JP2017224496A - Nonaqueous electrolyte battery, battery module and vehicle - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a nonaqueous electrolyte battery superior in input and output characteristics or life, a battery module and a vehicle according to embodiments.SOLUTION: A nonaqueous electrolyte battery according to an embodiment comprises: a positive electrode having a positive electrode active material layer and a positive electrode current collector; a negative electrode having a negative electrode active material layer and a negative electrode current collector; an electrolyte solution; and an oxide particle layer on the positive electrode active material layer and/or the negative electrode active material layer. In the nonaqueous electrolyte battery, the positive electrode having the oxide particle layer, the negative electrode having the oxide particle layer, or each of the positive electrode having the oxide particle layer and the oxide particle layer has at least two peaks in a log differential pore volume distribution curve obtained by a method of mercury penetration.SELECTED DRAWING: Figure 1

Description

  Embodiments relate to a nonaqueous electrolyte battery, a battery module, and a vehicle.

  In recent years, the use of secondary batteries as power for vehicles such as electric bicycles, electric motorcycles, and forklifts has been increasing due to increasing environmental awareness. One of the secondary batteries used for these is a lithium ion secondary battery, which requires high safety, long life, and excellent input / output performance.

JP 2007-172963 A

  Embodiments provide a nonaqueous electrolyte battery, a battery module, and a vehicle that are excellent in input / output characteristics or life characteristics.

  The non-aqueous electrolyte battery of the embodiment includes a positive electrode having a positive electrode active material layer and a positive electrode current collector, a negative electrode having a negative electrode active material layer and a negative electrode current collector, an electrolyte, a positive electrode active material layer, a negative electrode active material A positive electrode having an oxide particle layer, an oxide particle layer, a negative electrode having an oxide particle layer, or a positive electrode having an oxide particle layer on the layer, or on the positive electrode active material layer and the negative electrode active material layer The oxide particle layer has at least two peaks in a log differential pore volume distribution curve obtained by a mercury intrusion method.

The perspective view which shows the external appearance of the nonaqueous electrolyte battery of 1st Embodiment. The expansion | deployment perspective view of the nonaqueous electrolyte battery of FIG. The perspective view of the lid | cover of the nonaqueous electrolyte battery of FIG. The side view which shows the inside of the nonaqueous electrolyte battery of FIG. FIG. 2 is a development view of the wound electrode group of FIG. 1. Sectional drawing of the wound type electrode group of FIG. Sectional drawing of the wound type electrode group of FIG. The graph which shows the pore distribution of the negative electrode of 1st Embodiment. The graph which shows the pore distribution of the positive electrode of 1st Embodiment. The perspective expanded view of the battery module of 2nd Embodiment. Sectional drawing of the battery module of 2nd Embodiment. The conceptual diagram of the electrical storage apparatus of 3rd Embodiment. The conceptual diagram of the vehicle of 4th Embodiment. The conceptual diagram of the vehicle of 4th Embodiment.

  Hereinafter, embodiments will be described with reference to the drawings. In the following description, constituent elements that exhibit the same or similar functions are denoted by the same reference numerals throughout the drawings, and redundant descriptions are omitted. Each figure is a schematic diagram for promoting the explanation of the embodiment and its understanding, and its shape, dimensions, ratio, etc. are different from the actual device, but these are considered in the following explanation and known techniques. Thus, the design can be changed as appropriate.

(First embodiment)
The first embodiment relates to a non-aqueous electrolyte battery. The nonaqueous electrolyte battery according to the first embodiment includes a positive electrode having a positive electrode active material layer and a positive electrode current collector, a negative electrode having a negative electrode active material layer and a negative electrode current collector, and an electrolytic solution. As an example of the nonaqueous electrolyte battery of the first embodiment, FIG. 1 shows an external view of the nonaqueous electrolyte battery 100, FIG. 2 shows a developed perspective view of the nonaqueous electrolyte battery 100, and FIG. 3 shows a cover of the nonaqueous electrolyte battery. A perspective view and FIG. 4 is a side view showing the inside of the nonaqueous electrolyte battery. As shown in FIGS. 1 to 4, the nonaqueous electrolyte battery 100 includes an exterior material 1, a flat wound electrode group 2, a positive electrode lead 3, a negative electrode lead 4, a lid 5, a positive electrode terminal 6, a negative electrode terminal 7, and a positive electrode backup. The lead 8, the negative electrode backup lead 9, the positive electrode insulating cover 10, the negative electrode insulating cover 11, the positive electrode gasket 12, the negative electrode gasket 13, the safety valve 14, the electrolyte solution inlet 15, and an electrolyte solution (not shown) are provided. The electrolytic solution is preferably present in the exterior material 1 and filled in the exterior material 1. In addition, the nonaqueous electrolyte battery of embodiment is a secondary battery which can be charged / discharged, for example. Although FIG. 1 shows a rectangular nonaqueous electrolyte battery, the battery is not limited to a rectangular one.

  Examples of the exterior material 1 include a laminate film and a metal container. Examples of the shape include a flat type, a square type, a cylindrical type, a coin type, a button type, a sheet type, and a laminated type.

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

  As the metal container, aluminum, aluminum alloy, iron, stainless steel, or the like can be used. The lid can be made of aluminum, aluminum alloy, iron, stainless steel, or the like. The lid and the exterior material are preferably formed from the same type of metal. The thickness of the metallic container is preferably 0.5 mm or less, for example.

  The wound electrode group 2 is formed by further laminating a belt-like laminated body in which a belt-like positive electrode 20, a belt-like oxide particle layer 21 and a belt-like negative electrode 22 are laminated. The oxide particle layer 21 exists between the active material layer on the current collector of the positive electrode 20 and the active material layer on the current collector of the negative electrode 22, and is sandwiched between the active material layers of the positive electrode 20 and the negative electrode 22. . The oxide particle layer 21 is preferably present on the active material layer of the positive electrode 20, on the active material layer of the negative electrode 22, or on the active material layer of the positive electrode 20 and on the active material layer of the negative electrode 22. It is preferably in contact. The oxide particle layer 21 is preferably a layer mainly composed of inorganic oxide particles (mass ratio of 80% or more). When the oxide particle layer 21 is present on the active material layer of the positive electrode 20 and the active material layer of the negative electrode 22, the oxide particle layer 21 is formed between the positive electrode active material layer and the negative electrode active material layer, and the positive electrode current collector. Present on the upper or negative electrode current collector. The oxide particle layer 21 present on the positive electrode current collector is provided in contact with the positive electrode current collector along the positive electrode active material layer on the positive electrode current collector. The positive electrode active material layer on the positive electrode current collector, or the region where the positive electrode active material layer and the oxide particle layer 21 are provided is used as a coating portion, and the positive electrode active material layer and the oxide particle layer 21 on the positive electrode current collector are used. A region where none of these is provided is defined as a non-coated portion. The non-coated portion of the positive electrode current collector becomes a positive electrode current collector tab. The oxide particle layer 21 present on the negative electrode current collector is provided in contact with the negative electrode current collector along the negative electrode active material layer on the negative electrode current collector. The negative electrode active material layer on the negative electrode current collector, or the region where the negative electrode active material layer and the oxide particle layer 21 are provided is used as a coating portion, and the negative electrode active material layer and the oxide particle layer 21 on the negative electrode current collector are used. A region where none of these is provided is defined as a non-coated portion. The non-coated portion of the negative electrode current collector becomes a negative electrode current collector tab. The positive electrode 20, the positive electrode current collector, the positive electrode active material layer, the negative electrode 22, the negative electrode current collector, the negative electrode active material layer, and the oxide particle layer 21 are all band-shaped.

  Next, with reference to the development of the wound electrode group 2 shown in FIG. 5 and the partial sectional view of the wound electrode group 2 shown in FIG. 6, the wound electrode group 2 having the oxide particle layer 21 is described. This will be described in more detail. The cross-sectional view of FIG. 6 shows a portion in which four positive electrodes 20, oxide particle layers 21, and negative electrodes 22 are stacked. 5 and 6 show the electrode group before the current collector tab is bundled before being pressed, but the current collector tab of the wound electrode group 2 accommodated in the exterior material 1 is bundled. And is electrically connected to the positive terminal 6 or the negative terminal 7 through a lead. Although the flat wound electrode group 2 is shown, the present invention is not limited to this, and an electrode group having another shape may be used.

  5 and 6 includes a positive electrode 20 having a positive electrode current collector 20a, a first positive electrode active material layer 20b, and a second positive electrode active material layer 20c, and first oxide particles. Oxide layer 21 having layer 21a, second oxide particle layer 21b, third oxide particle layer 21c and fourth oxide particle layer 21d, negative electrode current collector 22a, first negative electrode active material A negative electrode 22 having a layer 22b and a second negative electrode active material layer 22c. The non-coated part of the positive electrode 20 becomes the positive electrode current collection tab 20d. The non-coated part of the negative electrode 22 is a negative electrode current collecting tab 22d. The wound electrode group 2 includes a first oxide particle layer 21a, a first negative electrode active material layer 22b, a negative electrode current collector 22a, a second negative electrode active material layer 22c, a second oxide particle layer 21b, The first positive electrode active material layer 20b, the positive electrode current collector 20a, and the second positive electrode active material layer 20c are stacked in this order. This laminated body is further laminated so that the first oxide particle layer 21a and the second positive electrode active material layer 20c are in contact with each other. The third oxide particle layer 21c is arranged in the order of the second oxide particle layer 21b, the third oxide particle layer 21c, and the positive electrode current collector 20a. The positive electrode 20, the oxide particle layer 21, and the negative electrode 22 have a strip shape extending in the first direction (I) and having a width in the second direction (II) orthogonal to the first direction. The wound electrode group 2 is preferably housed in the outer packaging 1 so as to be directed in a direction perpendicular to the winding axis.

  One surface of the first oxide particle layer 21a is in physical contact with the entire surface of the first negative electrode active material layer 22b, and the surface opposite to the one surface is the second positive electrode active material layer. The entire surface of 20c and the surface of the fourth oxide particle layer 21d are partially in physical contact. The first oxide particle layer 21a may be physically in contact with part of the surface of the negative electrode current collector 22a. When the first oxide particle layer 21a is also in contact with the surface of the negative electrode current collector 22a, the first oxide particle layer 21a on the first negative electrode active material layer 22b and the first oxide particle layer 21a on the negative electrode current collector 22a. One oxide particle layer 21a is continuous. Then, the first oxide particle layer 21a insulates the second positive electrode active material layer 20c and the first negative electrode active material layer 22b facing the first negative electrode active material layer 22b.

  The fourth oxide particle layer 21d has a second positive electrode active material layer 20c on the side where the second positive electrode active material layer 20c is provided, in the region where the second positive electrode active material layer 20c is not provided. The positive electrode current collector 20a and the second positive electrode active material layer 20c are provided in physical contact with each other along the positive electrode active material layer 20c. A surface of the fourth oxide particle layer 21d that faces the surface in contact with the positive electrode current collector 20a includes a surface that includes an end opposite to the negative electrode current collection tab 22d side of the first oxide particle layer 21a. opposite. Further, the band-like region excluding the coated portion where the fourth oxide particle layer 21d and the second positive electrode active material layer 20c of the positive electrode current collector 20a are present is a non-coated portion, and the positive electrode current collecting tab 20d. It becomes. Note that the outermost first oxide particle layer 21a of the wound electrode group 2 does not have a contact surface with the second positive electrode active material layer 20c.

  One surface of the second oxide particle layer 21b is in physical contact with the entire surface of the second negative electrode active material layer 22c, and the surface opposite to the one surface is the first positive electrode active material layer. The entire surface of 20b and the surface of the third oxide particle layer 21c are partially in physical contact. The second oxide particle layer 21b may be in physical contact with part of the surface of the negative electrode current collector 22a. In the case where the second oxide particle layer 21b is also in contact with the surface of the negative electrode current collector 22a, the second oxide particle layer 21b on the second negative electrode active material layer 22c and the second oxide particle layer 21b on the negative electrode current collector 22a. The two oxide particle layers 21b are continuous. Then, the second oxide particle layer 21b insulates the first positive electrode active material layer 20b and the second negative electrode active material layer 22c facing the second negative electrode active material layer 22c.

  The third oxide particle layer 21c has a first positive electrode active material layer 20b on the side where the first positive electrode active material layer 20b is provided in the region where the first positive electrode active material layer 20b is not provided. The positive electrode active material layer 20b is provided in physical contact with the positive electrode current collector 20a and the first positive electrode active material layer 20b. The surface of the third oxide particle layer 21c that faces the surface in contact with the positive electrode current collector 20a includes a surface that includes an end opposite to the negative electrode current collector tab 22d side of the second oxide particle layer 21b. opposite. Further, the band-like region excluding the coated portion where the third oxide particle layer 21c and the first positive electrode active material layer 20b of the positive electrode current collector 20a are present is a non-coated portion, and the positive electrode current collecting tab 20d. It becomes.

  In the cross-sectional view of FIG. 6, the third oxide particle layer 21 c and the fourth oxide particle layer 21 d are provided at positions where the positive electrode current collector 20 a is sandwiched, but the third oxide particle layer 21 c is provided. The fourth oxide particle layer 21d may be omitted. Further, as shown in the sectional view of FIG. 7, the third oxide particle layer 21c and the fourth oxide particle layer 21d do not sandwich the positive electrode current collector 20a, but sandwich the negative electrode current collector 22a. May be provided. The first oxide particle layer 21a and the second oxide particle layer 21b may be provided on both the surface of the positive electrode active material layer and the surface of the negative electrode active material layer that face each other. At this time, the first oxide particle layer 21a and the second oxide particle layer 21b have a two-layer structure.

  In the case of the form of FIG. 7, one surface of the first oxide particle layer 21a is in partial physical contact with the entire surface of the first negative electrode active material layer 22b and the surface of the fourth oxide particle layer 21d. In addition, one surface of the second oxide particle layer 21b is partially in physical contact with the entire surface of the second negative electrode active material layer 22c and the surface of the third oxide particle layer 21c. The third oxide particle layer 21c has a first negative electrode active material layer 22b on the side where the first negative electrode active material layer 22b is provided, in the region where the first negative electrode active material layer 22b is not provided. The negative electrode active material layer 22b is provided in physical contact with the negative electrode current collector 22a and the first negative electrode active material layer 22b. The fourth oxide particle layer 21d has a second negative electrode active material layer 22c on the side where the second negative electrode active material layer 22c is provided, in the region where the second negative electrode active material layer 22c is not provided. The negative electrode active material layer 22c is provided in physical contact with the negative electrode current collector 22a and the second negative electrode active material layer 22c. In the form of FIG. 7, the position of the oxide particle layer 21 is different from the form of FIG. 6, but corresponds to the oxide particle layer 21 of FIG. To do.

  6 and 7, in any form in which the third oxide particle layer 21c and the fourth oxide particle layer 21d are omitted, the entire surface of the opposing surfaces of the positive electrode active material layer and the negative electrode active material layer is If the third oxide particle layer 21c and the fourth oxide particle layer 21d that are in physical contact with the oxide particle layer 21 and insulate the positive electrode active material layer and the negative electrode active material layer are omitted, the electrode active material is omitted. The thinner the layer, the narrower the distance between the end of the electrode active material layer and the current collector tab facing, and the higher the probability of short circuit due to the contact of the current collector tab facing the end of the electrode active material layer. If the third oxide particle layer 21c and the fourth oxide particle layer 21d are present, the electrode active material layer does not come into contact even if the electrode active material layer is thinned, so that the electrode active material layer can be thinned, thereby improving input / output characteristics. Has the advantage of being able to 6 and 7, the thickness of the third oxide particle layer 21c and the fourth oxide particle layer 21d is equal to or less than the thickness of the active material layer arranged side by side on the current collector. It is preferable that the following preferable thickness conditions are satisfied.

  The positive electrode 20 and the negative electrode 22 are each wound after being produced, whereby the wound electrode group 2 is produced. Therefore, even when the wound electrode group 2 is disassembled, the oxide particle layer 21 formed during the production of the positive electrode 20 exists on the positive electrode active material layer, and the oxide particle layer formed during the production of the negative electrode 22. 21 exists on the negative electrode active material layer. The positive electrode active material layer is wound while adjusting the position so that the surface of the positive electrode active material layer faces the surface of the negative electrode active material layer, that is, no non-opposing portion is formed in the positive electrode 20. The layer on the outermost periphery of the wound electrode group 2 is preferably fixed with an insulating tape (not shown).

  The positive electrode current collecting tab 20 d is bundled by the positive electrode backup lead 8 and is electrically connected to the positive electrode terminal 6 through the positive electrode lead 3. Further, the negative electrode current collecting tab 22 d is bundled by the negative electrode backup lead 9 and is electrically connected to the negative electrode terminal 7 through the negative electrode lead 4.

  The positive electrode 20 typically includes a positive electrode active material layer including a positive electrode active material, a conductive material, and a binder, and a positive electrode current collector. A form in which a positive electrode active material layer exists on both surfaces of the positive electrode current collector is more preferable. The positive electrode active material layer is a layer in which the positive electrode active material, the conductive material, and the binder are dispersed, and is provided on the positive electrode current collector.

  The positive electrode active material is not particularly limited, and any positive electrode active material can be used as long as it can be charged and discharged by inserting and desorbing lithium and other alkali metal ions. Examples of materials that can be used as the positive electrode active material include lithium manganese composite oxide, lithium cobalt composite oxide, lithium manganese cobalt composite oxide, lithium nickel composite oxide, and lithium iron composite oxide. The positive electrode active material used for the positive electrode may contain one type or two or more types.

  Any conductive material may be used as long as it has a suitable conductivity. For example, carbon black such as acetylene black and carbon such as graphite can be used in combination.

  Any binder can be used as long as it is usually used in non-aqueous electrolyte batteries. For example, electrochemically stable polyvinylidene fluoride or polytetrafluoroethylene is used.

  The positive electrode current collector is a conductive thin film in which a positive electrode active material layer is provided on one side or both sides. As the positive electrode current collector, a non-porous metal foil, a punched metal having a large number of holes, a metal mesh formed with a thin metal wire, or the like can be used. As the positive electrode current collector, for example, a metal foil or an alloy foil can be used. Examples of the metal foil include an aluminum foil, a copper foil, and a nickel foil. Examples of the alloy foil include an aluminum alloy, a copper alloy, and a nickel alloy.

  The material of the positive electrode current collector is not particularly limited as long as it does not dissolve in the environment where the battery is used. For example, a metal such as Al or Ti, the main component of the metal, Zn, Mn, Fe, Cu, An alloy to which one or more elements selected from the group consisting of Si are added can be used. In particular, an aluminum alloy foil containing Al as a main component is preferably a thin film because it is flexible and excellent in formability. The thickness of the positive electrode current collector is typically 5 μm or more and 20 μm.

  For example, the positive electrode 20 is obtained by suspending a positive electrode active material, a conductive material, and a binder in a suitable solvent, applying the prepared slurry to a positive electrode current collector, drying, and rolling the positive electrode active material layer. It is produced by this. A portion where the positive electrode active material layer of the positive electrode current collector is not formed becomes a positive electrode current collecting tab. The mixing ratio of the positive electrode active material, the conductive material and the binder is such that the positive electrode active material is 70% by mass to 96% by mass, the conductive material is 3% by mass to 17% by mass, and the binder is 1% by mass to 13% by mass. % Or less is desirable. The positive electrode density (positive electrode packing density) is preferably 2.8 g / cc or more and 3.3 g / cc or less from the viewpoint of high capacity and input / output characteristics.

  The oxide particle layer 21 is a porous oxide particle layer having ion conductivity existing between the positive electrode 20 and the negative electrode 22. The oxide particle layer 21 includes oxide particles, a thickener, and a binder. Metal oxides such as aluminum oxide, titanium oxide, magnesium oxide, zinc oxide, and barium sulfate can be used for the oxide particles. Carboxymethylcellulose can be used as the thickener. As the binder, methyl acrylate, an acrylic copolymer containing the same, styrene butadiene rubber (SBR), or the like can be used.

  In the embodiment, the oxide particle layer 21 functions as a separator. In the non-aqueous electrolyte battery, a polymer compound such as polypropylene or polyethylene is used for the separator. However, in the embodiment, the polymer compound is not used and a layer of oxide particles is used. It is preferable that one surface of the oxide particle layer 21 is in physical contact with the entire surface of the positive electrode active material layer, and the other surface is in physical contact with the entire surface of the negative electrode active material layer.

  The oxide particle layer 21 is obtained by suspending, for example, oxide particles, a dispersant, and a binder in a solvent such as water, and preparing the slurry on the surface of the positive electrode active material layer, the surface of the negative electrode active material layer, or the positive electrode. It forms by apply | coating on the surface of an active material layer, and the surface of a negative electrode active material layer, and drying. In addition, about a positive electrode, an oxide particle layer may be formed by apply | coating also to a part of positive electrode current collection tab, and drying. The oxide particle layer may be formed by applying a slurry on the electrode surface before rolling. The mixing ratio of the oxide particles, the dispersant, and the binder of the obtained oxide particle layer 21 is 85.0% by mass or more and 98.5% by mass or less for the oxide particles, and 0.5% by mass or more for the dispersant. It is desirable that the content be 0.0 mass% or less and the binder is 1.0 mass% or more and 10.0 mass% or less. If the ratio of the oxide particles in the oxide particle layer 21 is too low, self-discharge increases and the life characteristics deteriorate. If the ratio of the oxide particles is too high, the oxide particles are likely to fall off, which is not preferable.

  The negative electrode 22 typically includes a negative electrode active material layer including a negative electrode active material, a conductive material, and a binder, and a negative electrode current collector. A form in which the negative electrode active material layer is present on one side or both sides of the negative electrode current collector is preferred, and a form in which the negative electrode active material layer is present on both sides of the negative electrode current collector is more preferred. The negative electrode active material layer is a layer in which the negative electrode active material, the conductive material, and the binder are dispersed, and is provided on the negative electrode current collector.

As the negative electrode active material, for example, Li _{4 + x} Ti ₅ O ₁₂ (x changes in the range of −1 ≦ x ≦ 3 by charge / discharge reaction), spinel type lithium titanate, ramsteride type Li _{2 + x} Ti ₃ O ₇ (x varies in the range of −1 ≦ x ≦ 3 due to charge / discharge reaction), a metal containing at least one element selected from the group consisting of Ti and P, V, Sn, Cu, Ni and Fe Examples include complex oxides. Examples of the metal composite oxide containing at least one element selected from the group consisting of Ti and P, V, Sn, Cu, Ni, and Fe include TiO ₂ —P ₂ O ₅ , TiO ₂ —V _2. O ₅ , TiO ₂ —P ₂ O ₅ —SnO ₂ , TiO ₂ —P ₂ O ₅ —MO (M is at least one element selected from the group consisting of Cu, Ni and Fe). These metal composite oxides change to lithium titanium composite oxides when lithium is inserted by charging. Among lithium titanium composite oxides, spinel type lithium titanate is preferable because of its excellent cycle characteristics.

The negative electrode active material may include other active materials, such as a carbonaceous material or a metal compound. Examples of the carbonaceous material include natural graphite, artificial graphite, coke, vapor grown carbon fiber, mesophase pitch carbon fiber, spherical carbon, and resin-fired carbon. More preferable carbonaceous materials include vapor grown carbon fiber, mesophase pitch carbon fiber, and spherical carbon. The carbonaceous material preferably has a (002) plane spacing d ₀₀₂ of 0.34 nm or less by X-ray diffraction.

As the metal compound, metal sulfide or metal nitride can be used. As the metal sulfide, for example, titanium sulfide such as TiS ₂ , molybdenum sulfide such as MoS ₂ , iron sulfide such as FeS, FeS ₂ , and LixFeS ₂ can be used. As the metal nitride, for example, lithium cobalt nitride (for example, Li _s Co _t N, 0 <s <4, 0 <t <0.5) can be used.

  Any conductive material may be used as long as it has a suitable conductivity. For example, carbon black such as acetylene black and carbon such as graphite can be used in combination.

  Any binder can be used as long as it is normally used in non-aqueous electrolyte batteries. It is preferred to use electrochemically stable materials such as polyvinylidene fluoride and polytetrafluoroethylene, carboxymethylcellulose, styrene butadiene rubber, and mixtures thereof.

  The negative electrode current collector is a conductive thin film in which a negative electrode active material layer is provided on one side or both sides. For the negative electrode current collector, a member similar to the positive electrode current collector can be used.

  The negative electrode is produced, for example, by suspending a negative electrode active material, a conductive material, and a binder in an appropriate solvent, applying the produced slurry to a negative electrode current collector, drying, and rolling. The negative electrode becomes a negative electrode current collecting tab in a portion where the negative electrode active material layer is not formed on the surface of the negative electrode current collector. The mixing ratio of the negative electrode active material, the conductive material and the binder is such that the negative electrode active material is 70% by mass to 96% by mass, the conductive material is 2% by mass to 28% by mass, and the binder is 2% by mass to 28% by mass. % Or less is desirable. By setting the amount of the conductive material to 2% by mass or more, the current collecting performance of the negative electrode active material layer can be improved. Further, by setting the amount of the binder to 2% by mass or more, the binding property between the negative electrode active material layer and the negative electrode current collector can be improved, and excellent cycle characteristics can be expected. On the other hand, the conductive material and the binder are each preferably 28% by mass or less in order to increase the capacity. The negative electrode density (negative electrode filling density) is desirably 2.0 g / cc or more and 2.3 g / cc or less from the viewpoint of higher capacity and input / output characteristics.

  The nonaqueous electrolyte battery according to the first embodiment includes the oxide particle layer 21 on the positive electrode active material layer, the negative electrode active material layer, or the positive electrode active material layer and the negative electrode active material layer. The positive electrode 20 having the oxide particle layer 21, the negative electrode 22 having the oxide particle layer 21, or the positive electrode 20 having the oxide particle layer 21 and the negative electrode having the oxide particle layer 21 can be obtained by a log intrusion method. The pore volume distribution curve preferably has at least two peaks.

FIG. 8 is a graph showing the pore size distribution of an example negative electrode according to the first embodiment, and FIG. 9 is a graph showing the pore size distribution of an example positive electrode according to the first embodiment. The pore distributions in FIGS. 8 and 9 are measured for the positive electrode and the negative electrode in the form shown in the cross-sectional view of FIG. 8 and 9, the horizontal axis represents the pore diameter (μm), and the vertical axis represents the log differential pore volume (mL · g ⁻¹ ).

The log differential pore volume distribution curve obtained by the mercury intrusion method has the highest abundance ratio, the first peak having the pore diameter D ₁ (first pore diameter), and the first pore diameter D _1. It is preferable that the pore diameter is large and the second peak is present in the range of 0.1 μm to 3.0 μm. The second peak is not limited to one, and the pore diameter may have two or more peaks in the range of 0.1 μm to 3.0 μm.

  The pore diameter of the first peak is smaller than the pore diameter of the second peak. Further, the log differential pore volume of the first peak is larger than the log differential pore volume of the second peak. A maximum peak having a pore diameter between 0.03 μm and 0.5 μm is defined as a first peak. The second peak has a pore diameter in the range of 0.1 μm or more and 3.0 μm or less, and the maximum peak that is 1/3 or less of the maximum value of the log differential pore volume of the first peak is defined as the second peak. . The peak in the embodiment can be easily recognized as a peak in a pore distribution curve, and specifically, the maximum value of each peak included in the pore size distribution curve (log differential pores). (Volume) refers to a value that is at least twice the minimum value (log differential pore volume) at the base of the peak. In the embodiment, a peak that does not satisfy this condition is treated as noise. The first peak is derived from the active material layer of the electrode, and the second peak is derived from the oxide particle layer 21. By measuring the sample from which the oxide particle layer 21 is removed, it can be confirmed whether the peak is derived from the electrode (electrode active material layer) or the oxide particle layer 21.

In the pore size distribution shown in FIGS. 8 and 9, there is a peak of the first pore diameter D ₁ having the highest abundance ratio and _one peak in the range of the pore diameter of 0.05 μm or more and 3.0 μm or less. . The peak having the highest abundance ratio is derived from the electrode active material layer, and one having two or less peaks having a pore diameter in the range of 0.05 μm or more and 3.0 μm or less has a small pore diameter D ₂ The (second pore diameter) is derived from the oxide particle layer 21 and has a large pore diameter among two peaks existing in the range of 0.05 μm or more and 3.0 μm or less (FIGS. 8 and 9). (The second peak does not exist) is derived from the interface between the oxide particle layer 21 and the electrode active material layer.

The average particle diameter _{D 3} of the oxide particles is preferably 5.5μm or less the range of 0.2 [mu] m, more preferably at least 5.2μm or less 0.31 .mu.m, further is 0.5μm or 5.0μm or less than preferable. If the average particle diameter of the oxide particles is too large or too small, the pore diameter of the oxide particle layer 21 cannot be set within a suitable range. From the same viewpoint, the particle diameter of the oxide particles is preferably 0.1 μm or more and 10.0 μm or less. Square particle diameter and average particle diameter D ₃ of the oxide particles, comprising a positive electrode, a negative electrode, or is the center of the first direction of the positive and negative electrodes (I), and the center of the second direction (II) The oxide particles in a 5 cm × 5 cm region are shaved and obtained by a laser diffraction method. NMP (N-methyl-2-pyrrolidone) was used as a solvent for dispersing the sample. The scraped sample was suspended in the solvent, and the sample was dispersed by applying ultrasonic waves at an output of 180 W and a time of 180 seconds, and degassing was performed twice. Measurements were made later. The measurement was repeated twice and the average was taken. The average particle diameter D ₃ is the volume average diameter of the oxide particles.

Second pore size _{D 2} of the oxide particle layer 21 is desirably 0.1μm or 1.8μm below. A second pore size D ₂ is 0.1μm less, since the oxide particle layer 21 becomes dense, the impregnation of the electrolytic solution is lowered, the input-output characteristic is lowered. In addition, the permeability of the gas generated on the electrode due to storage or cycling deteriorates, the gas stays between the oxide particle layer 21 and the electrode layer, the oxide particle layer 21 peels off, and a short circuit is likely to occur. A second pore size D ₂ is greater than 3.0 [mu] m, voids occur upon thinning, short circuit is likely to occur.

The ratio of the second pore diameter D ₂ derived from the oxide particle layer 21 and the average particle diameter D ₃ of the oxide particles contained in the oxide particle layer 21, D ₂ / D _3, is a battery with high input / output characteristics. From the viewpoint of obtaining _{, it} is preferably 0.1 or more _and 0.7 or less. When D ₂ / D ₃ is less than 0.1, the oxide particle layer 21 becomes dense, so that the electrolyte impregnation into the pores of the oxide particle layer 21 is deteriorated, and the input / output characteristics are easily deteriorated. . If D ₂ / D ₃ is greater than 0.7, the distance between the oxide particles becomes too large, the binding between the oxide particles is weak, and the oxide particles fall off and the input / output characteristics deteriorate. At this time, the thickness of the oxide particle layer 21 is preferably 2.5 μm or more and 10.0 μm or less. The oxide particle layer 21 having a thickness in such a range has a sufficient thickness to function as an insulating layer, and further has an advantage that it is not easily broken during winding. When the oxide particle layer 21 is cracked, the electrode is short-circuited, and the input / output characteristics and the life characteristics are degraded.

D ₂ / D ₃ is preferably 0.05 or more and 0.7 or less from the viewpoint of obtaining a battery having high life characteristics. When D ₂ / D ₃ is smaller than 0.05, the pore diameter is small, the impregnation property of the electrolyte is poor, the input / output characteristics are lowered, the gas is difficult to escape, and it is easy to drop and short circuit. When gas is generated during storage or cycling, the gas stays between the oxide particle layer 21 and the electrode active material layer, and the oxide particle layer 21 is easily peeled off, and the life characteristics are deteriorated. If D ₂ / D ₃ is greater than 0.7, the distance between the oxide particles becomes too large, the binding between the oxide particles is weak, and the oxide particles fall off. It will decline. At this time, the thickness of the oxide particle layer 21 is preferably 2.0 μm or more and 8.0 μm or less. The oxide particle layer 21 having a thickness in such a range has a sufficient thickness to function as an insulating layer, and further has an advantage that it is not easily broken during winding.

D ₂ / D ₃ is preferably 0.1 or more and 0.7 or less from the viewpoint of obtaining a battery having high input / output characteristics and life characteristics. At this time, the thickness of the oxide particle layer 21 is preferably 2.5 μm or more and 8.0 μm or less. The oxide particle layer 21 having a thickness in such a range has a sufficient thickness to function as an insulating layer, and further has an advantage that it is not easily broken during winding.

D ₂ / D ₃ is 0.07 or more and 0.67 or less from the viewpoint of obtaining a battery having high input / output characteristics and life characteristics, and the thickness of the oxide particle layer 21 is 3.0 μm or more and 10.0 μm. The following is preferred.

  The method for measuring the thickness of the oxide particle layer 21 is determined by observing the cross section of the electrode in the region having the oxide particle layer 21 with the SEM in the width direction. The thickness of the oxide particle layer 21 is 5 cm in the flow direction and 10 in the width direction. The obtained 10 samples have a region including the center as a measurement sample and a magnification of 1000 times. Measure the thickness at the position obtained by dividing the range observed in (5) into five, and take the average value of a total of 40 points, excluding 5 points for each of the 50 thicknesses obtained.

  By satisfying these physical properties, the non-aqueous electrolyte battery of the embodiment can realize improvements in input / output characteristics and life characteristics. The nonaqueous electrolyte battery according to the embodiment has a preferable pores in the oxide particle layer formed on the electrode surface, so that the impregnation property of the electrolytic solution is improved, so that the input / output characteristics are improved, and the long-term use The life characteristics are improved by securing the flow path of the gas generated at times.

The electrolytic solution is a solution containing an electrolyte salt present in the exterior material 1 and a non-aqueous solvent. The viscosity of the electrolytic solution at −20 ° C. is desirably 50 mPa · s or less. If it is higher than 50 mPa · s, the impregnation property of the electrolyte into the pores of the oxide particle layer 21 is lowered. Therefore, if the viscosity of the electrolyte is too high even if the physical properties of the oxide particle layer 21 are satisfied, battery characteristics are obtained. Becomes difficult to improve. More specifically, the viscosity of the electrolytic solution at −20 ° C. is preferably 21 mPa · s or more and 50 mPa · s or less. Examples of the electrolyte salt include LiPF ₆ , LiBF ₄ , Li (CF ₃ SO ₂ ) ₂ N (bistrifluoromethanesulfonylamidolithium; commonly known as LiTFSI), LiCF ₃ SO ₃ (commonly known as LiTFS), and Li (C ₂ F ₅ SO ₂ ). ₂ N (bis pentafluoroethanesulfonyl amide lithium; called _{LiBETI), LiClO 4, LiAsF 6} , LiSbF 6, bisoxalato Lato lithium borate _{{LiB (C 2 O 4)} 2, commonly known; LiBOB}, difluoro (tri-fluoro-2 Use of a lithium salt such as -oxide-2-trifluoro-methylpropionate (2-)-0,0) lithium borate {LiBF ₂ OCOOC (CF ₃ ) ₂ , commonly known; LiBF ₂ (HHIB)} it can. These electrolyte salts may be used alone or in combination of two or more. In particular, LiPF ₆ and LiBF ₄ are preferable. As the lithium salt, a supporting salt that conducts ions can be used. For example, lithium hexafluorophosphate (LiPF ₆ ), lithium tetrafluoroborate, an imide-based support salt, and the like can be given. The lithium salt may contain one type or two or more types.

  The electrolyte salt concentration is preferably in the range of 1 mol / L to 3 mol / L, and more preferably in the range of 1 mol / L to 2 mol / L. Such regulation of the electrolyte concentration makes it possible to further improve the performance when a high load current is passed while suppressing the influence of an increase in viscosity due to an increase in the electrolyte salt concentration.

  The non-aqueous solvent is not particularly limited, and examples thereof include cyclic carbonates such as propylene carbonate (PC) and ethylene carbonate (EC), diethyl carbonate (DEC), dimethyl carbonate (DMC), and methyl ethyl carbonate (MEC). Alternatively, linear carbonate such as dipropyl carbonate (DPC), 1,2-dimethoxyethane (DME), γ-butyrolactone (GBL), tetrahydrofuran (THF), 2-methyltetrahydrofuran (2-MeHF), 1,3-dioxolane , Sulfolane, acetonitrile (AN) can be used. These solvents may be used alone or in combination of two or more. A non-aqueous solvent containing a cyclic carbonate and / or a chain carbonate is preferred.

  The positive electrode lead 3 is a conductive member that physically connects the positive electrode terminal 6 and the positive electrode backup lead 8 as shown in FIGS. The positive electrode lead 3 is a conductive member such as aluminum or an aluminum alloy. The positive electrode lead 3 and the positive electrode backup lead 8 are preferably joined by, for example, laser welding.

  The negative electrode lead 4 is a conductive member that physically connects the negative electrode terminal 7 and the negative electrode backup lead 9 as shown in FIGS. The negative electrode lead 4 is a conductive member such as aluminum or an aluminum alloy. The negative electrode lead 4 and the negative electrode backup lead 9 are preferably joined by, for example, laser welding.

  The lid 5 is a lid of the exterior material 1 that houses the wound electrode group 2 as shown in FIGS. 1 to 4, and has a positive electrode terminal 6 and a negative electrode terminal 7. The lid 5 includes a positive electrode terminal 6, a negative electrode terminal 7, a negative electrode insulating cover 11, a positive electrode gasket 12, a negative electrode gasket 13, a safety valve 14, and an electrolyte solution inlet 15. The lid 5 is a molded member made of metal or alloy such as aluminum, aluminum alloy, iron or stainless steel. The lid 5 and the exterior material 1 are preferably laser welded or bonded by a sealing material such as an adhesive resin.

  The positive electrode terminal 6 is an electrode terminal for a positive electrode of a secondary battery provided on the lid 5 as shown in FIGS. The positive electrode terminal 6 is made of a conductive member such as aluminum or an aluminum alloy. The positive electrode terminal 6 is fixed to the lid 5 via an insulating positive electrode gasket 12. The positive electrode terminal 6 is electrically connected to the positive electrode 20 via the positive electrode lead 3 and the positive electrode backup lead 8.

  The negative electrode terminal 7 is an electrode terminal for a negative electrode of a secondary battery provided on the lid 5 as shown in FIGS. The negative terminal 7 is made of a conductive member such as aluminum or an aluminum alloy. The negative electrode terminal 7 is fixed to the lid 5 via an insulating negative electrode gasket 13. The negative electrode terminal 7 is electrically connected to the negative electrode 22 via the negative electrode lead 4 and the negative electrode backup lead 9.

  As shown in FIGS. 1 to 4, the positive electrode backup lead 8 is a conductive member bundled with the positive electrode current collecting tab 20 c and fixed to the positive electrode lead 3. The positive electrode backup lead 8 and the positive electrode current collecting tab 20d are preferably bonded by ultrasonic bonding.

  As shown in FIGS. 1 to 4, the negative electrode backup lead 9 is a conductive member bundled with the negative electrode current collecting tab 22 d and fixed to the negative electrode lead 4. The negative electrode backup lead 9 and the negative electrode current collecting tab 22c are preferably bonded by ultrasonic bonding.

  The positive insulating cover 10 is an insulating member that covers the positive lead 3 and the positive backup lead 8 as shown in FIG. The positive electrode insulating cover 10 is joined at one end including the positive electrode current collecting tab 20 d of the wound electrode group 2. The positive electrode insulating cover 10 is preferably an insulating and heat resistant member. The positive electrode insulating cover 10 is preferably a resin molded body, a molded body of a material mainly made of paper, or a member obtained by coating a molded body of a material mainly made of paper with a resin. As the resin, polyethylene resin or fluororesin is preferably used. The shape of the positive electrode insulating cover 10 is such that the positive electrode lead 3 and the positive electrode backup lead 8 are in contact with the exterior material 1. By using the positive electrode insulating cover 10, the positive electrode 20 and the exterior material 1 are insulated, and the current collecting tab region (current collecting tab, lead, backup lead) can be protected from external impact.

  The negative electrode insulating cover 11 is an insulating member that covers the negative electrode lead 4 and the negative electrode backup lead 9 as shown in FIG. The negative electrode insulating cover 11 is joined to one end portion of the wound electrode group 2 including the negative electrode current collecting tab 22d. The material and shape of the negative electrode insulating cover 11 are the same as those of the positive electrode insulating cover 10. Descriptions common to the positive electrode insulating cover 10 and the negative electrode insulating cover 11 are omitted.

  The positive electrode gasket 12 is a member that insulates the positive electrode terminal 6 and the exterior material 1 as shown in FIGS. The positive electrode gasket 12 is preferably a solvent-resistant and flame-retardant resin molded body. For the positive electrode gasket 12, for example, a polyethylene resin or a fluororesin is used.

  The negative electrode gasket 13 is a member that insulates the negative electrode terminal 7 from the exterior material 1 as shown in FIGS. The negative electrode gasket 13 is preferably a solvent-resistant and flame-retardant resin molded body. For the negative electrode gasket 13, for example, polyethylene resin or fluororesin is used.

  The safety valve 14 is a member that is provided on the lid as shown in FIGS. 1 to 3 and functions as a pressure reducing valve that reduces the pressure in the exterior material 1 when the internal pressure in the exterior material 1 increases. The safety valve 14 is preferably provided, but can be omitted in consideration of conditions such as a battery protection mechanism and an electrode material.

The electrolyte solution inlet 15 is a hole for injecting an electrolyte solution as shown in FIGS. After the injection of the electrolytic solution, it is preferably sealed with a resin or the like.
Although omitted in the drawing, it is preferable that each member is fixed or connected using an insulating adhesive tape.

(Second Embodiment)
Hereinafter, embodiments will be described with reference to the drawings. The battery module according to the second embodiment has one or more secondary batteries (that is, single cells) according to the first embodiment. When the battery module includes a plurality of single cells, the single cells are electrically connected in series, in parallel, or connected in series and parallel.

  The battery module 200 will be specifically described with reference to a perspective development view of FIG. 10 and a cross-sectional view of FIG. In the battery module 200 shown in FIG. 10, the nonaqueous electrolyte battery 100 shown in FIG. The cross-sectional view of FIG. 11 is a cross-section including the positive electrode terminal 203B and the negative electrode terminal 206B of the perspective development view of FIG.

  The plurality of single cells 201 are provided with a positive electrode terminal 203 (203A, 203B) provided on the positive electrode gasket 202, a safety valve 204, and a negative electrode terminal 206 (206A, 206B) provided on the negative electrode gasket 205 on the outside of the battery can. Have. The unit cells 201 shown in FIG. 10 are arranged so as to be arranged alternately. Although the unit cells 201 shown in FIG. 10 are connected in series, they may be connected in parallel by changing the arrangement method.

  The unit cell 201 is accommodated in the lower case 207 and the upper case 208. The upper case 208 is provided with power input / output terminals 209 and 210 (a positive terminal 209 and a negative terminal 210) of the battery module. An opening 211 is provided in the upper case 208 in accordance with the positions of the positive terminal 203 and the negative terminal 206 of the unit cell 201, and the positive terminal 203 and the negative terminal 206 are exposed from the opening 211. The exposed positive electrode terminal 203A is connected to the negative electrode terminal 206A of the adjacent unit cell 201 by the bus bar 212, and the exposed negative electrode terminal 206A is connected to the positive electrode terminal 203A and the bus bar 212 of the adjacent unit cell 201 on the opposite side. Connected by. The positive terminal 203B not connected by the bus bar 212 is connected to the positive terminal 214A provided on the substrate 213, and the positive terminal 214A is connected to the positive power input / output terminal 209 via a circuit on the substrate 213. Yes. Further, the negative electrode terminal 206B not connected by the bus bar 212 is connected to the negative electrode terminal 214B provided on the substrate 213, and the negative electrode terminal 214B is connected to the negative power input / output terminal 210 via a circuit on the substrate 213. doing. The power input / output terminals 209 and 210 are connected to a charging power source and a load (not shown), and the battery module 200 is charged and used. The upper case 208 is sealed with a lid 215. The substrate 213 is preferably provided with a charge / discharge protection circuit. Moreover, you may perform suitably addition of the structure of making it the structure which can output information, such as deterioration of the cell 201, from the terminal which is not illustrated.

(Third embodiment)
The battery module of the embodiment can be mounted on the power storage device 300. A power storage device 300 illustrated in the conceptual diagram of FIG. 12 includes a battery module 200, an inverter 302, and a converter 301. The external AC power supply 303 is converted into DC by the converter 301, the battery module is charged, the AC conversion is performed by the inverter 302 of the DC power supply from the battery module, and electricity is supplied to the load 304. By setting it as the electrical storage apparatus 300 of this structure which has the battery module 200 of embodiment, the electrical storage apparatus excellent in the battery characteristic is provided.

(Fourth embodiment)
The battery module 200 of the embodiment can be mounted on the vehicle 400. A vehicle 400 shown in the conceptual diagram of FIG. 13 includes at least a battery module 200, an inverter 401, a motor 402, and wheels 403. The DC power from the battery module 200 is AC converted by an inverter, and the motor 402 is driven by the AC power. When using a motor driven by direct current, the inverter is omitted. In the figure, the charging mechanism of the battery module is omitted. The wheels 403 can be rotated by the driving force of the motor 402. Note that the vehicle 400 includes an electric vehicle such as a train and a hybrid vehicle having another drive source such as an engine. The battery module 200 may be charged by regenerative energy from the motor 402. What is driven by the electric energy from the battery module is not limited to the motor, and may be used as a power source for operating the electric device 501 of the vehicle 500 as shown in the conceptual diagram of FIG. In the case of the vehicle 500 shown in the conceptual diagram of FIG. 14, for example, a regenerative energy is obtained by operating a generator 503 such as a motor attached to the axle portion of the wheel 502 during deceleration of the vehicle, and the obtained regenerative energy is used. The battery module 200 is preferably charged.

[Example]
Hereinafter, the present invention will be described in more detail with reference to examples. However, the present invention is not limited to the following examples as long as the gist of the invention is not exceeded.
Example 1
1. Production of Nonaqueous Electrolyte Battery In Example 1, a square nonaqueous electrolyte battery was produced as follows.
[Preparation of slurry for positive electrode]
Lithium manganese oxide LiMn ₂ O ₄ and lithium cobalt oxide LiCoO ₂ as a positive electrode active material, acetylene black as a conductive material, and polyvinylidene fluoride PVdF as a binder are suspended in N-methylpyrrolidone, and the positive electrode A slurry was obtained. The mixing ratios of lithium manganese oxide, lithium cobalt oxide, acetylene black, and PVdF added to N-methylpyrrolidone were 90% by mass, 7% by mass, and 3% by mass, respectively.

[Preparation of slurry for negative electrode]
Spinel-type lithium titanate Li ₄ Ti ₅ O ₁₂ as a negative electrode active material and PVdF as a binder were suspended in N-methylpyrrolidone to obtain a slurry for preparing a negative electrode. The mixing ratio of lithium titanate and PVdF charged into N-methylpyrrolidone was 95% by mass and 5% by mass, respectively.

[Preparation of slurry for oxide particle layer]
An acrylic copolymer containing 70% by mass of alumina Al ₂ O ₃ as oxide particles, carboxymethyl cellulose (CMC) as a dispersing agent, and methyl acrylate as a binder is suspended in pure water to form an oxide. A slurry for a particle layer was obtained. The mixing ratios of aluminum oxide, CMC, and acrylic binder introduced into pure water were 95% by mass, 1% by mass, and 4% by mass, respectively.

[Production of positive electrode]
An aluminum foil having a thickness of 15 μm was prepared as a positive electrode current collector. The positive electrode current collector had a strip shape extending in the first direction (I) and having a width in the second direction (II) perpendicular to the first direction. The positive electrode slurry prepared in the above procedure was applied to both surfaces of the positive electrode current collector so that the thickness of the positive electrode active material layer was 35 μm and dried. When applying the positive electrode slurry, 10 mm of a strip-shaped slurry uncoated portion extending in the first direction (I) was left on a part of the surface of the positive electrode current collector to form a positive electrode current collector tab. Next, the positive electrode current collector coated with the slurry was dried. After the application and drying of the positive electrode slurry, the oxide particle layer slurry prepared by the above procedure was applied onto the positive electrode current collector tab so as to have a width of 4 mm and a thickness of 20 μm after drying. After drying, the positive electrode active material layer was cut to have a width of 90 mm. After cutting, it was rolled to produce a positive electrode.

[Production of negative electrode]
An aluminum foil having a thickness of 15 μm was prepared as a negative electrode current collector. The negative electrode current collector had a strip shape extending in the first direction (I) and having a width in the second direction (II) perpendicular to the first direction. The negative electrode slurry prepared in the above procedure was applied and dried. When applying the negative electrode slurry, a strip-shaped slurry uncoated portion extending in the first direction (I) was left on a part of the surface of the negative electrode current collector to form a negative electrode current collector tab. After the application of the negative electrode slurry, the oxide particle layer slurry prepared by the above procedure was applied onto the negative electrode active material layer so as to have a thickness of 6 μm after drying and dried. After drying, the negative electrode current collector was cut so that the active material layer had a width of 95 mm. After cutting, it was rolled to prepare a negative electrode.

[Production of wound electrode group]
The positive electrode and the negative electrode thus obtained were wound around an axis extending in the width direction of the positive electrode and the negative electrode. At this time, while adjusting the position so that the surface of the positive electrode active material layer faces the surface of the negative electrode active material layer, that is, the surface of the positive electrode active material layer does not protrude from the surface of the negative electrode active material layer, the positive electrode 40 The circumference and the circumference of the negative electrode 41 were wound. An insulating tape having a thickness of 50 μm was attached to the surface of the outermost negative electrode active material layer of the electrode group to fix the electrode group. The electrode group produced by winding as described above was subjected to hot press to obtain a flat wound electrode group. The positive electrode current collector tab and the negative electrode current collector tab were ultrasonically welded to the aluminum current collector tab, respectively, and the current collector was bundled.

[Battery assembly]
The flat wound electrode group thus obtained and the nonaqueous electrolyte were housed in an aluminum bottomed rectangular container having an opening. At this time, the positive electrode current collecting tab and the negative electrode current collecting tab were extended from the end face of the electrode group facing the opening. Next, a rectangular sealing plate made of aluminum was prepared. The sealing plate was provided with three openings (not shown). In one of the three openings, a prismatic positive terminal was fitted and fixed. In the other one of the three openings, a prismatic negative electrode terminal was fitted and fixed via an insulating gasket. The remaining one of the three openings was an inlet for injecting electrolyte. Next, one end of the positive electrode terminal and the positive electrode current collecting tab of the electrode group were electrically connected by laser welding. Similarly, one end of the negative electrode terminal and the negative electrode current collecting tab of the electrode group were electrically connected by laser welding. Next, the peripheral edge of the sealing plate was welded to the container so as to close the opening of the container.

Next, an electrolytic solution was prepared. The electrolyte was a non-aqueous solvent prepared by mixing propylene carbonate (PC) and diethyl carbonate (DEC) at a volume ratio of 1: 1, and lithium hexafluorophosphate LiPF ₆ at a concentration of 1.0 mol / L. It was dissolved and prepared by dissolving lithium tetrafluoroborate (LiBF ₄ ) at a concentration of 0.5 mol / L. The viscosity of the adjusted electrolyte at −20 ° C. was 30 mPa · s.
Next, the electrolytic solution produced as described above was injected into the container through the electrolytic solution injection port provided on the sealing plate. Next, a battery was assembled by welding a sealing lid to the peripheral edge of the electrolyte inlet.

[Measurement of pore size distribution]
The pore size distribution of the negative electrode of Example 1 was measured by the method described below.
Shimadzu Autopore 9520 type was used as a measuring device. For the sample, the positive electrode was cut into a size of about 25 × 25 mm ² , folded and taken in a measurement cell, and measured under the conditions of an initial pressure of 20 kPa (about 3 psia, corresponding to a pore diameter of about 60 μm). The average value of three samples was used as a measurement result. In organizing the data, the pore specific surface area was calculated assuming that the pore shape was cylindrical. When one or two peaks exist in the range of 0.1 μm or more and 3.0 μm or less in the log differential pore volume distribution curve, the peak with the smaller pore diameter was identified as the second peak. .

The analysis principle of the mercury intrusion method is based on Washburn's formula (B).
D = −4γ cos θ / P (B) where P is the applied pressure, D is the pore diameter, γ is the surface tension of mercury (480 dyne · cm ⁻¹ ), and θ is the contact angle between mercury and the pore wall surface. °. Since γ and θ are constants, the relationship between the applied pressure P and the pore diameter D can be obtained from the Washburn equation. By measuring the mercury intrusion volume at that time, the pore diameter and its volume distribution can be derived. Can do. For details of the measurement method and principle, refer to Jinbo Motoni et al .: “Fine Particle Handbook” Asakura Shoten, (1991), Hayakawa Sohachiro Edition: “Powder Physical Property Measurement Method” Asakura Shoten (1978).

From the pore size distribution, the pore diameter D ₁ of the pore having the highest abundance ratio derived from the electrode layer was 0.10 μm, and the pore diameter D ₂ of the pore derived from the oxide particle layer was 0.55 μm. .
From the particle size distribution measurement, the average particle diameter D ₃ of the alumina contained in the oxide particle layer was 0.95 .mu.m.

[Measurement of discharge capacity ratio]
Input / output characteristics were evaluated by 5C low temperature capacity ratio. The battery of Example 1 was charged at a constant current up to 2.8 V at 1 C in a 25 ° C. environment, and then charged at a constant voltage until the current value reached 0.1 C, and rested at −20 ° C. for 3 hours. After that, constant current discharge was performed until the voltage became 1.5 V at 1C. The discharge capacity at this time was 1 C low temperature discharge capacity. Then return to the 25 ° C environment and rest for 3 hours. Charge at a constant current up to 2.8V at 1C, then charge at a constant voltage until the current value reaches 0.1C, and rest at -20 ° C for 3 hours. After that, constant current discharge was performed until the voltage became 1.5 V at 5C. The discharge capacity at this time was 5C low temperature discharge capacity. “(5C discharge capacity / 1C discharge capacity) × 100” was defined as the 5C low temperature capacity ratio. The 5C low-temperature discharge capacity rate of the battery of Example 1 was 99%.

[Voltage measurement after high temperature storage]
The life characteristics were evaluated by the voltage after high temperature storage. The battery of Example 1 was discharged at a constant current until the voltage became 1.5 V at 1 C in a 25 ° C. environment, paused for 10 minutes, and then charged at a constant current up to 2.8 V at 1 C. SOC 100% It was. Then, high temperature storage for 2 weeks was performed in a 60 degreeC environment. Then, it left still for 2 hours in 25 degreeC environment, and measured the voltage. The voltage of the battery of Example 1 was 2.620V. The production conditions and results are shown in Table 1.

(Example 2)
In Example 2, in [Preparation of positive electrode], after applying the slurry for positive electrode, the slurry for oxide particle layer was applied on the positive electrode active material layer so that the thickness after drying was 6 μm, and [Preparation of negative electrode] In Example 1, a nonaqueous electrolyte battery was produced in the same manner as in Example 1 except that the slurry for the oxide particle layer was not applied on the negative electrode active material layer. Similarly to Example 1, the 5C low temperature discharge capacity ratio and the voltage after high temperature storage were measured. The production conditions and results are shown in Table 1.

(Example 3)
In Example 3, in [Preparation of positive electrode], after applying the slurry for positive electrode, the slurry for oxide particle layer was applied so as to have a thickness of 3 μm after drying. After application, a nonaqueous electrolyte battery was produced in the same manner as in Example 1 except that the slurry for oxide particle layer was applied so that the thickness was 3 μm after drying. Similarly to Example 1, the 5C low temperature discharge capacity ratio and the voltage after high temperature storage were measured. The production conditions and results are shown in Table 1.

(Examples 4-11, 13-22)
In Examples 4 to 11 and 13 to 22, nonaqueous electrolyte batteries were produced in the same manner as in Example 1 except for the conditions shown in Table 1. Similarly to Example 1, the 5C low temperature discharge capacity ratio and the voltage after high temperature storage were measured. The production conditions and results are shown in Table 1.

(Example 12)
In Example 12, magnesia (MgO) particles were used instead of alumina particles in the production of the oxide particle layer slurry, and a nonaqueous electrolyte battery was produced in the same manner as in Example 1 except for the conditions shown in Table 1. . Similarly to Example 1, the 5C low temperature discharge capacity ratio and the voltage after high temperature storage were measured. The production conditions and results are shown in Table 1.

(Comparative Examples 1-14)
In Comparative Example 1, a nonaqueous electrolyte battery was produced in the same manner as in Example 1 except that the average particle diameter of the oxide particles contained in the oxide particle layer slurry was 0.24 μm. Similarly to Example 1, the 5C low temperature discharge capacity ratio and the voltage after high temperature storage were measured. The production conditions and results are shown in Table 1.

(Example 23)
In Example 23, in preparing the electrolytic solution, methyl ethyl carbonate (MEC) was used instead of diethyl carbonate, and propylene carbonate (PC) and methyl ethyl carbonate (MEC) were mixed at a volume ratio of 1: 1. A nonaqueous electrolyte battery was produced in the same manner as in Example 1 except that the nonaqueous solvent was used and the conditions shown in Table 1 were used. Similarly to Example 1, the 5C low temperature discharge capacity ratio and the voltage after high temperature storage were measured. The production conditions and results are shown in Table 1. The viscosity of the adjusted electrolyte at −20 ° C. was 21 mPa · s.

(Example 24)
In Example 24, in the adjustment of the electrolytic solution, lithium hexafluorophosphate LiPF ₆ was dissolved at a concentration of 1.2 mol / L, and lithium tetrafluoroborate (LiBF ₄ ) was dissolved at a concentration of 0.6 mol / L. Using the electrolyte prepared by dissolving, a nonaqueous electrolyte battery was produced in the same manner as in Example 1 except for the conditions shown in Table 1. Similarly to Example 1, the 5C low temperature discharge capacity ratio and the voltage after high temperature storage were measured. The production conditions and results are shown in Table 1. The viscosity of the adjusted electrolyte at −20 ° C. was 50 mPa · s.

(Comparative Example 15)
In Comparative Example 15, in adjusting the electrolytic solution, lithium hexafluorophosphate LiPF ₆ was dissolved at a concentration of 1.4 mol / L, and lithium tetrafluoroborate (LiBF ₄ ) was dissolved at a concentration of 0.7 mol / L. A nonaqueous electrolyte battery was produced in the same manner as in Example 1 except that the electrolyte prepared by dissolution was used except for the conditions shown in Table 1. Similarly to Example 1, the 5C low temperature discharge capacity ratio and the voltage after high temperature storage were measured. The production conditions and results are shown in Table 1. The viscosity of the adjusted electrolyte at −20 ° C. was 82 mPa · s.

  Compared with Examples 1-7, it turns out that the comparative example 1 has a low 5C low temperature discharge capacity rate, and the battery voltage after high temperature storage is low. Due to the small pore size and the dense oxide particle layer, the electrolyte does not penetrate into the pores of the oxide particle layer, and the input / output is reduced. It is presumed that due to the retention between the oxide particle layer and the electrode active material layer, the oxide particle layer peeled off from the negative electrode, a short circuit occurred, and a voltage drop occurred. Compared with Examples 1-7, the comparative example 2 shows that the battery voltage after high temperature storage is low. Since the pore diameter derived from the oxide particle layer was 3.48 μm, it is presumed that a void was generated in the oxide particle layer, a short circuit occurred, and a voltage drop was caused. Compared with Examples 1-7, it turns out that the comparative example 3 has low 5 C low temperature discharge capacity rate. It is inferred that the electrolyte solution was high in viscosity, so that the electrolyte solution did not penetrate into the pores of the oxide particle layer, causing a decrease in input / output.

Comparative Example 3, Example 8, Example 9, and Comparative Example 4 were on the negative electrode active material layer when D ₂ was 0.64 μm, D ₃ was 0.95 μm, and D ₂ / D ₃ was 0.67. This is an example in which the thickness of the oxide particle layer formed is adjusted to 2.0 μm, 3.0 μm, 10.0 μm, and 12.0 μm. From these examples, when the oxide particle layer is too thin, the voltage after high-temperature storage decreases, and when the oxide particle layer is too thick, the voltage after high-temperature storage decreases and the low-temperature discharge capacity ratio decreases. I understand that. This is presumed that when the oxide particle layer is too thin, defects occur in the oxide particle layer, so that a short circuit occurs in part and self-discharge occurs. In addition, if the oxide particle layer is too thick, it is presumed that the oxide particle layer was cracked during winding, causing a self-discharge due to a short circuit and a decrease in the low-temperature discharge capacity rate.

In Examples 10 to 13, D ₂ and D ₃ are changed, and the wound electrode group is manufactured so that D ₂ / D ₃ is between 0.11 and 0.65. Comparing Comparative Examples 5 and 6 with these Comparative Examples, D ₂ , D ₃ , even if each value is in a suitable range, by adjusting D ₂ / D ₃ , the low temperature discharge capacity ratio and high temperature storage It can be seen that the voltage can be increased. If D ₂ / D ₃ exceeds 0.7, the oxide particle layer becomes sparse, and the distance between the particles becomes too large, and it is assumed that the oxide particles fall off. In Example 13, since D ₃ and D ₂ / D ₃ are relatively large, the oxide particle layer is sparse compared to Examples 10 to 12, and the interparticle distance is too wide, so that the oxide particles are It is assumed that it is easy to drop out. Example 14 is an example in which magnesia is used as the oxide particles, but it can be seen that suitable characteristics are also obtained when magnesia is used.

Comparative Example 7, Example 15, Example 16, Comparative Example 8, the particle size and pore size is relatively large _{D 2 1.21μm, 1.87μm} and _{D 3,} and 0.65 D 2 / _{D 3} In this example, the thickness of the oxide particle layer formed on the negative electrode active material layer was adjusted to 2.0 μm, 4.0 μm, 8.0 μm, and 12.0 μm. From these examples, it can be seen that when the oxide particle layer is too thin, the voltage after high-temperature storage decreases, and when the oxide particle layer is too thick, the low-temperature discharge capacity ratio is low. This is presumed that when the oxide particle layer was too thin, a short circuit occurred in part and self-discharge occurred. Further, it is presumed that if the oxide particle layer is too thick, the impregnation property of the electrolytic solution is reduced or the oxide particle layer is cracked during winding.

  In Comparative Example 9, since the pore diameter was very small, the impregnation property of the electrolytic solution was poor, the low-temperature discharge capacity rate was reduced, and the voltage after high-temperature storage was further reduced. In Comparative Example 9, it is presumed that the gas is difficult to escape and the oxide particles are easily dropped or short-circuited. In Comparative Example 10, since the oxide particle size was large, it was difficult to make the oxide particle layer thin, the low-temperature discharge capacity ratio was reduced, and the voltage after high-temperature storage was further reduced. Since the particle diameter is too large, the contact area between the particles is small, and the binding between the particles is weak. Therefore, it is inferred that many oxide particles dropped off.

Comparative Example 11, Example 17, Example 18, and Comparative Example 12 had a relatively large particle size and pore size of D ₂ of 0.07 μm, D ₃ of 0.95 μm, and D ₂ / D ₃ of 0.07. In this example, the thickness of the oxide particle layer formed on the negative electrode active material layer was adjusted to 1.0 μm, 3.0 μm, 8.0 μm, and 9.0 μm. From these examples, it can be seen that when the oxide particle layer is too thin, the voltage after high-temperature storage decreases, and when the oxide particle layer is too thick, the low-temperature discharge capacity ratio is low. This is presumed that when the oxide particle layer was too thin, a short circuit occurred in part and self-discharge occurred. Further, if the oxide particle layer is too thick, it is presumed that the oxide particle layer was cracked during winding. Compared with Examples 8 and 15 and the like, when D ₂ / D ₃ is a small value, it is presumed that cracking is likely to occur even in a thin oxide particle layer than when D ₂ / D ₃ is a large value. Similar results were obtained in Comparative Example 13, Example 19, Example 20, and Comparative Example 14.

  In Example 21, oxide particles having a relatively large particle size are used. When the particle diameter is large, the contact area between the particles is small and the binding between the particles is weak. Therefore, it is inferred that the particles dropped out and self-discharged for a while. In Example 22, since the pore diameter and the particle diameter are suitable values, a battery having excellent low temperature discharge capacity ratio and voltage characteristics after high temperature storage is obtained. In Example 23, methyl ethyl carbonate was used as the solvent of the electrolytic solution of Example 22, but in this case as well, a battery having excellent low temperature discharge capacity ratio and voltage characteristics after high temperature storage was obtained. Moreover, in Example 24, since the electrolyte concentration of the electrolytic solution is increased, the viscosity of the electrolytic solution is high, but since the viscosity at −20 ° C. is 50 mPa / S or less, the low temperature discharge capacity is also used in this case. Batteries with excellent rate and voltage characteristics after high temperature storage have been obtained. In Comparative Example 15, the electrolyte concentration of the electrolytic solution is increased and the viscosity of the electrolytic solution is too high. The viscosity at −20 ° C. is higher than 50 mPa / S, the impregnation property of the electrolytic solution is lowered, and the low-temperature discharge capacity ratio is lowered.

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

DESCRIPTION OF SYMBOLS 100 ... Secondary battery, 1 ... Exterior can, 2 ... Winding electrode group, 3 ... Positive electrode lead, 4 ... Negative electrode lead, 5 ... Cover, 6 ... Positive electrode terminal, 7 ... Negative electrode terminal, 8 ... Positive electrode backup lead, 9 ... Negative electrode backup lead, 10 ... Positive electrode insulating cover, 11 ... Negative electrode insulating cover, 12 ... Positive electrode gasket, 13 ... Negative electrode gasket, 14 ... Safety valve, 15 ... Electrolyte inlet, 20 ... Positive electrode, 20a ... Positive electrode current collector, 20b, 20c ... positive electrode active material layer, 20d ... positive electrode current collector tab, 21 (a, b, c, d) ... oxide particle layer, 22 ... negative electrode, 22a ... negative electrode current collector, 22b, 22c ... negative electrode active material layer, 22d ... negative electrode current collecting tab, 200 ... battery module, 201 ... single cell, 202 ... positive electrode gasket, 203 ... positive electrode terminal, 204 ... safety valve, 205 ... negative electrode gasket, 206 ... negative electrode terminal, 207 ... lower case, 208 ... upper 209 ... Power input / output terminal (positive terminal), 210 ... Power input / output terminal (negative terminal), 211 ... Opening, 212 ... Bus bar, 213 ... Substrate, 214A ... Positive terminal, 214B ... Negative terminal, 215 ... Lid, 300 ... Power storage device, 301 ... Inverter, 302 ... Converter, 303 ... AC power supply, 304 ... Load, 400 ... Vehicle, 401 ... Inverter, 402 ... Motor, 403 ... Wheel, 500 ... Vehicle, 501 ... Electrical equipment 502 ... wheels, 503 ... generator

Claims (10)

A positive electrode having a positive electrode active material layer and a positive electrode current collector;
A negative electrode having a negative electrode active material layer and a negative electrode current collector;
An electrolyte,
An oxide particle layer on the positive electrode active material layer, on the negative electrode active material layer, or on the positive electrode active material layer and the negative electrode active material layer;
The positive electrode having the oxide particle layer, the negative electrode having the oxide particle layer, or the positive electrode having the oxide particle layer and the oxide particle layer are obtained by a log differential pore volume distribution curve obtained by a mercury intrusion method. A non-aqueous electrolyte battery having at least two peaks. In the log differential pore volume distribution curve obtained by the mercury intrusion method, the peak with the highest abundance ratio is defined as the first peak,
The pore size of the first peak is D ₁ , wherein the pore size is larger than D ₁ and the second peak is present in the range of 0.1 μm to 3.0 μm. The nonaqueous electrolyte battery described. Wherein the pore size of the second peak and _{D 2,} the average particle diameter of the oxide particles contained in the oxide particle layer when the _{D 3, D 2} and _{D 3} is, 0.1 ≦ _D 2 / _{D 3} ≦ 0.7 is satisfied,
The nonaqueous electrolyte battery according to claim 2, wherein the oxide particle layer has a thickness of 2.5 μm to 10.0 μm. Wherein the pore size of the second peak and _{D 2,} the average particle diameter of the oxide particles contained in the oxide particle layer when the _{D 3, D 2} and _{D 3} is, 0.05 ≦ _D 2 / _{D 3} ≦ 0.7 is satisfied,
The nonaqueous electrolyte battery according to claim 2, wherein the oxide particle layer has a thickness of 2.0 μm or more and 8.0 μm or less. Wherein the pore size of the second peak and _{D 2,} the average particle diameter of the oxide particles contained in the oxide particle layer when the _{D 3, D 2} and _{D 3} is, 0.1 ≦ _D 2 / _{D 3} ≦ 0.7 is satisfied,
5. The nonaqueous electrolyte battery according to claim 2, wherein the oxide particle layer has a thickness of 2.5 μm or more and 8.0 μm or less. 6. The nonaqueous electrolyte battery according to claim 1, wherein D ₃ , which is an average particle diameter of the oxide particles contained in the oxide particle layer, is 0.2 μm or more and 5.5 μm or less. D ₂ is a pore size of the second peak is a pore diameter of the oxide particle layer, wherein D ₂ is any one of claims 1 to 6 is 0.1μm or more 1.8μm or less The nonaqueous electrolyte battery according to item.   The nonaqueous electrolyte battery according to any one of claims 1 to 7, wherein a viscosity of the electrolytic solution at -20 ° C is 50 mPa · s or less.   The battery module using the nonaqueous electrolyte battery of any one of Claims 1 thru | or 8.   A vehicle using the battery module according to claim 9.