JP6571284B2 - Electrode, non-aqueous electrolyte battery and battery pack - Google Patents

Description

  The present invention relates to an electrode, a nonaqueous electrolyte battery, and a battery pack.

  Non-aqueous electrolyte batteries that are charged and discharged by moving lithium ions between a negative electrode and a positive electrode are actively studied as high energy density batteries.

  In addition to being used as a power source for small electronic devices, this nonaqueous electrolyte battery is also expected to be used as a medium-to-large power source such as in-vehicle use or stationary use. In such medium and large-sized applications, life characteristics and high safety are required. Further, these applications also require high input / output characteristics.

As an example of a non-aqueous electrolyte battery having life characteristics and high safety, a non-aqueous electrolyte battery using spinel type lithium titanate as a negative electrode is known. However, since spinel type lithium titanate has a high lithium occlusion / release potential of about 1.55 V (vs. Li / Li ⁺ ), the battery voltage of the nonaqueous electrolyte battery using spinel type lithium titanate as the negative electrode is low. Further, spinel type lithium titanate has a feature that the change of the potential accompanying the change of the charged state is very small in the lithium occlusion and release potential range. That is, the charge / discharge curve of the spinel type lithium titanate includes a flat portion of the potential in the lithium occlusion and release potential range.

Japanese Patent No. 4237659 WO2016 / 088193A1

  It is an object of the present invention to provide an electrode capable of exhibiting excellent input / output characteristics, a nonaqueous electrolyte battery including the electrode, and a battery pack including the nonaqueous electrolyte battery.

According to a first embodiment, an electrode is provided. This electrode includes a current collector and an electrode active material-containing layer formed on the current collector. The electrode active material-containing layer includes orthorhombic Na-containing niobium titanium composite oxide particles. Orthorhombic Akiragata Na-containing niobium titanium composite oxide is represented by the general formula _{Li 2 + v Na 2-y} M1 x Ti 6-yz Nb y M2 z O 14 + δ. In the general formula, M1 is at least one selected from the group consisting of Cs, K, Sr, Ba and Ca, and M2 is Zr, Sn, V, Ta, Mo, W, Fe, Co, Mn and At least one selected from the group consisting of Al, 0 ≦ v ≦ 4, 0 ≦ x <2, 0 <y <2, 0 ≦ z <3, −0.5 ≦ δ ≦ 0.5 . The electrode active material-containing layer has a porosity of 10% or more and 26% or less obtained by a mercury intrusion method. In the pore diameter distribution obtained by the mercury intrusion method for the electrode active material-containing layer, the strongest peak exists in a region where the pore diameter is smaller than 200 nm.

  According to the second embodiment, a nonaqueous electrolyte battery is provided. This nonaqueous electrolyte battery includes the electrode according to the first embodiment as a negative electrode, a positive electrode, and a negative electrode.

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

FIG. 1 is a pore diameter distribution of an electrode active material-containing layer of an example electrode according to the first embodiment. FIG. 2 is a schematic cross-sectional view of another example electrode according to the first embodiment. FIG. 3 is a schematic cross-sectional view of an example of a flat nonaqueous electrolyte battery according to the second embodiment. 4 is an enlarged cross-sectional view of a portion A in FIG. FIG. 5 is a schematic partially cutaway perspective view of another example of the nonaqueous electrolyte battery according to the second embodiment. 6 is an enlarged cross-sectional view of a portion B in FIG. It is a schematic exploded perspective view of an example battery pack concerning a 3rd embodiment. It is a block diagram which shows the electric circuit of the battery pack of FIG. FIG. 9 is a schematic perspective view of an example assembled battery that can be included in the battery pack according to the third embodiment.

  Hereinafter, embodiments will be described with reference to the drawings. In addition, the same code | symbol shall be attached | subjected to a common structure through embodiment, and the overlapping description is abbreviate | omitted. Each figure is a schematic diagram for promoting explanation and understanding of the embodiment, and its shape, dimensions, ratio, etc. are different from the actual device, but these are the following explanations and known techniques. The design can be changed as appropriate.

(First embodiment)
According to a first embodiment, an electrode is provided. This electrode includes a current collector and an electrode active material-containing layer formed on the current collector. The electrode active material-containing layer includes orthorhombic Na-containing niobium titanium composite oxide particles. Orthorhombic Akiragata Na-containing niobium titanium composite oxide is represented by the general formula _{Li 2 + v Na 2-y} M1 x Ti 6-yz Nb y M2 z O 14 + δ. In the general formula, M1 is at least one selected from the group consisting of Cs, K, Sr, Ba and Ca, and M2 is Zr, Sn, V, Ta, Mo, W, Fe, Co, Mn and At least one selected from the group consisting of Al, 0 ≦ v ≦ 4, 0 ≦ x <2, 0 <y <2, 0 ≦ z <3, −0.5 ≦ δ ≦ 0.5 . The electrode active material-containing layer has a porosity of 10% or more and 26% or less obtained by a mercury intrusion method. In the pore diameter distribution obtained by the mercury intrusion method for the electrode active material-containing layer, the strongest peak exists in a region where the pore diameter is smaller than 200 nm.

For example the general formula _{Li 2 + v Na 2-y} M1 x Ti 6-yz Nb y M2 z O 14 + orthorhombic Akiragata Na-containing niobium titanium composite oxide represented by _δ, the lithium at low potential among titanium oxide It is a complex oxide that can be occluded and released. For example, the lithium sodium titanium composite oxide represented by the above general formula can exhibit a lithium storage and release potential in the range of 1.2 to 1.4 V, that is, an operating potential.

Further, for example, the general formula _{Li 2 + v Na 2-y} M1 x Ti 6-yz Nb y M2 z O 14 + orthorhombic Akiragata Na-containing niobium titanium composite oxide represented by _δ, in the operating potential range, A large potential change can be shown as the state of charge changes.

  Therefore, a non-aqueous electrolyte battery using orthorhombic Na-containing niobium titanium composite oxide as a negative electrode can exhibit a higher battery voltage than a non-aqueous electrolyte battery using lithium titanate as a negative electrode, and is in a charged state. Can be easily grasped based on the change in potential.

  As a result of intensive studies, the inventors have found that the orthorhombic Na-containing niobium titanium composite oxide has a problem of poor input / output characteristics.

  As a result of further studies to solve the above problems, the inventors have found an electrode according to the first embodiment.

  In the electrode active material-containing layer included in the electrode according to the first embodiment, the orthorhombic Na-containing niobium titanium composite oxide particles sufficiently form a conductive path and exhibit excellent nonaqueous electrolyte impregnation properties. be able to. Therefore, the electrode according to the first embodiment can provide a nonaqueous electrolyte battery that can exhibit excellent input / output characteristics. The reason will be described in detail below.

  The orthorhombic Na-containing niobium titanium composite oxide has a small effect of improving the electron conductivity due to the occlusion of Li, unlike lithium titanate having a spinel crystal structure. Therefore, in order to form an excellent conductive path in the electrode active material-containing layer, the orthorhombic Na-containing niobium titanium composite oxide particles are preferably in contact with each other. As the contact between the particles contained in the electrode active material-containing layer increases, the porosity of the electrode active material-containing layer decreases. If the porosity is too high, a sufficient conductive path cannot be obtained, and the electrical resistance of the electrode active material-containing layer increases. On the other hand, when the porosity is too low, the nonaqueous electrolyte impregnation property of the electrode active material-containing layer is lowered. The lower the nonaqueous electrolyte impregnation property, the more the Li migration in the electrode active material-containing layer is inhibited. That is, a nonaqueous electrolyte battery using an electrode including an electrode active material-containing layer having a porosity of less than 10% or higher than 26% has high resistance and poor input / output characteristics.

  In addition, even when the porosity is in the range of 10% or more and 26% or less, the electrode active material-containing layer in which the strongest peak exists in the region where the pore diameter is 200 nm or more in the pore diameter distribution obtained by the mercury intrusion method The pore diameter of the pores present in the electrode active material-containing layer with the highest frequency is too large. Such an electrode active material-containing layer has large pores between the orthorhombic Na-containing niobium titanium composite oxide particles, and is sufficient between the orthorhombic Na-containing niobium titanium composite oxide particles. Cannot have a conductive path.

  The porosity is preferably 12% or more and 24% or less, and more preferably 15% or more and 20% or less. The strongest peak of the pore diameter distribution is preferably in a region where the pore diameter is smaller than 180 nm, and more preferably in a region where the pore diameter is smaller than 150 nm. The electrode having an aspect in which the porosity and / or the strongest peak position are within a preferable range can have a more sufficient conductive path between the particles of the orthorhombic Na-containing niobium titanium composite oxide, and is superior to the nonaqueous electrolyte. Can exhibit impregnation properties.

  Note that in an electrode including a lithium titanate having a spinel crystal structure, the porosity is within a range of 10% to 26% and the position of the strongest peak is a region where the diameter is smaller than 200 nm. An improvement in properties cannot be achieved. This point will be proved later in the present specification with a comparative example.

  Next, the electrode according to the first embodiment will be described in more detail.

  The electrode according to the first embodiment includes a current collector. The current collector is preferably formed from an aluminum foil or an aluminum alloy foil containing elements such as Mg, Ti, Zn, Mn, Fe, Cu and Si. The current collector can have, for example, two surfaces facing away from each other. The current collector has, for example, a band shape.

  The electrode according to the first embodiment further includes an electrode active material-containing layer formed on the current collector. The current collector can carry the electrode active material-containing layer only on one surface thereof, or can carry the electrode active material-containing layer on both surfaces. The current collector can also include a portion that does not carry the electrode active material-containing layer on the surface. This part can serve as an electrode tab, for example. Alternatively, the electrode according to the first embodiment can include an electrode tab that is separate from the current collector.

Electrode active material-containing layer, as previously indicated, the general formula _{Li 2 + v Na 2-y} M1 x Ti 6-yz Nb y M2 z O 14 + δ orthorhombic Akiragata Na-containing niobium titanium composite represented by Contains oxide particles. The orthorhombic Na-containing niobium titanium composite oxide particles can serve as an active material, for example.

  In the above general formula, the subscript v varies within the range of 0 ≦ v <4 depending on the state of charge of the orthorhombic Na-containing niobium titanium composite oxide.

  In the above general formula, M1 is at least one selected from the group consisting of Cs, K, Sr, Ba and Ca. The orthorhombic Na-containing niobium titanium composite oxide can realize more excellent cycle characteristics by containing Cs. By including K, the orthorhombic Na-containing niobium titanium composite oxide can realize more excellent cycle characteristics. 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 better rate characteristics by containing Ba. The orthorhombic Na-containing niobium titanium composite oxide can realize more excellent rate characteristics by containing Ca. More preferably, M1 contains at least one of Sr and Ba.

  In the above general formula, the subscript x takes a value in the range of 0 ≦ x <2. When orthorhombic Na-containing niobium titanium composite oxide contains M1 so that the subscript x is 2 or more, it is difficult to obtain a single-phase crystal phase, and the Li diffusibility in the solid is reduced, resulting in low input / output characteristics. Lower. The subscript x preferably takes a value in the range of 0.05 to 0.2. The orthorhombic Na-containing niobium titanium composite oxide having the subscript x within this range can exhibit more excellent rate characteristics.

  In the above general formula, the subscript y takes a value in the range of 0 <y <2. When the value of the subscript y is larger than 0, a higher reversible capacity can be realized. On the other hand, when the value of the subscript y is 2 or more, it is difficult to obtain a single-phase crystal phase, and further, the Li diffusibility in the solid is lowered and the input / output characteristics are lowered. Preferably 0.1 ≦ y ≦ 0.8. When the value of the subscript y is smaller than 0.1, the resistance reduction effect at high SOC cannot be obtained. On the other hand, when the value of the subscript y is larger than 0.8, the reversible charge / discharge capacity becomes small, and the input / output characteristics also deteriorate. The subscript y preferably takes a value in the range of 0.1 to 1. The orthorhombic Na-containing niobium titanium composite oxide having the value of the subscript y within this range can exhibit better rate characteristics.

  M2 is at least one selected from the group consisting of Zr, Sn, V, Ta, Mo, W, Fe, Co, Mn, and Al. 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 better rate characteristics by containing Sn. V and Ta can exhibit the same physical and chemical properties as Nb. The orthorhombic Na-containing niobium titanium composite oxide can realize more excellent rate characteristics by containing Mo. The orthorhombic Na-containing niobium titanium composite oxide can realize more excellent rate characteristics when it contains W. The orthorhombic Na-containing niobium titanium composite oxide can realize more excellent cycle characteristics by including 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 better rate characteristics by containing Al. More preferably, M2 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.

  In the above general formula, the subscript z takes a value in the range of 0 ≦ z <3. When orthorhombic Na-containing niobium titanium composite oxide contains M2 so that the value of the suffix z is 3 or more, it is difficult to obtain a single-phase crystal phase, and the Li diffusivity in the solid is further reduced, resulting in input / output. Characteristics are lowered. The subscript z preferably takes a value within the range of 0.1 to 0.3. An orthorhombic Na-containing niobium titanium composite oxide having a subscript z value within this range can exhibit more excellent rate characteristics.

  The subscript δ takes a value in the range of −0.5 ≦ δ ≦ 0.5. When the value of the subscript δ is smaller than −0.5, the charge / discharge cycle characteristics are deteriorated. On the other hand, when the value of the subscript δ is larger than 0.5, it is difficult to obtain a single phase crystal phase, and impurities are likely to be generated. The subscript δ preferably takes a value in the range of −0.1 ≦ δ ≦ 0.1. An orthorhombic Na-containing niobium titanium composite oxide having a subscript δ in this range can exhibit better rate characteristics and better cycle characteristics.

  The orthorhombic Na-containing niobium titanium composite oxide particles may be primary particles or secondary particles as aggregates of primary particles. Alternatively, the orthorhombic Na-containing niobium titanium composite oxide particles may be a mixture of primary particles and secondary particles. Further, the orthorhombic Na-containing niobium titanium composite oxide particles may have carbon attached to the surface. Carbon may be attached to the surface of the primary particle, or may be attached to the surface of the secondary particle. Alternatively, the orthorhombic Na-containing niobium titanium composite oxide particles may include secondary particles formed by agglomeration of primary particles having carbon attached to the surface. Such secondary particles can exhibit excellent conductivity because carbon is present between the primary particles. Such an embodiment containing secondary particles is preferable because the electrode active material-containing layer can exhibit a 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, and more preferably 0.9 μm or more and 2 μm or less. The average secondary particle diameter of the orthorhombic Na-containing niobium titanium composite oxide particles is preferably 5 μm or more and 20 μm or less, and more preferably 8 μm or more and 12 μm or less. These preferred particle sizes are those of particles that do not contain carbon. For the particles containing carbon, the average primary particle size is preferably 0.8 μm or more and 3 μm or less, and more preferably 1 μm or more and 2 μm or less. The average secondary particle diameter is preferably 5 μm or more and 25 μm or less, and more preferably 8 μm or more and 15 μm or less.

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

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

  The electrode active material-containing layer may further contain a conductive agent and / or a binder in addition to the orthorhombic Na-containing niobium titanium composite oxide particles.

  The conductive agent can improve the current collection performance and can exhibit an action of suppressing contact resistance between the active material and the current collector. Examples of the conductive agent include carbonaceous materials such as acetylene black, carbon black, graphite, carbon nanofiber, and carbon nanotube. Among these, graphite and carbon nanofiber are preferable. Graphite and carbon nanofibers can easily enter between the particles of orthorhombic Na-containing niobium titanium composite oxide, compared to acetylene black and carbon black, and can further reduce the voids in 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 particle here may be a particle containing a carbon material or a fiber 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 electrode active material-containing layer, and can realize higher input / output characteristics. As the conductive agent, one of the above-described carbonaceous materials 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), and fluorine-based rubber, styrene butadiene rubber, an acrylic resin or a copolymer thereof, polyacrylic acid, polyacrylonitrile, and the like. .

The electrode active material-containing layer can also contain an active material other than particles of orthorhombic Na-containing niobium titanium composite oxide. Examples of such an active material include Li ₄ Ti ₅ O ₁₂ , TiNb ₂ O ₇ , TiO ₂ (B), Li ₂ Na ₂ Ti ₆ O ₁₄ , and Li ₂ SrTi ₆ O ₁₄ . It is preferable that particles of the orthorhombic Na-containing niobium titanium composite oxide occupy 70% by mass or more of the active material included in the electrode active material-containing layer, and the electrode active material-containing layer has an orthorhombic Na-containing content. It is preferable that no active material other than the niobium titanium composite oxide particles be included.

  The compounding ratio of the active material, the conductive agent and the binder is 70% by mass to 96% by mass for the active material, 2% by mass to 28% by mass for the negative electrode conductive agent, and 2% by mass to 28% by mass for the binder. The following range is preferable. The active material is more preferably 85% by mass or more and 93% by mass. If the conductive agent is less than 2% by mass, the current collection performance of the electrode active material-containing layer may be reduced, and the large current characteristics of the nonaqueous electrolyte battery may be reduced. On the other hand, when the binder is less than 2% by mass, the binding property between the electrode active material-containing layer and the current collector is lowered, and the cycle characteristics may be lowered. On the other hand, from the viewpoint of increasing the capacity, the conductive agent and the binder are each preferably 28% by mass or less.

  The electrode which concerns on 1st Embodiment can be manufactured in the following procedures, for example. First, a slurry is prepared by suspending particles of orthorhombic Na-containing niobium titanium composite oxide, and an optional conductive agent and binder in a solvent. Next, this slurry is applied to one surface or both surfaces of the current collector, and the coating film is dried. Next, an electrode active material-containing layer can be obtained by subjecting the dried coating to a press.

The density of the electrode active material-containing layer is preferably 2.4 g / cm ³ or more and 2.7 g / cm ³ or less, and more preferably 2.5 g / cm ³ or more and 2.6 g / cm ³ or less. An electrode in which the density of the electrode active material-containing layer is within a preferable range has more sufficient contact between particles of the orthorhombic Na-containing niobium titanium composite oxide, and therefore the active material-containing layer has better electronic conductivity. Can be shown. In addition, the space impregnated with the nonaqueous electrolyte can be more sufficiently secured.

  As described above, the porosity and pore diameter distribution of the electrode active material-containing layer are affected by, for example, the particle size distribution of the orthorhombic Na-containing niobium titanium composite oxide and the material and aspect ratio of the conductive agent. . The porosity and pore diameter distribution of the electrode active material-containing layer are also affected by the press conditions of the dried coating film. For example, a roll press apparatus is used for pressing. The distance between the upper and lower rolls is adjusted to obtain the desired porosity and pore diameter distribution. The roll may be heated to about 100 ° C. and pressed. Further, in a single pressing step, the electrode may spring back, and the desired porosity and pore diameter distribution may not be obtained. In that case, you may press several times. That is, the porosity and pore diameter distribution of the electrode active material-containing layer can be controlled by adjusting, for example, a combination of these conditions. For example, the electrode according to the first embodiment can be obtained by the method described in each example in the subsequent stage.

[Method for confirming porosity and pore diameter distribution of electrode active material-containing layer]
First, an electrode to be measured is prepared. The electrode incorporated in the nonaqueous electrolyte battery is prepared as follows. First, the nonaqueous electrolyte battery is put into a discharged state. By subjecting the battery to constant current discharge at a current of 0.2 C and a battery voltage of 1.5 V in a 25 ° C. environment, the SOC of the battery can be brought into a 0% state, that is, a discharged state. . Next, the discharged nonaqueous electrolyte battery is decomposed in a glove box under an inert atmosphere such as argon. Remove the electrode from the disassembled battery. The extracted electrode is washed with a chain carbonate such as ethyl methyl carbonate. Thereafter, the electrode is dried. The dried electrode is cut into a size of about 10 mm × 25 mm to obtain a sample.

  Subsequently, the obtained sample is loaded into a measuring apparatus. By performing the mercury intrusion method on the charged sample, the pore size distribution and the porosity of the electrode layer can be obtained.

  The analysis principle of the mercury intrusion method is based on Washburn's formula (1).

D = −4γcos θ / P (1) where P is the applied pressure, D is the pore diameter, γ is the surface tension of mercury (480 dyne · cm−1), and θ is the contact angle between mercury and the pore wall surface. °. Since γ and θ are constants, the relationship between the applied pressure P and the pore diameter D is obtained from the Washburn equation, and the mercury intrusion volume at that time is measured to derive the pore diameter and its volume distribution. Can do. For details of the measuring method and principle, refer to Jinbo Motoji et al., “Fine Particle Handbook”, Asakura Shoten, (1991), Hayakawa Souhachiro Edition: “Powder Physical Property Measuring Method”, Asakura Shoten (1978).

  The porosity and the strongest peak position of the pore diameter of the electrode layer can be obtained from the pore diameter distribution thus obtained.

  Next, the pore diameter distribution of the electrode active material-containing layer included in the example electrode according to the first embodiment will be described with reference to the drawings.

  FIG. 1 is a pore diameter distribution of an electrode active material-containing layer of an example electrode according to the first embodiment.

  In the pore diameter distribution of FIG. 1, the strongest peak of the pore diameter was found at 120 nm. Moreover, the porosity obtained from the measurement results was 22%. As a result of the test, this electrode was able to show excellent input / output characteristics. This is considered to be because the contact between the particles is sufficiently maintained in the electrode active material-containing layer showing the pore diameter distribution as shown in FIG. Further, in this electrode, since the strongest peak of the pore diameter in the pore diameter distribution is 120 nm, the pore diameter is reduced while maintaining the impregnation property of the electrolytic solution, and the electron conduction in the electrode active material containing layer is reduced. This is thought to be because it became possible to increase the sex.

(Active material identification method)
For the active material incorporated in the nonaqueous electrolyte battery, the composition and crystal structure can be confirmed by the following procedure.

  First, in order to grasp the crystal state of the active material, the lithium ion is separated from the active material to be measured. The orthorhombic Na-containing niobium titanium composite oxide contains lithium which does not participate in charge / discharge in the structure. Therefore, the “state where lithium ions are released” as used herein means a state where lithium involved in charge / discharge is released. For example, when the battery active material to be measured is contained in the negative electrode, the battery is completely discharged. However, lithium ions remaining in the active material may exist even when the battery is discharged. Therefore, attention is paid to the analysis of the X-ray diffraction pattern.

  Next, the battery in such a state is disassembled in a glove box filled with argon. The electrode containing the active material to be measured is taken out from the decomposed battery. The electrode is washed with a suitable solvent. For example, ethyl methyl carbonate may be used. If the cleaning is insufficient, an impurity phase such as lithium carbonate or lithium fluoride may be mixed under the influence of lithium ions remaining in the electrode. In that case, it is preferable to use an airtight container in which the measurement atmosphere can be performed in an inert gas.

  The cross section of the electrode taken out as described above is cut out by an ion milling device. The cross section of the cut-out electrode is observed with a scanning electron microscope (SEM). Sampling of the sample should be performed in an inert atmosphere such as argon or nitrogen while avoiding exposure to the air.

  Several particles are selected in a 3000-magnification SEM observation image. At this time, the particle size distribution of the selected particles is selected to be as wide as possible.

  Next, each selected particle is subjected to elemental analysis by energy dispersive X-ray spectroscopy (EDX). Thereby, the kind and quantity of elements other than Li among the elements contained in each selected particle | grain can be specified.

  The crystal structure of the compound contained in each particle selected by SEM can be specified by X-ray diffraction (XRD) measurement.

  The measurement is performed in a measurement range of 2θ = 10 to 90 ° using CuKα ray as a radiation source. By this measurement, an X-ray diffraction pattern of the compound contained in the selected particle can be obtained.

  As an apparatus for powder X-ray diffraction measurement, SmartLab manufactured by Rigaku is used. Measurement conditions are as follows: Cu target; 45 kV, 200 mA; Solar slit: 5 ° for both incident and reception; Step width: 0.02 deg; Scan rate: 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 measurements using standard Si powder for powder X-ray diffraction so that the same measurement results as above can be obtained, under conditions where the peak intensity and peak top position match those of the above devices. Do.

  When orthorhombic Na-containing niobium titanium composite oxide is included in the particles to be measured, an X-ray diffraction pattern belonging to the orthorhombic type, such as space group Cmca or Fmmm, is obtained by X-ray diffraction measurement. I can confirm that.

  XRD measurement on the electrode can be performed by cutting 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, 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 mixture such as a conductive agent or a binder is also grasped in advance. When the peak of the current collector and the peak of the active material overlap, it is desirable to measure by peeling the active material from the current collector. This is for separating overlapping peaks when quantitatively measuring the 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 electrode thus collected, wide-angle X-ray diffraction measurement of the active material can be performed.

  The composition of the entire active material contained in the electrode can be measured by the following procedure.

  First, the electrode containing the active material to be measured is taken out from the nonaqueous electrolyte battery and washed by the procedure described above.

  The composition of the particles contained in the electrode is specified by the method described above using a part of the cleaned electrode.

  On the other hand, another part of the cleaned electrode is placed in an appropriate solvent and irradiated with ultrasonic waves. For example, the electrode layer containing the electrode active material can be peeled from the current collector substrate by placing the electrode body in ethyl methyl carbonate placed in a glass beaker and vibrating in an ultrasonic cleaner. Next, vacuum drying is performed to dry the peeled electrode layer. By pulverizing the obtained electrode layer with a mortar or the like, a powder containing an active material to be measured, a conductive aid, a binder and the like is obtained. By dissolving this powder with an acid, a liquid sample containing an 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 spectroscopic analysis, it is possible to know the concentration of the element in the active material contained in the electrode.

  For the particles contained in the electrode, the composition and crystal structure of the compound contained in the particles are obtained by combining the results of the identification of the composition by SEM and EDX, the identification of the crystal structure by XRD, and the ICP emission spectroscopic analysis. Can be specified.

[Method for confirming particle shape and average particle size of active material]
In the SEM observation of the active material described above, an image of the active material powder is obtained at a magnification of 3000 times. In the obtained visual field, a particle group capable of confirming that the primary particles are in contact is defined as a secondary particle.

  The size of the primary particle is determined from the diameter of the smallest circle corresponding to the primary particle. Specifically, in the SEM image at a magnification of 3000 times, the particle size is measured 10 times, and the average of the diameters of the smallest circles obtained in each is taken 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 10 measurements.

  The secondary particle size is also measured by the same method as the primary particle. That is, the diameter of the smallest circle corresponding to the secondary particle is obtained. Specifically, in the SEM image at a magnification of 3000 times, the particle size is measured 10 times, and the average of the diameters of the smallest circles obtained in each is taken as the secondary particle size. For the calculation of the average, the maximum value and the minimum value of the particle diameter are not used among 10 measurements.

[Definition and confirmation method of conductive agent aspect ratio]
In the SEM observation of the active material described above, an image of the conductive agent is obtained at a magnification of 3000 times. In the obtained field of view, particles made only of carbon are defined as conductive agent particles.

  The lengths of the long axis and the short axis of the conductive agent are obtained by measuring the longest part and the shortest part in the conductive agent particles. A value obtained by dividing the length of the obtained major axis by the length of the minor axis is defined as an aspect ratio. Specifically, in the SEM image at a magnification of 3000 times, the measurement of the major axis and the minor axis is performed 10 times, and the aspect ratio is calculated from the length of the major axis and the minor axis obtained in each. For the calculation of the average, the maximum value and the minimum value are not used among 10 measurements.

  Next, the electrode according to the first embodiment will be described in more detail with reference to the drawings.

  FIG. 2 is a schematic cross-sectional view of another example electrode according to the first embodiment.

  The electrode 5 shown in FIG. 2 includes a current collector 5a. Although the both ends are not shown in FIG. 2, the current collector 5a has a strip shape. The current collector 5a has two surfaces facing in opposite directions.

  The electrode 5 shown in FIG. 2 further includes an electrode active material-containing layer 5b. The electrode active material-containing layer 5b is formed on both surfaces of the current collector 5a.

  The electrode according to the first embodiment includes a current collector and an electrode active material-containing layer formed on the current collector. The electrode active material-containing layer includes orthorhombic Na-containing niobium titanium composite oxide particles. The electrode active material-containing layer has a porosity of 10% or more and 26% or less obtained by a mercury intrusion method. In the pore diameter distribution obtained by the mercury intrusion method for the electrode active material-containing layer, the strongest peak exists in a region where the pore diameter is smaller than 200 nm. In this electrode active material-containing layer, the orthorhombic Na-containing niobium titanium composite oxide particles can sufficiently form a conductive path, and can exhibit excellent impregnation properties of the nonaqueous electrolyte. Therefore, the electrode according to the first embodiment can provide a nonaqueous electrolyte battery that can exhibit excellent input / output characteristics.

(Second Embodiment)
According to the second embodiment, a nonaqueous electrolyte battery is provided. This nonaqueous electrolyte battery includes the electrode according to the first embodiment as a negative electrode, a positive electrode, and a negative electrode.

  Since the nonaqueous electrolyte battery according to the second embodiment includes the electrode according to the first embodiment, it can exhibit excellent input / output characteristics.

  Next, the nonaqueous electrolyte battery according to the second embodiment will be described in more detail.

  The nonaqueous electrolyte battery according to the second embodiment includes a negative electrode, a positive electrode, and a nonaqueous electrolyte.

  The negative electrode is an electrode according to the first embodiment. Hereinafter, the electrode according to the first embodiment, and the current collector and electrode active material-containing layer included therein are referred to as a negative electrode, and a negative electrode current collector and a negative electrode active material-containing layer, respectively. The active material that can be included in the electrode according to the first embodiment is referred to as a negative electrode active material.

The positive electrode includes a positive electrode current collector and a positive electrode active material-containing layer formed on the positive electrode current collector.
The positive electrode current collector can have, for example, two surfaces facing away from each other. The positive electrode current collector can carry the positive electrode active material-containing layer only on one surface thereof, or can carry the positive electrode active material-containing layer on both surfaces. The positive electrode current collector can also include a portion that does not carry the positive electrode active material-containing layer on the surface. This part can serve as a positive electrode tab, for example. Alternatively, the positive electrode can include a positive electrode tab separate from the positive electrode current collector.

  The positive electrode active material-containing layer includes a positive electrode active material. The positive electrode active material-containing layer can further contain a conductive agent and a binder in addition to the positive electrode active material.

  The positive electrode and the negative electrode can constitute an electrode group. In the electrode group, the positive electrode active material-containing layer and the negative electrode active material-containing layer can face each other through a separator, for example. The electrode group can have various structures. For example, the electrode group can have a stacked structure. A stack type electrode group can be obtained, for example, by laminating a plurality of positive electrodes and negative electrodes with a separator interposed between a positive electrode active material-containing layer and a negative electrode active material-containing layer. Alternatively, the electrode group may have a wound structure. For example, the wound electrode group is formed by laminating one separator, one positive electrode, another separator, and one negative electrode in this order. It can be obtained by winding so that the negative electrode is on the outside.

  In the nonaqueous electrolyte battery according to the second embodiment, the nonaqueous electrolyte can be held in a state of being impregnated in, for example, an electrode group.

  The nonaqueous electrolyte battery according to the second embodiment can further include a negative electrode terminal and a positive electrode terminal. The negative electrode terminal can function as a conductor for electrons to move between the negative electrode and the external terminal by being partly connected to a part of the negative electrode. The negative electrode terminal can be connected to, for example, a negative electrode current collector, particularly a negative electrode tab. Similarly, the positive electrode terminal can function as a conductor for electrons to move between the positive electrode and an external circuit by being electrically connected to a part of the positive electrode. The positive electrode terminal can be connected to, for example, a positive electrode current collector, particularly a positive electrode tab.

  The nonaqueous electrolyte battery according to the second embodiment can further include an exterior member. The exterior member can accommodate the electrode group and the nonaqueous electrolyte. The nonaqueous electrolyte can be impregnated in the electrode group within the exterior member. A part of each of the positive electrode terminal and the negative electrode terminal can be extended from the exterior member.

  Next, each member that can be included in the nonaqueous electrolyte battery according to the second embodiment will be described in more detail.

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

The positive electrode active material includes, for example, manganese dioxide (MnO ₂ ) that absorbs lithium, iron oxide, copper oxide, nickel oxide, lithium nickel composite oxide (eg, Li _u NiO ₂ ), lithium cobalt composite oxide (eg, Li _u CoO ₂ ), lithium nickel cobalt composite oxide (eg, Li _u Ni _1-s Co _s O ₂ ), lithium manganese cobalt composite oxide (eg, Li _u Mn _s Co _1-s O ₂ ), lithium nickel cobalt-manganese composite oxide _{(e.g., Li u Ni 1-st Co} s Mn t O 2), lithium-nickel-cobalt-aluminum composite oxide _{(e.g., Li u Ni 1-st Co} s Al t O 2), lithium manganese composite oxide objects (e.g., Li _u Mn ₂ O ₄ or Li _u MnO _2), lithium phosphates having an olivine structure (e.g., Li _u FePO _{4 Li u MnPO 4, Li u Mn} 1-s Fe s PO 4, Li u CoPO 4), from the group consisting of iron sulfate _{(Fe 2 (SO 4) 3} ), and vanadium oxides (e.g., V ₂ O ₅₎ At least one selected may be included. In the above, 0 <u ≦ 1, 0 ≦ s ≦ 1, and 0 ≦ t ≦ 1 are preferable. As the active material, a spinel type lithium manganese composite oxide may be used alone, or a plurality of compounds may be used in combination.

Since it is easy to obtain high input / output characteristics and excellent lifetime characteristics, lithium manganese composite oxide, lithium cobalt composite oxide (Li _u CoO ₂ ), lithium nickel cobalt composite oxide (Li _u Ni _{1- s} Co _s O _2), lithium manganese cobalt composite oxide _{(Li u Mn s Co 1-} s O 2), lithium-nickel-cobalt-manganese composite oxide (e.g. _{Li u Ni 1-st Co s} Mn t O 2), or It is preferable to include a lithium phosphorus oxide having an olivine structure (for example, Li _u FePO ₄ , Li _u MnPO ₄ , Li _u Mn _1-s Fe _s PO ₄ , Li _u CoPO ₄ ). In the above, 0 <u ≦ 1, 0 ≦ s ≦ 1, and 0 ≦ t ≦ 1 are preferable.

  The conductive agent that can be included in the positive electrode can have a function of improving current collection performance and suppressing contact resistance between the active material and the current collector. Examples of the conductive agent include carbonaceous materials such as acetylene black, carbon black, graphite, carbon nanofiber, and carbon nanotube. As the carbonaceous material, one of these 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), and fluorine-based rubber, styrene butadiene rubber, an acrylic resin or a copolymer thereof, polyacrylic acid, polyacrylonitrile, and the like. .

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

  The positive electrode can be produced, for example, by the following method. First, a positive electrode active material, a conductive agent, and a binder are suspended in a solvent to prepare a slurry. This slurry is applied to one surface or both surfaces of the positive electrode current collector, and the coating film is dried. Subsequently, a positive electrode active material content layer can be obtained by using the dried coating film for a press. Alternatively, the positive electrode active material, the conductive agent, and the binder can be formed into pellets, and these pellets can be arranged on the positive electrode current collector to be used as the positive electrode active material layer.

(Nonaqueous electrolyte)
As the non-aqueous electrolyte, for example, a liquid non-aqueous electrolyte or a gel non-aqueous electrolyte can be used.

  The liquid non-aqueous electrolyte can be prepared by dissolving the electrolyte in an organic solvent. The concentration of the electrolyte is preferably in the range of 0.5 to 2.5 mol / l. The gel-like nonaqueous electrolyte is prepared by combining a liquid electrolyte and a polymer material.

Examples of the electrolyte include lithium perchlorate (LiClO ₄ ), lithium hexafluorophosphate (LiPF ₆ ), lithium tetrafluoroborate (LiBF ₄ ), lithium hexafluoroarsenate (LiAsF ₆ ), trifluoromethane Lithium salts such as lithium sulfonate (LiCF ₃ SO ₃ ) and lithium bistrifluoromethylsulfonylimide [LiN (CF ₃ SO ₂ ) ₂ ] are included. As the electrolyte, one of these electrolytes may be used alone, or two or more kinds of electrolytes may be used in combination. The electrolyte preferably contains LiPF ₆ .

  Examples of organic solvents include propylene carbonate (PC), ethylene carbonate (EC), cyclic carbonates such as vinylene carbonate; Carbonates; cyclic ethers such as tetrahydrofuran (THF), 2-methyltetrahydrofuran (2MeTHF), dioxolane (DOX); chain ethers such as dimethoxyethane (DME) and dietoethane (DEE); acetonitrile (AN) and sulfolane ( SL). As the organic solvent, one of these solvents may be used alone, or two or more kinds of solvents may be used in combination.

  Examples of more preferable organic solvents include 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). A mixed solvent in which is mixed. By using such a mixed solvent, a nonaqueous electrolyte battery having excellent charge / discharge cycle characteristics can be obtained. Moreover, an additive can also be added to electrolyte solution.

(Separator)
As the separator, for example, a porous film formed from a material such as polyethylene, polypropylene, polyethylene terephthalate, cellulose, and polyvinylidene fluoride (PVdF), a synthetic resin nonwoven fabric, or the like can be used. Furthermore, the separator which apply | coated the inorganic compound to the porous film can also be used.

(Exterior material)
As the exterior member, for example, a bag-like container made of a laminate film or a metal container can be used.

  The shape is not particularly limited, and examples thereof include a flat shape, a square shape, a cylindrical shape, a coin shape, a button shape, a sheet shape, and a laminated shape. Of course, in addition to a small battery mounted on a portable electronic device or the like, a large battery mounted on a two-wheel to four-wheel automobile or the like may be used.

  As the laminate film, for example, a multilayer film in which a metal layer is sandwiched between resin films can be used. Or the multilayer film which consists of a metal layer and the resin layer which coat | covers a metal layer can also be used.

  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, and polyethylene terephthalate (PET) can be used. The laminate film can be formed into the shape of an exterior member by sealing by heat sealing. The laminate film preferably has a thickness of 0.2 mm or less.

  The metallic container can be formed from aluminum or an aluminum alloy. The aluminum alloy preferably contains elements such as magnesium, zinc and silicon. On the other hand, the content of transition metals such as iron, copper, nickel and chromium is preferably 100 ppm or less. Thereby, it becomes possible to dramatically improve long-term reliability and heat dissipation in a high temperature environment. The metal container preferably has a thickness of 0.5 mm or less, and more preferably has a thickness of 0.2 mm or less.

(Positive terminal)
The positive electrode terminal is formed from a material that is electrically stable and has conductivity, for example, in a range where the potential with respect to the oxidation-reduction potential of lithium is 3.0 V to 4.5 V. It is preferably formed from aluminum or an aluminum alloy containing elements such as Mg, Ti, Zn, Mn, Fe, Cu and Si. The positive electrode terminal is preferably formed of the same material as the positive electrode current collector in order to reduce contact resistance with the positive electrode current collector.

(Negative terminal)
The negative electrode terminal is formed of a material that is electrically stable and has conductivity in a range where the potential with respect to the oxidation-reduction potential of lithium is 0.8 V or more and 3.0 V or less. It is preferably formed from aluminum or an aluminum alloy containing an element such as Mg, Ti, Zn, Mn, Fe, Cu, or Si. The negative electrode terminal is preferably formed from the same material as the negative electrode current collector in order to reduce the contact resistance with the negative electrode current collector.

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

  FIG. 3 is a schematic cross-sectional view of an example of a flat nonaqueous electrolyte battery according to the second embodiment. 4 is an enlarged cross-sectional view of a portion A in FIG.

  The nonaqueous electrolyte battery 1 shown in FIGS. 3 and 4 includes a flat wound electrode group 3 shown in FIG. The flat wound electrode group 3 is accommodated in a bag-shaped exterior member 2 made of a laminate film including a metal layer and two resin films sandwiching the metal layer.

  As shown in FIG. 4, the flat wound electrode group 3 is formed by winding a laminate of the negative electrode 5, the separator 6, the positive electrode 4, and the separator 6 in this order from the outside in a spiral shape and press-molding. Has been. As shown in FIG. 4, the outermost portion of the negative electrode 5 forms a negative electrode active material-containing layer 5b containing a negative electrode active material on one surface on the inner surface side of the negative electrode current collector 5a. In the other part of the negative electrode 5, the negative electrode active material containing layer 5b is formed on both surfaces of the negative electrode current collector 5a. For the positive electrode 4, positive electrode active material-containing layers 4b are formed on both surfaces of the positive electrode current collector 4a.

  In the vicinity of the outer peripheral end of the wound electrode group 3, the negative electrode terminal 8 is connected to the negative electrode current collector 5 a in the outermost layer portion of the negative electrode 5, and the positive electrode terminal 7 is the positive electrode of the positive electrode 4 positioned inside. It is connected to the current collector 4a. The negative terminal 8 and the positive terminal 7 are extended to the outside from the opening of the bag-shaped exterior member 2.

  The nonaqueous electrolyte battery 1 shown in FIGS. 3 and 4 further includes a nonaqueous electrolyte (not shown). The nonaqueous electrolyte is accommodated in the exterior member 2 in a state of being impregnated in the electrode group 3.

  A nonaqueous electrolyte can be inject | poured from the opening part of the bag-shaped exterior member 2, for example. After the nonaqueous electrolyte is injected, the wound electrode group 1 and the nonaqueous electrolyte can be completely sealed by heat-sealing the opening of the bag-shaped exterior member 2 with the negative electrode terminal 8 and the positive electrode terminal 7 interposed therebetween.

  The nonaqueous electrolyte battery according to the second embodiment is not limited to the configuration shown in FIGS. 3 and 4 described above, and can be configured as shown in FIGS. 4 and 5, for example.

  FIG. 5 is a schematic partially cutaway perspective view of another example of the nonaqueous electrolyte battery according to the second embodiment. 6 is an enlarged cross-sectional view of a portion B in FIG.

  A nonaqueous electrolyte battery 10 shown in FIGS. 5 and 6 includes a stacked electrode group 11. The laminated electrode group 11 is housed in an exterior member 12 made of a laminate film including a metal layer and two resin films sandwiched between the metal layers.

  As shown in FIG. 6, the stacked electrode group 11 has a structure in which positive electrodes 13 and negative electrodes 14 are alternately stacked with separators 15 interposed therebetween. There are a plurality of positive electrodes 13, each of which includes a current collector 13 a and a positive electrode active material-containing layer 13 b supported on both surfaces of the current collector 13 a. There are a plurality of negative electrodes 14, each of which includes a current collector 14a and a negative electrode active material-containing layer 14b supported on both surfaces of the current collector 14a. One side of the current collector 14 a of each negative electrode 14 protrudes from the positive electrode 13. A portion of the current collector 14 a that protrudes from the positive electrode 13 is electrically connected to the strip-shaped negative electrode terminal 16. The tip of the strip-shaped negative electrode terminal 16 is drawn out from the exterior member 12 to the outside. Although not shown, the current collector 13a of the positive electrode 13 protrudes from the negative electrode 14 on the side opposite to the protruding side of the current collector 14a. A portion of the current collector 13 a that protrudes from the negative electrode 14 is electrically connected to the belt-like positive electrode terminal 17. The tip of the strip-like positive electrode terminal 17 is located on the opposite side of the negative electrode terminal 16 and is drawn out from the side of the exterior member 12 to the outside.

  Since the nonaqueous electrolyte battery according to the second embodiment includes the electrode according to the first embodiment, it can exhibit excellent input / output characteristics.

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

  The battery pack according to the third embodiment can also include a plurality of nonaqueous electrolyte batteries. The plurality of nonaqueous electrolyte batteries can be electrically connected in series, or can be electrically connected in parallel. Alternatively, a plurality of nonaqueous electrolyte batteries can be connected in a combination of series and parallel.

  For example, the battery pack according to the third embodiment can also include five non-aqueous electrolyte batteries according to the second embodiment. These non-aqueous electrolyte batteries can be connected in series. Moreover, the non-aqueous electrolyte battery connected in series can comprise an assembled battery. That is, the battery pack according to the third embodiment can include an assembled battery.

  The battery pack according to the third embodiment can include a plurality of assembled batteries. The plurality of assembled batteries can be connected in series, parallel, or a combination of series and parallel.

  The battery pack according to the third embodiment will be described in detail with reference to FIGS. The flat battery shown in FIGS. 3 and 4 can be used as the unit cell.

  A plurality of unit cells 21 composed of the flat type non-aqueous electrolyte battery shown in FIGS. 3 and 4 are laminated so that the negative electrode terminal 8 and the positive electrode terminal 7 extending to the outside are aligned in the same direction, and are adhered. The assembled battery 23 is configured by fastening with the tape 22. These unit cells 21 are electrically connected to each other in series as shown in FIG.

  The printed wiring board 24 is disposed to face the side surface of the unit cell 21 from which the negative electrode terminal 8 and the positive electrode terminal 7 extend. As shown in FIG. 8, a thermistor 25, a protection circuit 26, and a terminal 27 for energizing external devices are mounted on the printed wiring board 24. An insulating plate (not shown) is attached to the surface of the protection circuit board 24 facing the assembled battery 23 in order to avoid unnecessary connection with the wiring of the assembled battery 23.

  The positive electrode side lead 28 is connected to the positive electrode terminal 7 positioned at the lowermost layer of the assembled battery 23, and the tip thereof is inserted into the positive electrode side connector 29 of the printed wiring board 24 and electrically connected thereto. The negative electrode side lead 30 is connected to the negative electrode terminal 8 located in the uppermost layer of the assembled battery 23, and the tip thereof is inserted into and electrically connected to the negative electrode side connector 31 of the printed wiring board 24. These connectors 29 and 31 are connected to the protection circuit 26 through wirings 32 and 33 formed on the printed wiring board 24.

  The thermistor 25 detects the temperature of the unit cell 21, and the detection signal is transmitted 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 energization terminal 27 to the external device under a predetermined condition. The predetermined condition is, for example, when the temperature detected by the thermistor 25 is equal to or higher than a predetermined temperature. The predetermined condition is when the overcharge, overdischarge, overcurrent, etc. of the cell 21 are detected. This detection of overcharge or the like is performed for each individual cell 21 or the entire assembled battery 23. When detecting each single cell 21, the battery voltage may be detected, or the positive electrode potential or the negative electrode potential may be detected. In the latter case, a lithium electrode used as a reference electrode is inserted into each unit cell 21. In the case of FIG. 7 and FIG. 8, a wiring 35 for voltage detection is connected to each single cell 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 disposed on the three side surfaces of the assembled battery 23 excluding the side surfaces from which the positive electrode terminal 7 and the negative electrode terminal 8 protrude.

  The assembled battery 23 is stored in a storage container 37 together with the protective sheets 36 and the printed wiring board 24. That is, the protective sheet 36 is disposed on each of the inner side surface in the long side direction and the inner side surface in the short side direction of the storage container 37, and the printed wiring board 24 is disposed on the inner side surface on the opposite side in the short side direction. The assembled battery 23 is located in a space surrounded by the protective sheet 36 and the printed wiring board 24. The lid 38 is attached to the upper surface of the storage container 37.

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

  7 and 8 show the configuration in which the unit cells 21 are connected in series, but in order to increase the battery capacity, they may be connected in parallel. The assembled battery packs can be connected in series and / or in parallel.

  Moreover, the battery pack according to the third embodiment can include the nonaqueous electrolyte battery according to the first embodiment in various forms.

  FIG. 9 is a schematic perspective view of an example assembled battery that can be included in the battery pack according to the third embodiment.

The assembled battery 23 shown in FIG. 9 includes five unit cells 21 _{1 to} 21 ₅ . Each of the batteries 21 _{1 to} 21 ₅ is an example nonaqueous electrolyte battery according to the second embodiment. Each of the batteries 21 _{1 to} 21 ₅ includes a metal square exterior member 2. The exterior member 2 accommodates an electrode group similar to the electrode group 3 shown in FIG. 3 and a nonaqueous electrolyte impregnated in the electrode group.

Cell 21 ₁ of the positive electrode terminal 7 shown in the left end is connected to the positive electrode side lead 28 for external connection. The negative terminal of the battery 21 ₁ 8 is connected via a lead 40 to the positive terminal 7 of the battery 21 ₂ adjacent to the right of the battery 21 _1. The negative terminal of the battery 21 ₂ 8 is connected via a lead 40 to the positive terminal 7 of the battery 21 ₃ adjacent to the right of the battery 21 _2. The negative terminal of the battery 21 ₃ 8 is connected via a lead 40 to the positive terminal 7 of the battery 21 ₄ adjacent to the right of the battery 21 _3. The negative terminal of the battery 21 ₄ 8 is connected via a lead 40 to the positive terminal 7 of the battery 21 ₅ adjacent the right side of the battery 21 _4. The negative terminal 8 of the battery 21 ₅ shown in the right end is connected to the negative lead 30 for external connection. With such connection, the five batteries 21 _{1 to} 21 ₅ are electrically connected in series.

  An assembled battery configured by connecting five nonaqueous electrolyte batteries according to the second embodiment in series can exhibit an average operating voltage of 12V to 14V. The average operating voltage within this range is about the same as the average operating voltage of a 12V battery pack including a lead storage battery. Therefore, an assembled battery capable of exhibiting such an average operating voltage can assist input / output of the lead storage battery when used in parallel with a 12V system assembled battery including the lead storage battery. Thereby, the charge by the overdischarge and excessive current which cause deterioration of a lead storage battery can be prevented. Therefore, the assembled battery configured by connecting five nonaqueous electrolyte batteries according to the second embodiment in series can exhibit excellent voltage compatibility with an assembled battery including a lead storage battery.

  Since the battery pack according to the third embodiment includes the nonaqueous electrolyte battery according to the second embodiment, it can exhibit excellent input / output characteristics.

[Example]
Examples will be described below, but the present invention is not limited to the examples described below unless the gist of the present invention is exceeded.

Example 1
In Example 1, the nonaqueous electrolyte battery of Example 1 was produced by the following procedure.

[Production of positive electrode]
First, a powder of a spinel type lithium manganese composite oxide LiAl _0.1 Mn _1.9 O ₄ was prepared as a positive electrode active material. This composite oxide, acetylene black as a conductive agent, and polyvinylidene fluoride (PVdF) as a binder are mixed at a mixing ratio of 90% by mass: 5% by mass: 5% by mass with N-methyl as a solvent. Poured into pyrrolidone (NMP) and mixed. Next, the mixture thus obtained was dispersed using a rotation and revolution mixer to prepare a slurry.

Next, the prepared slurry was applied to both surfaces of a current collector made of an aluminum foil having a thickness of 15 μm. The coating amount per unit area was 95 g / m ² . Next, the coating film was dried and subjected to pressing. Thus, a positive electrode having an electrode density (not including the current collector) of 2.7 g / cm ³ was produced.

[Production of negative electrode]
First, orthorhombic Na-containing niobium titanium composite oxide Li ₂ Na _1.7 Ti _5.7 Nb _0.3 O ₁₄ powder was prepared by the following procedure.

As raw materials, and titanium oxide TiO _2, and lithium carbonate Li ₂ CO _3, sodium carbonate Na ₂ CO _3, and prepared and niobium hydroxide _{(V) Nb (OH) 5} . These raw materials were mixed so that the molar ratio of Li: Na: Ti: Nb in the mixture was 2: 1.7: 5.7: 0.3. Prior to mixing, the raw material was thoroughly pulverized. The mixed raw material was heat-treated at 900 ° C. for 3 hours in an air atmosphere. A product powder was thus obtained. The produced Li ₂ Na _1.7 Ti _5.7 Nb _0.3 O ₁₄ was in the form of primary particles with an average primary particle size of 3 μm.

Next, 90% by mass: 5% by mass: 5% by mass of Li ₂ Na _1.7 Ti _5.7 Nb _0.3 O ₁₄ powder, acetylene black as a conductive agent, and polyvinylidene fluoride (PVdF) as a binder. At a mixing ratio of N-methylpyrrolidone (NMP) as a solvent. Next, the mixture thus obtained was dispersed using a rotation and revolution mixer to prepare a slurry.

Next, the prepared slurry was applied to both surfaces of a current collector made of an aluminum foil having a thickness of 15 μm. Next, the coating film was dried and subjected to pressing. The distance between the rolls of the roll press apparatus was adjusted to produce a negative electrode having an electrode density (not including the current collector) of 2.5 g / cm ³ .

[Production of electrode group]
Next, two separators made of a polyethylene porous film having a thickness of 25 μm were prepared.

  Next, the positive electrode prepared earlier, one separator, the negative electrode prepared earlier, and another separator were laminated in this order to obtain a laminate. This laminate was wound in a spiral. This was heated and pressed at 90 ° C. to produce a flat electrode group having a width of 30 mm and a thickness of 3.0 mm.

  The obtained electrode group was housed in a pack made of a laminate film and vacuum dried at 80 ° C. for 24 hours. The laminate film was constituted by forming a polypropylene layer on both sides of an aluminum foil having a thickness of 40 μm, and the overall thickness was 0.1 mm.

[Preparation of liquid non-aqueous electrolyte]
Propylene carbonate (PC) and diethyl carbonate (DEC) were mixed at a volume ratio of 1: 1 to obtain a mixed solvent. A liquid non-aqueous electrolyte was prepared by dissolving 1M of LiPF ₆ as an electrolyte in this mixed solvent.

[Manufacture of non-aqueous electrolyte secondary batteries]
A liquid nonaqueous electrolyte was injected into the laminate film pack containing the electrode group as described above. Thereafter, the pack was completely sealed by heat sealing. Thus, a nonaqueous electrolyte battery having the structure shown in FIGS. 3 and 4 described above, having a width of 35 mm, a thickness of 3.2 mm, and a height of 65 mm was manufactured. The capacity of this nonaqueous electrolyte battery was 300 mAh.

(Example 2)
In Example 2, synthesis was performed by changing the firing temperature of the active material from 900 ° C. to 830 ° C. during the production of the negative electrode, and the average primary particle diameter of the Li ₂ Na _1.7 Ti _5.7 Nb _0.3 O ₁₄ powder was 1 μm. A nonaqueous electrolyte battery of Example 2 was produced in the same procedure as in Example 1 except that. Also in the negative electrode density, the negative electrode was produced at 2.5 g / cm ^{3 in the same} manner as in Example 1.

(Example 3)
In Example 3, the nonaqueous electrolyte battery of Example 3 was produced in the same procedure as in Example 1 except for the following points. In Example 3, at the time of producing the negative electrode, a powder of Li ₂ Na _1.7 Ti _5.7 Nb _0.3 O ₁₄ was granulated to obtain a secondary particle form.

Furthermore, carbon was adhered to the surface of the secondary particles by the following procedure.
First, primary particles of Li ₂ Na _1.7 Ti _5.7 Nb _0.3 O ₁₄ were put into an aqueous solution of carboxymethyl cellulose as a binder for forming secondary particles to prepare a slurry. Further, carboxymethyl cellulose, were added 0.8% by weight, based on the weight of the primary particles of _{Li 2 Na 1.7 Ti 5.7 Nb 0.3} O 14.

  The slurry obtained as described above was sprayed by a two-fluid nozzle method and granulated. At this time, the drying temperature was 120 ° C.

  Next, the obtained secondary particles were heat-treated at 600 ° C. for 1 hour. The average secondary particle diameter of the negative electrode active material thus obtained was 15 μm.

The electrode density of the negative electrode (not including the current collector) was 2.5 g / cm ³ as in Example 1.

(Example 4)
In Example 4, the nonaqueous electrolyte battery of Example 4 was produced in the same procedure as in Example 1 except for the following points. In Example 4, during the production of the negative electrode, a powder of Li ₂ Na _1.7 Ti _5.7 Nb _0.3 O ₁₄ was granulated into a secondary particle form. The granulation method was the same as that of Example 3 except that 0.5% by mass of carboxymethyl cellulose was added to the mass of primary particles of Li ₂ Na _1.7 Ti _5.7 Nb _0.3 O ₁₄ . The average secondary particle diameter of the obtained active material was 8 μm. The electrode density of the negative electrode (not including the current collector) was 2.5 g / cm ³ as in Example 1.

(Example 5)
In Example 5, the nonaqueous electrolyte battery of Example 5 was produced in the same procedure as in Example 1 except for the following points. In Example 5, during the production of the negative electrode, a powder of Li ₂ Na _1.7 Ti _5.7 Nb _0.3 O ₁₄ was granulated into a secondary particle form. The granulation method was the same as Example 3 except that 1% by mass of carboxymethyl cellulose was added to the mass of primary particles of Li ₂ Na _1.7 Ti _5.7 Nb _0.3 O ₁₄ . The average secondary particle diameter of the obtained active material was 18 μm. The electrode density of the negative electrode (not including the current collector) was 2.5 g / cm ³ as in Example 1.

(Example 6)
In Example 6, the nonaqueous electrolyte battery of Example 6 was produced in the same procedure as in Example 1 except for the following points. In Example 6, during the production of the negative electrode, a powder of Li ₂ Na _1.7 Ti _5.7 Nb _0.3 O ₁₄ was granulated into a secondary particle form. The granulation method was the same as that of Example 3 except that 0.3% by mass of carboxymethyl cellulose was added to the mass of primary particles of Li ₂ Na _1.7 Ti _5.7 Nb _0.3 O ₁₄ . The average secondary particle diameter of the obtained active material was 5 μm. Further, in Example 6, when dispersing the slurry using a rotation and revolution mixer, glass beads having a diameter of 2 mm were placed in a container at 33% of the slurry volume to prepare a slurry. Furthermore, the distance between the rolls of the roll press apparatus was adjusted to be narrower than that of Example 1, so that the electrode density of the negative electrode (excluding the current collector) was 2.6 g / cm ³ .

(Example 7)
In Example 7, the same procedure as in Example 1 was used, except that 2.5% by mass of acetylene black and 2.5% by mass of graphite were used instead of 5% by mass of acetylene black as a conductive agent when producing the negative electrode. Thus, a nonaqueous electrolyte battery of Example 7 was produced. The electrode density of the negative electrode (not including the current collector) was 2.5 g / cm ³ as in Example 1.

(Example 8)
In Example 8, 2.5% by mass of vapor-grown carbon fiber having an acetylene black of 2.5% by mass and an aspect ratio of 50 was used in place of acetylene black of 5% by mass as a conductive agent in producing the negative electrode. A nonaqueous electrolyte battery of Example 8 was produced in the same procedure as in Example 1 except that. The electrode density of the negative electrode (not including the current collector) was 2.5 g / cm ³ as in Example 1.

Example 9
In Example 9, when producing the negative electrode, instead of 5% by mass of acetylene black as a conductive agent, 2.5% by mass of graphite and 2.5% by mass of vapor grown carbon fiber having an aspect ratio of 30 were used. A nonaqueous electrolyte battery of Example 9 was produced in the same procedure as in Example 1 except for the above. The electrode density of the negative electrode (not including the current collector) was 2.5 g / cm ³ as in Example 1.

(Example 10)
In Example 10, in the production of the negative electrode, instead of 5% by mass of acetylene black as a conductive agent, 2.5% by mass of graphite and 2.5% by mass of vapor-grown carbon fiber having an aspect ratio of 18 were used. A nonaqueous electrolyte battery of Example 10 was produced in the same procedure as in Example 1 except for the above. The electrode density of the negative electrode (not including the current collector) was 2.5 g / cm ³ as in Example 1.

(Example 11)
In Example 11, at the time of producing the negative electrode, instead of 5% by mass of acetylene black as the conductive agent, 2.5% by mass of graphite and 2.5% by mass of vapor-grown carbon fiber having an aspect ratio of 18 were used. A nonaqueous electrolyte battery of Example 11 was produced in the same procedure as in Example 1 except for the above. The distance between the rolls of the roll press apparatus was adjusted to be wider than that of Example 1, and the electrode density of the negative electrode (not including the current collector) was 2.35 g / cm ³ .

(Example 12)
In Example 12, the non-aqueous electrolyte battery of Example 12 was prepared in the same manner as in Example 1 except that 5% by mass of graphite was used instead of 5% by mass of acetylene black as a conductive agent when producing the negative electrode. Was made. The distance between the rolls of the roll press apparatus was adjusted to be narrower than that of Example 1, and the electrode density of the negative electrode (not including the current collector) was 2.65 g / cm ³ .

(Example 13)
In Example 13, the nonaqueous electrolyte battery of Example 13 was produced in the same procedure as in Example 1 except that the negative electrode active material was changed. In Example 13, a powder of orthorhombic Na-containing niobium titanium composite oxide Li ₂ Na _1.9 Ti _5.9 Nb _0.1 O ₁₄ was used as the negative electrode active material. This powder was orthorhombic used in Example 1 except that the raw materials were mixed so that the molar ratio of Li: Na: Ti: Nb in the mixture was 2: 1.9: 5.9: 0.1. It was synthesized in the same manner as the procedure for synthesizing the powder of type Na-containing niobium titanium composite oxide. The electrode density of the negative electrode (not including the current collector) was 2.5 g / cm ³ as in Example 1.

(Example 14)
In Example 14, the nonaqueous electrolyte battery of Example 14 was produced in the same procedure as in Example 1 except that the negative electrode active material was changed. In Example 14, an orthorhombic Na-containing niobium titanium composite oxide Li _2.1 Na _1.8 Ti _5.9 Nb _0.1 O ₁₄ powder was used as the negative electrode active material. This powder was the same as that used in Example 1 except that the raw materials were mixed so that the molar ratio of Li: Na: Ti: Nb in the mixture was 2.1: 1.8: 5.9: 0.1. Synthesis was performed in the same manner as the procedure for synthesizing powder of the tetragonal Na-containing niobium titanium composite oxide. The electrode density of the negative electrode (not including the current collector) was 2.5 g / cm ³ as in Example 1.

(Example 15)
In Example 15, the nonaqueous electrolyte battery of Example 15 was produced in the same procedure as in Example 1 except that the negative electrode active material was changed. In Example 15, orthorhombic Na-containing niobium titanium composite oxide Li ₂ Na _1.5 Ti _5.5 Nb _0.5 O ₁₄ powder was used as the negative electrode active material. This powder was orthorhombic used in Example 1 except that the raw materials were mixed so that the molar ratio of Li: Na: Ti: Nb in the mixture was 2: 1.5: 5.5: 0.5. It was synthesized in the same manner as the procedure for synthesizing the powder of type Na-containing niobium titanium composite oxide. The electrode density of the negative electrode (not including the current collector) was 2.5 g / cm ³ as in Example 1.

(Example 16)
In Example 16, the nonaqueous electrolyte battery of Example 16 was produced in the same procedure as in Example 1 except that the negative electrode active material was changed. In Example 16, orthorhombic Na-containing niobium titanium composite oxide Li _2.2 Na _1.3 Ti _5.5 Nb _0.5 O ₁₄ powder was used as the negative electrode active material. This powder is the same as that used in Example 1 except that the raw materials were mixed so that the molar ratio of Li: Na: Ti: Nb in the mixture was 2.2: 1.3: 5.5: 0.5. Synthesis was performed in the same manner as the procedure for synthesizing powder of the tetragonal Na-containing niobium titanium composite oxide. The electrode density of the negative electrode (not including the current collector) was 2.5 g / cm ³ as in Example 1.

(Example 17)
In Example 17, the nonaqueous electrolyte battery of Example 17 was produced in the same procedure as in Example 1 except that the negative electrode active material was changed. In Example 17, a powder of orthorhombic Na-containing niobium titanium composite oxide Li ₂ Na _1.2 Ti _5.2 Nb _0.8 O ₁₄ was used as the negative electrode active material. This powder was orthorhombic used in Example 1 except that the raw materials were mixed so that the molar ratio of Li: Na: Ti: Nb in the mixture was 2: 1.2: 5.2: 0.8. It was synthesized in the same manner as the procedure for synthesizing the powder of type Na-containing niobium titanium composite oxide. The electrode density of the negative electrode (not including the current collector) was 2.5 g / cm ³ as in Example 1.

(Example 18)
In Example 18, the nonaqueous electrolyte battery of Example 18 was produced in the same procedure as in Example 1 except that the negative electrode active material was changed. In Example 18, a powder of orthorhombic Na-containing niobium titanium composite oxide Li ₂ NaSr _0.5 Ti _5.9 Nb _0.1 O ₁₄ was used as the negative electrode active material. In this powder, a powder of strontium nitrate Sr (NO ₃ ) ₂ was further used as a raw material, and the molar ratio of Li: Na: Sr: Ti: Nb in the mixture of the raw material was 2: 1: 0.5: 5. 9: The synthesis was performed in the same manner as the synthesis procedure of the orthorhombic Na-containing niobium titanium composite oxide powder used in Example 1 except that the mixture was mixed to 0.1. The electrode density of the negative electrode (not including the current collector) was 2.5 g / cm ³ as in Example 1.

(Example 19)
In Example 19, a nonaqueous electrolyte battery of Example 19 was produced in the same procedure as in Example 1 except that the negative electrode active material was changed. In Example 19, an orthorhombic Na-containing niobium titanium composite oxide Li ₂ Na _1.5 Sr _0.2 Ti _5.9 Nb _0.1 O ₁₄ powder was used as the negative electrode active material. This powder was prepared in Example 1 except that the raw materials were mixed so that the molar ratio of Li: Na: Sr: Ti: Nb in the mixture was 2: 1.5: 0.2: 5.9: 0.1. The orthorhombic Na-containing niobium titanium composite oxide powder used in the above was synthesized in the same manner as described above. The electrode density of the negative electrode (not including the current collector) was 2.5 g / cm ³ as in Example 1.

(Example 20)
In Example 20, the nonaqueous electrolyte battery of Example 20 was produced in the same procedure as in Example 1 except that the negative electrode active material was changed. In Example 20, a powder of orthorhombic Na-containing niobium titanium composite oxide Li ₂ Na _1.5 Mg _0.2 Ti _5.9 Nb _0.1 O ₁₄ was used as the negative electrode active material. This powder was obtained by further using magnesium acetate Mg (CH ₃ COO) ₂ powder as a raw material, and the molar ratio of Li: Na: Mg: Ti: Nb of the raw material mixture was 2: 1.5: 0.2. Was synthesized in the same manner as the procedure for synthesizing the orthorhombic Na-containing niobium titanium composite oxide powder used in Example 1, except that the mixture was mixed to 5.9: 0.1. The electrode density of the negative electrode (not including the current collector) was 2.5 g / cm ³ as in Example 1.

(Example 21)
In Example 21, the nonaqueous electrolyte battery of Example 21 was produced in the same procedure as in Example 1 except that the negative electrode active material was changed. In Example 21, a powder of orthorhombic Na-containing niobium titanium composite oxide Li ₂ Na _1.5 Ba _0.2 Ti _5.9 Nb _0.1 O ₁₄ was used as the negative electrode active material. This powder was obtained by further using a powder of barium carbonate BaCO ₃ as a raw material, and the molar ratio of Li: Na: Ba: Ti: Nb in the mixture of the raw materials was 2: 1.5: 0.2: 5.9: It was synthesized in the same manner as the procedure for synthesizing the orthorhombic Na-containing niobium titanium composite oxide powder used in Example 1, except that the mixture was mixed to 0.1. The electrode density of the negative electrode (not including the current collector) was 2.5 g / cm ³ as in Example 1.

(Example 22)
In Example 22, a nonaqueous electrolyte battery of Example 22 was produced in the same procedure as in Example 1 except that the negative electrode active material was changed. In Example 22, a powder of orthorhombic Na-containing niobium titanium composite oxide Li ₂ Na _1.5 Ba _0.2 Ti _5.5 Nb _0.5 O ₁₄ was used as the negative electrode active material. This powder was prepared in Example 22 except that the raw materials were mixed so that the molar ratio of Li: Na: Ba: Ti: Nb in the mixture was 2: 1.5: 0.2: 5.5: 0.5. The orthorhombic Na-containing niobium titanium composite oxide powder used in the above was synthesized in the same manner as described above. The electrode density of the negative electrode (not including the current collector) was 2.5 g / cm ³ as in Example 1.

(Example 23)
In Example 23, the nonaqueous electrolyte battery of Example 23 was produced in the same procedure as in Example 1 except that the negative electrode active material was changed. In Example 23, powder of orthorhombic Na-containing niobium titanium composite oxide Li ₂ Na _1.9 Ti _5.7 Nb _0.1 Al _0.2 O ₁₄ was used as the negative electrode active material. This powder further used aluminum oxide Al ₂ O ₃ powder as a raw material, and the molar ratio of Li: Na: Ti: Nb: Al in the mixture of the raw materials was 2: 1.9: 5.7: 0. It was synthesized in the same manner as the procedure for synthesizing the orthorhombic Na-containing niobium titanium composite oxide powder used in Example 1, except that the mixture was mixed so as to be 1: 0.2. The electrode density of the negative electrode (not including the current collector) was 2.5 g / cm ³ as in Example 1.

(Example 24)
In Example 24, the nonaqueous electrolyte battery of Example 24 was produced in the same procedure as in Example 1 except that the negative electrode active material was changed. In Example 24, powder of orthorhombic Na-containing niobium titanium composite oxide Li ₂ Na _1.9 Ti _5.8 Nb _0.1 Zr _0.1 O ₁₄ was used as the negative electrode active material. This powder was obtained by further using a powder of zirconium oxide ZrO ₂ as a raw material, and the molar ratio of Li: Na: Ti: Nb: Zr in the mixture of the raw materials was 2: 1.9: 5.8: 0.1: It was synthesized in the same manner as the procedure for synthesizing the orthorhombic Na-containing niobium titanium composite oxide powder used in Example 1, except that the mixture was mixed to 0.1. The electrode density of the negative electrode (not including the current collector) was 2.5 g / cm ³ as in Example 1.

(Example 25)
In Example 25, a nonaqueous electrolyte battery of Example 25 was produced in the same procedure as in Example 1 except that the negative electrode active material was changed. In Example 25, a powder of orthorhombic Na-containing niobium titanium composite oxide Li ₂ Na _1.9 Ti _5.8 Nb _0.1 Sn _0.1 O ₁₄ was used as the negative electrode active material. This powder was obtained by further using a tin oxide SnO ₂ powder as a raw material, and a molar ratio of Li: Na: Ti: Nb: Sn in the mixture of the raw materials was 2: 1.9: 5.8: 0.1: It was synthesized in the same manner as the procedure for synthesizing the orthorhombic Na-containing niobium titanium composite oxide powder used in Example 1, except that the mixture was mixed to 0.1. The electrode density of the negative electrode (not including the current collector) was 2.5 g / cm ³ as in Example 1.

(Example 26)
In Example 26, the nonaqueous electrolyte battery of Example 26 was produced in the same procedure as in Example 1 except that the negative electrode active material was changed. In Example 26, a powder of orthorhombic Na-containing niobium titanium composite oxide Li _2.1 Na _1.9 Ti _5.8 Nb _0.1 Ta _0.1 O ₁₄ was used as the negative electrode active material. In this powder, a powder of tantalum (V) Ta ₂ O ₅ was further used as a raw material, and the molar ratio of Li: Na: Ti: Nb: Ta in the raw material mixture was 2.1: 1.9: 5. .8: 0.1: Synthesis was performed in the same manner as the synthesis procedure of the orthorhombic Na-containing niobium titanium composite oxide powder used in Example 1 except that mixing was performed so that 0.1: 0.1. The electrode density of the negative electrode (not including the current collector) was 2.5 g / cm ³ as in Example 1.

(Example 27)
In Example 27, the nonaqueous electrolyte battery of Example 27 was produced in the same procedure as in Example 1 except that the negative electrode active material was changed. In Example 27, a powder of orthorhombic Na-containing niobium titanium composite oxide Li _2.1 Na _1.9 Ti _5.8 Nb _0.1 V _0.1 O ₁₄ was used as the negative electrode active material. In this powder, vanadium (V) V ₂ O ₅ powder was further used as a raw material, and the molar ratio of Li: Na: Ti: Nb: V of the raw material mixture was 2.1: 1.9: 5. .8: 0.1: Synthesis was performed in the same manner as the synthesis procedure of the orthorhombic Na-containing niobium titanium composite oxide powder used in Example 1 except that mixing was performed so that 0.1: 0.1. The electrode density of the negative electrode (not including the current collector) was 2.5 g / cm ³ as in Example 1.

(Example 28)
In Example 28, the nonaqueous electrolyte battery of Example 28 was produced in the same procedure as in Example 1 except that the negative electrode active material was changed. In Example 28, an orthorhombic Na-containing niobium titanium composite oxide Li ₂ Na _1.9 Ti _5.8 Nb _0.1 Fe _0.1 O ₁₄ powder was used as the negative electrode active material. In this powder, iron (III) Fe ₂ O ₃ powder was further used as a raw material, and the molar ratio of Li: Na: Ti: Nb: Fe in the mixture of the raw material was 2: 1.9: 5.8. Was synthesized in the same manner as the procedure for synthesizing the orthorhombic Na-containing niobium titanium composite oxide powder used in Example 1, except that the mixing ratio was 0.1: 0.1. The electrode density of the negative electrode (not including the current collector) was 2.5 g / cm ³ as in Example 1.

(Example 29)
In Example 29, the nonaqueous electrolyte battery of Example 29 was produced in the same procedure as in Example 1 except that the negative electrode active material was changed. In Example 29, powder of orthorhombic Na-containing niobium titanium composite oxide Li ₂ Na _1.9 Ti _5.8 Nb _0.1 Co _0.1 O ₁₄ was used as the negative electrode active material. In this powder, a powder of cobalt oxide Co ₃ O ₄ was further used as a raw material, and the molar ratio of Li: Na: Ti: Nb: Co in the raw material mixture was 2: 1.9: 5.8: 0. It was synthesized in the same manner as the procedure for synthesizing the orthorhombic Na-containing niobium titanium composite oxide powder used in Example 1, except that the mixture was mixed so as to be 1: 0.1. The electrode density of the negative electrode (not including the current collector) was 2.5 g / cm ³ as in Example 1.

(Example 30)
In Example 30, the nonaqueous electrolyte battery of Example 30 was produced in the same procedure as in Example 1 except that the negative electrode active material was changed. In Example 30, a powder of orthorhombic Na-containing niobium titanium composite oxide Li ₂ Na _1.9 Ti _5.8 Nb _0.1 Mn _0.1 O ₁₄ was used as the negative electrode active material. This powder further used manganese oxide Mn ₃ O ₄ powder as a raw material, and the molar ratio of Li: Na: Ti: Nb: Mn in the mixture of the raw materials was 2: 1.9: 5.8: 0. It was synthesized in the same manner as the procedure for synthesizing the orthorhombic Na-containing niobium titanium composite oxide powder used in Example 1, except that the mixture was mixed so as to be 1: 0.1. The electrode density of the negative electrode (not including the current collector) was 2.5 g / cm ³ as in Example 1.

(Example 31)
In Example 31, the nonaqueous electrolyte battery of Example 31 was produced in the same procedure as in Example 1 except that the negative electrode active material was changed. In Example 31, a powder of orthorhombic Na-containing niobium titanium composite oxide Li ₂ Na _1.9 Ti _5.8 Nb _0.1 Mo _0.1 O ₁₄ was used as the negative electrode active material. This powder was obtained by further using a molybdenum oxide MoO ₃ powder as a raw material, and a molar ratio of Li: Na: Ti: Nb: Mo in the mixture of the raw materials was 2: 1.9: 5.8: 0.1: It was synthesized in the same manner as the procedure for synthesizing the orthorhombic Na-containing niobium titanium composite oxide powder used in Example 1, except that the mixture was mixed to 0.1. The electrode density of the negative electrode (not including the current collector) was 2.5 g / cm ³ as in Example 1.

(Example 32)
In Example 32, the nonaqueous electrolyte battery of Example 32 was produced in the same procedure as in Example 1 except that the positive electrode was produced in the following procedure.

In Example 32, lithium nickel cobalt manganese composite oxide LiNi _0.33 Co _0.33 Mn _0.33 O ₂ was used as the positive electrode active material. This composite oxide, acetylene black as a conductive agent, and polyvinylidene fluoride (PVdF) as a binder are mixed at a mixing ratio of 90% by mass: 5% by mass: 5% by mass with N-methyl as a solvent. Poured into pyrrolidone (NMP) and mixed. Next, the mixture thus obtained was dispersed using a rotation and revolution mixer to prepare a slurry.

Next, the prepared slurry was applied to both surfaces of a current collector made of an aluminum foil having a thickness of 15 μm. The coating amount per unit area was 91 g / m ² . Next, the coating film was dried and subjected to pressing. Thus, a positive electrode having an electrode density (not including the current collector) of 3.0 g / cm ³ was produced.

(Example 33)
In Example 33, the nonaqueous electrolyte battery of Example 33 was produced in the same procedure as in Example 1 except that the positive electrode was produced in the following procedure.

In Example 33, lithium cobaltate LiCoO ₂ was used as the positive electrode active material. This composite oxide, acetylene black as a conductive agent, and polyvinylidene fluoride (PVdF) as a binder are mixed at a mixing ratio of 90% by mass: 5% by mass: 5% by mass with N-methyl as a solvent. Poured into pyrrolidone (NMP) and mixed. Next, the mixture thus obtained was dispersed using a rotation and revolution mixer to prepare a slurry.

Next, the prepared slurry was applied to both surfaces of a current collector made of an aluminum foil having a thickness of 15 μm. The coating amount per unit area was 91 g / m ² . Next, the coating film was dried and subjected to pressing. Thus, a positive electrode having an electrode density (not including the current collector) of 3.0 g / cm ³ was produced.

(Example 34)
In Example 34, the nonaqueous electrolyte battery of Example 34 was produced in the same procedure as in Example 1 except that the positive electrode was produced in the following procedure.

In Example 34, lithium nickel cobalt manganese composite oxide LiNi _0.5 Co _0.2 Mn _0.3 O ₂ was used as the positive electrode active material. This composite oxide, acetylene black as a conductive agent, and polyvinylidene fluoride (PVdF) as a binder are mixed at a mixing ratio of 90% by mass: 5% by mass: 5% by mass with N-methyl as a solvent. Poured into pyrrolidone (NMP) and mixed. Next, the mixture thus obtained was dispersed using a rotation and revolution mixer to prepare a slurry.

Next, the prepared slurry was applied to both surfaces of a current collector made of an aluminum foil having a thickness of 15 μm. The coating amount per unit area was 91 g / m ² . Next, the coating film was dried and subjected to pressing. Thus, a positive electrode having an electrode density (not including the current collector) of 3.0 g / cm ³ was produced.

(Example 35)
In Example 35, the nonaqueous electrolyte battery of Example 35 was produced in the same procedure as in Example 1 except that the positive electrode was produced in the following procedure.
In Example 35, lithium nickel cobalt manganese composite oxide LiNi _0.6 Co _0.2 Mn _0.2 O ₂ was used as the positive electrode active material. This composite oxide, acetylene black as a conductive agent, and polyvinylidene fluoride (PVdF) as a binder are mixed at a mixing ratio of 90% by mass: 5% by mass: 5% by mass with N-methyl as a solvent. Poured into pyrrolidone (NMP) and mixed. Next, the mixture thus obtained was dispersed using a rotation and revolution mixer to prepare a slurry.

Next, the prepared slurry was applied to both surfaces of a current collector made of an aluminum foil having a thickness of 15 μm. The coating amount per unit area was 91 g / m ² . Next, the coating film was dried and subjected to pressing. Thus, a positive electrode having an electrode density (not including the current collector) of 3.0 g / cm ³ was produced.

(Example 36)
In Example 36, the nonaqueous electrolyte battery of Example 36 was produced in the same procedure as in Example 1 except that the positive electrode was produced in the following procedure.

In Example 36, lithium nickel cobalt manganese composite oxide LiNi _0.8 Co _0.1 Mn _0.1 O ₂ was used as the positive electrode active material. This composite oxide, acetylene black as a conductive agent, and polyvinylidene fluoride (PVdF) as a binder are mixed at a mixing ratio of 90% by mass: 5% by mass: 5% by mass with N-methyl as a solvent. Poured into pyrrolidone (NMP) and mixed. Next, the mixture thus obtained was dispersed using a rotation and revolution mixer to prepare a slurry.

Next, the prepared slurry was applied to both surfaces of a current collector made of an aluminum foil having a thickness of 15 μm. The coating amount per unit area was 91 g / m ² . Next, the coating film was dried and subjected to pressing. Thus, a positive electrode having an electrode density (not including the current collector) of 3.0 g / cm ³ was produced.

(Example 37)
In Example 37, the nonaqueous electrolyte battery of Example 37 was produced in the same procedure as in Example 1 except that the positive electrode was produced in the following procedure.

In Example 37, a lithium phosphorous oxide LiMn _0.85 Fe _0.1 Mg _0.05 PO ₄ having an olivine structure was used as the positive electrode active material. This composite oxide, acetylene black as a conductive agent, and polyvinylidene fluoride (PVdF) as a binder are mixed at a mixing ratio of 90% by mass: 5% by mass: 5% by mass with N-methyl as a solvent. Poured into pyrrolidone (NMP) and mixed. Next, the mixture thus obtained was dispersed using a rotation and revolution mixer to prepare a slurry.

Next, the prepared slurry was applied to both surfaces of a current collector made of an aluminum foil having a thickness of 15 μm. The coating amount per unit area was 91 g / m ² . Next, the coating film was dried and subjected to pressing. Thus, a positive electrode having an electrode density (not including the current collector) of 2.0 g / cm ³ was produced.

(Example 38)
In Example 38, the nonaqueous electrolyte battery of Example 38 was produced in the same procedure as in Example 1 except that the positive electrode was produced in the following procedure.

In Example 38, a mixture of lithium nickel cobalt manganese composite oxide LiNi _0.33 Co _0.33 Mn _0.33 O ₂ and lithium cobalt oxide LiCoO ₂ was used as the positive electrode active material. 72% by mass: 18% by mass: 5% by mass of LiNi _0.33 Co _0.33 Mn _0.33 O ₂ powder, LiCoO ₂ powder, acetylene black as a conductive agent, and polyvinylidene fluoride (PVdF) as a binder. %: 5% by mass was added to N-methylpyrrolidone (NMP) as a solvent and mixed. Next, the mixture thus obtained was dispersed using a rotation and revolution mixer to prepare a slurry.

Next, the prepared slurry was applied to both surfaces of a current collector made of an aluminum foil having a thickness of 15 μm. The coating amount per unit area was 91 g / m ² . Next, the coating film was dried and subjected to pressing. Thus, a positive electrode having an electrode density (not including the current collector) of 3.0 g / cm ³ was produced.

(Example 39)
In Example 39, a nonaqueous electrolyte battery of Example 39 was produced in the same procedure as in Example 1 except that the positive electrode was produced in the following procedure.

In Example 39, a mixture of lithium nickel cobalt manganese composite oxide LiNi _0.33 Co _0.33 Mn _0.33 O ₂ and lithium cobalt oxide LiCoO ₂ was used as the positive electrode active material. LiNi _0.33 Co _0.33 Mn _0.33 O ₂ powder, LiCoO ₂ powder, acetylene black as a conductive agent, and polyvinylidene fluoride (PVdF) as a binder are 45% by mass: 45% by mass: 5% by mass. %: 5% by mass was added to N-methylpyrrolidone (NMP) as a solvent and mixed. Next, the mixture thus obtained was dispersed using a rotation and revolution mixer to prepare a slurry.

Next, the prepared slurry was applied to both surfaces of a current collector made of an aluminum foil having a thickness of 15 μm. The coating amount per unit area was 91 g / m ² . Next, the coating film was dried and subjected to pressing. Thus, a positive electrode having an electrode density (not including the current collector) of 3.0 g / cm ³ was produced.

(Example 40)
In Example 40, the nonaqueous electrolyte battery of Example 40 was produced in the same procedure as in Example 1 except that the positive electrode was produced in the following procedure.

In Example 40, as the positive electrode active material, a mixture of spinel type lithium manganese composite oxide LiAl _0.1 Mn _1.9 O ₄ and lithium nickel cobalt manganese composite oxide LiNi _0.33 Co _0.33 Mn _0.33 O ₂ was used. 72% by mass: 18% by mass of LiAl _0.1 Mn _1.9 O ₄ powder, LiNi _0.33 Co _0.33 Mn _0.33 O ₂ powder, acetylene black as a conductive agent, and polyvinylidene fluoride (PVdF) as a binder The mixture was introduced into N-methylpyrrolidone (NMP) as a solvent at a mixing ratio of%: 5% by mass: 5% by mass and mixed. Next, the mixture thus obtained was dispersed using a rotation and revolution mixer to prepare a slurry.

Next, the prepared slurry was applied to both surfaces of a current collector made of an aluminum foil having a thickness of 15 μm. The coating amount per unit area was 91 g / m ² . Next, the coating film was dried and subjected to pressing. Thus, a positive electrode having an electrode density (not including the current collector) of 2.8 g / cm ³ was produced.

(Example 41)
In Example 41, the nonaqueous electrolyte battery of Example 41 was produced in the same procedure as in Example 1 except that the positive electrode was produced in the following procedure.

In Example 41, as the positive electrode active material, a mixture of spinel type lithium manganese composite oxide LiAl _0.1 Mn _1.9 O ₄ and lithium nickel cobalt manganese composite oxide LiNi _0.33 Co _0.33 Mn _0.33 O ₂ was used. 45% by mass: 45% by mass of LiAl _0.1 Mn _1.9 O ₄ powder, LiNi _0.33 Co _0.33 Mn _0.33 O ₂ powder, acetylene black as a conductive agent, and polyvinylidene fluoride (PVdF) as a binder The mixture was introduced into N-methylpyrrolidone (NMP) as a solvent at a mixing ratio of%: 5% by mass: 5% by mass and mixed. Next, the mixture thus obtained was dispersed using a rotation and revolution mixer to prepare a slurry.

Next, the prepared slurry was applied to both surfaces of a current collector made of an aluminum foil having a thickness of 15 μm. The coating amount per unit area was 91 g / m ² . Next, the coating film was dried and subjected to pressing. Thus, a positive electrode having an electrode density (not including the current collector) of 2.8 g / cm ³ was produced.

(Example 42)
In Example 42, the nonaqueous electrolyte battery of Example 42 was produced in the same procedure as in Example 1 except that the positive electrode was produced in the following procedure.

In Example 42, a mixture of spinel type lithium manganese oxide LiAl _0.1 Mn _1.9 O ₄ and lithium cobaltate LiCoO ₂ was used as the positive electrode active material. 72% by mass: 18% by mass: 5% by mass of LiAl _0.1 Mn _1.9 O ₄ powder, LiCoO ₂ powder, acetylene black as a conductive agent, and polyvinylidene fluoride (PVdF) as a binder. The mixture was introduced into N-methylpyrrolidone (NMP) as a solvent at a mixing ratio of 5% by mass and mixed. Next, the mixture thus obtained was dispersed using a rotation and revolution mixer to prepare a slurry.

Next, the prepared slurry was applied to both surfaces of a current collector made of an aluminum foil having a thickness of 15 μm. The coating amount per unit area was 91 g / m ² . Next, the coating film was dried and subjected to pressing. Thus, a positive electrode having an electrode density (not including the current collector) of 2.8 g / cm ³ was produced.

(Example 43)
In Example 43, the nonaqueous electrolyte battery of Example 43 was produced in the same procedure as in Example 1 except that the positive electrode was produced in the following procedure.

In Example 43, as the positive electrode active material, a mixture of a lithium phosphorous oxide LiMn _0.85 Fe _0.1 Mg _0.05 PO ₄ having an olivine structure and a spinel type lithium manganese composite oxide LiAl _0.1 Mn _1.9 O ₄ was used. 45% by mass: 45% by mass of LiMn _0.85 Fe _0.1 Mg _0.05 PO ₄ powder, LiAl _0.1 Mn _1.9 O ₄ powder, acetylene black as a conductive agent, and polyvinylidene fluoride (PVdF) as a binder The mixture was introduced into N-methylpyrrolidone (NMP) as a solvent at a mixing ratio of%: 5% by mass: 5% by mass and mixed. Next, the mixture thus obtained was dispersed using a rotation and revolution mixer to prepare a slurry.

Next, the prepared slurry was applied to both surfaces of a current collector made of an aluminum foil having a thickness of 15 μm. The coating amount per unit area was 91 g / m ² . Next, the coating film was dried and subjected to pressing. Thus, a positive electrode having an electrode density (not including the current collector) of 2.3 g / cm ³ was produced.

(Example 44)
In Example 44, the nonaqueous electrolyte battery of Example 44 was produced in the same procedure as in Example 1 except that the positive electrode was produced in the following procedure.

In Example 44, a mixture of a lithium phosphorous oxide LiMn _0.85 Fe _0.1 Mg _0.05 PO ₄ having an olivine structure and a spinel type lithium manganese composite oxide LiAl _0.1 Mn _1.9 O ₄ was used as the positive electrode active material. 72% by mass: 18% by mass of LiMn _0.85 Fe _0.1 Mg _0.05 PO ₄ powder, LiAl _0.1 Mn _1.9 O ₄ powder, acetylene black as a conductive agent, and polyvinylidene fluoride (PVdF) as a binder The mixture was introduced into N-methylpyrrolidone (NMP) as a solvent at a mixing ratio of%: 5% by mass: 5% by mass and mixed. Next, the mixture thus obtained was dispersed using a rotation and revolution mixer to prepare a slurry.

Next, the prepared slurry was applied to both surfaces of a current collector made of an aluminum foil having a thickness of 15 μm. The coating amount per unit area was 91 g / m ² . Next, the coating film was dried and subjected to pressing. Thus, a positive electrode having an electrode density (not including the current collector) of 2.2 g / cm ³ was produced.

(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 for the following points. In Comparative Example 1, when the slurry was dispersed using a rotation and revolution mixer in the production of the negative electrode, a glass bead having a diameter of 2 mm was placed in a container at 33% of the slurry volume to prepare a slurry. The electrode density (not including the current collector) was 2.7 g / cm ³ .

(Comparative Example 2)
In Comparative Example 2, a nonaqueous electrolyte battery of Comparative Example 2 was produced in the same procedure as in Example 1 except for the following points. In Comparative Example 2, as the negative electrode active material, a powder of Li ₂ Na _1.7 Ti _5.7 Nb _0.3 O _{14 having} an average primary particle diameter of 1 μm, similar to that used in Example 2, was used. Furthermore, when the negative electrode was pressed, the gap between the upper and lower rolls of the roll press apparatus was adjusted so that the electrode density of the negative electrode (not including the current collector) was 2.3 g / cm ³ .

(Comparative Example 3)
In Comparative Example 3, a nonaqueous electrolyte battery of Comparative Example 3 was produced in the same procedure as in Example 1 except for the following points. In Comparative Example 3, a powder of Li ₂ Na _1.7 Ti _5.7 Nb _0.3 O _{14 having} an average primary particle diameter of 3 μm, similar to that used in Example 1, was used as the negative electrode active material. Furthermore, when the negative electrode was pressed, the gap between the upper and lower rolls of the roll press apparatus was adjusted so that the electrode density of the negative electrode (not including the current collector) was 2.3 g / cm ³ .

(Comparative Example 4)
In Comparative Example 4, the same procedure as in Example 1 was used except that a powder of lithium titanate Li ₄ Ti ₅ O ₁₂ having a spinel crystal structure was used as the negative electrode active material when the negative electrode was produced. 4 non-aqueous electrolyte batteries were produced. The average primary particle diameter of Li ₄ Ti ₅ O ₁₂ was 3 μm. When pressing the negative electrode, the gap between the upper and lower rolls of the roll press apparatus was adjusted so that the electrode density of the negative electrode (not including the current collector) was 2.0 g / cm ³ .

(Comparative Example 5)
In Comparative Example 5, the same procedure as in Example 1 was used except that a powder of lithium titanate Li ₄ Ti ₅ O ₁₂ having a spinel type crystal structure was used as the negative electrode active material during the production of the negative electrode. 5 non-aqueous electrolyte batteries were produced. The average primary particle diameter of Li ₄ Ti ₅ O ₁₂ was 3 μm. Furthermore, when the negative electrode was pressed, the gap between the upper and lower rolls of the roll press apparatus was adjusted so that the electrode density of the negative electrode (not including the current collector) was 2.3 g / cm ³ .

(Comparative Example 6)
In Comparative Example 6, the nonaqueous electrolyte battery of Comparative Example 6 was manufactured in the same procedure as in Example 1 except that the powder of the composite oxide Li ₂ MgTi ₆ O ₁₄ was used as the negative electrode active material when the negative electrode was produced. Produced. The average primary particle diameter of Li ₂ MgTi ₆ O ₁₄ was 3 μm. The electrode density of the negative electrode (not including the current collector) was 2.5 g / cm ³ as in Example 1.

(Comparative Example 7)
In Comparative Example 7, the nonaqueous electrolyte battery of Comparative Example 7 was prepared in the same procedure as in Example 1 except that the powder of the composite oxide Li ₂ CaTi ₆ O ₁₄ was used as the negative electrode active material when the negative electrode was produced. Produced. The average primary particle diameter of Li ₂ CaTi ₆ O ₁₄ was 3 μm. The electrode density of the negative electrode (not including the current collector) was 2.5 g / cm ³ as in Example 1.

[Evaluation]
The nonaqueous electrolyte batteries of Examples 1 to 44 and Comparative Examples 1 to 7 were evaluated by the following procedure.

[Pulse resistance test]
Each battery produced as described above was adjusted to a 50% state of charge (SOC) by the following procedure.

  First, the battery was subjected to constant current discharge in a 25 ° C. environment at a current of 0.2 C until the battery voltage reached 1.5V. As a result, the SOC of the battery was set to 0%.

  Subsequently, the battery was subjected to constant current charging to 50% of the battery capacity at a current of 0.2C. Thus, the SOC of each battery was adjusted to 50%. After the adjustment, each battery was left in an open circuit state for 1 hour or longer.

  Subsequently, each battery was subjected to an output pulse test according to the following procedure.

First, the battery was discharged at a constant current of 0.2 C for 10 seconds. The resistance value R _{0.2C (output)} at this time was measured. Thereafter, each battery was adjusted to 50% SOC in the same procedure as described above, and kept in an open circuit state for 1 hour. Subsequently, the battery was discharged at a constant current of 5 C for 10 seconds. The resistance value R _{5C (output)} at this time was measured. The ratio R _{5C (output)} / R _{0.2C (output)} was calculated.

Tables 1 and 2 show the ratio R _{5C (output)} / R _{0.2C (output)} for the nonaqueous electrolyte batteries of Examples 1 to 44 and Comparative Examples 1 to 7.

[Measurement of pore diameter distribution of negative electrode active material-containing layer]
The pore diameter distribution of the negative electrode active material-containing layer of the negative electrode included in each battery was measured by the procedure described above. Tables 3 and 4 below show the porosity and the position of the strongest peak in the negative electrode active material-containing layers of the negative electrodes of Examples 1 to 44 and Comparative Examples 1 to 7 obtained as a result of the measurement. The pore diameter distribution shown in FIG. 1 is the pore diameter distribution of the negative electrode active material-containing layer of the negative electrode of Example 1.

[Discussion]
By comparing the results of Examples 1 to 6 and Comparative Examples 1 to 3 shown in Tables 1 to 4, the porosity obtained by the mercury intrusion method for the negative electrode active material-containing layer is 10% or more and 26% or less. It can be seen that the negative electrode having the strongest peak in the region where the pore diameter is smaller than 200 nm in the pore diameter distribution can realize a non-aqueous electrolyte battery capable of exhibiting low resistance at high SOC. This is presumably because good electronic conductivity in the negative electrode active material-containing layer containing the orthorhombic Na-containing niobium titanium composite oxide is compatible with the impregnation property of the electrolytic solution.

  Further, from the results of Examples 7 to 12, the porosity obtained by the mercury intrusion method for the electrode active material-containing layer even when a vapor-grown carbon fiber or graphite having a large aspect ratio is used as the conductive agent contained in the negative electrode 10% or more and 26% or less, and the electrode having the strongest peak in the region where the pore diameter is smaller than 200 nm in the pore diameter distribution realizes a non-aqueous electrolyte battery capable of exhibiting low resistance at high SOC. You can see that you can. Furthermore, it can be seen that, among the conductive agents, the vapor-grown carbon fiber can easily form a good electronic conductive path in the negative electrode active material-containing layer, so that the resistance can be reduced.

  From the comparison of the results of Example 1 and Examples 13 to 31, even when M1 and / or M2 in the orthorhombic Na-containing niobium titanium composite oxide is changed, a low resistance value can be exhibited with a high SOC. It can be seen that a water electrolyte battery could be realized.

  Example 1 and Examples 32-44 are nonaqueous electrolyte batteries with different positive electrode active materials. From the results of these Examples, it can be seen that the effect of reducing the resistance is high in the non-aqueous electrolyte battery containing a large amount of spinel type lithium manganese composite oxide and lithium cobaltate among the positive electrode active materials.

In Comparative Examples 4 and 5, Li ₄ Ti ₅ O ₁₂ was used as the negative electrode active material. From the results of Comparative Examples 4 and 5, it can be seen that when Li ₄ Ti ₅ O ₁₂ was used as the negative electrode active material, the resistance did not change even when the strongest peak of the pore diameter distribution was smaller than 200 nm. This is probably because when Li ₄ Ti ₅ O ₁₂ is charged, the electron conductivity is remarkably improved, and the influence of the electron conductivity in the active material-containing layer due to the difference in the contact property between the particles is small. Further, it is presumed that there was no difference enough to change the resistance value in the impregnation with the electrolytic solution. In addition, as a result of the battery evaluation test, the nonaqueous electrolyte batteries of Examples 1 to 44 were easier to grasp the state of charge due to voltage change than Comparative Examples 4 and 5. Moreover, the nonaqueous electrolyte battery of Example 1 had a battery voltage higher than that of Comparative Examples 4 and 5.

The nonaqueous electrolyte batteries of Comparative Examples 6 and 7 using the composite oxide Li ₂ MgTi ₆ O ₁₄ and the composite oxide Li ₂ CaTi ₆ O ₁₄ as the negative electrode active material were obtained by the mercury intrusion method for the negative electrode active material-containing layer. The obtained porosity was 10% or more and 26% or less, and the strongest peak was present in a region where the pore diameter was smaller than 200 nm in the pore diameter distribution, but the resistance at high SOC was high. This is presumed to be because the diffusion resistance of lithium in the solid of the composite oxide Li ₂ MgTi ₆ O ₁₄ and the composite oxide Li ₂ CaTi ₆ O ₁₄ was large, and the influence of the electronic conductivity of the negative electrode active material-containing layer was small. Is done.

  According to one or more embodiments and examples described above, an electrode is provided. This electrode includes a current collector and an electrode active material-containing layer formed on the current collector. The electrode active material-containing layer includes orthorhombic Na-containing niobium titanium composite oxide particles. The electrode active material-containing layer has a porosity of 10% or more and 26% or less obtained by a mercury intrusion method. In the pore diameter distribution obtained by the mercury intrusion method for the electrode active material-containing layer, the strongest peak exists in a region where the pore diameter is smaller than 200 nm. In this electrode active material-containing layer, the orthorhombic Na-containing niobium titanium composite oxide particles can sufficiently form a conductive path, and can exhibit excellent impregnation properties of the nonaqueous electrolyte. Therefore, this electrode can provide a nonaqueous electrolyte battery that can exhibit excellent input / output characteristics.

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

  DESCRIPTION OF SYMBOLS 1 ... Nonaqueous electrolyte battery, 2 ... Exterior member, 3 ... Electrode group, 4 ... Positive electrode, 4a ... Positive electrode collector, 4b ... Positive electrode active material content layer, 5 ... Electrode (negative electrode), 5a ... Current collector (negative electrode) Current collector), 5b ... electrode active material-containing layer (negative electrode active material-containing layer), 6 ... separator, 7 ... positive electrode terminal, 8 ... negative electrode terminal, 10 ... nonaqueous electrolyte battery, 11 ... laminated electrode group, 12 ... Exterior member, 13 ... positive electrode, 13a ... current collector, 13b ... positive electrode active material containing layer, 14 ... negative electrode, 14a ... current collector, 14b ... negative electrode active material containing layer, 15 ... separator, 16 ... negative electrode terminal, 17 ... Positive terminal, 20 ... Battery pack, 21 ... Single cell, 22 ... Adhesive tape, 23 ... Assembly battery, 24 ... Printed circuit board, 25 ... Thermistor, 26 ... Protection circuit, 27 ... Terminal for energizing external terminals, 37 ... Storage container, 40 ... lead.

Claims (8)

A current collector,
An electrode active material-containing layer formed on the current collector,
The electrode active material-containing layer may include particles of the general formula _{Li 2 + v Na 2-y} M1 x Ti 6-yz Nb y M2 z O 14 + δ with orthorhombic Akiragata Na-containing niobium titanium composite oxide represented ,
In the above general formula, M1 is at least one selected from the group consisting of Cs, K, Sr, Ba and Ca, and M2 is Zr, Sn, V, Ta, Mo, W, Fe, Co, Mn. And at least one selected from the group consisting of Al, 0 ≦ v ≦ 4, 0 ≦ x <2, 0 <y <2, 0 ≦ z <3, −0.5 ≦ δ ≦ 0.5 Yes,
The electrode active material-containing layer has a porosity of 10% to 26% obtained by a mercury intrusion method,
In the pore diameter distribution obtained by the mercury intrusion method for the electrode active material-containing layer, the electrode has a strongest peak in a region where the pore diameter is smaller than 200 nm.   The electrode according to claim 1, wherein the electrode active material-containing layer further includes carbon material particles having an aspect ratio of 15 or more.   The electrode according to claim 1 or 2, wherein the particles of the orthorhombic Na-containing niobium titanium composite oxide are in the form of primary particles and / or secondary particles.   3. The electrode according to claim 1, wherein the particles of the orthorhombic Na-containing niobium titanium composite oxide have an average secondary particle diameter in a range of 5 to 20 μm. The electrode according to any one of claims 1 to 4 as a negative electrode;
A positive electrode;
A non-aqueous electrolyte battery comprising: a non-aqueous electrolyte.   The non-aqueous electrolyte battery according to claim 5, wherein the positive electrode includes a spinel type lithium manganese composite oxide.   A battery pack comprising the nonaqueous electrolyte battery according to claim 5. Comprising a plurality of the non-aqueous electrolyte batteries,
The battery pack according to claim 7, wherein the nonaqueous electrolyte batteries are electrically connected in series, parallel, or a combination of series and parallel.

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