Electrodes, secondary batteries, battery packs, and vehicles

Abstract

To provide an electrode having excellent cycle performance and output performance, a secondary battery including the electrode, a battery pack including the secondary battery, and a vehicle including the battery pack.SOLUTION: An electrode includes inorganic particles 13, niobium titanium oxide particles 11, and an inorganic particle-containing layer 12 that covers at least a part of the surface of the niobium titanium oxide particles. The average particle size of the inorganic particles 13 is larger than the thickness of the inorganic particle-containing layer 12.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] Embodiments of the present invention relate to electrodes, secondary batteries, battery packs, and vehicles. [Background technology]

[0002] Non-aqueous electrolyte batteries, such as lithium-ion secondary batteries, face the challenge of decreasing electrode discharge capacity with each charge-discharge cycle. [Prior art documents] [Patent Documents]

[0003] [Patent Document 1] Japanese Patent Publication No. 2015-11929 [Patent Document 2] Japanese Patent Publication No. 2012-209064 [Patent Document 3] Japanese Patent Publication No. 2021-44221 [Overview of the project] [Problems that the invention aims to solve]

[0004] The embodiment aims to provide an electrode with excellent cycle performance and output performance, a secondary battery including the electrode, a battery pack including the secondary battery, and a vehicle including the battery pack. [Means for solving the problem]

[0005] According to the embodiment, an electrode is provided. The electrode includes inorganic particles, niobium titanium oxide particles, and an inorganic particle-containing layer covering at least a portion of the surface of the niobium titanium oxide particles. The average particle diameter of the inorganic particles is greater than the thickness of the inorganic particle-containing layer. The inorganic particles include at least one selected from the group consisting of metal oxides containing at least one element selected from the group consisting of Al, Ti, Si, Zr, and Mg, and solid electrolytes.

[0006] According to other embodiments, a secondary battery including the electrodes of the embodiment is provided.

[0007] According to another embodiment, a battery pack including a secondary battery of the embodiment is provided.

[0008] According to other embodiments, a vehicle including the battery pack of the embodiment is provided. [Brief explanation of the drawing]

[0009] [Figure 1] A schematic cross-sectional view showing an example of an electrode according to the embodiment. [Figure 2] An enlarged view showing the vicinity of the active material particles in an example of an electrode according to the embodiment. [Figure 3] A schematic cross-sectional view showing an example of an electrode related to a reference example. [Figure 4] A schematic diagram showing the HAADF-STEM image of the first particle. [Figure 5] A schematic cross-sectional view showing an example of a secondary battery according to this embodiment. [Figure 6] Figure 5 shows an enlarged cross-sectional view of section A of the secondary battery. [Figure 7] A schematic partial cutaway perspective view showing another example of a secondary battery according to the embodiment. [Figure 8] Figure 7 shows an enlarged cross-sectional view of section B of the secondary battery. [Figure 9] A schematic perspective view showing an example of a battery pack according to this embodiment. [Figure 10] An exploded perspective view schematically showing an example of a battery pack according to this embodiment. [Figure 11] A block diagram showing an example of the electrical circuit of the battery pack shown in Figure 10. [Figure 12] A partially transparent view schematically showing an example of a vehicle according to the embodiment. [Figure 13] A schematic diagram showing an example of a control system for the electrical system in a vehicle according to this embodiment. [Modes for carrying out the invention]

[0010] The embodiments will be described below with reference to the drawings as appropriate. Common components throughout the embodiments will be denoted by the same reference numerals, and redundant explanations will be omitted. Furthermore, each figure is a schematic diagram intended to illustrate the embodiments and facilitate understanding; their shapes, dimensions, ratios, etc., may differ from those of the actual device. These can be appropriately modified in accordance with the following description and known technology.

[0011] (First embodiment) One of the factors that reduces the cycle performance and output performance of electrodes is the degradation of niobium titanium oxide in the electrodes. This degradation can occur, for example, when hydrofluoric acid produced by a side reaction comes into contact with the niobium titanium oxide.

[0012] As a result of diligent research, the inventors have found that inorganic particles can trap hydrofluoric acid. However, simply incorporating inorganic particles into the electrode is insufficient; if hydrofluoric acid approaches the niobium titanium oxide without being trapped by the inorganic particles, the degradation of the niobium titanium oxide cannot be avoided.

[0013] Based on these results, the inventors conducted further research and realized the electrode according to the first embodiment.

[0014] According to the first embodiment, an electrode is provided. The electrode according to the first embodiment includes inorganic particles, niobium titanium oxide particles, and an inorganic particle-containing layer covering at least a portion of the surface of the niobium titanium oxide particles. The average particle diameter of the inorganic particles is greater than the thickness of the inorganic particle-containing layer.

[0015] Both the inorganic particles and the inorganic particle-containing layer can trap hydrofluoric acid.

[0016] Therefore, the inorganic particles can suppress the approach of hydrofluoric acid to the niobium titanium oxide particles. Furthermore, even if hydrofluoric acid approaches the niobium titanium oxide particles without being captured by the inorganic particles, the inorganic particle-containing layer can capture the hydrofluoric acid. Thus, with this electrode, contact between hydrofluoric acid and niobium titanium oxide particles can be suppressed, resulting in the suppression of niobium titanium oxide degradation. Consequently, this contributes to improvements in cycle performance and output performance.

[0017] Furthermore, in this electrode, the average particle size of the inorganic particles is greater than the thickness of the inorganic particle-containing layer. Therefore, the average particle size of the inorganic particles does not become too small, making it difficult for the inorganic particles to aggregate during the electrode manufacturing process. As a result, the inorganic particles can be uniformly distributed within the electrode, allowing for efficient capture of hydrofluoric acid. Consequently, the degradation of niobium titanium oxide can be suppressed. Therefore, this contributes to improvements in cycle performance and output performance.

[0018] Furthermore, the thickness of the inorganic particle-containing layer is smaller than the average particle diameter of the inorganic particles. Therefore, the decrease in ion conductivity caused by an excessively thick inorganic particle-containing layer can be suppressed. As a result, output performance can be improved.

[0019] While a thicker inorganic particle-containing layer tends to increase hydrofluoric acid capture capacity, it can also lead to lower electronic conductivity of the active material particles compared to a thinner inorganic particle-containing layer.

[0020] On the other hand, the larger the average particle size of inorganic particles, the more effectively the inorganic particles can be suppressed from aggregating with each other, thus allowing the inorganic particles to be more uniformly dispersed in the electrode. Furthermore, the electrode may contain a conductive agent. By suppressing the aggregation of inorganic particles, the conductive agent is less likely to adsorb onto the inorganic particles, improving the dispersibility of the conductive agent. This contributes to improved output performance. Therefore, even when the thickness of the inorganic particle-containing layer is high, combining it with inorganic particles that have a large average particle size can maintain high output performance as an electrode.

[0021] In this electrode, the average particle size of the inorganic particles is greater than the thickness of the inorganic particle-containing layer. Therefore, the high dispersibility of the inorganic particles and conductive agent significantly improves output performance, mitigating the decrease in electronic conductivity associated with increasing the thickness of the inorganic particle-containing layer. Thus, high output performance can be maintained.

[0022] Furthermore, if the thickness of the inorganic particle-containing layer is thin, the electronic conductivity of the active material particles can be maintained at a high level. Therefore, as long as the thickness is greater than that of the inorganic particle-containing layer, even when combined with inorganic particles having a relatively small average particle diameter, the effect of improving electronic conductivity due to the thin inorganic particle-containing layer can be greatly increased, offsetting the decrease in output performance caused by the small average particle diameter of the inorganic particles. Thus, the output performance as an electrode can be maintained at a high level.

[0023] The electrodes according to the embodiment will be described in detail below with reference to the drawings.

[0024] Such electrodes may, for example, be used in non-aqueous electrolyte batteries. Non-aqueous electrolyte batteries may, for example, be non-aqueous electrolyte batteries that use alkali metal ions as carrier ions. For example, they may be lithium batteries (lithium-ion batteries). Such electrodes may, for example, be used in secondary batteries.

[0025] In the manufacturing process of non-aqueous electrolyte batteries, water is an unavoidable impurity that is prone to contamination. When a non-aqueous electrolyte containing fluorine atoms is used as the non-aqueous electrolyte in combination with the electrodes, a side reaction occurs between water and the non-aqueous electrolyte, and hydrofluoric acid (hydrogen fluoride, HF) may be produced as a decomposition product of the non-aqueous electrolyte. Details of non-aqueous electrolytes will be described later.

[0026] Hydrofluoric acid, when in contact with materials contained in electrodes, can dissolve, for example, transition metals. The dissolved transition metals can, for example, deposit on the electrodes. In addition, when electrodes are combined with an electrolyte, hydrofluoric acid can react with the electrolyte to form lithium fluoride. Lithium fluoride can, for example, deposit on the electrodes. These substances deposited on the electrodes can be a factor in increasing resistance.

[0027] The electrode in question includes inorganic particles and an inorganic particle-containing layer. Therefore, the elution of transition metals and the formation of lithium fluoride can be suppressed. Consequently, the output performance of the electrode can be improved.

[0028] Figure 1 is a schematic cross-sectional view showing an example of an electrode. Figure 2 is a magnified view showing the vicinity of the active material particles in an example of an electrode. For convenience, the depiction of conductive agents and binders that may be contained in the active material-containing layer is omitted in Figures 1 and 2.

[0029] The electrode 3 includes a current collector 3a and an active material-containing layer 3b formed on the current collector 3a. The active material-containing layer 3b includes first particles 10 and inorganic particles 13. The first particles 10 include niobium titanium oxide particles 11 and an inorganic particle-containing layer 12 that covers at least a portion of the surface of the niobium titanium oxide particles 11.

[0030] As shown in Figure 2, the first particle 10 may include an exposed portion 14. The exposed portion 14 is the part of the surface of the niobium titanium oxide particle 11 that is not covered by the inorganic particle-containing layer 12. In other words, the exposed portion 14 is the part of the surface of the first particle 10 in which the surface of the niobium titanium oxide particle 11 is exposed. Although the first particle 10 shown in Figure 2 includes an exposed portion 14, the first particle 10 does not have to include an exposed portion. That is, the entire surface of the niobium titanium oxide particle 11 may be covered by the inorganic particle-containing layer 12.

[0031] It is preferable for the first particle 10 to include an exposed portion 14, as this allows for high ion conductivity and improved output performance.

[0032] If the first particle 10 includes an exposed portion 14, at least a portion of the surface of the niobium titanium oxide particle 11 may be exposed on the surface of the electrode 3. The surface of the electrode 3 may be the main surface of the active material-containing layer 3b that is not in contact with the current collector 3a.

[0033] The electrodes in the example will be explained with reference to Figure 3.

[0034] Figure 3 is a schematic cross-sectional view showing an example of an electrode according to a reference example. For convenience, Figure 3 omits the depiction of conductive agents and binders that may be contained in the active material-containing layer. The electrode 30 according to the reference example includes a current collector 3a and an active material-containing layer 30b formed on the current collector 3a. The active material-containing layer 30b includes niobium titanium oxide particles 11 and inorganic particles 13.

[0035] As shown in Figure 3, in the electrode 30 according to the reference example, there is no inorganic particle-containing layer on the surface of the niobium titanium oxide particles 11. Therefore, the entire surface of the niobium titanium oxide particles 11 is exposed. Consequently, if hydrofluoric acid that is not captured by the inorganic particles 13 approaches the niobium titanium oxide particles 11, the hydrofluoric acid can come into contact with the surface of the niobium titanium oxide particles 11. As a result, the niobium titanium oxide particles may deteriorate.

[0036] The electrodes according to the embodiment will be described in more detail below.

[0037] The electrode according to the embodiment may include a current collector and an active material-containing layer. The active material-containing layer may be formed on one or both sides of the current collector. The active material-containing layer includes first particles and inorganic particles. The first particles include niobium titanium oxide particles and an inorganic particle-containing layer that covers at least a portion of the surface of the niobium titanium oxide particles.

[0038] Niobium titanium oxide can function as an active material. The first particle contains niobium titanium oxide particles and can therefore be an active material particle. The active material-containing layer may contain the first particle alone as the active material, or it may contain a mixture of the first particle and one or more other active materials.

[0039] The active material-containing layer may include an active material containing first particles, inorganic particles, and optionally a conductive agent and a binder.

[0040] The average particle diameter of the first particles including niobium titanate oxide particles and an inorganic particle-containing layer is preferably in the range of 0.5 μm or more and 2.0 μm or less. When the average particle diameter of the first particles is 0.5 μm or more, the surface energy of the first particles can be lowered. For example, aggregation during the dispersion step in slurry preparation can be suppressed. When the average particle diameter of the first particles is 2.0 μm or less, the Li + solid-state diffusivity can be increased. Therefore, the Li + solid-state diffusivity of the active material can be increased.

[0041] Examples of the niobium titanate oxide contained in the niobium titanate oxide particles include monoclinic niobium titanate oxide.

[0042] Examples of the monoclinic niobium titanate oxide include compounds represented by Li x Ti 1-y M1 y Nb 2-z M2 z O 7+δ Here, M1 is at least one selected from the group consisting of Zr, Si, and Sn. M2 is at least one selected from the group consisting of V, Ta, and Bi. Each subscript in the composition formula satisfies 0 ≦ x ≦ 5, 0 ≦ y < 1, 0 ≦ z < 2, and -0.3 ≦ δ ≦ 0.3. Specific examples of the monoclinic niobium titanate oxide include Li x Nb2TiO7 (0 ≦ x ≦ 5).

[0043] Other examples of the monoclinic niobium titanate oxide include compounds represented by Li x Ti 1-y M3 y+z Nb 2-z O 7-δ Here, M3 is at least one selected from Mg, Fe, Ni, Co, W, Ta, and Mo. Each subscript in the composition formula satisfies 0 ≦ x ≦ 5, 0 ≦ y < 1, 0 ≦ z < 2, and -0.3 ≦ δ ≦ 0.3.

[0044] The form of the inorganic particle-containing layer is not particularly limited, but for example, it may be a form in which particles containing an inorganic material aggregate on the surface of niobium titanium oxide particles, covering at least a portion of the surface of the niobium titanium oxide particles. The particles containing the inorganic material may be primary particles, or they may be in the form of secondary particles formed by the aggregation of primary particles.

[0045] The inorganic particle-containing layer may cover a portion of the surface of the niobium titanium oxide particles, or it may cover the entire surface of the niobium titanium oxide particles. If the inorganic particle-containing layer does not cover the entire surface of the niobium titanium oxide particles, the surface of the niobium titanium oxide particles may include portions that are not covered by the inorganic particle-containing layer. If the surface of the niobium titanium oxide includes portions that are not covered by the inorganic particle-containing layer, at least a portion of these uncovered portions may be exposed on the electrode surface.

[0046] The thickness of the inorganic particle-containing layer can be in the range of 0.0005 μm to 0.7 μm. Preferably, the thickness of the inorganic particle-containing layer is in the range of 0.001 μm to 0.4 μm. When the thickness of the inorganic particle-containing layer is 0.001 μm or more, the durability against hydrofluoric acid can be increased. Specifically, the amount of hydrofluoric acid that the inorganic particle-containing layer can capture increases, so it is possible to suppress contact between hydrofluoric acid exceeding the amount that the inorganic particle-containing layer can capture and the niobium titanium oxide particles. When the thickness of the inorganic particle-containing layer is 0.4 μm or less, the increase in resistance can be suppressed. The lower limit of the thickness of the inorganic particle-containing layer can be, for example, 0.0010 μm.

[0047] The thickness of the inorganic particle-containing layer is more preferably within the range of 0.01 μm to 0.35 μm. Even more preferably, the thickness of the inorganic particle-containing layer is within the range of 0.05 μm to 0.3 μm.

[0048] The mass of the inorganic particle-containing layer is preferably within the range of 1% to 20% by mass relative to the mass of the niobium titanium oxide particles. If it is 1% or more by mass, contact between hydrogen fluoride and the niobium titanium oxide particles can be suppressed. If it is 20% or less by mass, an increase in interfacial resistance can be suppressed.

[0049] The particles containing inorganic materials preferably include at least one selected from the group consisting of particles containing a metal oxide containing at least one element selected from the group consisting of Al, Ti, Si, Zr, and Mg, and particles containing a solid electrolyte.

[0050] The inorganic particle-containing layer may contain particles containing metal oxides alone, particles containing solid electrolytes alone, or both particles containing metal oxides and particles containing solid electrolytes. The types of particles containing metal oxides can be one or more. The types of particles containing solid electrolytes can be one or more.

[0051] Particles containing metal oxides may further contain solid electrolytes. Solid electrolyte-containing particles may further contain metal oxides.

[0052] Examples of metal oxides include Al2O3, TiO2, SiO2, ZrO2, and MgO. The number of metal oxides can be one or more.

[0053] Solid electrolytes are solid materials that have lithium ion conductivity. Here, lithium ion conductivity means 1 × 10⁻⁶ at 25°C. -6 This refers to exhibiting a lithium ion conductivity of S / cm or higher. Examples of solid electrolytes include oxide-based solid electrolytes or sulfide-based solid electrolytes. Specific examples of solid electrolytes are as follows.

[0054] As the oxide-based solid electrolyte, a lithium phosphate solid electrolyte having a NASICON (Sodium (Na) Super Ionic Conductor) type structure can be used. For example, the general formula is Li 1+x It is preferable to use a lithium phosphate solid electrolyte represented by Mα2(PO4)3. Mα in the above general formula is, for example, one or more selected from the group consisting of titanium (Ti), germanium (Ge), strontium (Sr), zirconium (Zr), tin (Sn), aluminum (Al), and calcium (Ca). The subscript x is within the range of 0≦x≦2.

[0055] As another example of the lithium phosphate solid electrolyte having a NASICON type structure, Li 1+x Al x Ti 2-x (PO4)3, an LATP compound where 0.1≦x≦0.5; Li 1+x Al y Mβ 2-y (PO4)3, a compound where Mβ is one or more selected from the group consisting of Ti, Ge, Sr, Zr, Sn, and Ca and 0≦x≦1 and 0≦y≦1; Li 1+x Al x Ge 2-x (PO4)3, a compound where 0≦x≦2; and, Li 1+x Al x Zr 2-x (PO4)3, a compound where 0≦x≦2; Li 1+x+y Al x Mγ 2-x Si y P 3-y O 12 A compound represented by Mγ is one or more selected from the group consisting of Ti and Ge and 0<x≦2, 0≦y<3; Li 1+2x Zr 1-x Ca x (PO4)3, a compound where 0≦x<1 can be mentioned.

[0056] In addition, as an example of the oxide-based solid electrolyte, in addition to the above lithium phosphate solid electrolyte, Li x PO y [[ID=z Amorphous lipon compounds (e.g., Li) are represented as such that 2.6≦x≦3.5, 1.9≦y≦3.8, and 0.1≦z≦1.3. 2.9 PO 3.3 N 0.46 ); Garnet-type structure La 5+x A x La 3-x Mδ2O 12 A compound represented as follows: A is one or more selected from the group consisting of Ca, Sr, and Ba, and Mδ is one or more selected from the group consisting of Nb and Ta, and 0 ≤ x ≤ 0.5; Li3Mδ 2-x L2O 12 A compound represented by where Mδ is 1 or more selected from the group consisting of Nb and Ta, and L may contain Zr, with 0 ≤ x ≤ 0.5; Li 7-3x Al x La3Zr3O 12 Compounds represented by 0 ≤ x ≤ 0.5; Li 5+x La3MCSR 2-x Zr x O 12 Represented as such, Mδ is 1 or more selected from the group consisting of Nb and Ta, and 0 ≤ x ≤ 2, and is an LLZ compound (e.g., Li7La3Zr2O 12 ); and having a perovskite-type structure La 2 / 3-x Li x Examples include compounds represented as TiO3 where 0.3 ≤ x ≤ 0.7.

[0057] One or more of the above compounds can be used as a solid electrolyte. Two or more of the above solid electrolytes may also be used.

[0058] The inorganic particle-containing layer preferably contains solid electrolyte-containing particles. An inorganic particle-containing layer containing solid electrolyte-containing particles can have high ionic conductivity. Therefore, output performance can be increased.

[0059] If the electrode according to the embodiment includes, for example, the first particle as the negative electrode active material, other examples of active materials include lithium titanate having a ramsdellite structure (e.g., Li 2+yLi3O7 (0≦y≦3), lithium titanate having a spinel structure (e.g., Li 4+x Ti5O 12 Examples include titanium dioxide (TiO2), anatase-type titanium dioxide, rutile-type titanium dioxide, niobium pentoxide (Nb2O5), hollandite-type titanium composite oxide, orthorhombic titanium composite oxide, and monoclinic niobium titanium oxide. For example, the same monoclinic niobium titanium oxide described above can be used.

[0060] As an example of the above orthorhombic titanium-containing composite oxide, Li 2+a M I 2-b Ti 6-c M II d O 14+σ Examples of compounds represented by are given. Here, M I It is at least one selected from the group consisting of Sr, Ba, Ca, Mg, Na, Cs, Rb, and K. II is at least one selected from the group consisting of Zr, Sn, V, Nb, Ta, Mo, W, Y, Fe, Co, Cr, Mn, Ni, and Al. In the composition formula, each subscript has the following properties: 0≦a≦6, 0≦b<2, 0≦c<6, 0≦d<6, -0.5≦σ≦0.5. As a specific example of an orthorhombic titanium-containing composite oxide, Li 2+a Na2Li6O 14 (0 ≤ a ≤ 6) is one example.

[0061] The average particle diameter of inorganic particles can be within the range of 0.3 μm to 2.0 μm. Preferably, the average particle diameter of inorganic particles is within the range of 0.4 μm to 1.0 μm. When the average particle diameter of inorganic particles is 0.4 μm or more, the amount of hydrofluoric acid that can be captured per inorganic particle can be increased. Furthermore, aggregation of inorganic particles can be suppressed during the electrode manufacturing process, allowing the inorganic particles to be uniformly dispersed in the electrode. When the average particle diameter of inorganic particles is 1.0 μm or less, the number of inorganic particles per unit mass can be increased. In addition, inorganic particles can be uniformly distributed even in the fine gaps in the electrode. Therefore, inorganic particles with an average particle diameter within the range of 0.4 μm to 1.0 μm can efficiently capture hydrofluoric acid.

[0062] It is more preferable that the average particle diameter of the inorganic particles is within the range of 0.4 μm to 0.9 μm. It is even more preferable that the average particle diameter of the inorganic particles is within the range of 0.4 μm to 0.8 μm.

[0063] The inorganic particles may be primary particles, secondary particles formed by aggregation of primary particles, or a mixture of primary and secondary particles.

[0064] The inorganic particles preferably contain at least one element selected from the group consisting of a metal oxide containing at least one element selected from the group consisting of Al, Ti, Si, Zr, and Mg, and a solid electrolyte. The inorganic particles may contain only a metal oxide, only a solid electrolyte, or both a metal oxide and a solid electrolyte.

[0065] The metal oxides and solid electrolytes described above can be used.

[0066] Inorganic particles preferably contain a solid electrolyte. Inorganic particles containing a solid electrolyte can have high ionic conductivity. Therefore, the output performance of the electrode can be increased.

[0067] The inorganic particles and the inorganic particle-containing layer may be made of the same material, or they may contain different materials. Preferably, the inorganic particles contain a solid electrolyte, and the inorganic particle-containing layer contains solid electrolyte-containing particles.

[0068] Conductive agents are added to enhance current collection performance and reduce contact resistance between the active material and the current collector. Examples of conductive agents include carbonaceous materials such as vapor-grown carbon fiber (VGCF), carbon black such as acetylene black, graphite, carbon nanotubes, and carbon nanofibers. One of these may be used as a conductive agent, or two or more may be used in combination. Alternatively, instead of using a conductive agent, the surface of the active material particles may be coated with a carbon coating or an electronically conductive inorganic material coating.

[0069] A binder is added to fill the gaps between dispersed active materials and to bond the active materials to the current collector. Examples of binders include polytetrafluoroethylene (PTFE), polyvinylidene fluoride (PVdF), fluororubber, styrene-butadiene rubber (SBR), polyacrylic acid compounds, imide compounds, carboxymethyl cellulose (CMC), and salts of CMC. One of these may be used as a binder, or two or more may be used in combination.

[0070] The mixing ratio of active material, inorganic particles, conductive agent, and binder in the active material-containing layer can be appropriately changed depending on the application of the electrode. For example, when the electrode is used as the negative electrode of a secondary battery, it is preferable to mix the active material (negative electrode active material), inorganic particles, conductive agent, and binder in the following proportions: 68% to 96% by mass, 1% to 10% by mass, 2% to 30% by mass, and 2% to 30% by mass, respectively. By setting the amount of inorganic particles to 1% by mass or more, the hydrofluoric acid trapping effect can be ensured. By setting the amount of conductive agent to 2% by mass or more, the current collection performance of the active material-containing layer can be improved. Furthermore, by setting the amount of binder to 2% by mass or more, sufficient bonding between the active material-containing layer and the current collector can be expected, resulting in excellent cycle performance. On the other hand, it is preferable to set the amount of inorganic particles to 10% by mass or less in terms of ensuring electronic conductivity. It is preferable to set the amount of conductive agent and binder to 30% by mass or less each in order to achieve high capacity.

[0071] The proportion of first particles in the active material is preferably 80% by mass or more. The proportion of first particles in the active material can be 100% by mass.

[0072] The current collector is made of a material that is electrochemically stable at the potential at which lithium (Li) is inserted into and removed from the active material. For example, when the active material is used as the negative electrode active material, the current collector is preferably made of copper, nickel, stainless steel, or aluminum, or an aluminum alloy containing one or more elements selected from Mg, Ti, Zn, Mn, Fe, Cu, and Si. The thickness of the current collector is preferably 5 μm to 20 μm. A current collector with such a thickness can balance electrode strength and weight reduction.

[0073] Furthermore, the current collector may include portions on its surface where the active material-containing layer is not formed. These portions can function as current-collecting tabs.

[0074] <Method for fabricating electrodes> The electrodes can be fabricated, for example, by the following method.

[0075] First, a first particle containing niobium titanium oxide particles and an inorganic particle-containing layer is prepared. Next, the active material containing the first particle, the inorganic particles, a conductive agent, and a binder are suspended in a solvent to prepare a slurry. For example, water or N-methylpyrrolidone (NMP) can be used as the solvent for the slurry. This slurry is applied to one or both sides of a current collector. Next, the applied slurry is dried to obtain a laminate of the active material-containing layer and the current collector. After that, this laminate is pressed. In this way, an electrode is prepared.

[0076] During the suspension phase of slurry preparation, stirring with a bead mill may be performed. When forming exposed portions in the preparation of the first particles described later, the stirring conditions for suspension are preferably a glass bead diameter of about 2 mm, a packing rate of about 50%, a stirring speed of about 3000 rpm, and a stirring time of about 1 hour. By using the above conditions, the stirring intensity does not become too strong, which prevents the first particles from being excessively scraped and thus prevents the thickness of the inorganic particle-containing layer from becoming too thin.

[0077] Alternatively, electrodes may be manufactured by the following method: First, an active material containing the first particle, inorganic particles, a conductive agent, and a binder are mixed to obtain a mixture. Next, this mixture is formed into pellets. Then, electrodes can be obtained by placing these pellets on a current collector.

[0078] (Method for producing the first particle) The first particle can be produced, for example, as follows:

[0079] First, an inorganic particle-containing layer precursor solution is prepared by dissolving or dispersing the inorganic particle-containing layer precursor in a solvent.

[0080] For example, water can be used as a solvent. Nitric acid and polyvinyl alcohol (PVA) may be further added to the solvent. Adding nitric acid makes it easier to dissolve the metal elements contained in the inorganic particle-containing layer precursor in the solvent. Adding PVA helps maintain dispersibility. The concentrations of nitric acid and PVA can be within the ranges of 0.01% to 0.05% by mass and 0.1% to 20% by mass, respectively.

[0081] As an inorganic particle-containing layer precursor, a material containing the elements to be contained in the desired inorganic particle-containing layer can be used. For example, an alkoxide or nitrate containing the metal element to be contained in the desired inorganic particle-containing layer can be used. Also, if the desired inorganic particle-containing layer contains phosphorus (P) in its composition, for example, ammonium dihydrogen phosphate can be used as a phosphorus (P) source. By mixing these materials in a molar ratio that results in the composition of the desired inorganic particle-containing layer and dissolving or dispersing them in a solvent, an inorganic particle-containing layer precursor solution can be obtained.

[0082] Niobium titanium oxide particles are added to an inorganic particle-containing layer precursor solution and stirred to prepare a dispersion. The solvent is removed from the dispersion after stirring to obtain a dry powder. By calcining the dry powder, first particles can be produced in which an inorganic particle-containing layer is formed on the surface of the niobium titanium oxide particles.

[0083] The mixing ratio of the inorganic particle-containing layer precursor solution to the niobium titanium oxide particles can be such that, for example, the mass of the inorganic particle-containing layer obtained after firing is between 1% and 20% by mass relative to the mass of the niobium titanium oxide particles. A ratio of 1% or more by mass facilitates the formation of the inorganic particle-containing layer after firing. A ratio of 20% or less by mass suppresses the formation of an excessive amount of the inorganic particle-containing layer.

[0084] While there are no particular restrictions on firing conditions, it is preferable that the firing temperature be between 600°C and 1000°C. The firing time is preferably between 5 hours and 10 hours. The firing time can be varied depending on the firing temperature.

[0085] (Formation of exposed area) An exposed portion may be formed on the first particle obtained as described above. The exposed portion can be formed, for example, by subjecting the first particle to a bead mill. As the bead mill, for example, a wet bead mill can be used.

[0086] A bead mill for forming exposed parts can be operated under the following conditions, for example: The diameter of the glass beads used in the bead mill is preferably in the range of 2 mm to 10 mm. If the diameter of the glass beads is 2 mm or more, the grinding force can be ensured. If the diameter of the glass beads is 10 mm or less, the grinding efficiency can be increased. The packing rate of the glass beads in the bead mill is preferably in the range of 50% to 80%. If the packing rate of the glass beads is 50% or more, the grinding efficiency can be increased. If the packing rate of the glass beads is 80% or less, the movement efficiency of the beads is high, and as a result, the grinding efficiency can be increased. The bead mill is preferably operated at 1000 rpm to 3000 rpm. If it is 1000 rpm or more, the grinding efficiency can be increased. If it is 3000 rpm or less, excessive grinding of the first particles can be suppressed. The stirring time is preferably 30 minutes to 60 minutes. If it is 30 minutes or more, exposed parts can be easily formed. If it is 60 minutes or less, excessive grinding of the first particles can be suppressed.

[0087] A pre-formed exposed portion 1 The particles can be used in the preparation of the slurry described above. Alternatively, the exposed portion can be formed simultaneously with the preparation of the slurry as follows.

[0088] First, the first particles, which have not formed exposed parts, and inorganic particles are added to the solvent, and the first bead mill is performed. By setting the conditions for the first bead mill to the conditions for forming exposed parts as described above, exposed parts are formed on the first particles. Next, the conductive agent and CMC as a binder are added, and the second bead mill is performed. The conditions for the second bead mill are the stirring conditions for suspension described earlier. Finally, a slurry can be prepared by adding a binder of a type other than CMC and stirring. Alternatively, the slurry can also be prepared by adding the active material containing the first particles, which have not formed exposed parts, inorganic particles, a conductive agent, and a binder to the solvent, and performing a bead mill under the conditions for forming exposed parts. In this way, a slurry containing exposed parts can be prepared. 1 A slurry containing particles can be prepared.

[0089] <Various measurement methods for active materials> Next, we will explain the method for measuring the composition and structure of the active material.

[0090] When measuring the active material contained in electrodes incorporated into a battery, the electrodes are removed from the battery, and then the active material is extracted from the electrodes and subjected to measurement, as described below.

[0091] (Removal of electrodes) First, the lithium ions must be completely released from the niobium-titanium oxide contained in the electrode. For example, when measuring the negative electrode, the battery should be completely discharged. However, even in a completely discharged battery, a small amount of lithium ions may remain within the niobium-titanium oxide particles in the negative electrode.

[0092] Next, the battery is disassembled in a glove box filled with argon, and the electrode containing the active material to be measured is removed. Then, the removed electrode is washed with a suitable solvent. If the battery is a non-aqueous electrolyte battery, it is preferable to use an organic solvent contained in the non-aqueous electrolyte, such as ethyl methyl carbonate.

[0093] (Extraction of active material) The removed electrodes are cut as appropriate, immersed in a solvent, and subjected to ultrasonic testing. It is preferable to use an organic solvent such as alcohol or NMP. This allows the active material-containing layer to be peeled off from the current collector foil. Next, the dispersion obtained by dispersing the peeled active material-containing layer in the solvent is subjected to centrifugation. This allows the active material to be separated from the active material-containing layer powder containing conductive agents such as carbon.

[0094] (Identification of the first particle) The presence of niobium-titanium oxide particles in the separated active material can be identified by inductively coupled plasma (ICP) emission spectroscopy. Specifically, ICP analysis can be performed as follows: The active material separated by the aforementioned method is dissolved in acid to prepare a sample. The prepared sample is then analyzed by ICP emission spectroscopy to measure the concentration of each element per unit weight in the sample. Examples of ICP analytical instruments include the SPS-3520UV manufactured by SII Nanotechnology Co., Ltd. or an equivalent instrument. From these measurement results, the composition ratio of metal elements in the active material can be calculated. From this composition ratio, it can be identified that the active material contains niobium-titanium oxide particles.

[0095] The presence of an inorganic particle-containing layer in particles containing niobium titanium oxide can be identified as follows: By observing the active material separated by the method described above using a transmission electron microscope (TEM) and performing elemental mapping using energy dispersive X-ray spectroscopy (EDX), it is possible to distinguish between particles containing niobium titanium oxide that also contain an inorganic particle-containing layer.

[0096] Among the particles containing niobium titanium oxide, those that further contain an inorganic particle-containing layer can be identified as the first particle.

[0097] (Distinguishing between niobium titanium oxide particles and inorganic particle-containing layers) Niobium titanium oxide particles and inorganic particle-containing layers can be distinguished by observing the first particle in the active material using a transmission electron microscope (TEM).

[0098] For TEM observation, it is preferable to use high-angle Annular Dark Field Scanning Transmission Electron Microscope (HAADF-STEM) images. HAADF-STEM is a technique that detects and observes transmitted electrons scattered at high angles, and can obtain contrast proportional to atomic weight. In the first particle, the niobium-titanium oxide particles containing niobium-titanium composite oxide may contain more Nb elements than the inorganic particle-containing layer. Therefore, in the HAADF-STEM image of the first particle, the niobium-titanium oxide particles can be observed as darker than the inorganic particle-containing layer. This allows for clear differentiation between the inorganic particle-containing layer and the niobium-titanium oxide particles based on the difference in contrast.

[0099] (Method for measuring the thickness of the inorganic particle-containing layer) Referring to Figure 4, the method for measuring the thickness of the inorganic particle-containing layer is described. Figure 4 is a schematic diagram showing the HAADF-STEM image of the first particle.

[0100] First, an arbitrary first particle 10 is selected from the TEM observation image. Next, HAADF-STEM observation is performed on the selected first particle 10. In the obtained HAADF-STEM image, the niobium titanium oxide particles 11 and the inorganic particle-containing layer 12 can be distinguished by contrast.

[0101] In the HAADF-STEM image of the first particle 10, a point on the surface of the niobium titanium oxide particle 11 is designated as point R. Point R can be in the innermost part of the inorganic particle-containing layer 12. Next, a tangent line r is drawn to point R in the niobium titanium oxide particle 11. A line s is drawn perpendicular to the tangent line r of point R. The point where this line s intersects with the outermost part of the first particle 10 is designated as point S. Point S can be in the outermost part of the inorganic particle-containing layer 12. The same procedure is performed for the same first particle 10, and the largest distance RS in the first particle 10 is taken as the thickness of the inorganic particle-containing layer 12 for that first particle. The same operation is performed for 10 first particles, and the average value is defined as the thickness of the inorganic particle-containing layer 12.

[0102] On the surface of the niobium titanium oxide particles 11, the portion where the inorganic particle-containing layer 12 is not formed may be the exposed portion 14.

[0103] (FE-TEM) The presence of an exposed portion in the first particle can be determined by observing the first particle using a field-emission transmission electron microscope (FE-TEM).

[0104] The surface of the first particle is observed using FE-TEM at a high magnification of approximately 1 million times. In the first particle, the portion on the surface of the niobium titanium oxide particle that does not contain compounds of other compositions can be defined as the exposed portion.

[0105] <Measurement of average particle size of inorganic particles> The average particle size of inorganic particles can be measured by TEM observation of the cross-section of the electrode.

[0106] When measuring electrodes incorporated into a battery, remove the electrodes from the battery and use them for measurement in the same manner as described earlier.

[0107] The cross-section of the electrode is observed using TEM at a magnification of 1500x. Among the particles in the observation field, those containing elements found in the solid electrolyte described above can be identified as solid electrolyte-containing particles. For example, if a particle contains Al, Ti, and P, it can be identified that the particle contains a lithium phosphate solid electrolyte, which is a LATP compound. Also, among the particles in the observation field, those containing elements found in the metal oxide described above can be identified as metal oxide-containing particles. For example, particles containing Al can be identified as Al2O3-containing particles, particles containing Si as SiO2-containing particles, particles containing Ti as TiO2-containing particles, particles containing Zr as ZrO2-containing particles, and particles containing Mg as MgO-containing particles. Furthermore, by determining through TEM-EDX measurement that the particle does not contain metal elements other than those found in the metal oxide described above, the type of metal oxide contained in the particle being measured can be determined. For example, if the particle being measured does not contain any metal elements other than Ti, it can be identified that the particle contains TiO2. The above-mentioned solid electrolyte-containing particles and metal oxide-containing particles can be identified as inorganic particles. The particle size of five inorganic particles within the observation field is measured, and the average value is taken as the average particle size.

[0108] The electrode according to the first embodiment includes inorganic particles, niobium titanium oxide particles, and an inorganic particle-containing layer that covers at least a portion of the surface of the niobium titanium oxide particles. The average particle diameter of the inorganic particles is greater than the thickness of the inorganic particle-containing layer. Therefore, such an electrode can improve cycle performance and output performance.

[0109] (Second embodiment) According to the second embodiment, a secondary battery is provided that includes a negative electrode, a positive electrode, and an electrolyte. At least one of the positive electrode and the negative electrode is the electrode according to the first embodiment. In other words, the secondary battery includes the electrode according to the first embodiment.

[0110] The secondary battery may further include a separator positioned between the positive electrode and the negative electrode. The negative electrode, positive electrode, and separator can constitute an electrode group. The electrolyte can be held within the electrode group.

[0111] Furthermore, the secondary battery may further comprise an outer casing that houses the electrode group and the electrolyte.

[0112] Furthermore, the secondary battery may further include a negative terminal electrically connected to the negative electrode and a positive terminal electrically connected to the positive electrode.

[0113] The secondary battery in question may be, for example, a lithium secondary battery. Furthermore, the secondary battery may include a non-aqueous electrolyte secondary battery containing a non-aqueous electrolyte.

[0114] The following provides a detailed explanation of the negative electrode, positive electrode, electrolyte, separator, outer casing, negative electrode terminal, and positive electrode terminal.

[0115] 1) Negative electrode The negative electrode may include a negative electrode current collector and a negative electrode active material-containing layer. The negative electrode current collector and the negative electrode active material-containing layer may be a current collector and an active material-containing layer that can be included in the electrode according to the first embodiment, respectively. The negative electrode active material-containing layer may contain first particles, which include niobium titanium oxide particles and an inorganic particle-containing layer, as the negative electrode active material.

[0116] Details of the negative electrode that overlap with the details described in the first embodiment will be omitted.

[0117] The density of the negative electrode active material layer (excluding the current collector) is 1.8 g / cm³. 3 More than 2.8g / cm 3 The following is preferable. A negative electrode with a density of the negative electrode active material-containing layer within this range exhibits excellent energy density and electrolyte retention. The density of the negative electrode active material-containing layer is 2.1 g / cm³. 3 More than 2.6g / cm 3 The following is more preferable:

[0118] The negative electrode can be manufactured, for example, by the same method as the electrode according to the first embodiment.

[0119] 2) Positive electrode The positive electrode can include a positive electrode current collector and a positive electrode active material-containing layer. The positive electrode active material-containing layer can be formed on one or both sides of the positive electrode current collector. The positive electrode active material-containing layer can contain a positive electrode active material, and optionally a conductive agent and a binder.

[0120] As the positive electrode active material, for example, an oxide or a sulfide can be used. The positive electrode may contain, as the positive electrode active material, one type of compound alone, or may contain a combination of two or more types of compounds. Examples of the oxide and the sulfide can include compounds into which Li or Li ions can be inserted and desorbed.

[0121] Examples of such compounds include, for example, manganese dioxide (MnO2), iron oxide, copper oxide, nickel oxide, lithium manganese composite oxide (for example, Li x Mn2O4 or Li x MnO2; 0 < x ≦ 1), lithium nickel composite oxide (for example, Li x NiO2; 0 < x ≦ 1), lithium cobalt composite oxide (for example, Li x CoO2; 0 < x ≦ 1), lithium nickel cobalt composite oxide (for example, Li x Ni 1-y Co y O2; 0 < x ≦ 1, 0 < y < 1), lithium manganese cobalt composite oxide (for example, Li x Mn y Co 1-y O_{2}; 0 < x ≦ 1, 0 < y < 1), lithium manganese nickel composite oxide having a spinel structure (for example, Li<( x Mn 2-y Ni y O4; 0 < x ≦ 1, 0 < y < 2), lithium phosphate having an olivine structure (for example, Li x FePO4; 0 < x ≦ 1, Li x Fe 1-y Mn y PO4; 0 < x ≦ 1, 0 < y ≦ 1, Li x CoPO4; 0 < x ≦ 1), iron sulfate (Fe2(SO4)3), vanadium oxide (for example, V2O5), and lithium nickel cobalt manganese composite oxide (Li x Ni1-y-z Co y Mn z O2; where 0 < x ≤ 1, 0 < y < 1, 0 < z < 1, and y + z < 1 is included.

[0122] Among the above, examples of more preferable compounds as the positive electrode active material include lithium manganese composite oxides having a spinel structure (e.g., Li x Mn2O4; 0 < x ≤ 1), lithium nickel composite oxides (e.g., Li x NiO2; 0 < x ≤ 1), lithium cobalt composite oxides (e.g., Li x CoO2; 0 < x ≤ 1), lithium nickel cobalt composite oxides (e.g., Li x Ni 1-y Co y O2; 0 < x ≤ 1, 0 < y < 1), lithium manganese nickel composite oxides having a spinel structure (e.g., Li x Mn 2-y Ni y O4; 0 < x ≤ 1, 0 < y < 2), lithium manganese cobalt composite oxides (e.g., Li x Mn y Co 1-y O2; 0 < x ≤ 1, 0 < y < 1), lithium iron phosphate (e.g., Li x FePO4; 0 < x ≤ 1), and lithium nickel cobalt manganese composite oxides (Li x Ni 1-y-z Co y Mn[[ID=4s2]] z O2; 0 < x ≤ 1, 0 < y < 1, 0 < z < 1, and y + z < 1 is included. Using these compounds as the positive electrode active material can increase the positive electrode potential.

[0123] When using a room temperature molten salt as the electrolyte of the battery, it is preferable to use a positive electrode active material containing lithium iron phosphate, Li x VPO4F (0 ≤ x ≤ 1), a lithium manganese composite oxide, a lithium nickel composite oxide, a lithium nickel cobalt composite oxide, or a mixture thereof. Since these compounds have low reactivity with the room temperature molten salt, the cycle life can be improved. Details of the room temperature molten salt will be described later.

[0124] The primary particle size of the positive electrode active material is preferably between 100 nm and 1 μm. Positive electrode active material with a primary particle size of 100 nm or more is easy to handle in industrial production. Positive electrode active material with a primary particle size of 1 μm or less allows for smooth diffusion of lithium ions within the solid.

[0125] The specific surface area of ​​the positive electrode active material is 0.1 m². 2 / g or more 10m 2 It is preferable that it be less than or equal to / g. 0.1m 2 A positive electrode active material with a specific surface area of ​​10m or more can adequately secure sites for Li ion intercalation and release. 2 Positive electrode active materials with a specific surface area of ​​less than / g are easy to handle in industrial production and can ensure good charge-discharge cycle performance.

[0126] A binder is added to fill the gaps between dispersed positive electrode active materials and to bond the positive electrode active materials to the positive electrode current collector. Examples of binders include polytetrafluoroethylene (PTFE), polyvinylidene fluoride (PVdF), fluororubber, polyacrylic acid compounds, imide compounds, carboxymethyl cellulose (CMC), and salts of CMC. One of these may be used as a binder, or two or more may be used in combination.

[0127] Conductive agents are added to enhance current collection performance and reduce contact resistance between the positive electrode active material and the positive electrode current collector. Examples of conductive agents include vapor-grown carbon fiber (VGCF), carbon black such as acetylene black, and carbonaceous materials such as graphite. One of these may be used as a conductive agent, or two or more may be used in combination. Conductive agents may also be omitted.

[0128] In the positive electrode active material-containing layer, it is preferable that the positive electrode active material and the binder are blended in proportions of 80% to 98% by mass and 2% to 20% by mass, respectively.

[0129] Sufficient electrode strength can be obtained by using a binder amount of 2% by mass or more. Furthermore, the binder can function as an insulator. Therefore, reducing the binder amount to 20% by mass or less reduces the amount of insulator contained in the electrode, thereby reducing internal resistance.

[0130] When a conductive agent is added, it is preferable that the positive electrode active material, binder, and conductive agent are blended in proportions of 77% to 95% by mass, 2% to 20% by mass, and 3% to 15% by mass, respectively.

[0131] The above-mentioned effects can be achieved by increasing the amount of conductive agent to 3% by mass or more. Furthermore, by reducing the amount of conductive agent to 15% by mass or less, the proportion of conductive agent in contact with the electrolyte can be reduced. This lower proportion reduces the decomposition of the electrolyte under high-temperature storage conditions.

[0132] 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, Ni, Cr, Mn, Fe, Cu, and Si.

[0133] The thickness of the aluminum foil or aluminum alloy foil is preferably 5 μm or more and 20 μm or less, and more preferably 15 μm or less. The purity of the aluminum foil is preferably 99% by mass or more. The content of transition metals such as iron, copper, nickel, and chromium in the aluminum foil or aluminum alloy foil is preferably 1% by mass or less.

[0134] Furthermore, the positive electrode current collector may include portions on its surface where the positive electrode active material-containing layer is not formed. These portions can function as positive electrode current collector tabs.

[0135] The positive electrode can be manufactured, for example, by the following method. First, a slurry is prepared by suspending the positive electrode active material, conductive agent, and binder in a solvent. This slurry is applied to one or both sides of the current collector. Next, the applied slurry is dried to obtain a laminate of the active material-containing layer and the current collector. After that, this laminate is pressed. In this way, the electrode is manufactured.

[0136] Alternatively, electrodes may be manufactured by the following method: First, an active material containing the first particle, inorganic particles, a conductive agent, and a binder are mixed to obtain a mixture. Next, this mixture is formed into pellets. Then, electrodes can be obtained by placing these pellets on a current collector.

[0137] The positive electrode can be manufactured, for example, by a method similar to that of the electrode according to the first embodiment. When the positive electrode is the electrode according to the first embodiment, the niobium titanium oxide contained in the first particles can function as the positive electrode active material. The negative electrode combined with the positive electrode does not have to be the electrode according to the first embodiment. For example, it can be combined with the inorganic particle-containing layer or the inorganic particle-free negative electrode described in the first embodiment.

[0138] 3) Electrolyte As the electrolyte, for example, a non-aqueous electrolyte can be used. As the non-aqueous electrolyte, for example, a liquid non-aqueous electrolyte, a gel-like non-aqueous electrolyte, or a polymer solid electrolyte can be used. A liquid non-aqueous electrolyte is prepared by dissolving an electrolyte salt as a solute in an organic solvent. A gel-like non-aqueous electrolyte is prepared by compounding a liquid non-aqueous electrolyte with a polymer material. A polymer solid electrolyte is prepared by dissolving an electrolyte salt in a polymer material and solidifying it. The type of non-aqueous electrolyte can be one or more types.

[0139] The concentration of the electrolyte salt is preferably between 0.5 mol / L and 2.5 mol / L.

[0140] Non-aqueous electrolytes may contain fluorine atoms. Examples of non-aqueous electrolytes containing fluorine atoms include non-aqueous electrolytes containing electrolyte salts that contain fluorine atoms.

[0141] Examples of electrolyte salts that can be contained in non-aqueous electrolytes include lithium salts such as lithium perchlorate (LiClO4), lithium hexafluoride phosphate (LiPF6), lithium tetraborate (LiBF4), lithium hexafluoride arsenate (LiAsF6), lithium trifluoromethanesulfonate (LiCF3SO3), and lithium bistrifluoromethylsulfonyliimide (LiN(CF3SO2)2), and mixtures thereof. The electrolyte salt is preferably one that is difficult to oxidize even at high potentials, with LiPF6 being the most preferred. Examples of electrolyte salts containing fluorine atoms among the above include lithium hexafluoride phosphate (LiPF6), lithium tetraborate (LiBF4), lithium hexafluoride arsenate (LiAsF6), lithium trifluoromethanesulfonate (LiCF3SO3), or lithium bistrifluoromethylsulfonyliimide (LiN(CF3SO2)2). The type of electrolyte salt can be one or more.

[0142] Examples of organic solvents include cyclic carbonates such as propylene carbonate (PC), ethylene carbonate (EC), and vinylene carbonate (VC); linear carbonates such as diethyl carbonate (DEC), dimethyl carbonate (DMC), and methyl ethyl carbonate (MEC); cyclic ethers such as tetrahydrofuran (THF), 2-methyl tetrahydrofuran (2MeTHF), and dioxolane (DOX); linear ethers such as dimethoxyethane (DME) and diethoxyethane (DEE); and γ-butyrolactone (GBL), acetonitrile (AN), and sulfolane (SL). These organic solvents can be used alone or as mixed solvents.

[0143] Examples of polymer materials containing gel-like non-aqueous electrolytes include polyvinylidene fluoride (PVdF), polyacrylonitrile (PAN), polyethylene oxide (PEO), or mixtures thereof.

[0144] Alternatively, in addition to liquid nonaqueous electrolytes, gel-type nonaqueous electrolytes, and polymer solid electrolytes, room-temperature molten salts (ionic melts) or inorganic solid electrolytes containing lithium ions may be used as nonaqueous electrolytes. The nonaqueous electrolyte may consist of one of the above types alone, or two or more types. Among the above nonaqueous electrolytes, room-temperature molten salts or inorganic solid electrolytes may be used in mixture with liquid nonaqueous electrolytes, gel-type nonaqueous electrolytes, or polymer solid electrolytes.

[0145] Room temperature molten salts (ionic melts) refer to organic salts consisting of a combination of organic cations and anions that can exist as liquids at room temperature (15°C to 25°C). Room temperature molten salts include room temperature molten salts that exist as liquids on their own, room temperature molten salts that become liquid when mixed with an electrolyte salt, room temperature molten salts that become liquid when dissolved in an organic solvent, or mixtures thereof. Generally, the melting point of room temperature molten salts used in secondary batteries is 25°C or lower. Also, organic cations generally have a quaternary ammonium skeleton.

[0146] Inorganic solid electrolytes are solid materials that have lithium ion conductivity. Here, "having lithium ion conductivity" means that at 25°C, they have a conductivity of 1 × 10⁻⁶. -6 This refers to exhibiting a lithium ion conductivity of S / cm or higher. Examples of inorganic solid electrolytes include oxide-based solid electrolytes and sulfide-based solid electrolytes. Specific examples of inorganic solid electrolytes are as follows.

[0147] As an oxide-based solid electrolyte, it has a NASICON (Sodium (Na) Super Ionic Conductor) type structure, and its general formula is Li 1+x It is preferable to use a lithium phosphate solid electrolyte represented by Mα2(PO4)3. In the above general formula, Mα is one or more selected from the group consisting of, for example, titanium (Ti), germanium (Ge), strontium (Sr), zirconium (Zr), tin (Sn), aluminum (Al), and calcium (Ca). The subscript x is in the range of 0 ≤ x ≤ 2.

[0148] A specific example of a lithium phosphate solid electrolyte having a NASICON-type structure is Li 1+x Al x Ti 2-x LATP compounds represented as (PO4)3 where 0.1 ≤ x ≤ 0.5; Li 1+x Al y Mβ 2-y A compound represented as (PO4)3 where Mβ is 1 or more selected from the group consisting of Ti, Ge, Sr, Zr, Sn, and Ca, and 0≦x≦1 and 0≦y≦1; Li 1+x Alx Ge 2-x (PO4)3 represented compound where 0 ≦ x ≦ 2; and, Li 1+x Al x Zr 2-x (PO4)3 represented compound where 0 ≦ x ≦ 2; Li 1+x+y Al x Mγ 2-x Si y P 3-y O 12 represented compound where Mγ is one or more selected from the group consisting of Ti and Ge, 0 < x ≦ 2, 0 ≦ y < 3; Li 1+2x Zr 1-x Ca x Compounds represented by (PO4)3 where 0 ≦ x < 1 can be mentioned.

[0149] Also, as the oxide-based solid electrolyte, in addition to the above lithium phosphate solid electrolyte, Li x PO y N z represented amorphous LIPON compound where 2.6 ≦ x ≦ 3.5, 1.9 ≦ y ≦ 3.8, and 0.1 ≦ z ≦ 1.3 (for example, Li 2.9 PO 3.3 N 0.46 ); Garnet-type structure La 5+x A x La 3-x Mδ2O 12 represented compound where A is one or more selected from the group consisting of Ca, Sr, and Ba, Mδ is one or more selected from the group consisting of Nb and Ta, and 0 ≦ x ≦ 0.5; Li3Mδ 2-x L2O 12 represented compound where Mδ is one or more selected from the group consisting of Nb and Ta, L may contain Zr, and 0 ≦ x ≦ 0.5; Li 7-3x Al x La3Zr3O 12 represented compound where 0 ≦ x ≦ 0.5; Li<H 5+x La3Mδ 2-x Zr x O 12 represented compound where Mδ is one or more selected from the group consisting of Nb and Ta, and 0 ≦ x ≦ 2 LLZ compound (for example, Li7La3Zr2O 12); and having a perovskite-type structure La 2 / 3-x Li x Examples include compounds represented as TiO3 where 0.3 ≤ x ≤ 0.7.

[0150] One or more of the above compounds can be used as a solid electrolyte. Two or more of the above solid electrolytes may also be used.

[0151] 4) Separator The separator is formed from a porous film containing, for example, polyethylene (PE), polypropylene (PP), cellulose, or polyvinylidene fluoride (PVdF), or from a synthetic resin nonwoven fabric. From a safety standpoint, it is preferable to use a porous film made of polyethylene or polypropylene. This is because these porous films can melt at a certain temperature and interrupt the electric current.

[0152] 5) Exterior components For example, the outer packaging material can be a container made of laminate film or a metal container.

[0153] The thickness of the laminating film is, for example, 0.5 mm or less, and preferably 0.2 mm or less.

[0154] As the laminate film, a multilayer film is used that includes multiple resin layers and a metal layer interposed between these resin layers. The resin layers include polymer materials such as polypropylene (PP), polyethylene (PE), nylon, and polyethylene terephthalate (PET). The metal layer is preferably made of aluminum foil or aluminum alloy foil for weight reduction. The laminate film can be molded into the shape of an exterior component by sealing it by heat fusion.

[0155] The thickness of the metal container wall is, for example, 1 mm or less, more preferably 0.5 mm or less, and even more preferably 0.2 mm or less.

[0156] Metal containers are made from, for example, aluminum or aluminum alloys. Aluminum alloys preferably contain elements such as magnesium, zinc, and silicon. If aluminum alloys contain transition metals such as iron, copper, nickel, and chromium, their content is preferably 100 ppm by mass or less.

[0157] The shape of the exterior components is not particularly limited. For example, the exterior components may be flat (thin), rectangular, cylindrical, coin-shaped, or button-shaped. The exterior components can be appropriately selected according to the battery dimensions and intended use.

[0158] 6) Negative terminal The negative terminal has a potential range of 1V to 3V relative to the oxidation-reduction potential of lithium (vs.Li / Li + The negative electrode terminal can be formed from an electrically stable and conductive material. Specifically, examples of materials for the negative electrode terminal include copper, nickel, stainless steel, or aluminum, or an aluminum alloy containing at least one element selected from the group consisting of Mg, Ti, Zn, Mn, Fe, Cu, and Si. It is preferable to use aluminum or an aluminum alloy as the material for the negative electrode terminal. It is preferable that the negative electrode terminal be made of the same material as the negative electrode current collector in order to reduce contact resistance with the negative electrode current collector.

[0159] 7) Positive terminal The positive terminal has a potential range of 3V to 4.5V relative to the oxidation-reduction potential of lithium (vs.Li / Li +The positive electrode terminal can be formed from an electrically stable and conductive material. Examples of positive electrode terminal materials include aluminum, or an aluminum alloy containing at least one element selected from the group consisting of Mg, Ti, Zn, Mn, Fe, Cu, and Si. It is preferable that the positive electrode terminal be formed from the same material as the positive electrode current collector in order to reduce contact resistance with the positive electrode current collector.

[0160] Next, the secondary battery according to the embodiment will be described in more detail with reference to the drawings.

[0161] Figure 5 is a schematic cross-sectional view showing an example of a secondary battery. Figure 6 is an enlarged cross-sectional view of part A of the secondary battery shown in Figure 5.

[0162] The secondary battery 100 shown in Figures 5 and 6 comprises a bag-shaped outer casing member 2 shown in Figure 5, an electrode group 1 shown in Figures 5 and 6, and an electrolyte (not shown). The electrode group 1 and the electrolyte are housed within the bag-shaped outer casing member 2. The electrolyte (not shown) is held by the electrode group 1.

[0163] The bag-shaped outer packaging member 2 consists of a laminate film comprising two resin layers and a metal layer interposed between them.

[0164] As shown in Figure 5, electrode group 1 is a flat, wound electrode group. As shown in Figure 6, the flat, wound electrode group 1 includes a negative electrode 3, a separator 4, and a positive electrode 5. The separator 4 is interposed between the negative electrode 3 and the positive electrode 5.

[0165] The negative electrode 3 includes a negative electrode current collector 3a and a negative electrode active material containing layer 3b. In the portion of the negative electrode 3 located in the outermost shell of the wound electrode group 1, the negative electrode active material containing layer 3b is formed only on the inner surface side of the negative electrode current collector 3a, as shown in Figure 6. In the other portions of the negative electrode 3, the negative electrode active material containing layer 3b is formed on both sides of the negative electrode current collector 3a.

[0166] The positive electrode 5 includes a positive electrode current collector 5a and positive electrode active material-containing layers 5b formed on both sides thereof.

[0167] As shown in Figure 5, the negative electrode terminal 6 and the positive electrode terminal 7 are located near the outer edge of the wound electrode group 1. The negative electrode terminal 6 is connected to the outermost part of the negative electrode current collector 3a. The positive electrode terminal 7 is connected to the outermost part of the positive electrode current collector 5a. These negative electrode terminals 6 and positive electrode terminals 7 extend outward from the opening of the bag-shaped outer casing member 2. A thermoplastic resin layer is installed on the inner surface of the bag-shaped outer casing member 2, and the opening is closed by heat sealing of this layer.

[0168] The secondary battery according to this embodiment is not limited to the secondary battery with the configuration shown in Figures 5 and 6, but may also be a battery with the configuration shown in Figures 7 and 8, for example.

[0169] Figure 7 is a schematic partially cutaway perspective view showing another example of a secondary battery. Figure 8 is an enlarged cross-sectional view of section B of the secondary battery shown in Figure 7.

[0170] The secondary battery 100 shown in Figures 7 and 8 comprises an electrode group 1 shown in Figures 7 and 8, an outer casing member 2 shown in Figure 7, and an electrolyte (not shown). The electrode group 1 and the electrolyte are housed within the outer casing member 2. The electrolyte is held within the electrode group 1.

[0171] The exterior component 2 consists of a laminate film comprising two resin layers and a metal layer interposed between them.

[0172] As shown in Figure 8, electrode group 1 is a stacked electrode group. The stacked electrode group 1 has a structure in which negative electrodes 3 and positive electrodes 5 are alternately stacked with separators 4 interposed between them.

[0173] The electrode group 1 includes a plurality of negative electrodes 3. Each of the plurality of negative electrodes 3 comprises a negative electrode current collector 3a and a negative electrode active material-containing layer 3b supported on both sides of the negative electrode current collector 3a. The electrode group 1 also includes a plurality of positive electrodes 5. Each of the plurality of positive electrodes 5 comprises a positive electrode current collector 5a and a positive electrode active material-containing layer 5b supported on both sides of the positive electrode current collector 5a.

[0174] Each negative electrode 3's negative electrode current collector 3a includes a portion on one side where the negative electrode active material-containing layer 3b is not supported on any surface. This portion functions as a negative electrode current collector tab 3c. As shown in Figure 8, the negative electrode current collector tab 3c does not overlap with the positive electrode 5. Furthermore, multiple negative electrode current collector tabs 3c are electrically connected to a strip-shaped negative electrode terminal 6. The tip of the strip-shaped negative electrode terminal 6 is extended to the outside of the outer casing member 2.

[0175] Although not shown in the diagram, the positive electrode current collector 5a of each positive electrode 5 includes a portion on one side where the positive electrode active material-containing layer 5b is not supported on any surface. This portion acts as a positive electrode current collector tab. Just as the negative electrode current collector tab 3c does not overlap with the positive electrode 5, the positive electrode current collector tab does not overlap with the negative electrode 3. Furthermore, the positive electrode current collector tab is located on the opposite side of the electrode group 1 from the negative electrode current collector tab 3c. The positive electrode current collector tab is electrically connected to a strip-shaped positive electrode terminal 7. The tip of the strip-shaped positive electrode terminal 7 is located on the opposite side from the negative electrode terminal 6 and is extended to the outside of the outer casing member 2.

[0176] The secondary battery according to the second embodiment includes the electrodes according to the first embodiment. Therefore, according to this embodiment, a secondary battery with improved cycle performance and output performance can be provided.

[0177] (Third embodiment) According to the third embodiment, a battery pack is provided. This battery pack comprises a plurality of secondary batteries according to the second embodiment.

[0178] In such a battery pack, each individual cell may be arranged in series or parallel connections, or a combination of series and parallel connections may be used.

[0179] Next, an example of a battery pack according to the embodiment will be described with reference to the drawings.

[0180] Figure 9 is a schematic perspective view showing an example of a battery pack. The battery pack 200 shown in Figure 9 comprises five single cells 100a to 100e, four busbars 21, a positive electrode lead 22, and a negative electrode lead 23. Each of the five single cells 100a to 100e is a secondary battery according to the second embodiment.

[0181] The busbar 21 connects, for example, the negative terminal 6 of one cell 100a to the positive terminal 7 of the adjacent cell 100b. In this way, the five cells 100 are connected in series by four busbars 21. That is, the battery pack 200 in Figure 9 is a battery pack with five cells in series. Although not illustrated, in a battery pack containing multiple cells that are electrically connected in parallel, the multiple cells can be electrically connected, for example, by connecting multiple negative terminals to each other and multiple positive terminals to each other by busbars.

[0182] The positive terminal 7 of at least one of the five single cells 100a to 100e is electrically connected to the positive lead 22 for external connection. In addition, the negative terminal 6 of at least one of the five single cells 100a to 100e is electrically connected to the negative lead 23 for external connection.

[0183] The battery pack according to the third embodiment includes a secondary battery according to the second embodiment. Therefore, excellent cycle performance and output performance can be achieved.

[0184] (Fourth embodiment) According to the fourth embodiment, a battery pack is provided. This battery pack comprises a battery pack according to the third embodiment. This battery pack may also comprise a single secondary battery according to the second embodiment instead of the battery pack according to the third embodiment.

[0185] The battery pack may further include a protection circuit. The protection circuit has the function of controlling the charging and discharging of the secondary battery. Alternatively, a circuit included in a device that uses the battery pack as a power source (e.g., electronic equipment, automobile, etc.) may be used as the protection circuit for the battery pack.

[0186] Furthermore, such a battery pack may also be equipped with external terminals for power supply. These external terminals are for outputting current from the secondary battery to the outside and / or for inputting current from the outside to the secondary battery. In other words, when the battery pack is used as a power source, current is supplied to the outside through the external terminals. Also, when charging the battery pack, the charging current (including regenerative energy from the power of an automobile, etc.) is supplied to the battery pack through the external terminals.

[0187] Next, an example of a battery pack according to the embodiment will be described with reference to the drawings.

[0188] Figure 10 is an exploded perspective view schematically showing an example of a battery pack. Figure 11 is a block diagram showing an example of the electrical circuit of the battery pack shown in Figure 10.

[0189] The battery pack 300 shown in Figures 10 and 11 comprises a housing container 31, a lid 32, a protective sheet 33, a battery pack 200, a printed circuit board 34, wiring 35, and an insulating plate (not shown).

[0190] The container 31 shown in Figure 10 is a bottomed rectangular container with a rectangular base. The container 31 is configured to accommodate a protective sheet 33, a battery pack 200, a printed circuit board 34, and wiring 35. The lid 32 has a rectangular shape. The lid 32 covers the container 31, thereby housing the battery pack 200 and the other components. The container 31 and the lid 32 are provided with openings or connection terminals for connecting to external devices, etc., although these are not shown in the figures.

[0191] The battery pack 200 comprises multiple individual cells 100, a positive electrode lead 22, a negative electrode lead 23, and an adhesive tape 24.

[0192] At least one of the multiple single cells 100 is a secondary battery according to the second embodiment. Each of the multiple single cells 100 is electrically connected in series as shown in Figure 11. The multiple single cells 100 may also be electrically connected in parallel, or a combination of series and parallel connections may be used. When the multiple single cells 100 are connected in parallel, the battery capacity increases compared to when they are connected in series.

[0193] The adhesive tape 24 fastens multiple single cells 100 together. Alternatively, heat-shrinkable tape may be used to secure the multiple single cells 100 instead of the adhesive tape 24. In this case, protective sheets 33 are placed on both sides of the battery pack 200, the heat-shrinkable tape is wrapped around it, and then the heat-shrinkable tape is heat-shrinked to bundle the multiple single cells 100 together.

[0194] One end of the positive lead 22 is connected to the battery pack 200. One end of the positive lead 22 is electrically connected to the positive terminal of one or more single cells 100. One end of the negative lead 23 is connected to the battery pack 200. One end of the negative lead 23 is electrically connected to the negative terminal of one or more single cells 100.

[0195] The printed circuit board 34 is installed along one of the shorter sides of the inner surface of the housing container 31. The printed circuit board 34 includes a positive terminal connector 342, a negative terminal connector 343, a thermistor 345, a protection circuit 346, wiring 342a and 343a, an external terminal 350 for energization, a positive side wiring (positive wiring) 348a, and a negative side wiring (negative wiring) 348b. One main surface of the printed circuit board 34 faces one side of the battery pack 200. An insulating plate (not shown) is interposed between the printed circuit board 34 and the battery pack 200.

[0196] The other end 22a of the positive lead 22 is electrically connected to the positive connector 342. The other end 23a of the negative lead 23 is electrically connected to the negative connector 343.

[0197] The thermistor 345 is fixed to one main surface of the printed circuit board 34. The thermistor 345 detects the temperature of each of the single cells 100 and transmits the detection signal to the protection circuit 346.

[0198] The external power supply terminal 350 is fixed to the other main surface of the printed circuit board 34. The external power supply terminal 350 is electrically connected to equipment located outside the battery pack 300. The external power supply terminal 350 includes a positive terminal 352 and a negative terminal 353.

[0199] The protection circuit 346 is fixed to the other main surface of the printed circuit board 34. The protection circuit 346 is connected to the positive terminal 352 via the positive side wiring 348a. The protection circuit 346 is connected to the negative terminal 353 via the negative side wiring 348b. The protection circuit 346 is also electrically connected to the positive side connector 342 via wiring 342a. The protection circuit 346 is also electrically connected to the negative side connector 343 via wiring 343a. Furthermore, the protection circuit 346 is electrically connected to each of the multiple single cells 100 via wiring 35.

[0200] The protective sheet 33 is positioned on both inner surfaces in the long-side direction of the housing container 31 and on the inner surface in the short-side direction facing the printed circuit board 34 via the battery pack 200. The protective sheet 33 is made of, for example, resin or rubber.

[0201] The protection circuit 346 controls the charging and discharging of multiple single cells 100. The protection circuit 346 also disconnects the electrical connection between the protection circuit 346 and the external terminals 350 (positive terminal 352, negative terminal 353) for supplying power to external devices, based on a detection signal transmitted from the thermistor 345 or a detection signal transmitted from an individual single cell 100 or a battery pack 200.

[0202] An example of a detection signal transmitted from the thermistor 345 is a signal indicating that the temperature of a single cell 100 is above a predetermined temperature. An example of a detection signal transmitted from an individual single cell 100 or a battery pack 200 is a signal indicating that overcharging, over-discharging, or overcurrent has been detected in a single cell 100. When detecting overcharging, etc., in an individual single cell 100, the battery voltage may be detected, or the positive electrode potential or negative electrode potential may be detected. In the latter case, a lithium electrode to be used as a reference electrode is inserted into each individual single cell 100.

[0203] Furthermore, the protection circuit 346 may be a circuit included in a device that uses the battery pack 300 as a power source (for example, an electronic device, an automobile, etc.).

[0204] Furthermore, as described above, the battery pack 300 is equipped with an external terminal 350 for power supply. Therefore, the battery pack 300 can output current from the battery pack 200 to an external device and input current from an external device to the battery pack 200 via the external terminal 350. In other words, when the battery pack 300 is used as a power source, current from the battery pack 200 is supplied to the external device through the external terminal 350. Also, when charging the battery pack 300, charging current from an external device is supplied to the battery pack 300 through the external terminal 350. When this battery pack 300 is used as an on-board battery, the regenerative energy of the vehicle's power can be used as the charging current from the external device.

[0205] The battery pack 300 may have multiple battery packs 200. In this case, the multiple battery packs 200 may be connected in series, in parallel, or in a combination of series and parallel connections. The printed circuit board 34 and wiring 35 may also be omitted. In this case, the positive lead 22 and the negative lead 23 may be used as the positive terminal 352 and negative terminal 353 of the external terminal 350 for energization, respectively.

[0206] Such battery packs are used in applications where excellent cycle performance is required, for example, when drawing high currents. Specifically, these battery packs are used as power supplies for electronic devices, stationary batteries, and on-board batteries for various vehicles. Examples of electronic devices include digital cameras. These battery packs are particularly suitable for use as on-board batteries.

[0207] The battery pack according to the fourth embodiment comprises a secondary battery according to the second embodiment or a battery pack according to the third embodiment. Therefore, such a battery pack can achieve excellent cycle performance and output performance.

[0208] (Fifth embodiment) According to the fifth embodiment, a vehicle is provided, which is equipped with the battery pack according to the fourth embodiment.

[0209] In such a vehicle, the battery pack, for example, recovers regenerative energy from the vehicle's power. The vehicle may also include a mechanism (regenerator) that converts the vehicle's kinetic energy into regenerative energy.

[0210] Examples of vehicles include, for example, two-wheeled or four-wheeled hybrid electric vehicles, two-wheeled or four-wheeled electric vehicles, electric assist bicycles, and railway vehicles.

[0211] The mounting location of the battery pack in a vehicle is not particularly limited. For example, when a battery pack is installed in an automobile, it can be mounted in the engine compartment, at the rear of the vehicle, or under the seats.

[0212] The vehicle may be equipped with a plurality of battery packs. In this case, the batteries included in each battery pack may be electrically connected in series, may be electrically connected in parallel, or may be electrically connected by combining series connection and parallel connection. For example, when each battery pack includes a battery module, the battery modules may be electrically connected in series, may be electrically connected in parallel, or may be electrically connected by combining series connection and parallel connection. Alternatively, when each battery pack includes a single battery, the respective batteries may be electrically connected in series, may be electrically connected in parallel, or may be electrically connected by combining series connection and parallel connection.

[0213] Next, an example of a vehicle according to an embodiment will be described while referring to the drawings.

[0214] FIG. 12 is a partially transparent view schematically showing an example of a vehicle.

[0215] The vehicle 400 shown in FIG. 12 includes a vehicle body 40 and a battery pack 300 according to the fourth embodiment. In the example shown in FIG. 12, the vehicle 400 is a four-wheel automobile.

[0216] This vehicle 400 may be equipped with a plurality of battery packs 300. In this case, the batteries (for example, single batteries or battery modules) included in the battery pack 300 may be connected in series, may be connected in parallel, or may be connected by combining series connection and parallel connection.

[0217] In FIG. 12, an example in which the battery pack 300 is mounted in an engine room located in front of the vehicle body 40 is illustrated. As described above, the battery pack 300 may be mounted, for example, behind the vehicle body 40 or under the seat. This battery pack 300 can be used as a power source for the vehicle 400. Further, this battery pack 300 can recover the regenerative energy of the power of the vehicle 400.

[0218] Next, an embodiment of a vehicle according to an embodiment will be described while referring to FIG. 13.

[0219] Figure 13 is a schematic diagram illustrating an example of a control system for the electrical system in a vehicle. The vehicle 400 shown in Figure 13 is an electric vehicle.

[0220] The vehicle 400 shown in Figure 13 comprises a vehicle body 40, a vehicle power supply 41, a vehicle ECU (ECU: Electric Control Unit) 42 which is a control device higher up than the vehicle power supply 41, an external terminal (terminal for connecting to an external power supply) 43, an inverter 44, and a drive motor 45.

[0221] Vehicle 400 has its vehicle power supply 41 mounted, for example, in the engine compartment, at the rear of the vehicle body, or under the seats. Note that in vehicle 400 shown in Figure 13, the mounting location of the vehicle power supply 41 is shown in a schematic manner.

[0222] The vehicle power supply 41 comprises a plurality (for example, three) of battery packs 300a, 300b, and 300c, a battery management unit (BMU) 411, and a communication bus 412.

[0223] Battery pack 300a comprises a battery pack 200a and a battery pack monitoring device 301a (e.g., VTM: Voltage Temperature Monitoring). Battery pack 300b comprises a battery pack 200b and a battery pack monitoring device 301b. Battery pack 300c comprises a battery pack 200c and a battery pack monitoring device 301c. Battery packs 300a to 300c are similar to the aforementioned battery pack 300, and battery packs 200a to 200c are similar to the aforementioned battery pack 200. Battery packs 200a to 200c are electrically connected in series. Battery packs 300a, 300b, and 300c can each be independently removed and replaced with another battery pack 300.

[0224] Each of the battery packs 200a to 200c comprises multiple single cells connected in series. At least one of the multiple single cells is a secondary battery according to the second embodiment. Each of the battery packs 200a to 200c is charged and discharged through a positive terminal 413 and a negative terminal 414.

[0225] The battery management device 411 communicates with the battery pack monitoring devices 301a to 301c and collects information such as voltage and temperature for each of the single cells 100 included in the battery packs 200a to 200c included in the vehicle power supply 41. In this way, the battery management device 411 collects information related to the maintenance of the vehicle power supply 41.

[0226] The battery management device 411 and the battery pack monitoring devices 301a to 301c are connected via a communication bus 412. On the communication bus 412, one set of communication lines is shared by multiple nodes (the battery management device 411 and one or more battery pack monitoring devices 301a to 301c). The communication bus 412 is a communication bus configured, for example, based on the CAN (Control Area Network) standard.

[0227] The battery pack monitoring devices 301a to 301c measure the voltage and temperature of each individual cell constituting the battery packs 200a to 200c based on commands communicated from the battery management device 411. However, temperature can be measured at only a few locations per battery pack, and it is not necessary to measure the temperature of all individual cells.

[0228] The vehicle power supply 41 may also have an electromagnetic contactor (for example, a switch device 415 shown in Figure 13) that switches the presence or absence of an electrical connection between the positive terminal 413 and the negative terminal 414. The switch device 415 includes a pre-charge switch (not shown) that turns on when charging is performed on the battery packs 200a to 200c, and a main switch (not shown) that turns on when the output from the battery packs 200a to 200c is supplied to the load. Each of the pre-charge switch and the main switch includes a relay circuit (not shown) that is switched on or off by a signal supplied to a coil located near the switch element. Electromagnetic contactors such as the switch device 415 are controlled based on a control signal from the battery management device 411 or the vehicle ECU 42 that controls the operation of the entire vehicle 400.

[0229] The inverter 44 converts the input DC voltage into a high voltage of three-phase alternating current (AC) for motor drive. The three-phase output terminals of the inverter 44 are connected to the three-phase input terminals of the drive motor 45. The inverter 44 is controlled based on control signals from the battery management device 411 or the vehicle ECU 42 for controlling the operation of the entire vehicle. By controlling the inverter 44, the output voltage from the inverter 44 is adjusted.

[0230] The drive motor 45 rotates using power supplied from the inverter 44. The driving force generated by the rotation of the drive motor 45 is transmitted to the axle and drive wheels W, for example, via a differential gear unit.

[0231] Although not shown in the diagram, vehicle 400 is also equipped with a regenerative braking mechanism (regenerator). The regenerative braking mechanism rotates the drive motor 45 when vehicle 400 is braked, converting kinetic energy into regenerative energy as electrical energy. The regenerative energy recovered by the regenerative braking mechanism is input to the inverter 44 and converted into a DC current. The converted DC current is input to the vehicle power supply 41.

[0232] One terminal of the connection line L1 is connected to the negative terminal 414 of the vehicle power supply 41. The other terminal of the connection line L1 is connected to the negative input terminal 417 of the inverter 44. A current detection unit (current detection circuit) 416 in the battery management device 411 is provided in the connection line L1 between the negative terminal 414 and the negative input terminal 417.

[0233] One terminal of the connection line L2 is connected to the positive terminal 413 of the vehicle power supply 41. The other terminal of the connection line L2 is connected to the positive input terminal 418 of the inverter 44. A switch device 415 is provided in the connection line L2 between the positive terminal 413 and the positive input terminal 418.

[0234] The external terminal 43 is connected to the battery management device 411. The external terminal 43 can be connected to, for example, an external power supply.

[0235] The vehicle ECU 42 cooperatively controls the vehicle power supply 41, the switch device 415, the inverter 44, etc. together with other management devices and control devices including the battery management device 411 in response to operation inputs from the driver or the like. By the cooperative control of the vehicle ECU 42 etc., the output of electric power from the vehicle power supply 41 and the charging of the vehicle power supply 41 etc. are controlled, and the overall management of the vehicle 400 is performed. Between the battery management device 411 and the vehicle ECU 42, data transfer regarding the preservation of the vehicle power supply 41, such as the remaining capacity of the vehicle power supply 41, is performed via a communication line.

[0236] The vehicle according to the fifth embodiment mounts the battery pack according to the fourth embodiment. Therefore, since such a vehicle has high cycle performance and output performance of the battery pack, the reliability of the vehicle is high.

Example

[0237] Examples will be described below, but the embodiments are not limited to the examples described below.

[0238] (Example 1) <Production of the First Particles> The first particle was prepared by adding niobium titanium oxide particles to an inorganic particle-containing layer precursor solution and then calcining it, as described below.

[0239] <Preparation of Solution 1> To 500 mL of water, 1 g of nitric acid and 10 g of a 20% by mass solution of polyvinyl alcohol were added and stirred with a stirrer for 10 minutes. Then, 12 g of titanium tetraisopropoxide was added and stirred for 1 hour. Furthermore, 2.6 g of lithium nitrate, 9 g of ammonium dihydrogen phosphate, and 4 g of aluminum nitrate nonahydrate were added and stirred for 30 minutes. Thus, the first solution was obtained.

[0240] <Formation of an inorganic particle-containing layer> As a precursor solution for the inorganic particle-containing layer, the previously prepared first solution was prepared. Niobium titanium oxide particles were added to the first solution. At this time, the particles were added in a ratio such that the mass of the inorganic particle-containing layer obtained after calcination was 3% by mass relative to the mass of the niobium titanium oxide particles. This dispersion was stirred for 1 hour. After stirring, it was heated to 200°C and evaporated to dryness to obtain a dry powder. The dry powder was transferred to an alumina crucible and calcined in an electric furnace at 700°C for 8 hours. Thus, the first particle was obtained in which an inorganic particle-containing layer was formed on the surface of the niobium titanium oxide particles. The inorganic particle-containing layer contained solid electrolyte-containing particles. The solid electrolyte was Li 1.3 Al 0.3 Ti 1.7 The oxide-based solid electrolyte had a composition represented by (PO4)3. Thus, the first particle was obtained.

[0241] <Fabrication of the negative electrode> As negative electrode active material particles, 88% by mass of first particles, 4% by mass of acetylene black as a conductive agent, 2% by mass of carboxymethylcellulose (CMC) and 2% by mass of styrene-butadiene rubber (SBR) as binders, and 4% by mass of inorganic particles were mixed with pure water as a solvent. The inorganic particles used had an average particle size of 0.5 μm and contained a solid electrolyte. The solid electrolyte was Li 1.3 Al 0.3 Ti 1.7The oxide-based solid electrolyte had a composition represented by (PO4)3. The mixture was placed in a stirring vessel, and φ2 mm glass beads were added to a packing density of 60%. The mixture was stirred at 1500 rpm for 3 minutes to obtain a slurry. The stirred slurry was applied to one side of a current collector made of 12 μm thick aluminum foil and dried on a hot plate at 100°C. The slurry was also applied to the other side and dried on a hot plate at 100°C. A negative electrode was then obtained by pressing. The obtained negative electrode was a double-sided negative electrode in which negative electrode active material-containing layers were formed on both sides of the current collector.

[0242] <Fabrication of the positive electrode> Lithium nickel cobalt manganese composite oxide (LiNi) is used as the positive electrode active material. 0.8 Co 0.1 Mn 0.1 A slurry was prepared by mixing 90% by mass of O2, 5% by mass of acetylene black as a conductive agent, and 5% by mass of polyvinylidene fluoride (PVdF) as a binder with N-methylpyrrolidone (NMP) as a solvent. This slurry was applied to one side of a current collector made of 12 μm thick aluminum foil and dried in a constant temperature bath at 120°C. A positive electrode was then obtained by pressing. The resulting positive electrode was a single-sided positive electrode, in which a positive electrode active material-containing layer was formed on one side of the current collector.

[0243] <Fabrication of electrode groups> A laminate was obtained by stacking a single-sided positive electrode, a separator, a double-sided negative electrode, a separator, and a single-sided positive electrode in this order. The single-sided positive electrode was stacked so that the side coated with slurry faced the separator. A 15 μm thick porous polyethylene film was used as the separator. A flattened electrode group was fabricated by heating and pressing the laminate at 80°C. The obtained electrode group was placed in a pack made of a laminate film with a three-layer structure of nylon / aluminum / polyethylene layers and a thickness of 0.1 mm, and dried in a vacuum at 120°C for 16 hours.

[0244] <Preparation of non-aqueous electrolytes and fabrication of secondary batteries> A non-aqueous electrolyte was obtained by dissolving LiPF6 at a concentration of 1 mol / L as an electrolyte in a mixed solvent of propylene carbonate (PC) and diethyl carbonate (DEC) (volume ratio 1:2). The preparation of the non-aqueous electrolyte was carried out in an argon box.

[0245] After injecting a non-aqueous electrolyte into a laminate film pack containing the electrode array, the pack was completely sealed by heat sealing. This resulted in a secondary battery with a capacity of 300 mAh.

[0246] (Example 2) The addition ratio of niobium titanium oxide particles to the first solution was adjusted so that the mass of the inorganic particle-containing layer obtained after firing was 10% by mass relative to the mass of niobium titanium oxide particles. The average particle size of the inorganic particles was also changed to 1.0 μm. A secondary battery was fabricated in the same manner as in Example 1, except for the above.

[0247] (Example 3) The addition ratio of niobium titanium oxide particles to the first solution was adjusted so that the mass of the inorganic particle-containing layer obtained after firing was 0.5% by mass relative to the mass of the niobium titanium oxide particles. The average particle size of the inorganic particles was also changed to 0.9 μm. A secondary battery was fabricated in the same manner as in Example 1, except for the above.

[0248] (Example 4) The addition ratio of niobium titanium oxide particles to the first solution was adjusted so that the mass of the inorganic particle-containing layer obtained after firing was 15% by mass relative to the mass of niobium titanium oxide particles. The average particle size of the inorganic particles was also changed to 0.9 μm. A secondary battery was fabricated in the same manner as in Example 1, except for the above.

[0249] (Example 5) The addition ratio of niobium titanium oxide particles to the first solution was adjusted so that the mass of the inorganic particle-containing layer obtained after firing was 0.05% by mass relative to the mass of the niobium titanium oxide particles. The average particle size of the inorganic particles was also changed to 0.8 μm. A secondary battery was fabricated in the same manner as in Example 1, except for the above.

[0250] (Example 6) The average particle size of the inorganic particles was changed to 1.0 μm. Aside from the above, a secondary battery was fabricated in the same manner as in Example 1.

[0251] (Example 7) The average particle size of the inorganic particles was changed to 0.4 μm. Aside from the above, a secondary battery was fabricated in the same manner as in Example 1.

[0252] (Example 8) The average particle size of the inorganic particles was changed to 2.0 μm. Aside from the above, a secondary battery was fabricated in the same manner as in Example 1.

[0253] (Example 9) The average particle size of the inorganic particles was changed to 0.3 μm. Aside from the above, a secondary battery was fabricated in the same manner as in Example 1.

[0254] (Example 10) A secondary battery was fabricated in the same manner as in Example 2, except that glass beads were not added during the preparation of the negative electrode.

[0255] (Example 11) As the inorganic particle-containing layer precursor solution, a commercially available 98% aluminum isopropoxide solution was prepared instead of the first solution. Furthermore, the inorganic particles were changed to Al2O3 particles with an average particle size of 0.5 μm. A secondary battery was fabricated in the same manner as in Example 1, except for the above.

[0256] (Example 12) As the inorganic particle-containing layer precursor solution, a commercially available 97% titanium tetraisopropoxide solution was prepared instead of the first solution. Furthermore, the inorganic particles were changed to TiO2 particles with an average particle size of 0.5 μm. A secondary battery was fabricated in the same manner as in Example 1, except for the above.

[0257] (Example 13) As the inorganic particle-containing layer precursor solution, a commercially available 70% zirconium propoxide solution was prepared instead of the first solution. Furthermore, the inorganic particles were changed to ZrO2 particles with an average particle size of 0.5 μm. A secondary battery was fabricated in the same manner as in Example 1, except for the above.

[0258] (Example 14) As a precursor solution for the inorganic particle-containing layer, an aqueous magnesium sulfate solution was prepared instead of the first solution. The aqueous magnesium sulfate solution was prepared as follows: 20 g of magnesium sulfate heptahydrate was added to 100 g of water and stirred to obtain an aqueous magnesium sulfate solution. In addition, the inorganic particles were changed to MgO particles with an average particle size of 0.5 μm. A secondary battery was fabricated in the same manner as in Example 1, except for the above.

[0259] (Comparative Example 1) The preparation of the first particle was omitted. In the preparation of the negative electrode, niobium titanium oxide particles were used as the negative electrode active material particles. Except for the above, a secondary battery was prepared in the same manner as in Example 1.

[0260] (Comparative Example 2) A secondary battery was fabricated in the same manner as in Example 1, except that the addition of inorganic particles was omitted in the preparation of the negative electrode.

[0261] (Comparative Example 3) The addition ratio of niobium titanium oxide particles to the first solution was adjusted so that the mass of the inorganic particle-containing layer obtained after firing was 15% by mass relative to the mass of niobium titanium oxide particles. The average particle size of the inorganic particles was also changed to 0.5 μm. A secondary battery was fabricated in the same manner as in Example 1, except for the above.

[0262] (Comparative Example 4) The preparation of the first particle was omitted. In the preparation of the negative electrode, niobium titanium oxide particles were used as the negative electrode active material particles. In addition, the average particle size of the inorganic particles was changed to 1.0 μm. Furthermore, 5% by mass of solid electrolyte-containing particles with an average particle size of 0.5 μm was added. The solid electrolyte was Li 1.3 Al 0.3 Ti1.7 It was an oxide-based solid electrolyte represented as (PO4)3.

[0263] The cycle performance and output performance of the fabricated secondary batteries were evaluated using the following method. <Cycle Testing> The obtained secondary batteries were charged to 3.0V at 25°C with a constant current of 1C. Then, they were discharged to 1.5V at a 1C rate. This charge-discharge cycle was defined as one cycle. The discharge capacity was measured during the first discharge cycle. Next, the above charge-discharge cycle was repeated for a total of 200 cycles. The discharge capacity was measured during the 200th discharge cycle. The capacity retention rate (%) was calculated by dividing the discharge capacity at the 200th cycle by the discharge capacity at the first cycle and multiplying by 100. <0°C discharge performance test> The battery was charged to 3.0V at 25°C with a constant current of 1C, and then discharged to 1.5V at 0°C with a constant current of 1C. The discharge capacity was measured during discharge. The obtained discharge capacity was defined as the 0°C discharge capacity (mAh).

[0264] These measurement results are shown in Table 1. Note that the type and thickness of the inorganic particle-containing layer for the comparative example in which the preparation of the first particle was omitted, and the type of inorganic particles and the average particle diameter of the inorganic particles for the comparative example in which no inorganic particles were added, are indicated with "-".

[0265] [Table 1]

[0266] In the examples of secondary batteries containing an electrode that includes inorganic particles and a first particle, and in which the average particle diameter of the inorganic particles is greater than the thickness of the inorganic particle-containing layer, both the capacity retention rate and the 0°C discharge capacity were high. In other words, they exhibited excellent cycle performance and output performance.

[0267] Comparative Examples 1 and 4, in which the preparation of the first particle, i.e., the formation of an inorganic particle-containing layer on the surface of the niobium titanium oxide particle, was omitted, showed low capacity retention rates. This is thought to be because when hydrofluoric acid that was not captured by the inorganic particles approached the niobium titanium oxide particle, the hydrofluoric acid came into contact with the surface of the niobium titanium oxide particle, resulting in degradation of the niobium titanium oxide particle and a decrease in cycle performance.

[0268] Comparative Example 4 is an example in which the formation of the inorganic particle-containing layer was omitted, and solid electrolyte-containing particles were further added, but the cycle performance was lower compared to the example. From this, it is considered that when the solid electrolyte-containing particles are not formed in a layer on the surface of the niobium titanium oxide particles, that is, when they exist separately from the niobium titanium oxide particles, the effect of suppressing contact of hydrofluoric acid with the niobium titanium oxide particles is low.

[0269] Comparative Example 2, in which the addition of inorganic particles was omitted, showed a low capacity retention rate. This is thought to be because, in the electrode of Comparative Example 2, hydrofluoric acid was not captured by the inorganic particles, resulting in a greater amount of hydrofluoric acid approaching the first particle in the electrode compared to the electrode of the example. As a result, for example, the amount of hydrofluoric acid that came into contact with the surface of the niobium titanium oxide particles increased from the exposed portion of the first particle. Furthermore, it is thought that the amount of hydrofluoric acid that came into contact with the niobium titanium oxide particles increased as the amount of hydrofluoric acid exceeding the amount that the inorganic particle-containing layer could capture approached the first particle. As a result, it is thought that the niobium titanium oxide deteriorated, leading to a decrease in cycle performance.

[0270] Comparative Example 3, in which the thickness of the inorganic particle-containing layer was greater than the average particle diameter of the inorganic particles, had a lower 0°C discharge capacity compared to the example. In other words, its output performance was lower compared to the example. It is thought that in Comparative Example 3, the average particle diameter of the inorganic particles was relatively small compared to the thickness of the inorganic particle-containing layer, which reduced the dispersibility of the inorganic particles and conductive agent during the electrode manufacturing process, resulting in reduced uniformity of the presence of inorganic particles and conductive agent within the electrode. Furthermore, the active material particles in Comparative Example 3 had relatively low electronic conductivity due to the thickness of the inorganic particle-containing layer being greater than the average particle diameter of the inorganic particles. These factors are thought to have contributed to the reduced output performance of Comparative Example 3.

[0271] Comparing Examples 1-3 with Example 4, in which the inorganic particle-containing layer had a thickness of 0.7 μm, Examples 1-3 showed particularly high discharge capacity at 0°C. This is thought to be because Examples 1-3, with an inorganic particle-containing layer thickness of 0.4 μm or less, had a high effect in suppressing resistance increase. Therefore, it was revealed that electrodes containing the first particle with an inorganic particle-containing layer thickness of 0.4 μm or less exhibited particularly excellent output performance.

[0272] Furthermore, when comparing Examples 1-3 with Example 5, in which the inorganic particle-containing layer had a thickness of 0.0005 μm, Examples 1-3 showed particularly high capacity retention. This is thought to be because Examples 1-3 had higher durability against hydrofluoric acid due to the inorganic particle-containing layer having a thickness of 0.0010 μm or more. Therefore, it was revealed that electrodes containing the first particle with an inorganic particle-containing layer thickness of 0.0010 μm or more exhibited particularly excellent cycle performance.

[0273] Comparing Examples 1, 6, and 7 with Example 8, where the average particle size of the inorganic particles was 2.0 μm, and Example 9, where the average particle size of the inorganic particles was 0.3 μm, Examples 1, 6, and 7 showed particularly high volume retention rates. From these results, it is considered that the inorganic particles included in Examples 1, 6, and 7, with an average particle size of 0.4 μm to 1.0 μm, are within a suitable range for exhibiting hydrofluoric acid trapping ability. Therefore, it was revealed that electrodes with an average particle size of inorganic particles in the range of 0.4 μm to 1.0 μm exhibit particularly excellent cycle performance.

[0274] Example 10 is a secondary battery manufactured in the same manner as Example 2, except that glass beads were not added during the preparation of the negative electrode. It is thought that in Example 2, where glass beads were added during stirring, a portion of the surface of the niobium titanium oxide particles was exposed due to the abrasion of a portion of the surface of the inorganic particle-containing layer. In other words, it is thought that the first particles had exposed portions. Compared to Example 10, where glass beads were not added during stirring, Example 2 had a particularly high discharge capacity at 0°C. From this, it became clear that electrodes containing first particles with exposed portions have particularly excellent output performance.

[0275] Example 11 is an electrode in which the inorganic particle-containing layer contains particles containing a metal oxide containing Al, and the inorganic particles include Al2O3 particles. Example 12 is an electrode in which the inorganic particle-containing layer contains particles containing a metal oxide containing Ti, and the inorganic particles include TiO2 particles. Example 13 is an electrode in which the inorganic particle-containing layer contains particles containing a metal oxide containing Zr, and the inorganic particles include ZrO2 particles. Example 14 is an electrode in which the inorganic particle-containing layer contains particles containing a metal oxide containing Mg, and the inorganic particles include MgO particles. Examples 11 to 14 showed high values ​​for both capacity retention and 0°C discharge capacity. That is, they exhibited excellent cycle performance and output performance.

[0276] This demonstrates that the inorganic particle-containing layer can improve cycle performance and power output even when it contains particles that include a metal oxide containing at least one element selected from the group consisting of Al, Ti, Zr, and Mg.

[0277] According to at least one embodiment described above, an electrode is provided. The electrode comprises inorganic particles, niobium titanium oxide particles, and an inorganic particle-containing layer covering at least a portion of the surface of the niobium titanium oxide particles. The average particle diameter of the inorganic particles is greater than the thickness of the inorganic particle-containing layer. Therefore, such an electrode can improve cycle performance and output performance.

[0278] The invention according to the embodiment is described below.

[0279] <1> It comprises inorganic particles, niobium titanium oxide particles, and an inorganic particle-containing layer that covers at least a portion of the surface of the niobium titanium oxide particles. An electrode in which the average particle diameter of the inorganic particles is greater than the thickness of the inorganic particle-containing layer.

[0280] <2> The thickness of the inorganic particle-containing layer is within the range of 0.001 μm or more and 0.4 μm or less. <1> The electrodes described above.

[0281] <3> The average particle diameter of the inorganic particles is within the range of 0.4 μm to 1 μm. <1> or <2> The electrodes described above.

[0282] <4> The surface of the niobium titanium oxide particles includes portions not covered by the inorganic particle-containing layer, and at least a portion of the portions not covered by the inorganic particle-containing layer is exposed on the surface of the electrode. <1> ~ <3> The electrode described in any one of the items.

[0283] <5> The inorganic particles include at least one selected from the group consisting of metal oxides containing at least one element selected from the group consisting of Al, Ti, Si, Zr, and Mg, and solid electrolytes. <1> ~ <4> The electrode described in any one of the items.

[0284] <6> The inorganic particle-containing layer includes particles containing a metal oxide containing at least one element selected from the group consisting of Al, Ti, Si, Zr, and Mg, and at least one element selected from the group consisting of solid electrolyte-containing particles. <1> ~ <5> The electrode described in any one of the items.

[0285] <7> The inorganic particles contain a solid electrolyte, and the inorganic particle-containing layer contains solid electrolyte-containing particles. <1> ~ <6> The electrode described in any one of the items.

[0286] <8> It includes a positive electrode, a negative electrode, and a non-aqueous electrolyte. The non-aqueous electrolyte contains a fluorine atom, At least one of the positive electrode and the negative electrode is <1> ~ <7> A secondary battery having electrodes as described in any one of the items.

[0287] <9> <8> A battery pack comprising the rechargeable battery described above.

[0288] <10> External terminals for power supply, Protection circuit and It further comprises <9> The battery pack described above.

[0289] <11> The device comprises multiple secondary batteries, The aforementioned secondary batteries are electrically connected in series, parallel, or a combination of series and parallel. <9> or <10> The battery pack described above.

[0290] <12> <9> ~ <11> A vehicle equipped with a battery pack as described in any one of the items.

[0291] <13> This includes a mechanism that converts the kinetic energy of the vehicle into regenerative energy. <12> The vehicles listed.

[0292] While several embodiments of the present invention have been described, these embodiments are presented as examples only and are not intended to limit the scope of the invention. These novel embodiments can be carried out in a variety of other forms, and various omissions, substitutions, and modifications can be made without departing from the spirit of the invention. These embodiments and their variations are included in the scope and spirit of the invention, as well as in the claims of the invention and its equivalents. [Explanation of Symbols]

[0293] 1…Electrode group, 2…Outer material, 3…Electrode (negative electrode), 3a…Current collector (negative electrode current collector), 3b…Active material containing layer (negative electrode active material containing layer), 3c…Negative electrode current collector tab, 4…Separator, 5…Positive electrode, 5a…Positive electrode current collector, 5b…Positive electrode active material containing layer, 6…Negative electrode terminal, 7…Positive electrode terminal, 10…First particle, 11…Niobium titanium oxide particles, 12…Inorganic particle containing layer, 13…Inorganic particles, 14…Exposed part, 21…Bus bar -, 22...Positive electrode lead, 22a...Other end, 23...Negative electrode lead, 23a...Other end, 24...Adhesive tape, 30...Electrode, 30b...Active material-containing layer, 31...Housing container, 32...Lid, 33...Protective sheet, 34...Printed circuit board, 35...Wiring, 40...Vehicle body, 41...Vehicle power supply, 42...Electrical control device, 43...External terminals, 44...Inverter, 45...Drive motor, 100...Secondary battery, 200...Set Battery, 200a...Battery pack, 200b...Battery pack, 200c...Battery pack, 300...Battery pack, 300a...Battery pack, 300b...Battery pack, 300c...Battery pack, 301a...Battery pack monitoring device, 301b...Battery pack monitoring device, 301c...Battery pack monitoring device, 342...Positive side connector, 343...Negative side connector, 345...Thermistor, 346...Protection circuit, 342a...Wiring, 343a...Distribution 350... External terminal for power supply, 352... Positive terminal, 353... Negative terminal, 348a... Positive wiring, 348b... Negative wiring, 400... Vehicle, 411... Battery management device, 412... Communication bus, 413... Positive terminal, 414... Negative terminal, 415... Switch device, 416... Current detection unit, 417... Negative input terminal, 418... Positive input terminal, L1... Connection line, L2... Connection line, W... Drive wheel.

Claims

1. It comprises inorganic particles, niobium titanium oxide particles, and an inorganic particle-containing layer that covers at least a portion of the surface of the niobium titanium oxide particles. The average particle diameter of the inorganic particles is greater than the thickness of the inorganic particle-containing layer. The inorganic particles include at least one selected from the group consisting of metal oxides containing at least one element selected from the group consisting of Al, Ti, Si, Zr, and Mg, and solid electrolytes, and the electrode.

2. The electrode according to claim 1, wherein the thickness of the inorganic particle-containing layer is in the range of 0.001 μm or more and 0.4 μm or less.

3. The electrode according to claim 1, wherein the average particle diameter of the inorganic particles is in the range of 0.4 μm or more and 1 μm or less.

4. The electrode according to claim 1, wherein the surface of the niobium titanium oxide particles includes portions not covered by the inorganic particle-containing layer, and at least a portion of the portions not covered by the inorganic particle-containing layer is exposed on the surface of the electrode.

5. The electrode according to claim 1, wherein the inorganic particle-containing layer comprises particles containing a metal oxide containing at least one element selected from the group consisting of Al, Ti, Si, Zr, and Mg, and at least one selected from the group consisting of solid electrolyte-containing particles.

6. The electrode according to claim 1, wherein the inorganic particles contain a solid electrolyte, and the inorganic particle-containing layer contains solid electrolyte-containing particles.

7. It includes a positive electrode, a negative electrode, and a non-aqueous electrolyte. The non-aqueous electrolyte contains a fluorine atom, A secondary battery in which at least one of the positive electrode and the negative electrode is the electrode described in claim 1.

8. A battery pack comprising the secondary battery described in claim 7.

9. External terminals for power supply, Protection circuit and The battery pack according to claim 8, further comprising the above.

10. The device comprises multiple secondary batteries, The battery pack according to claim 8, wherein the secondary batteries are electrically connected in series, in parallel, or in a combination of series and parallel.

11. A vehicle equipped with the battery pack described in claim 8.

12. The vehicle according to claim 11, which includes a mechanism for converting the kinetic energy of the vehicle into regenerative energy.

Images