the negative electrode surface comprising the Comparative Example 1. Further, the spectrum of the negative electrode surface comprising a non-aqueous electrolyte battery of Example 1 has a peak P ₂ have a peak top at a binding energy of 284 eV. Intensity I ₂ of the peak P ₂ is greater than the non-aqueous electrolyte ₂ 'intensity I _2' peak P appearing in the same binding energy in the spectrum of the negative electrode surface the battery is equipped in Comparative Example 1. Then, the intensity ratio I _'2 / I' ₁ of Comparative Example 1 whereas was 0.95, the intensity ratio I ₂ / I ₁ of Example 1 was 1.67.

As shown in Tables 3 and 4, each of the nonaqueous electrolyte batteries of Examples 1 to 47 in which the intensity ratio I ₂ / I ₁ is 1 or more is a comparative example in which the intensity ratio I ′ ₂ / I ′ ₁ is less than 1. The non-aqueous electrolyte batteries of Nos. 1 to 8 exhibited higher cycle capacity retention rates. That is, each of the non-aqueous electrolyte batteries of Examples 1 to 47 in which the intensity ratio I ₂ / I ₁ was 1 or more was able to exhibit better life characteristics than each of the non-aqueous electrolyte batteries of Comparative Examples 1 to 8. .

  In Comparative Example 1, the same first and second aging as in Example 1 were performed, but a sufficient film was not formed on the negative electrode active material-containing layer. This is considered to be due to the composition of the electrolytic solution.

Comparative Example 2 is an example in which the first aging and the second aging performed in Example 1 are performed by changing the order. From the results of Comparative Example 2, when the battery unit adjusted to a higher SOC was subjected to aging at a higher temperature, and then the battery unit adjusted to a lower SOC than the previous aging was subjected to aging at a lower temperature than the previous aging, The strength ratio I ₂ / I ₁ was less than 1, indicating that a sufficient film was not formed on the negative electrode active material-containing layer.

Comparative Examples 3 to 6 are examples in which aging was performed only once. From these results, even if the conditions were changed, when aging was performed only once, the intensity ratio I ₂ / I ₁ was less than 1, and a sufficient film was not formed on the negative electrode active material-containing layer. You can see that

  For example, excellent life characteristics can be obtained by a battery newly manufactured using the negative electrode included in the nonaqueous electrolyte battery of each embodiment.

(Example 48)
Example 48 was the same as Example 1 except that an orthorhombic Na-containing niobium titanium composite oxide having a composition represented by the formula Li ₂ Na _0.2 Ti _4.2 Nb _1.8 O ₁₄ was used as the negative electrode active material. By the procedure, the nonaqueous electrolyte battery of Example 48 was produced.

An orthorhombic Na-containing niobium titanium composite oxide having a composition represented by the formula Li ₂ Na _0.2 Ti _4.2 Nb _1.8 O ₁₄ was synthesized by the following procedure.

First, titanium oxide TiO ₂ , lithium carbonate Li ₂ CO ₃ , sodium carbonate Na ₂ CO _3, and niobium (V) Nb (OH) ₅ were prepared as raw materials. These raw materials were mixed such that the molar ratio of Li: Na: Ti: Nb in the mixture was 2.0: 0.2: 4.2: 1.8. Prior to mixing, the raw materials were thoroughly ground.

  The mixed raw material was subjected to a heat treatment in an air atmosphere at 1000 ° C. for 10 hours. Thus, a product powder was obtained. The obtained product powder was subjected to a wet ball mill treatment in pure water for 5 hours, filtered, and then heat-treated again. The condition of the reheat treatment was 600 ° C. for 3 hours. Thus, a powder of the negative electrode active material was obtained.

The obtained negative electrode active material was analyzed by ICP, SEM-EDX and XRD described above. As a result, it was found that the obtained negative electrode active material was a powder of an orthorhombic Na-containing niobium titanium composite oxide having a composition represented by the formula: Li ₂ Na _0.2 Ti _4.2 Nb _1.8 O ₁₄ .

Using the active material obtained as described above, a negative electrode intermediate member was produced in the following procedure.
The active material, acetylene black and polyvinylidene fluoride (PVdF) prepared above were dispersed and mixed in N-methylpyrrolidone (NMP) at a blending ratio of 90% by mass: 5% by mass: 5% by mass to obtain a mixture. Was. This mixture was further stirred using a rotation and revolution mixer to prepare a slurry. This slurry was applied to both surfaces of a current collector made of aluminum foil having a thickness of 15 μm, and the coating film was dried. Next, the dried coating film is pressed to form a current collector and a negative electrode active material-containing layer formed on the current collector and having an electrode density (not including the current collector) of 2.3 g / cm ^3. A negative electrode intermediate member containing the same was produced.

  When the slurry was applied, an uncoated portion of the slurry was left on a part of the current collector. This portion was used as a negative electrode tab. The negative electrode terminal was ultrasonically bonded to the negative electrode tab.

(Example 49)
Example 49 was the same as Example 1 except that an orthorhombic Na-containing niobium titanium composite oxide having a composition represented by the formula Li ₂ Na _1.3 Mg _0.1 Ti _5.5 Nb _0.5 O ₁₄ was used as the negative electrode active material. The nonaqueous electrolyte battery of Example 49 was manufactured in the same procedure.

An orthorhombic Na-containing niobium titanium composite oxide having a composition represented by the formula Li ₂ Na _1.3 Mg _0.1 Ti _5.5 Nb _0.5 O ₁₄ was synthesized by the following procedure.

First, titanium oxide TiO ₂ , lithium carbonate Li ₂ CO ₃ , sodium carbonate Na ₂ CO ₃ , niobium (V) Nb (OH) _5, and magnesium oxide MgO were prepared as raw materials. These raw materials were mixed such that the molar ratio of Li: Na: Ti: Nb: Mg in the mixture was 2.0: 1.3: 5.5: 0.5: 0.1. Prior to mixing, the raw materials were thoroughly ground.

  The mixed raw material was subjected to a heat treatment in an air atmosphere at 1000 ° C. for 10 hours. Thus, a product powder was obtained. The obtained product powder was subjected to a wet ball mill treatment in pure water for 5 hours, filtered, and then heat-treated again. The condition of the reheat treatment was 600 ° C. for 3 hours. Thus, a powder of the negative electrode active material was obtained.

The obtained negative electrode active material was analyzed by ICP, SEM-EDX and XRD described above. As a result, it was found that the obtained negative electrode active material was an orthorhombic Na-containing niobium titanium composite oxide powder having a composition represented by the formula: Li ₂ Na _1.3 Mg _0.1 Ti _5.5 Nb _0.5 O ₁₄ .

Using the active material obtained as described above, a negative electrode intermediate member was produced in the following procedure.
The active material, acetylene black and polyvinylidene fluoride (PVdF) prepared above were dispersed and mixed in N-methylpyrrolidone (NMP) at a blending ratio of 90% by mass: 5% by mass: 5% by mass to obtain a mixture. Was. This mixture was further stirred using a rotation and revolution mixer to prepare a slurry. This slurry was applied to both surfaces of a current collector made of aluminum foil having a thickness of 15 μm, and the coating film was dried. Next, the dried coating film is pressed to form a current collector and a negative electrode active material-containing layer formed on the current collector and having an electrode density (not including the current collector) of 2.3 g / cm ^3. A negative electrode intermediate member containing the same was produced.

  When the slurry was applied, an uncoated portion of the slurry was left on a part of the current collector. This portion was used as a negative electrode tab. The negative electrode terminal was ultrasonically bonded to the negative electrode tab.

(Example 50)
Example 50 was the same as Example 1 except that an orthorhombic Na-containing niobium titanium composite oxide having a composition represented by the formula Li ₂ Na _1.3 Ca _0.1 Ti _5.5 Nb _0.5 O ₁₄ was used as the negative electrode active material. The nonaqueous electrolyte battery of Example 50 was manufactured in the same procedure.

An orthorhombic Na-containing niobium titanium composite oxide having a composition represented by the formula Li ₂ Na _1.3 Ca _0.1 Ti _5.5 Nb _0.5 O ₁₄ was synthesized by the following procedure.

First, titanium oxide TiO ₂ , lithium carbonate Li ₂ CO ₃ , sodium carbonate Na ₂ CO ₃ , niobium (V) Nb (OH) _5, and calcium oxide CaO were prepared as raw materials. These raw materials were mixed such that the molar ratio of Li: Na: Ti: Nb: Ca of the mixture was 2.0: 1.3: 5.5: 0.5: 0.1. Prior to mixing, the raw materials were thoroughly ground.

  The mixed raw material was subjected to a heat treatment in an air atmosphere at 1000 ° C. for 10 hours. Thus, a product powder was obtained. The obtained product powder was subjected to a wet ball mill treatment in pure water for 5 hours, filtered, and then heat-treated again. The condition of the reheat treatment was 600 ° C. for 3 hours. Thus, a powder of the negative electrode active material was obtained.

The obtained negative electrode active material was analyzed by ICP, SEM-EDX and XRD described above. As a result, it was found that the obtained negative electrode active material was an orthorhombic Na-containing niobium titanium composite oxide powder having a composition represented by the formula: Li ₂ Na _1.3 Ca _0.1 Ti _5.5 Nb _0.5 O ₁₄ .

Using the active material obtained as described above, a negative electrode intermediate member was produced in the following procedure.
The active material, acetylene black and polyvinylidene fluoride (PVdF) prepared above were dispersed and mixed in N-methylpyrrolidone (NMP) at a blending ratio of 90% by mass: 5% by mass: 5% by mass to obtain a mixture. Was. This mixture was further stirred using a rotation and revolution mixer to prepare a slurry. This slurry was applied to both surfaces of a current collector made of aluminum foil having a thickness of 15 μm, and the coating film was dried. Next, the dried coating film is pressed to form a current collector and a negative electrode active material-containing layer formed on the current collector and having an electrode density (not including the current collector) of 2.3 g / cm ^3. A negative electrode intermediate member containing the same was produced.

  When the slurry was applied, an uncoated portion of the slurry was left on a part of the current collector. This portion was used as a negative electrode tab. The negative electrode terminal was ultrasonically bonded to the negative electrode tab.

(Example 51)
Example 51 was the same as Example 1 except that an orthorhombic Na-containing niobium titanium composite oxide having a composition represented by the formula: Li ₂ Na _1.3 Sr _0.1 Ti _5.5 Nb _0.5 O ₁₄ was used as the negative electrode active material. The nonaqueous electrolyte battery of Example 51 was manufactured in the same procedure.

An orthorhombic Na-containing niobium titanium composite oxide having a composition represented by the formula Li ₂ Na _1.3 Sr _0.1 Ti _5.5 Nb _0.5 O ₁₄ was synthesized by the following procedure.

First, titanium oxide TiO ₂ , lithium carbonate Li ₂ CO ₃ , sodium carbonate Na ₂ CO ₃ , niobium (V) Nb (OH) _5, and strontium oxide SrO were prepared as raw materials. These raw materials were mixed such that the molar ratio of Li: Na: Ti: Nb: Sr in the mixture was 2.0: 1.3: 5.5: 0.5: 0.1. Prior to mixing, the raw materials were thoroughly ground.

  The mixed raw material was subjected to a heat treatment in an air atmosphere at 1000 ° C. for 10 hours. Thus, a product powder was obtained. The obtained product powder was subjected to a wet ball mill treatment in pure water for 5 hours, filtered, and then heat-treated again. The condition of the reheat treatment was 600 ° C. for 3 hours. Thus, a powder of the negative electrode active material was obtained.

The obtained negative electrode active material was analyzed by ICP, SEM-EDX and XRD described above. As a result, it was found that the obtained negative electrode active material was a powder of orthorhombic Na-containing niobium titanium composite oxide having a composition represented by the formula: Li ₂ Na _1.3 Sr _0.1 Ti _5.5 Nb _0.5 O ₁₄ .

Using the active material obtained as described above, a negative electrode intermediate member was produced in the following procedure.
The active material, acetylene black and polyvinylidene fluoride (PVdF) prepared above were dispersed and mixed in N-methylpyrrolidone (NMP) at a blending ratio of 90% by mass: 5% by mass: 5% by mass to obtain a mixture. Was. This mixture was further stirred using a rotation and revolution mixer to prepare a slurry. This slurry was applied to both surfaces of a current collector made of aluminum foil having a thickness of 15 μm, and the coating film was dried. Next, the dried coating film is pressed to form a current collector and a negative electrode active material-containing layer formed on the current collector and having an electrode density (not including the current collector) of 2.3 g / cm ^3. A negative electrode intermediate member containing the same was produced.

  When the slurry was applied, an uncoated portion of the slurry was left on a part of the current collector. This portion was used as a negative electrode tab. The negative electrode terminal was ultrasonically bonded to the negative electrode tab.

(Example 52)
Example 52 was the same as Example 1 except that an orthorhombic Na-containing niobium titanium composite oxide having a composition represented by the formula Li ₂ Na _1.7 Ti _5.5 Nb _0.4 Al _0.1 O ₁₄ was used as the negative electrode active material. The nonaqueous electrolyte battery of Example 52 was manufactured in the same procedure.

An orthorhombic Na-containing niobium titanium composite oxide having a composition represented by the formula Li ₂ Na _1.7 Ti _5.5 Nb _0.4 Al _0.1 O ₁₄ was synthesized by the following procedure.

First, titanium oxide TiO ₂ , lithium carbonate Li ₂ CO ₃ , sodium carbonate Na ₂ CO ₃ , niobium (V) Nb (OH) _5, and aluminum hydroxide Al (OH) ₃ were used as raw materials. Got ready. These raw materials were mixed such that the molar ratio of Li: Na: Ti: Nb: Al in the mixture was 2.0: 1.7: 5.5: 0.4: 0.1. Prior to mixing, the raw materials were thoroughly ground.

  The mixed raw material was subjected to a heat treatment in an air atmosphere at 1000 ° C. for 10 hours. Thus, a product powder was obtained. The obtained product powder was subjected to a wet ball mill treatment in pure water for 5 hours, filtered, and then heat-treated again. The condition of the reheat treatment was 600 ° C. for 3 hours. Thus, a powder of the negative electrode active material was obtained.

The obtained negative electrode active material was analyzed by ICP, SEM-EDX and XRD described above. As a result, it was found that the obtained negative electrode active material was a powder of an orthorhombic Na-containing niobium titanium composite oxide having a composition represented by the formula: Li ₂ Na _1.7 Ti _5.5 Nb _0.4 Al _0.1 O ₁₄ .

Using the active material obtained as described above, a negative electrode intermediate member was produced in the following procedure.
The active material, acetylene black and polyvinylidene fluoride (PVdF) prepared above were dispersed and mixed in N-methylpyrrolidone (NMP) at a blending ratio of 90% by mass: 5% by mass: 5% by mass to obtain a mixture. Was. This mixture was further stirred using a rotation and revolution mixer to prepare a slurry. This slurry was applied to both surfaces of a current collector made of aluminum foil having a thickness of 15 μm, and the coating film was dried. Next, the dried coating film is pressed to form a current collector and a negative electrode active material-containing layer formed on the current collector and having an electrode density (not including the current collector) of 2.3 g / cm ^3. A negative electrode intermediate member containing the same was produced.

  When the slurry was applied, an uncoated portion of the slurry was left on a part of the current collector. This portion was used as a negative electrode tab. The negative electrode terminal was ultrasonically bonded to the negative electrode tab.

(Example 53)
Example 53 was the same as Example 1 except that as the negative electrode active material, an orthorhombic Na-containing niobium titanium composite oxide having a composition represented by the formula Li ₂ Na _1.4 Ti _5.5 Nb _0.4 Mo _0.1 O ₁₄ was used. The nonaqueous electrolyte battery of Example 53 was manufactured in the same procedure.

An orthorhombic Na-containing niobium titanium composite oxide having a composition represented by the formula Li ₂ Na _1.4 Ti _5.5 Nb _0.4 Mo _0.1 O ₁₄ was synthesized by the following procedure.

First, titanium oxide TiO ₂ , lithium carbonate Li ₂ CO ₃ , sodium carbonate Na ₂ CO ₃ , niobium (V) Nb (OH) _5, and molybdenum oxide MoO ₂ were prepared as raw materials. These raw materials were mixed such that the molar ratio of Li: Na: Ti: Nb: Mo in the mixture was 2.0: 1.4: 5.5: 0.4: 0.1. Prior to mixing, the raw materials were thoroughly ground.

  The mixed raw material was subjected to a heat treatment in an air atmosphere at 1000 ° C. for 10 hours. Thus, a product powder was obtained. The obtained product powder was subjected to a wet ball mill treatment in pure water for 5 hours, filtered, and then heat-treated again. The condition of the reheat treatment was 600 ° C. for 3 hours. Thus, a powder of the negative electrode active material was obtained.

The obtained negative electrode active material was analyzed by ICP, SEM-EDX and XRD described above. As a result, it was found that the obtained negative electrode active material was a powder of an orthorhombic Na-containing niobium titanium composite oxide having a composition represented by the formula: Li ₂ Na _1.4 Ti _5.5 Nb _0.4 Mo _0.1 O ₁₄ .

Using the active material obtained as described above, a negative electrode intermediate member was produced in the following procedure.
The active material, acetylene black and polyvinylidene fluoride (PVdF) prepared above were dispersed and mixed in N-methylpyrrolidone (NMP) at a blending ratio of 90% by mass: 5% by mass: 5% by mass to obtain a mixture. Was. This mixture was further stirred using a rotation and revolution mixer to prepare a slurry. This slurry was applied to both surfaces of a current collector made of aluminum foil having a thickness of 15 μm, and the coating film was dried. Next, the dried coating film is pressed to form a current collector and a negative electrode active material-containing layer formed on the current collector and having an electrode density (not including the current collector) of 2.3 g / cm ^3. A negative electrode intermediate member containing the same was produced.

  When the slurry was applied, an uncoated portion of the slurry was left on a part of the current collector. This portion was used as a negative electrode tab. The negative electrode terminal was ultrasonically bonded to the negative electrode tab.

(Example 54)
In Example 54, a nonaqueous electrolyte battery of Example 54 was produced in the same procedure as in Example 1 except that the used negative electrode active material was changed.

In Example 54, the same orthorhombic Na-containing niobium titanium composite oxide powder as used in Example 1 and a niobium titanium composite oxide having a composition represented by the formula Nb ₂ TiO ₇ were used as the negative electrode active material. Powder mixed with the above powder was used. The weight ratio of the powder of the orthorhombic Na-containing niobium titanium composite oxide to the powder of the niobium titanium composite oxide was 70:30.

A niobium titanium composite oxide having a composition represented by the formula Nb ₂ TiO ₇ was synthesized by the following procedure.
First, titanium oxide TiO ₂ and niobium oxide Nb ₂ O ₅ were prepared as raw materials. These raw materials were mixed such that the molar ratio of Nb: Ti in the mixture was 2.0: 1.0. Prior to mixing, the raw materials were thoroughly ground.
The mixed raw material was subjected to a heat treatment at 1350 ° C. for 30 hours in an air atmosphere. Thus, a powder of the product was obtained.

The resulting product powder was analyzed by ICP, SEM-EDX and XRD as described above. As a result, it was found that the obtained product powder was a niobium titanium composite oxide powder having a composition represented by the formula Nb ₂ TiO ₇ .

Using the mixed powder prepared as described above, a negative electrode intermediate member was manufactured in the following procedure.
The mixed powder, acetylene black and polyvinylidene fluoride (PVdF) were dispersed and mixed in N-methylpyrrolidone (NMP) at a mixing ratio of 90% by mass: 5% by mass: 5% by mass to obtain a mixture. This mixture was further stirred using a rotation and revolution mixer to prepare a slurry. This slurry was applied to both surfaces of a current collector made of aluminum foil having a thickness of 15 μm, and the coating film was dried. Next, the dried coating film is pressed to form a current collector and a negative electrode active material-containing layer formed on the current collector and having an electrode density (not including the current collector) of 2.3 g / cm ^3. A negative electrode intermediate member containing the same was produced.

  When the slurry was applied, an uncoated portion of the slurry was left on a part of the current collector. This portion was used as a negative electrode tab. The negative electrode terminal was ultrasonically bonded to the negative electrode tab.

(Example 55)
In Example 55, a nonaqueous electrolyte battery of Example 55 was produced in the same procedure as in Example 1 except that the used negative electrode active material was changed.

In Example 55, the same orthorhombic Na-containing niobium titanium composite oxide powder as used in Example 1 was used as a negative electrode active material, and titanic acid having a composition represented by the formula Li ₄ Ti ₅ O ₁₂ was used. A mixture with lithium powder was used. The weight ratio between the powder of the orthorhombic Na-containing niobium titanium composite oxide and the powder of lithium titanate was 70:30.

Lithium titanate having a composition represented by the formula Li ₄ Ti ₅ O ₁₂ was synthesized by the following procedure.
First, titanium oxide TiO ₂ and lithium carbonate Li ₂ CO ₃ were prepared as raw materials. These raw materials were mixed such that the molar ratio of Li: Ti in the mixture was 4.0: 5.0. Prior to mixing, the raw materials were thoroughly ground.
The mixed raw material was subjected to a heat treatment at 800 ° C. for 12 hours in an air atmosphere. Thus, a powder of the product was obtained.

The resulting product powder was analyzed by ICP, SEM-EDX and XRD as described above. As a result, it was found that the obtained product powder was a lithium titanate powder having a composition represented by the formula Li ₄ Ti ₅ O ₁₂ .

Using the mixed powder prepared as described above, a negative electrode intermediate member was manufactured in the following procedure.
The mixed powder, acetylene black and polyvinylidene fluoride (PVdF) were dispersed and mixed in N-methylpyrrolidone (NMP) at a mixing ratio of 90% by mass: 5% by mass: 5% by mass to obtain a mixture. This mixture was further stirred using a rotation and revolution mixer to prepare a slurry. This slurry was applied to both surfaces of a current collector made of aluminum foil having a thickness of 15 μm, and the coating film was dried. Next, the dried coating film is pressed to form a current collector and a negative electrode active material-containing layer formed on the current collector and having an electrode density (not including the current collector) of 2.3 g / cm ^3. A negative electrode intermediate member containing the same was produced.

  When the slurry was applied, an uncoated portion of the slurry was left on a part of the current collector. This portion was used as a negative electrode tab. The negative electrode terminal was ultrasonically bonded to the negative electrode tab.

  Table 5 below shows the composition of the negative electrode active material and the aging conditions of each of the nonaqueous electrolyte batteries of Examples 48 to 55. The aging conditions of Examples 48 to 55 were the same as those of Example 1. Further, each of the non-aqueous electrolyte batteries of Examples 48 to 55 was subjected to a test similarly to the non-aqueous electrolyte battery of Example 1. The results are shown in Table 6 below.

From the results shown in Tables 3-5, each of the non-aqueous electrolyte batteries of Examples 48 to 55 the intensity ratio I ₂ / I ₁ is 1 or more, like the battery of Example 1-47, the intensity ratio I ' It can be seen that the non-aqueous electrolyte batteries of Comparative Examples 1 to 8 in which ₂ / I ′ ₁ was less than ₁ exhibited higher cycle capacity retention rates. That is, each of the non-aqueous electrolyte batteries of Examples 48 to 55 the intensity ratio I ₂ / I ₁ is 1 or more, were able to exhibit excellent life characteristics than each of the non-aqueous electrolyte batteries of Comparative Examples 1 to 8 .

  Also, from Tables 1 to 3, 5 and 6, even if the composition of the Na-containing niobium titanium composite oxide having the orthorhombic crystal structure is changed, each of the nonaqueous electrolyte batteries of Examples 1 to 53 has excellent life. It can be seen that the characteristics could be shown. From Tables 1, 3, 5 and 6, it can be seen from Examples 54 and 55 that the negative electrode active material-containing layer contained a negative electrode active material other than the Na-containing niobium titanium composite oxide having an orthorhombic crystal structure. It can be seen that the electrolyte battery was able to exhibit excellent life characteristics similarly to the non-aqueous electrolyte batteries of Examples 1 to 53.

According to at least one embodiment and example described above, a non-aqueous electrolyte battery is provided. This non-aqueous electrolyte battery includes a negative electrode, a positive electrode, and a non-aqueous electrolyte. The negative electrode includes a negative electrode active material containing layer. The negative electrode active material-containing layer contains a Na-containing niobium titanium composite oxide having an orthorhombic crystal structure. In the negative electrode active material-containing layer, the ratio I ₂ / I _{1 determined} by X-ray photoelectron spectroscopy satisfies I ₂ / I ₁ ≧ 1. This nonaqueous electrolyte battery can suppress a side reaction between the Na-containing niobium titanium composite oxide contained in the negative electrode active material containing layer and the nonaqueous electrolyte. As a result, this non-aqueous electrolyte battery can exhibit excellent life characteristics.

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

  1 and 11: electrode group, 2 and 12: exterior member, 2a, 2b and 2c: heat seal portion, 2A and 2B: cut line, 3 and 14: negative electrode, 3a and 14a: negative electrode current collector, 3b and 14b ... Negative electrode active material-containing layers, 4 and 15 separators, 5 and 13 positive electrodes, 5a and 13a positive electrode current collectors, 5b and 13b positive electrode active material-containing layers, 6 and 16 negative electrode terminals, 7 and 17 positive electrode terminals , 8: liquid non-aqueous electrolyte, 10: non-aqueous electrolyte battery, 20 and 42: battery pack, 22: adhesive tape, 23: assembled battery, 24: printed wiring board, 25: thermistor, 26: protection circuit, 27: energization Terminals, 28: Positive lead, 29: Positive connector, 30: Negative lead, 31: Negative connector, 32 and 33: Wiring, 34a: Positive wiring, 34b: Negative wiring, 35: Electric Wiring for detection, 36 ... Protective sheet, 37 ... Storage container, 38 ... Lid, 41 and 300 ... Vehicle, 301 ... Vehicle power supply, 310 ... Communication bus, 311 ... Battery management device, 312a, 312b and 312c ... Battery Packs, 314a, 314b, and 314c: assembled batteries, 313a, 313b, and 313c: assembled battery monitoring devices, 316, positive terminals, 317, negative terminals, 331, wiring, 333, switching devices, 340, inverters, 345, driving motors, 370: external terminal; 380: vehicle ECU.

Claims (14)

An active material-containing layer containing a Na-containing niobium titanium composite oxide having an orthorhombic crystal structure,
The active material-containing layer satisfies I ₂ / I ₁ ≧ 1, and I ₁ falls within a binding energy range of 289 to 292 eV in an X-ray photoelectron spectrum obtained by X-ray photoelectron spectroscopy on the active material-containing layer. is the intensity of peak P ₁ appearing, I _2, the electrode is the intensity of peak P ₂ appearing in the binding energy range of 283~285eV in the X-ray photoelectron spectroscopy. The Na-containing niobium titanium composite oxide is represented by the general formula _{Li 2 + v Na 2-w} M1 x Ti 6-yz Nb y M2 z O 14 + δ,
In the general formula, v, w, x, y, z and δ are respectively 0 ≦ v ≦ 4, 0 <w <2, 0 ≦ x <2, 0 <y <2, 0 ≦ z <3, -0.5 ≦ δ ≦ 0.5,
M1 is at least one metal element selected from the group consisting of Cs, K, Mg, Sr, Ba and Ca;
The electrode according to claim 1, wherein the M2 is at least one metal element selected from the group consisting of Zr, Sn, V, Ta, Mo, W, Fe, Co, Mn, and Al. The electrode according to claim ₁ , wherein the active material-containing layer satisfies 1 ≦ I ₂ / I ₁ ≦ 5. The electrode according to claim ₁ , wherein the active material-containing layer satisfies 1 ≦ I ₂ / I ₁ ≦ 3. A negative electrode including a negative electrode active material-containing layer containing a Na-containing niobium titanium composite oxide having an orthorhombic crystal structure;
A positive electrode,
And a non-aqueous electrolyte,
The negative electrode active material-containing layer satisfies I ₂ / I ₁ ≧ 1, and I ₁ is a binding energy of 289 to 292 eV in an X-ray photoelectron spectroscopy spectrum obtained by X-ray photoelectron spectroscopy on the negative electrode active material-containing layer. is the intensity of peak P ₁ appearing in the range, I ₂ is a non-aqueous electrolyte battery is the intensity of peak P ₂ appearing in the binding energy range of 283~285eV in the X-ray photoelectron spectroscopy. The Na-containing niobium titanium composite oxide is represented by the general formula _{Li 2 + v Na 2-w} M1 x Ti 6-yz Nb y M2 z O 14 + δ,
In the general formula, v, w, x, y, z and δ are respectively 0 ≦ v ≦ 4, 0 <w <2, 0 ≦ x <2, 0 <y <2, 0 ≦ z <3, -0.5 ≦ δ ≦ 0.5,
M1 is at least one metal element selected from the group consisting of Cs, K, Mg, Sr, Ba and Ca;
The non-aqueous electrolyte battery according to claim 5, wherein M2 is at least one metal element selected from the group consisting of Zr, Sn, V, Ta, Mo, W, Fe, Co, Mn, and Al. The nonaqueous electrolyte battery according to claim 5, wherein the negative electrode active material-containing layer satisfies 1 ≦ I ₂ / I ₁ ≦ 5. The nonaqueous electrolyte battery according to claim 5, wherein the negative electrode active material-containing layer satisfies 1 ≦ I ₂ / I ₁ ≦ 3.   The nonaqueous electrolyte battery according to any one of claims 5 to 8, wherein the nonaqueous electrolyte contains ethylene carbonate.   A battery pack comprising the nonaqueous electrolyte battery according to claim 5. An external terminal for conducting electricity,
The battery pack according to claim 10, further comprising a protection circuit. Comprising a plurality of said non-aqueous electrolyte batteries,
The battery pack according to claim 10, wherein the nonaqueous electrolyte batteries are electrically connected in series, in parallel, or in a combination of series and parallel.   A vehicle equipped with the battery pack according to claim 10.   The vehicle according to claim 13, further comprising a mechanism for converting kinetic energy of the vehicle into regenerative energy.