Non-aqueous electrolyte batteries, battery packs, and vehicles

Abstract

To provide a nonaqueous electrolyte battery with suppressed self-discharge, a battery pack including the nonaqueous electrolyte battery, and a vehicle including the battery pack.SOLUTION: A nonaqueous electrolyte battery 100 according to an embodiment includes an electrode group 1 including a positive electrode 5, a negative electrode 3, and a separator 4. The separator 4 includes one or more metal element-containing portions containing at least one selected from a group consisting of metal, metal oxides, and metal fluorides on a surface in contact with the negative electrode 3. An area of the one or more metal element-containing portions is 0.3 mm2 or more and 3.2 mm2 or less.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] Embodiments of the present invention relate to a non-aqueous electrolyte battery, a battery pack, and a vehicle. [Background technology]

[0002] Non-aqueous electrolyte batteries, such as lithium-ion secondary batteries, have the problem of increasing self-discharge over time. [Prior art documents] [Patent Documents]

[0003] [Patent Document 1] Japanese Patent Publication No. 2019-21510 [Patent Document 2] Japanese Patent Publication No. 2013-127857 [Overview of the Initiative] [Problems that the invention aims to solve]

[0004] The present invention has been made in view of the above circumstances, and aims to provide a non-aqueous electrolyte battery with suppressed self-discharge, a battery pack containing this non-aqueous electrolyte battery, and a vehicle containing this battery pack. [Means for solving the problem]

[0005] According to the embodiment, a non-aqueous electrolyte battery is provided. The non-aqueous electrolyte battery includes an electrode group comprising a positive electrode, a negative electrode, and a separator. The separator includes one or more metal element-containing portions on its surface in contact with the negative electrode, each containing at least one selected from the group consisting of metals, metal oxides, and metal fluorides. The area of ​​the one or more metal element-containing portions is 0.3 mm². 2 3.2mm 2 The following applies:

[0006] According to another embodiment, a battery pack including a non-aqueous electrolyte battery according to the embodiment is provided.

[0007] According to other embodiments, a vehicle including a battery pack according to the embodiment is provided. [Brief explanation of the drawing]

[0008] [Figure 1] A schematic cross-sectional view showing an example of a non-aqueous electrolyte battery according to this embodiment. [Figure 2] An enlarged cross-sectional view of section A of the non-aqueous electrolyte battery shown in Figure 1. [Figure 3] An enlarged cross-sectional view of section C of the non-aqueous electrolyte battery shown in Figure 1. [Figure 4] A schematic diagram showing an example of a separator included in a non-aqueous electrolyte battery according to this embodiment. [Figure 5] A schematic partially cutaway perspective view showing another example of a non-aqueous electrolyte battery according to the embodiment. [Figure 6] Figure 5 shows an enlarged cross-sectional view of section B of the non-aqueous electrolyte battery. [Figure 7] A schematic perspective view showing an example of a battery pack according to this embodiment. [Figure 8] An exploded perspective view schematically showing an example of a battery pack according to this embodiment. [Figure 9] A block diagram showing an example of the electrical circuit of the battery pack shown in Figure 8. [Figure 10] A partially transparent view schematically showing an example of a vehicle according to the embodiment. [Figure 11] 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]

[0009] (First Embodiment) The inventors of this invention conducted a detailed analysis of the self-discharge of non-aqueous electrolyte batteries and found that the inclusion of metal element-containing impurities during the manufacturing process of non-aqueous electrolyte batteries is one of the causes of increased self-discharge. The metal components contained in these impurities are oxidized and dissolved within the non-aqueous electrolyte battery, releasing metal ions. These metal ions can precipitate on the negative electrode, for example, when the negative electrode potential decreases during charging, forming crystal nuclei. Further deposition of metal components on these crystal nuclei can lead to the formation of coarse metal crystals on the negative electrode. When these metal crystals penetrate the separator and come into electrical contact with the positive electrode, an internal short circuit occurs, increasing self-discharge.

[0010] Based on these results, the inventors conducted diligent research and successfully realized a non-aqueous electrolyte battery according to the first embodiment.

[0011] According to the first embodiment, a non-aqueous electrolyte battery is provided. The non-aqueous electrolyte battery according to the first embodiment includes an electrode group comprising a positive electrode, a negative electrode, and a separator. The separator includes one or more metal element-containing portions on its surface in contact with the negative electrode, each containing at least one selected from the group consisting of metals, metal oxides, and metal fluorides. The area of ​​the one or more metal element-containing portions is 0.3 mm². 2 3.2mm 2 The following applies:

[0012] Non-aqueous electrolyte batteries may contain impurities containing metal elements during the manufacturing process. However, according to the non-aqueous electrolyte battery of this embodiment, even when the negative electrode potential decreases during charging, the deposition of metal on the surface of the separator in contact with the negative electrode can be suppressed. In this non-aqueous electrolyte battery, the area of ​​the metal element-containing portion is 0.3 mm². 2 3.2mm 2 Because it is so small, internal short circuits can be suppressed. Therefore, self-discharge can be suppressed. The method for measuring the area of ​​the metal element-containing portion of the separator will be described later.

[0013] The non-aqueous electrolyte battery according to this embodiment will be described in detail below with reference to the drawings.

[0014] The non-aqueous electrolyte battery may, for example, be a non-aqueous electrolyte battery that uses alkali metal ions as carrier ions. For example, it may be a lithium battery (lithium-ion battery). The non-aqueous electrolyte battery may be a rechargeable battery.

[0015] The non-aqueous electrolyte battery may further include an outer casing that houses an electrode group and an electrolyte.

[0016] Furthermore, the non-aqueous electrolyte battery may further include a negative electrode terminal electrically connected to the negative electrode and a positive electrode terminal electrically connected to the positive electrode.

[0017] Figure 1 is a schematic cross-sectional view showing an example of a non-aqueous electrolyte battery. Figure 2 is an enlarged cross-sectional view of part A of the non-aqueous electrolyte battery shown in Figure 1.

[0018] The non-aqueous electrolyte battery 100 shown in Figures 1 and 2 comprises a bag-shaped outer casing member 2 shown in Figure 1, an electrode group 1 shown in Figures 1 and 2, 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 within the electrode group 1.

[0019] The bag-shaped outer packaging member 2 consists of a laminate film comprising two resin layers and a metal layer interposed between them.

[0020] As shown in Figure 1, electrode group 1 is a flat, wound electrode group. As shown in Figure 2, 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.

[0021] 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 2. 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.

[0022] The positive electrode 5 includes a positive electrode current collector 5a and positive electrode active material-containing layers 5b formed on both sides thereof.

[0023] As shown in Figure 1, 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 fusion of this layer.

[0024] The electrode group shown in Figure 1 has a structure in which a positive electrode, separator, negative electrode, and separator (not shown) are stacked in this order and wound so that the negative electrode is located outside the positive electrode. Figure 3 is an enlarged cross-sectional view of section C of the non-aqueous electrolyte battery shown in Figure 1. In the examples shown in Figures 1 and 3, for example, at the outer peripheral end (winding end) of electrode group 1, the end of the positive electrode 5 protrudes more than the end of the negative electrode 3, and the end 18 of the separator 4 protrudes more than the end of the positive electrode 5.

[0025] The separator has a region 11. Region 11 is the portion located between the negative electrode 3 and the positive electrode 5. The end of region 11 may be, for example, the portion corresponding to the end of the negative electrode 3, located at the outer circumference end (winding end) of the electrode group 1 shown in Figures 1 and 3. The portion corresponding to the end of the negative electrode 3 may be, for example, the portion where the separator is in contact with the end of the negative electrode 3. If the end of the negative electrode 3 protrudes more than the end of the positive electrode 5 at the winding end of the electrode group 1, the end of region 11 may be the portion corresponding to the end of the positive electrode 5 located at the winding end. Note that the portion of the separator 4 shown in Figure 2 located between the outer casing member 2 and the negative electrode current collector 3a is not located between the negative electrode 3 and the positive electrode 5. That is, this portion is not included in region 11.

[0026] The separator 4 has a surface that contacts the negative electrode 3. At least a portion of the surface that contacts the negative electrode 3 is located within region 11. Furthermore, the surface that contacts the negative electrode 3 may also exist outside region 11. At least a portion of the surface that contacts the negative electrode 3 is included in region 11.

[0027] Region 11 includes the outermost layer 12. One end 16 of the outermost layer 12 may be the end of region 11. In the electrode group 1 shown in Figures 1 and 3, the other end 17 of the outermost layer 12 is located on the inner side of the outermost layer 12, at a position corresponding to the one end 16 of the outermost layer. In Figures 1 and 3, one end 16 of the outermost layer 12 and its extension are shown by a dashed line. The position corresponding to one end 16 of the outermost layer is, for example, the position where the dashed line intersects with the separator 4 on the inner side of the outermost layer 12 in the electrode group 1.

[0028] The inner layer 13 is the portion of region 11 excluding the outermost layer 12. The other end 17 of the outermost layer also serves as one end of the inner layer 13.

[0029] Figure 4 is a schematic diagram showing an example of a separator included in the wound electrode group shown in Figures 1 to 3, having an outermost layer 12 and an inner layer 13. The separator illustrated in Figure 4 includes parts other than region 11, but the separator may consist only of region 11.

[0030] The non-aqueous electrolyte battery according to this embodiment is not limited to the non-aqueous electrolyte battery with the configuration shown in Figures 1 to 3, but may also be a battery with the configuration shown in Figures 5 and 6, for example.

[0031] Figure 5 is a schematic partially cutaway perspective view showing another example of a non-aqueous electrolyte battery. Figure 6 is an enlarged cross-sectional view of section B of the non-aqueous electrolyte battery shown in Figure 5.

[0032] The non-aqueous electrolyte battery 100 shown in Figures 5 and 6 comprises an electrode group 1 shown in Figures 5 and 6, an outer casing member 2 shown in Figure 5, 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.

[0033] The exterior component 2 consists of a laminate film comprising two resin layers and a metal layer interposed between them.

[0034] As shown in Figure 6, 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 stacked alternately with a separator 4 interposed between them.

[0035] 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.

[0036] 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 6, 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.

[0037] 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 functions as a positive electrode current collector tab. The positive electrode current collector tab, like the negative electrode current collector tab 3c, 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.

[0038] The separator includes a region 11 located between the negative electrode 3 and the positive electrode 5. The separator also has a surface that contacts the negative electrode 3. At least a portion of the surface that contacts the negative electrode 3 is located within region 11. Furthermore, the surface that contacts the negative electrode 3 may also exist outside region 11. At least a portion of the surface that contacts the negative electrode 3 is included in region 11. However, in the stacked electrode group 1 shown in Figures 5 and 6, the separator located in the uppermost layer and the separator located in the lowermost layer are not located between the negative electrode 3 and the positive electrode 5. Therefore, these separators do not include region 11.

[0039] As shown in Figure 6, the positive electrode 5 is in contact with the uppermost separator 4. This positive electrode is the outermost (upper) positive electrode in the electrode group. The negative electrode 3 is in contact with the lowermost separator 4. This negative electrode is the outermost (lower) negative electrode in the electrode group.

[0040] The stacked electrode group 1 includes two outermost layers 12. There is one outermost layer 12 at the top and one at the bottom in Figure 6. The outermost layer 12 located at the top is the region of the separator that contacts the outermost (upper) positive electrode of the electrode group, and is positioned between the positive electrode and the negative electrode 3. The outermost layer 12 located at the bottom is the region of the separator that contacts the outermost (lower) negative electrode of the electrode group, and is positioned between the negative electrode and the positive electrode 5.

[0041] The inner layer 13 is the region of the separator located inward along the stacking direction of the electrode group, relative to the two outermost layers 12 mentioned above, and positioned between the positive and negative electrodes. In other words, the inner layer 13 is the portion of the region 11 positioned between the positive and negative electrodes, excluding the outermost layer 12.

[0042] The following provides a detailed explanation of the negative electrode, positive electrode, electrolyte, separator, outer casing, negative electrode terminal, and positive electrode terminal.

[0043] 1) Negative electrode The negative electrode can include a negative electrode current collector and a negative electrode active material-containing layer. The negative electrode active material-containing layer can be formed on one or both sides of the negative electrode current collector. The negative electrode active material-containing layer can include a negative electrode active material, and optionally a conductive agent and a binder.

[0044] Examples of the negative electrode active material include lithium titanate having a ramsdellite structure (e.g., Li 2+y Ti3O7, 0 ≦ y ≦ 3), lithium titanate having a spinel structure (e.g., Li 4+x Ti5O 12 , 0 ≦ x ≦ 3), 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 titanate oxide. The type of the negative electrode active material can be one kind or two or more kinds.

[0045] Examples of the orthorhombic titanium-containing composite oxide include compounds represented by Li 2+a M I 2-b Ti 6-c M II d O 14+σ Here, M I is at least one selected from the group consisting of Sr, Ba, Ca, Mg, Na, Cs, Rb, and K. M 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. Each subscript in the composition formula is 0 ≦ a ≦ 6, 0 ≦ b < 2, 0 ≦ c < 6, 0 ≦ d < 6, -0.5 ≦ σ ≦ 0.5. Specific examples of the orthorhombic titanium-containing composite oxide include Li 2+a Na2Ti6O 14 (0 ≦ a ≦ 6).

[0046] Examples of the monoclinic niobium titanate oxide include Li x Ti 1-y M1 y Nb 2-z M2 z O 7+δExamples of compounds represented by the formula are: 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. The subscripts in the compositional formula are 0≦x≦5, 0≦y<1, 0≦z<2, and -0.3≦δ≦0.3. A specific example of monoclinic niobium titanium oxide is Li x Nb2TiO7 (0≦x≦5) is one example.

[0047] Another example of monoclinic niobium titanium oxide is Li x Ti 1-y M3 y+z Nb 2-z O 7-δ A compound represented by the formula is shown below. Here, M3 is at least one selected from Mg, Fe, Ni, Co, W, Ta, and Mo. In the compositional formula, each subscript represents 0≦x≦5, 0≦y<1, 0≦z<2, and -0.3≦δ≦0.3.

[0048] Conductive agents are added to enhance current collection performance and reduce contact resistance between the negative electrode active material and the negative electrode 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, a carbon coating or an electronically conductive inorganic material coating may be applied to the surface of the negative electrode active material particles.

[0049] Binding agents are added to fill the gaps between dispersed negative electrode active materials and to bind the negative electrode active materials to the negative electrode current collector. Examples of binding agents include polytetrafluoroethylene (PTFE), polyvinylidene fluoride (PVdF), fluororubber, styrene-butadiene rubber, polyacrylic acid compounds, imide compounds, carboxymethyl cellulose (CMC), and salts of CMC. One of these may be used as a binding agent, or two or more may be used in combination.

[0050] The proportions of the negative electrode active material, conductive agent, and binder in the negative electrode active material-containing layer can be appropriately changed depending on the application of the negative electrode. For example, when the negative electrode is used as the negative electrode of a non-aqueous electrolyte battery, it is preferable to blend the negative electrode active material, conductive agent, and binder in proportions of 68% to 96% by weight, 2% to 30% by weight, and 2% to 30% by weight, respectively. By setting the amount of conductive agent to 2% by weight or more, the current collection performance of the negative electrode active material-containing layer can be improved. Furthermore, by setting the amount of binder to 2% by weight or more, sufficient bonding between the negative electrode active material-containing layer and the negative electrode current collector can be achieved, and excellent cycle performance can be expected. On the other hand, it is preferable to set the amount of conductive agent and binder to 30% by weight or less, respectively, in order to achieve high capacity.

[0051] The negative electrode 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 negative electrode active material. For example, the negative electrode 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 negative electrode current collector is preferably 5 μm to 20 μm. A negative electrode current collector with such a thickness can balance the strength of the negative electrode with weight reduction.

[0052] Furthermore, the negative electrode current collector may include portions on its surface where the negative electrode active material-containing layer is not formed. These portions can function as negative electrode current collector tabs.

[0053] The negative electrode can be manufactured, for example, by the following method. First, a slurry is prepared by suspending the negative electrode active material, conductive agent, and binder in a solvent. This slurry is applied to one or both sides of the negative electrode current collector. Next, the applied slurry is dried to obtain a laminate of the negative electrode active material-containing layer and the negative electrode current collector. After that, this laminate is pressed. In this way, the negative electrode is manufactured.

[0054] Alternatively, the negative electrode may be manufactured by the following method: First, a negative electrode active material, a conductive agent, and a binder are mixed to obtain a mixture. Next, this mixture is formed into pellets. Then, these pellets are placed on a negative electrode current collector to obtain the negative electrode.

[0055] The density of the negative electrode active material-containing layer (excluding the negative electrode 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:

[0056] 2) Positive electrode The positive electrode may include a positive electrode current collector and a positive electrode active material-containing layer. The positive electrode active material-containing layer may be formed on one or both sides of the positive electrode current collector. The positive electrode active material-containing layer may optionally include a positive electrode active material and a conductive agent and a binder.

[0057] For example, oxides or sulfides can be used as the positive electrode active material. The positive electrode may contain one compound alone or a combination of two or more compounds as the positive electrode active material. Examples of oxides and sulfides include compounds that can insert and remove Li or Li ions.

[0058] Examples of such compounds include, for example, manganese dioxide (MnO2), iron oxide, copper oxide, nickel oxide, lithium manganese composite oxide (e.g., Li x Mn2O4 or Li x MnO2; 0 < x ≦ 1), lithium nickel composite oxide (e.g., Li x NiO2; 0 < x ≦ 1), lithium cobalt composite oxide (e.g., Li x CoO2; 0 < x ≦ 1), lithium nickel cobalt composite oxide (e.g., Li x Ni 1-y Co y O2; 0 < x ≦ 1, 0 < y < 1), lithium manganese cobalt composite oxide (e.g., Li x Mn[[ID=Twenty]] y Co 1-y O2; 0 < x ≦ 1, 0 < y < 1), lithium manganese nickel composite oxide having a spinel structure (e.g., Li x Mn 2-y Ni y O4; 0 < x ≦ 1, 0 < y < 2), lithium phosphate having an olivine structure (e.g., Li x [[ID=三十一]]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 (e.g., V2O5), and lithium nickel cobalt manganese composite oxide (Li x Ni 1-y-z Co y Mn z O2; 0 < x ≦ 1, 0 < y < 1, 0 < z < 1, y + z < 1) are included.

[0059] Among the above, examples of more preferred compounds as the positive electrode active material include lithium manganese composite oxide having a spinel structure (e.g., Li x Mn2O4; 0 < x ≦ 1), lithium nickel composite oxide (e.g., Li x NiO2; 0 < x ≦ 1), lithium cobalt composite oxide (e.g., Li xCoO2; 0 < x ≤ 1), lithium nickel cobalt composite oxide (e.g., Li x Ni 1-y Co y O2; 0 < x ≤ 1, 0 < y < 1), lithium manganese nickel composite oxide having a spinel structure (e.g., Li x Mn 2-y Ni y O4; 0 < x ≤ 1, 0 < y < 2), lithium manganese cobalt composite oxide (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 oxide (Li x Ni 1-y-z Co y Mn z O2; 0 < x ≤ 1, 0 < y < 1, 0 < z < 1, y + z < 1) are included. When these compounds are used as the positive electrode active material, the positive electrode potential can be increased.

[0060] When a room temperature molten salt is used 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), lithium manganese composite oxide, lithium nickel composite oxide, 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.

[0061] The primary particle size of the positive electrode active material is preferably 100 nm or more and 1 μm or less. A positive electrode active material with a primary particle size of 100 nm or more is easy to handle in industrial production. A positive electrode active material with a primary particle size of 1 μm or less can allow the solid-state diffusion of lithium ions to proceed smoothly.

[0062] The specific surface area of the positive electrode active material is preferably 0.1 m 2 / g or more and 10 m 2 / g or less. A positive electrode active material with a specific surface area of 0.1 m 2A 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 ensure good charge-discharge cycle performance.

[0063] 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.

[0064] 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.

[0065] 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 weight and 2% to 20% by weight, respectively.

[0066] Sufficient electrode strength can be obtained by using a binder amount of 2% by weight or more. Furthermore, the binder can function as an insulator. Therefore, reducing the binder amount to 20% by weight or less reduces the amount of insulator contained in the electrode, thereby reducing internal resistance.

[0067] 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 weight, 2% to 20% by weight, and 3% to 15% by weight, respectively.

[0068] The above-mentioned effects can be achieved by increasing the amount of conductive agent to 3% by weight or more. Furthermore, by reducing the amount of conductive agent to 15% by weight 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.

[0069] 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.

[0070] 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 weight 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 weight or less.

[0071] 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.

[0072] The positive electrode can be fabricated, for example, using a positive electrode active material in the same manner as the negative electrode.

[0073] 3) Electrolyte As the electrolyte, for example, a liquid non-aqueous electrolyte or a gel-type non-aqueous electrolyte can be used. A liquid non-aqueous electrolyte is prepared by dissolving an electrolyte salt as a solute in an organic solvent. The concentration of the electrolyte salt is preferably 0.5 mol / L or more and 2.5 mol / L or less.

[0074] Examples of electrolyte salts include lithium salts such as lithium perchlorate (LiClO4), lithium hexafluoride phosphate (LiPF6), lithium tetrafluoroborate (LiBF4), lithium arsenide hexafluoride (LiAsF6), lithium trifluoromethanesulfonate (LiCF3SO3), and lithium bistrifluoromethylsulfonylimide (LiN(CF3SO2)2), as well as mixtures thereof. The electrolyte salt is preferably resistant to oxidation even at high potentials, with LiPF6 being the most preferred.

[0075] 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.

[0076] Gel-like non-aqueous electrolytes are prepared by compounding a liquid non-aqueous electrolyte with a polymer material. Examples of polymer materials include polyvinylidene fluoride (PVdF), polyacrylonitrile (PAN), polyethylene oxide (PEO), or mixtures thereof.

[0077] Alternatively, in addition to liquid nonaqueous electrolytes and gel-type nonaqueous electrolytes, room-temperature molten salts (ionic melts) containing lithium ions, polymer solid electrolytes, and inorganic solid electrolytes may be used as nonaqueous electrolytes. The type of nonaqueous electrolyte can be one or more.

[0078] 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 non-aqueous electrolyte batteries is 25°C or lower. Also, organic cations generally have a quaternary ammonium skeleton.

[0079] Polymeric solid electrolytes are prepared by dissolving an electrolyte salt in a polymer material and then solidifying it.

[0080] Inorganic 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 inorganic solid electrolytes include oxide-based solid electrolytes and sulfide-based solid electrolytes. Specific examples of inorganic solid electrolytes are as follows.

[0081] As an oxide-based solid electrolyte, it has a NASICON (Sodium (Na) Super Ionic Conductor) type structure, and its general formula is Li1+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.

[0082] Specific examples of the lithium phosphate solid electrolyte having a NASICON-type structure include Li 1+x Al x Ti 2-x (PO4)3 and the LATP compound where 0.1≦x≦0.5; Li 1+x Al y Mβ 2-y (PO4)3 and the 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 and the compound where 0≦x≦2; and, Li 1+x Al x Zr 2-x (PO4)3 and the compound where 0≦x≦2; Li 1+x+y Al x Mγ 2-x Si y P 3-y O 12 and the compound where 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 and the compound where 0≦x<1 can be mentioned.

[0083] In addition, as the oxide-based solid electrolyte, in addition to the above lithium phosphate solid electrolyte, there is also an amorphous LIPON compound represented by Li x PO y N z 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 N0.46 ); 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 by , where Mδ is 1 or more selected from the group consisting of Nb and Ta, and 0 ≤ x ≤ 2, it 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.

[0084] 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.

[0085] The electrolyte may contain metal ions released, for example, by the oxidation of the aforementioned impurities. Examples of metal ions include Co ions, Fe ions, Cu ions, Ni ions, and Mn ions. The number of metal ions can be one or more.

[0086] 4) Separator The separator includes a metal element-containing portion on the surface that contacts the negative electrode.

[0087] The separator may be, for example, a sheet having two main surfaces. The surface in contact with the negative electrode may be present on at least one of the main surfaces of the separator. The surface in contact with the negative electrode may be present on both main surfaces of the separator, but it is preferable that the portion of the separator in which a surface in contact with the negative electrode is present on one main surface is not in contact with the negative electrode on the other main surface.

[0088] As explained earlier, the separator includes a region positioned between the positive and negative electrodes. At least a portion of the surface in contact with the negative electrode is located within this region. Furthermore, there may be additional surfaces in contact with the negative electrode outside this region.

[0089] 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.

[0090] The metal element-containing portion is included on the surface of the separator that is in contact with the negative electrode. The metal element-containing portion may also be included on the surface of the separator that is in contact with the positive electrode, and may penetrate the separator along its thickness. Furthermore, the metal element-containing portion may span both the negative electrode and the separator.

[0091] The area containing the metal element is 0.3 mm². 2 3.2mm 2The area is small. Therefore, even when the metal element-containing portion penetrates the separator, the contact interface with the positive electrode is unlikely to become dense. Also, the positive electrode surface has a high potential. Therefore, the metal elements contained in the metal element-containing portion can be oxidized and ionized on the surface of the separator that is in contact with the positive electrode, and can dissolve in the electrolyte. When the area of ​​the metal element-containing portion is small, the dissolution of the metal element-containing portion tends to proceed more favorably than its growth. Therefore, the metal element-containing portion is unlikely to come into contact with the positive electrode. Consequently, even when the metal element-containing portion penetrates the separator, internal short circuits are unlikely to occur, and self-discharge can be suppressed.

[0092] The separator may contain one or more metal element-containing portions.

[0093] If the separator contains multiple metal element-containing portions, the area of ​​the metal element-containing portion with the largest area among the multiple metal element-containing portions shall be 0.3 mm². 2 3.2mm 2 The following range is preferable.

[0094] The separator preferably contains multiple metal element-containing portions. When the separator contains multiple metal element-containing portions, the number of metal deposition sites can be increased.

[0095] When the number of precipitation sites is small, metal ions can be reduced and precipitated on a small number of sites. As a result, coarse metal crystals may form on each precipitation site. Consequently, internal short circuits may occur. When the number of precipitation sites is large, metal ions can be dispersed on many of the precipitation sites. Therefore, even when metal ions are reduced, coarse metal crystals are less likely to form. Thus, if the separator contains multiple metal element-containing sections, internal short circuits can be further suppressed.

[0096] For example, it is desirable that the number of metal element-containing regions per unit area in the outermost layer is greater than the number of metal element-containing regions per unit area in the inner layers.

[0097] The number of metallic elements per unit area in the outermost layer is 200 / m². 2 More than 1290 pieces / m 2 Preferably, it is 200 pieces / m 2 More than 1000 pieces / m 2 The following is more preferable: The number of metal element-containing parts per unit area in the outermost layer is 200 / m². 2 As a result, more metal deposition sites can be created, thus suppressing the formation of coarse metal crystals. Therefore, internal short circuits can be suppressed. In addition, the number of metal element-containing parts per unit area in the outermost layer is 1000 / m². 2 The following conditions can prevent the formation of excessive short circuits and reduce self-discharge.

[0098] The metal element-containing portion includes, for example, at least one metal element selected from the group consisting of Co, Fe, Cu, Ni, and Mn.

[0099] Metallic elements may originate from impurities that may be introduced during the manufacturing process of non-aqueous electrolyte batteries. During the manufacturing process of non-aqueous electrolyte batteries, foreign substances such as metal powder may be introduced as impurities. These impurities may include the aforementioned metallic elements. Furthermore, Co and Fe are contained, for example, in catalysts used in the production of carbon nanotubes. These catalysts may remain as impurities in the carbon nanotubes. Carbon nanotubes can be added to electrodes as conductive agents, for example. Therefore, Co and Fe may be introduced into non-aqueous electrolyte batteries.

[0100] The metal element-containing portion may be, for example, a metal, a metal oxide, or a metal fluoride. The metal element-containing portion may contain one of the above, or two or more. Each of the metal, metal oxide, and metal fluoride may contain at least one metal element selected from the group consisting of Co, Fe, Cu, Ni, and Mn.

[0101] Examples of metals include metals containing at least one metallic element selected from the group consisting of Co, Fe, Cu, Ni, and Mn. The metal may be a single element containing one metallic element, or it may contain two or more metallic elements. Examples of metal oxides include MO, M2O3, M3O4, M2O3, and M3O4. Here, M is at least one metallic element selected from the group consisting of Co, Fe, Cu, Ni, and Mn. The metal element-containing portion may contain one of the above metal oxides, or it may contain two or more. Examples of metal fluorides include MF, MF2, and MF3. Here, M is at least one metallic element selected from the group consisting of Co, Fe, Cu, Ni, and Mn. The metal element-containing portion may contain one of the above metal fluorides, or it may contain two or more.

[0102] Metals can be elemental metals, for example, precipitated by the reduction of metal ions in an electrolyte. Metal oxides can be formed, for example, by the oxidation of precipitated metals. Metal fluorides can be formed, for example, by the reaction of hydrogen fluoride with precipitated metals. Hydrogen fluoride will be discussed later.

[0103] The metal element-containing portion may be formed by the deposition of metal. The metal element-containing portion may also be formed by the layered deposition of at least one selected from the group consisting of metals, metal oxides, and metal fluorides. Furthermore, the shape of the metal element-containing portion can be any shape, such as granular or striped.

[0104] The metal element-containing portion may or may not be conductive. However, from the viewpoint of preventing internal short circuits, it is preferable that the metal element-containing portion is not conductive.

[0105] 5) Exterior components For example, the outer packaging material can be a container made of laminate film or a metal container.

[0106] The thickness of the laminating film is, for example, 0.5 mm or less, and preferably 0.2 mm or less.

[0107] 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.

[0108] 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.

[0109] 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 weight or less.

[0110] 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.

[0111] 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.

[0112] 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.

[0113] (Method for forming a metal element-containing portion) The metal element-containing portion can be formed, for example, as follows:

[0114] First, after assembling the electrode group, the electrolyte is injected and the opening of the outer casing is closed to create a non-aqueous electrolyte battery. Then, before the initial charge, it is preferable to hold the non-aqueous electrolyte battery in a pre-charge state. Pre-charge hold is preferably performed at a high temperature of 60°C to 80°C for 4 to 48 hours.

[0115] In the manufacturing process of non-aqueous electrolyte batteries, water inevitably becomes an impurity. When water reacts with the electrolyte, hydrogen fluoride (HF) can be produced. This reaction consumes the water inside the non-aqueous electrolyte battery. The produced hydrogen fluoride can react with metal elements contained in the impurities. As a result, the impurities may dissolve, and metal ions may be released into the electrolyte.

[0116] The hydrogen fluoride generation reaction and the impurity dissolution reaction described above tend to increase exponentially with increasing temperature. Therefore, by holding the electrolyte at 60°C or higher before charging, these reactions can be further promoted. As a result, the concentration of metal ions in the electrolyte can be increased.

[0117] The formation of metal element-containing regions tends to be less likely when the metal ion concentration in the electrolyte is below a threshold. Conversely, when the metal ion concentration is above the threshold, the frequency of metal element-containing region formation tends to increase in proportion to the metal ion concentration. As a result, the number of metal element-containing regions per unit area contained in the separator can increase.

[0118] Even when the metal ion concentration is above a threshold, if the metal ion concentration is relatively low, the frequency of metal element-containing regions tends to decrease. Therefore, each metal element-containing region can grow coarsely.

[0119] Therefore, by holding the electrolyte at a high temperature before charging, the initial charge can be performed with a high concentration of metal ions in the electrolyte. As a result, in an environment where the metal ion concentration has increased to the level necessary for nucleation of the deposition sites, the electrochemical overpotential necessary for metal deposition is applied. This leads to the formation of minute deposition sites at a high frequency, increasing the number of metal element-containing parts per unit area in the separator. For example, the number of metal element-containing parts per unit area in the outermost layer of the separator can be increased to 200 parts / m². 2 More than 1290 pieces / m 2 The following is preferable:

[0120] Furthermore, holding the battery at a high temperature before charging allows for the consumption of water inside the non-aqueous electrolyte battery before the initial charge. This reduces the amount of water remaining inside the non-aqueous electrolyte battery after the initial charge. Consequently, the generation of hydrogen fluoride and the dissolution of impurities after the initial charge can be suppressed. Therefore, for example, self-discharge caused by the growth of metal element-containing parts during storage and charge / discharge after the initial charge can be suppressed.

[0121] By performing the pre-charge hold at 80°C or lower, deterioration of the electrolyte can be suppressed.

[0122] After the pre-charge hold, the first charge can be carried out. The first charge is preferably carried out at a charge rate of 2C or more and 10C or less (rapid charging). Also, it is preferably carried out at a low temperature of about -20°C to 0°C. It is more preferable to perform the first charge rapidly at a low temperature.

[0123] By rapidly performing the first charge at a charge rate of 2C or more and 10C or less, an overvoltage required for metal deposition can be applied, so that metal can be efficiently deposited. Therefore, a metal element-containing portion can be efficiently formed. By performing the first charge at a low temperature, growth of the metal element-containing portion can be suppressed.

[0124] When the pre-charge hold is performed at a high temperature and then the first charge is rapidly performed at a low temperature, a small metal element-containing portion with an area of, for example, 0.3 mm 2 or more and 3.2 mm 2 can be formed frequently, which is preferable.

[0125] The metal element-containing portion containing a metal oxide can be formed, for example, by electrochemically reducing metal ions dissolved in the electrolyte to deposit a metal and then oxidizing the metal. The metal element-containing portion containing a metal fluoride can be formed, for example, when the electrolyte contains a fluorine-containing salt such as LiPF6 or LiBF4 as a Li salt, by the reaction of HF generated by the reaction of those Li salts with metal ions.

[0126] The negative electrode active material preferably contains at least one selected from the group consisting of titanium oxide and niobium titanate. Since these negative electrode active materials are less likely to react with the electrolyte even at high temperatures, deterioration of the electrolyte can be suppressed even when the pre-charge hold is performed at a high temperature. Also, since lithium ion conduction is good even at low temperatures, the first charge can be rapidly performed at a low temperature.

[0127] <XRF Analysis> Compositional analysis of metal element-containing regions, measurement of the area of ​​metal element-containing regions, and measurement of the number of metal element-containing regions per unit area can be performed by X-ray fluorescence (XRF) analysis. Specifically, this can be done as follows.

[0128] First, after completely discharging the non-aqueous electrolyte battery, the battery is disassembled in a glove box filled with argon, and the separator is removed. The side of the separator facing the negative electrode is used for measurement. If necessary, the portion of the separator to be observed is cut out. For example, the outermost and inner layers of the separator are cut out. The obtained separator is soaked in ethanol and ultrasonically cleaned for 5 minutes. The cleaned separator is dried in the air. If electrode fragments are attached to the separator, they are removed by compressed air or wiping. In this way, a sample for observation is obtained.

[0129] The observation samples will be subjected to XRF analysis under the following conditions.

[0130] Tube voltage: 50kV Tube current: 1000μA Collimator: 1.2 x 1.2 mm Field of view: 30mm x 50mm area (276 x 494 pixels) The composition of the metal element-containing region is qualitatively analyzed from the elemental mapping data obtained by XRF.

[0131] Next, the XRF mapping image data within the measurement field of view is binarized using Image J (version 1.52a). Specifically, the acquired image is converted to grayscale, the substrate region of the separator is used as the baseline, and the median value of the maximum brightness peak of the metal element-containing area is set as the threshold to perform binarization of the image data. In binarization, for example, areas with brightness below the threshold can be represented as white, and areas with brightness above the threshold can be represented as black.

[0132] For the obtained binarized image, the area of ​​the metal element-containing region and the number of metal element-containing regions per unit area are measured. In the binarized image, as mentioned above, the areas where the brightness is above the threshold are the metal element-containing regions. If the observation sample contains multiple metal element-containing regions, the area of ​​the metal element-containing region with the largest area is taken as the area of ​​the metal element-containing region contained in the observation sample. If the observation sample contains only one metal element-containing region, the area of ​​that metal element-containing region is taken as the area of ​​the metal element-containing region contained in the observation sample. The number of metal element-containing regions per unit area can be calculated using the particle counting process (Analyze particle) in Image J. The particle detection conditions are set to size from 0 to infinity and roundness from 0 to 1 for the analysis. This allows for the measurement of the total number of black regions with boundaries in the binarized image, i.e., regions where the brightness is above the threshold.

[0133] If the measurement field of view is insufficient, measurements should be taken using multiple fields of view, and the entire sample for observation should be analyzed. When acquiring images from multiple fields of view, it is preferable to acquire images at a resolution of 0.1 mm / 1 pixel or less to obtain sufficient accuracy for extracting boundaries during image analysis. If the resolution is larger than 0.1 mm / 1 pixel, there is a concern that the size and boundaries of the metal element-containing area to be detected may become unclear.

[0134] The fact that the number of metal element-containing particles per unit area in the outermost layer is greater than the number of metal element-containing particles per unit area in the inner layer can be confirmed by measuring the number of metal element-containing particles per unit area in both the outermost and inner layers and comparing the values.

[0135] The non-aqueous electrolyte battery according to the first embodiment includes an electrode group comprising a positive electrode, a negative electrode, and a separator. The separator contains one or more metal element-containing portions on its surface in contact with the negative electrode, each containing at least one selected from the group consisting of metals, metal oxides, and metal fluorides. The area of ​​the one or more metal element-containing portions is 0.3 mm². 2 3.2mm 2The following applies. Therefore, such a non-aqueous electrolyte battery can suppress self-discharge.

[0136] (Second embodiment) According to a second embodiment, a battery pack is provided, which includes a plurality of non-aqueous electrolyte batteries according to the first embodiment.

[0137] 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.

[0138] Next, an example of a battery pack according to the embodiment will be described with reference to the drawings.

[0139] Figure 7 is a schematic perspective view showing an example of a battery pack. The battery pack 200 shown in Figure 7 includes 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 non-aqueous electrolyte battery according to the first embodiment.

[0140] 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 7 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.

[0141] 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.

[0142] The battery pack according to the second embodiment includes a non-aqueous electrolyte battery according to the first embodiment. Therefore, self-discharge can be suppressed.

[0143] (Third embodiment) According to a third embodiment, a battery pack is provided. This battery pack includes a battery pack according to a second embodiment. This battery pack may include a single non-aqueous electrolyte battery according to a first embodiment instead of the battery pack according to the second embodiment.

[0144] The battery pack may further include a protection circuit. The protection circuit has the function of controlling the charging and discharging of the non-aqueous electrolyte 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.

[0145] Furthermore, such a battery pack may also include external terminals for power supply. These external terminals are for outputting current from the non-aqueous electrolyte battery to the outside and / or for inputting current from the outside to the non-aqueous electrolyte 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.

[0146] Next, an example of a battery pack according to the embodiment will be described with reference to the drawings.

[0147] Figure 8 is an exploded perspective view schematically showing an example of a battery pack. Figure 9 is a block diagram showing an example of the electrical circuit of the battery pack shown in Figure 8.

[0148] The battery pack 300 shown in Figures 8 and 9 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).

[0149] The container 31 shown in Figure 8 is a rectangular-bottomed rectangular container. 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.

[0150] The battery pack 200 comprises multiple individual cells 100, a positive electrode lead 22, a negative electrode lead 23, and an adhesive tape 24.

[0151] At least one of the multiple single cells 100 is a non-aqueous electrolyte battery according to the first embodiment. Each of the multiple single cells 100 is electrically connected in series as shown in Figure 9. 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.

[0152] 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.

[0153] 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.

[0154] 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.

[0155] 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.

[0156] 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.

[0157] 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.

[0158] 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.

[0159] 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.

[0160] 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.

[0161] 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.

[0162] 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.).

[0163] 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.

[0164] 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.

[0165] 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.

[0166] The battery pack according to the third embodiment comprises a non-aqueous electrolyte battery according to the first embodiment or a battery pack according to the second embodiment. Therefore, self-discharge can be suppressed.

[0167] (Fourth embodiment) According to a fourth embodiment, a vehicle is provided, which includes a battery pack according to a third embodiment.

[0168] 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.

[0169] 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.

[0170] 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.

[0171] A vehicle may be equipped with multiple battery packs. In this case, the batteries contained in each battery pack may be electrically connected in series, in parallel, or a combination of series and parallel connections. For example, if each battery pack contains a battery pack, the battery packs may be electrically connected in series, in parallel, or a combination of series and parallel connections. Alternatively, if each battery pack contains a single battery, the batteries may be electrically connected in series, in parallel, or a combination of series and parallel connections.

[0172] Next, an example of a vehicle according to the embodiment will be described with reference to the drawings.

[0173] Figure 10 is a schematic partial transparency drawing showing an example of a vehicle.

[0174] The vehicle 400 shown in Figure 10 includes a vehicle body 40 and a battery pack 300 according to the third embodiment. In the example shown in Figure 10, the vehicle 400 is a four-wheeled automobile.

[0175] This vehicle 400 may be equipped with multiple battery packs 300. In this case, the batteries contained in the battery pack 300 (for example, single cells or battery packs) may be connected in series, in parallel, or in a combination of series and parallel connections.

[0176] Figure 10 illustrates an example in which the battery pack 300 is mounted in the engine compartment located in front of the vehicle body 40. As described above, the battery pack 300 may also be mounted, for example, in the rear of the vehicle body 40 or under the seats. This battery pack 300 can be used as a power source for the vehicle 400. In addition, this battery pack 300 can recover regenerative energy from the vehicle 400's power.

[0177] Next, an embodiment of the vehicle according to the embodiment will be described with reference to Figure 11.

[0178] Figure 11 is a schematic diagram illustrating an example of a control system for the electrical system in a vehicle. The vehicle 400 shown in Figure 11 is an electric vehicle.

[0179] The vehicle 400 shown in Figure 11 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.

[0180] Vehicle 400 has a 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 the vehicle 400 shown in Figure 11, the mounting location of the vehicle power supply 41 is shown in a schematic manner.

[0181] 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.

[0182] 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.

[0183] Each of the battery packs 200a to 200c comprises a plurality of single cells connected in series. At least one of the plurality of single cells is a non-aqueous electrolyte battery according to the first embodiment. Each of the battery packs 200a to 200c is charged and discharged through the positive terminal 413 and the negative terminal 414, respectively.

[0184] 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.

[0185] 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.

[0186] 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.

[0187] The vehicle power supply 41 may also have an electromagnetic contactor (for example, a switch device 415 shown in Figure 11) 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.

[0188] 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.

[0189] 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.

[0190] 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.

[0191] One terminal of connection line L1 is connected to the negative terminal 414 of the vehicle power supply 41. The other terminal of connection line L1 is connected to the negative input terminal 417 of the inverter 44. A current detection unit (current detection circuit) 416 within the battery management device 411 is provided on connection line L1 between the negative terminal 414 and the negative input terminal 417.

[0192] One terminal of connection line L2 is connected to the positive terminal 413 of the vehicle power supply 41. The other terminal of connection line L2 is connected to the positive input terminal 418 of the inverter 44. A switch device 415 is provided between the positive terminal 413 and the positive input terminal 418 of connection line L2.

[0193] External terminal 43 is connected to battery management device 411. External terminal 43 can be connected to an external power supply, for example.

[0194] The vehicle ECU 42, in response to operational inputs from the driver and others, coordinates control of the vehicle power supply 41, switch device 415, inverter 44, etc., together with other management and control devices, including the battery management device 411. Through the coordinated control of the vehicle ECU 42, etc., the output of power from the vehicle power supply 41 and the charging of the vehicle power supply 41 are controlled, and the entire vehicle 400 is managed. Data related to the maintenance of the vehicle power supply 41, such as the remaining capacity of the vehicle power supply 41, is transferred between the battery management device 411 and the vehicle ECU 42 via a communication line.

[0195] The vehicle according to the fourth embodiment includes a battery pack according to the third embodiment. Therefore, according to this embodiment, it is possible to provide a vehicle that includes a battery pack capable of suppressing self-discharge. [Examples]

[0196] Examples are described below, but the embodiments are not limited to those described below.

[0197] (Example 1) <Fabrication of the positive electrode> The positive electrode was fabricated as follows.

[0198] A slurry was prepared by mixing 90% by weight of LiMn2O4 powder as the positive electrode active material, 5% by weight of acetylene black (AB) as the conductive agent, and 5% by weight of polyvinylidene fluoride (PVdF) as the binder with N-methylpyrrolidone (NMP) as the solvent. This slurry was then applied to a 20 μm thick aluminum foil as the positive electrode current collector at a density of 100 g / m². 2 The coating was applied using the specified amount. The solvent was then removed by drying on a hot plate at 120°C. The same coating process was carried out on the reverse side. After that, the electrodes were pressed to an electrode density of 2.5 g / cc using a roll press. Thus, a positive electrode coated on both sides was fabricated.

[0199] <Fabrication of the negative electrode> The negative electrode was fabricated as follows.

[0200] A slurry was prepared by mixing 87 wt% Ti2NbO7 (monoclinic titanium niobium oxide) particles as the negative electrode active material, 4 wt% acetylene black (AB) and 4 wt% multi-walled carbon nanotubes (MWCNT) as conductive agents, and 5 wt% polyvinylidene fluoride (PVdF) as a binder, with N-methylpyrrolidone (NMP) as the solvent. The multi-walled carbon nanotubes had an average fiber diameter of 10 nm and an average fiber length of 25 μm, and contained 10,000 ppm of Co as an impurity. For mixing, 1 mm diameter glass beads equivalent to 50% by weight of the negative electrode active material were mixed, and the mixture was heated in a rotary-orbit mixer at 2000 rpm for 10 minutes at a solid content concentration of 60%. The glass beads were removed from the slurry after mixing by filtering through a mesh. This slurry was then applied to 20 μm thick aluminum foil as a current collector at a density of 100 g / m². 2 The coating was applied using the specified amount. The solvent was then removed by drying on a hot plate at 120°C. The same coating process was carried out on the reverse side. After that, the electrodes were pressed to an electrode density of 2.0 g / cc using a roll press. Thus, a negative electrode coated on both sides was fabricated.

[0201] <Fabrication of electrode groups> The positive and negative electrodes were punched out to have an electrode area of ​​65 mm x 30 mm. The positive electrode, a separator made of 25 μm thick porous polyethylene film, the negative electrode, and the separator were repeatedly stacked in this order, and each side of the outer perimeter was secured with tape. In this stacked structure, the top and bottom layers were made of separators. The stacked electrode group was fabricated by heating and pressing at 80°C.

[0202] <Fabrication of non-aqueous electrolyte batteries> The positive and negative terminals were welded to the electrode group. The positive terminal was welded to the portion of the positive electrode current collector that was not coated with slurry. The negative terminal was welded to the portion of the negative electrode current collector that was not coated with slurry.

[0203] Next, the electrode group was placed in a pack made of laminate film and vacuum-dried at 80°C for 24 hours. The laminate film used was constructed by forming polypropylene layers on both sides of a 40 μm thick aluminum foil, with an overall thickness of 0.1 mm. An electrolyte was prepared by dissolving 1.2 M of LiPF6 as the electrolyte salt in a solution of polypropylene carbonate (PC) and diethyl carbonate (DEC) mixed in a volume ratio of 1:1, and this electrolyte was injected into the laminate film pack containing the electrode group. After that, the pack was completely sealed by heat sealing, and a 2Ah capacity non-aqueous electrolyte battery with a width of 35 mm, a thickness of 3.2 mm, and a height of 65 mm was manufactured. The manufactured non-aqueous electrolyte battery was a rechargeable battery.

[0204] <Initial adjustment> The fabricated non-aqueous electrolyte battery was initially adjusted as follows.

[0205] First, a pre-charge hold was performed. This was done by holding the non-aqueous electrolyte battery in an uncharged state at 80°C for 24 hours. After that, the initial charge was performed. The initial charge was performed at 0°C at a constant current (CC) charge rate of 5C.

[0206] Subsequently, the battery was discharged at 25°C at a rate of 1C until the battery voltage reached 1.5V. Then, it was charged at a rate of 1C until the battery voltage reached 2.8V. This discharge and charge cycle was considered one cycle, and 100 charge-discharge cycles were performed.

[0207] (Example 2) A non-aqueous electrolyte battery was prepared in the same manner as in Example 1, except that the multi-walled carbon nanotubes (MWCNTs) were changed to those containing 5000 ppm of Fe as an impurity. Initial adjustments were made in the same manner as in Example 1.

[0208] (Example 3) The MWCNTs were changed to those with an impurity content of 50 ppm or less. In addition, Cu powder was added at a concentration of 10,000 ppm relative to the mass of the MWCNTs. Except for the above, a non-aqueous electrolyte battery was prepared in the same manner as in Example 1. Initial adjustments were made in the same manner as in Example 1.

[0209] (Example 4) A non-aqueous electrolyte battery was prepared in the same manner as in Example 3, except that Ni powder was added instead of Cu powder. Initial preparation was carried out in the same manner as in Example 1.

[0210] (Example 5) A non-aqueous electrolyte battery was prepared in the same manner as in Example 1. Initial adjustments were made in the same manner as in Example 1, except that the initial charging was performed at 25°C.

[0211] (Example 6) A non-aqueous electrolyte battery was prepared in the same manner as in Example 1. Initial adjustments were made in the same manner as in Example 1, except that a pre-charging hold period of 48 hours was performed.

[0212] (Example 7) A non-aqueous electrolyte battery was prepared in the same manner as in Example 1. Initial adjustments were made in the same manner as in Example 1, except that a pre-charging hold period of 6 hours was performed.

[0213] (Example 8) A non-aqueous electrolyte battery was prepared in the same manner as in Example 1. Initial adjustments were made in the same manner as in Example 6, except that the initial charge rate was set to 10C.

[0214] (Example 9) Li4Ti5O is used as the negative electrode active material. 12 A non-aqueous electrolyte battery was prepared in the same manner as in Example 1, except that (TLO) was used. Initial adjustments were performed in the same manner as in Example 1.

[0215] (Example 10) A non-aqueous electrolyte battery was fabricated in the same manner as in Example 1, except that a wound electrode group was used instead of a stacked electrode group. Initial adjustments were performed in the same manner as in Example 1.

[0216] The wound electrode group was fabricated as follows. A positive electrode, a separator made of a porous polyethylene film with a thickness of 25 μm, a negative electrode, and the separator were laminated in this order and then wound in a spiral shape. By heating and pressing this at 90°C, a flat wound electrode group with a width of 30 mm and a thickness of 3.0 mm was fabricated.

[0217] (Comparative Example 1) A non-aqueous electrolyte battery was fabricated in the same manner as in Example 1. The initial adjustment was performed by charging at a constant current until the battery voltage reached 2.0 V and holding for 200 hours.

[0218] <Evaluation> The non-aqueous electrolyte battery after the initial adjustment was adjusted so that the battery voltage became 2.25 V. For this non-aqueous electrolyte battery, the change in the battery voltage up to the point when 180 days had elapsed was measured.

[0219] The non-aqueous electrolyte battery after the storage test was completely discharged at 0.2 C, and the non-aqueous electrolyte battery was disassembled in a glove box filled with argon to take out the separator. Among the taken-out separators, the outermost layer and the innermost layer were cut out as follows.

[0220] Regarding Examples 1 to 9 and Comparative Example 1 in which the structure of the electrode group is a laminated type, the outermost layer and the innermost layer of the separator were cut out as follows.

[0221] Among the separators in contact with the positive electrode located outermost in the electrode group, the region disposed between the positive electrode and the negative electrode was cut out. Also, among the separators in contact with the negative electrode located outermost in the electrode group, the region disposed between the negative electrode and the positive electrode was cut out. These two were obtained as the outermost layer.

[0222] From the two outermost layers described above, among the separators located inside along the lamination direction of the electrode group, the region disposed between the positive electrode and the negative electrode was cut out and obtained as the innermost layer.

[0223] Regarding Example 10 in which the structure of the electrode group is a wound type, the outermost layer and the inner layer of the separator were cut out as follows.

[0224] First, from the separator, a region where the separator is located between the negative electrode and the positive electrode was cut out. Among this region, the terminal located at the outer peripheral side end in the electrode group was taken as one end of the outermost layer. Inside one circumference of the outermost layer, the portion corresponding to one end of the outermost layer was taken as the other end of the outermost layer. The portion defined by the above one end and the other end was cut out to obtain the outermost layer.

[0225] Among the above region, the portion located inside the outermost layer in the electrode group was obtained as the inner layer. One end of the inner layer was the other end of the above outermost layer.

[0226] The outermost layer and the inner layer of the separator obtained as described above were ultrasonically cleaned for 5 minutes in a state of being impregnated with ethanol. The separator after cleaning was dried in the atmosphere. In this way, a sample for observation was obtained.

[0227] The sample for observation was subjected to the above-described XRF analysis, and the composition, area, number per unit area in the outermost layer, and number per unit area in the inner layer of the metal element-containing portion were measured.

[0228] In the measurement of the composition and area of the metal element-containing portion, XRF analysis was performed with the range of the central 5 cm square of the sample as the measurement range. As the sample, the outermost layer and the inner layer of the separator were used.

[0229] For each of the outermost layer and the inner layer of the above sample, measurement of the number per unit area was performed by binarization processing of the mapping image of the XRF analysis and image analysis.

[0230] Regarding the non-aqueous electrolyte batteries of each example and comparative example, the types of metal elements contained in the metal element-containing portion, the area (mm 2 ) of the metal element-containing portion, the number per unit area (pieces / m 2), the number of metal element-containing parts per unit area in the inner layer (pieces / m 2 The structure of the negative electrode active material, the electrode group, and the battery voltage change are shown in Table 1. The battery voltage change is shown in Table 1 as the difference (V) between the battery voltage on day 1 and the battery voltage on day 180.

[0231] [Table 1]

[0232] Compositional analysis of the metal element-containing portion revealed that the metal element-containing portion in both the example and comparative example non-aqueous electrolyte batteries consisted of elemental metals.

[0233] Measurement of the number of metal element-containing parts per unit area revealed that in all of the non-aqueous electrolyte batteries of the examples, the number of metal element-containing parts per unit area in the outermost layer was greater than the number of metal element-containing parts per unit area in the inner layers.

[0234] In all of the non-aqueous electrolyte batteries according to the examples, the area of ​​the metal element-containing portion is 0.3 mm². 2 3.2mm 2 The following was observed. The non-aqueous electrolyte battery of Comparative Example 1 had a metal element-containing area of ​​3.2 mm². 2 It was larger than that. Compared to Comparative Example 1, the non-aqueous electrolyte batteries in the examples all showed smaller changes in battery voltage.

[0235] The types of metal elements contained in the metal element-containing portion were Co in Example 1, Fe in Example 2, Cu in Example 3, and Ni in Example 4. In all of Examples 1 to 4, the change in battery voltage was smaller compared to Comparative Example 1. From this, it became clear that the non-aqueous electrolyte battery according to the embodiment can suppress self-discharge regardless of the type of metal element.

[0236] Furthermore, the metal elements contained in the metal element-containing portions of Examples 1 and 2 originated from impurities in the raw material MWCNT. The metal elements contained in the metal element-containing portions of Examples 3 and 4 originated from metal powder. Therefore, it became clear that the non-aqueous electrolyte battery according to the embodiment can suppress self-discharge regardless of whether the impurities originate from the raw material or from foreign matter.

[0237] Comparing Example 1 and Example 5, Example 1, in which the initial charge was performed at a low temperature, tended to have a smaller area of ​​metal element-containing parts and a higher number of metal element-containing parts per unit area in the outermost layer compared to Example 5. In addition, it tended to exhibit smaller changes in battery voltage.

[0238] Comparing Example 1 with Examples 6 and 7, Example 6, which had a longer pre-charging holding time, tended to have a higher number of metal element-containing parts per unit area in the outermost layer than Examples 1 and 7. Example 7, which had a shorter pre-charging holding time, tended to have a lower number of metal element-containing parts per unit area in the outermost layer than Examples 1 and 6. Furthermore, comparing Example 6 with Example 8, Example 8, which had a higher initial charging rate, tended to have a higher number of metal element-containing parts per unit area in the outermost layer than Example 6.

[0239] Example 9, which used TLO as the negative electrode active material, tended to show smaller changes in battery voltage compared to Comparative Example 1. Therefore, it became clear that self-discharge can be suppressed even when TLO is used as the negative electrode active material.

[0240] In Example 10, where the electrode group structure was of the wound type, the change in battery voltage was smaller compared to Comparative Example 1. Therefore, it became clear that self-discharge can be suppressed even when the electrode group structure is of the wound type.

[0241] According to at least one embodiment described above, a non-aqueous electrolyte battery including an electrode group including a positive electrode, a negative electrode, and a separator is provided. The separator includes one or more metal element-containing portions including at least one selected from the group consisting of a metal, a metal oxide, and a metal fluoride on a surface in contact with the negative electrode. The area of the one or more metal element-containing portions is 0.3 mm 2 or more and 3.2 mm 2 or less. Therefore, such a non-aqueous electrolyte battery can suppress self-discharge.

[0242] The invention according to the embodiment is appended below.

[0243] [1] A non-aqueous electrolyte battery including an electrode group including a positive electrode, a negative electrode, and a separator, where the separator includes one or more metal element-containing portions including at least one selected from the group consisting of a metal, a metal oxide, and a metal fluoride on a surface in contact with the negative electrode, and the area of the one or more metal element-containing portions is 0.3 mm 2 or more and 3.2 mm 2 or less.

[0244] [2] The separator includes a region disposed between the positive electrode and the negative electrode, and among the regions, the outermost layer located in the outermost layer of the electrode group includes a plurality of the metal element-containing portions, and the number of the metal element-containing portions per unit area in the outermost layer is 200 pieces / m 2 or more and 1290 pieces / m 2 or less. The non-aqueous electrolyte battery according to [1].

[0245] [3] The separator includes a region disposed between the positive electrode and the negative electrode, [[ID=Y38]]and the number of the metal element-containing portions per unit area in the outermost layer located in the outermost layer of the electrode group among the regions is more than the number of the metal element-containing portions per unit area in the inner layer located inside the outermost layer. The non-aqueous electrolyte battery according to [1] or [2].

[0246] [4] The negative electrode includes a negative electrode active material, The non-aqueous electrolyte battery according to any one of [1] to [3], wherein the negative electrode active material comprises at least one selected from the group consisting of titanium oxide and niobium titanium oxide.

[0247] [5] The metal element-containing portion comprises at least one selected from the group consisting of a metal containing the metal element, a metal oxide containing the metal element, and a metal fluoride containing the metal element. The non-aqueous electrolyte battery according to any one of [1] to [4], wherein the metal element is at least one selected from the group consisting of Co, Fe, Cu, Ni, and Mn.

[0248] [6] A battery pack containing a non-aqueous electrolyte battery as described in any one of items [1] to [5].

[0249] [7] External terminals for power supply, Protection circuit and The battery pack described in [6] further includes the following.

[0250] [8] comprising a plurality of the aforementioned non-aqueous electrolyte batteries, The battery pack according to [6] or [7], wherein the non-aqueous electrolyte batteries are electrically connected in series, parallel, or a combination of series and parallel.

[0251] A vehicle containing a battery pack as described in any one of the items [9] [6] to [8].

[0252]

[10] The vehicle according to [9], which includes a mechanism for converting the kinetic energy of the vehicle into regenerative energy.

[0253] 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]

[0254] 1…Electrode group, 2…Outer casing, 3…Negative electrode, 3a…Negative electrode current collector, 3b…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, 21…Bus bar, 22…Positive electrode side lead, 22a…Other end, 23…Negative electrode side lead, 23a…Other end, 24…Adhesive tape, 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…Non-aqueous electrolyte battery, 200…Battery pack, 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...Wiring, 350...External terminal for energization, 352...Positive side terminal, 353...Negative side terminal, 348a...Positive side wiring, 348b...Negative side wiring, 400...Vehicle, 411...Battery management device, 412...Communication bus, 413...Positive terminal, 414...Negative terminal, 415...Switching 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 includes an electrode group comprising a positive electrode, a negative electrode, and a separator. The separator includes one or more metal element-containing portions, each containing at least one selected from the group consisting of metals, metal oxides, and metal fluorides, on the surface in contact with the negative electrode. The area of ​​the portion containing one or more metal elements is 0.3 mm². ２ 3.2 mm ２ The following is a non-aqueous electrolyte battery.

2. The separator includes a region positioned between the positive electrode and the negative electrode, Of the aforementioned regions, the outermost layer located in the electrode group contains a plurality of metal element-containing portions, The number of metal element-containing portions per unit area in the outermost layer is 200 pieces / m². ２ More than 1290 pieces / m ２ The non-aqueous electrolyte battery according to claim 1, which is as follows:

3. The separator includes a region positioned between the positive electrode and the negative electrode, In the region described above, the number of metal element-containing portions per unit area in the outermost layer, which is the outermost layer in the electrode group, is: The non-aqueous electrolyte battery according to claim 1, wherein the number of metal element-containing portions per unit area in the inner layer located inside the outermost layer is greater than the number of metal element-containing portions per unit area.

4. The aforementioned negative electrode includes a negative electrode active material. The non-aqueous electrolyte battery according to claim 1, wherein the negative electrode active material comprises at least one selected from the group consisting of titanium oxide and niobium titanium oxide.

5. The metal element-containing portion includes at least one selected from the group consisting of a metal containing the metal element, a metal oxide containing the metal element, and a metal fluoride containing the metal element. The non-aqueous electrolyte battery according to claim 1, wherein the metal element is at least one selected from the group consisting of Co, Fe, Cu, Ni, and Mn.

6. A battery pack comprising a non-aqueous electrolyte battery according to any one of claims 1 to 5.

7. External terminals for power supply, Protection circuit and The battery pack according to claim 6, further comprising:

8. The batteries include a plurality of the aforementioned non-aqueous electrolyte batteries, The battery pack according to claim 7, wherein the non-aqueous electrolyte batteries are electrically connected in series, in parallel, or in a combination of series and parallel.

9. A vehicle comprising the battery pack described in claim 6.

10. The vehicle according to claim 9, which includes a mechanism for converting the kinetic energy of the vehicle into regenerative energy.

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