JP6877094B2 - Non-aqueous electrolyte batteries, battery modules and vehicles - Google Patents

Description

Embodiments relate to non-aqueous electrolyte batteries, battery modules and vehicles.

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

Japanese Unexamined Patent Publication No. 2007-172963

The embodiment provides a non-aqueous electrolyte battery, a battery module and a vehicle having excellent input / output characteristics or life characteristics.

The non-aqueous electrolyte battery of the embodiment has 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 electrolytic solution, and a negative electrode active material on the positive electrode active material layer. 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 and having an oxide particle layer, a negative electrode having an oxide particle layer, or a positive electrode having an oxide particle layer. And the negative electrode having the oxide particle layer has at least two peaks in the log differential pore volume distribution curve obtained by the mercury intrusion method, and is most present in the log differential pore volume distribution curve obtained by the mercury intrusion method. the high peak ratio to the first peak, the pore size of the first peak when the D _1, large pore diameter than D _1, pore size of the second to 3.0μm below the range of 0.1μm When a peak exists , the pore diameter of the second peak is D _2, and the average particle size of the oxide particles contained in the oxide particle layer is D ₃ , D ₂ and D ₃ are 0.1 ≦ D. ₂ / D ₃ ≦ 0.7 is satisfied, the thickness of the oxide particle layer is 2.5 μm or more and 10.0 μm or less, and the viscosity of the electrolytic solution at −20 ° C. is 50 mPa · s or less .

The perspective view which shows the appearance of the non-aqueous electrolyte battery of 1st Embodiment. The developed perspective view of the non-aqueous electrolyte battery of FIG. The perspective view of the lid of the non-aqueous electrolyte battery of FIG. The side view which shows the inside of the non-aqueous electrolyte battery of FIG. The development view of the winding type electrode group of FIG. FIG. 3 is a cross-sectional view of the wound electrode group of FIG. FIG. 3 is a cross-sectional view of the wound 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 development view of the battery module of the 2nd Embodiment. FIG. 3 is a cross-sectional view of the battery module of the second embodiment. The conceptual diagram of the power storage device of the 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, components exhibiting the same or similar functions are designated by the same reference numerals throughout the drawings, and duplicate description will be omitted. It should be noted that each figure is a schematic diagram for explaining the embodiment and promoting its understanding, and there are differences in its shape, dimensions, ratio, etc. from the actual device, but these are based on the following explanation and known techniques. The design can be changed as appropriate.

(First Embodiment)
The first embodiment relates to a non-aqueous electrolyte battery. The non-aqueous electrolyte battery of the first embodiment has 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 non-aqueous electrolyte battery of the first embodiment, FIG. 1 shows the appearance of the non-aqueous electrolyte battery 100, FIG. 2 shows a developed perspective view of the non-aqueous electrolyte battery 100, and FIG. 3 shows the lid of the non-aqueous electrolyte battery. A perspective view is shown in FIG. 4, and a side view showing the inside of the non-aqueous electrolyte battery is shown in FIG. As shown in FIGS. 1 to 4, the non-aqueous electrolyte battery 100 includes an exterior material 1, a flat-shaped 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. It includes a lead 8, a negative electrode backup lead 9, a positive electrode insulating cover 10, a negative electrode insulating cover 11, a positive electrode gasket 12, a negative electrode gasket 13, a safety valve 14, an electrolytic solution injection port 15, and an electrolytic solution (not shown). The electrolytic solution is preferably present in the exterior material 1 and is filled in the exterior material 1. The non-aqueous electrolyte battery of the embodiment is, for example, a secondary battery that can be charged and discharged. FIG. 1 shows a square non-aqueous electrolyte battery, but the battery is not limited to the square type.

Examples of the exterior material 1 include a laminated 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 laminated film, a multilayer film having a metal layer 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, or polyethylene terephthalate (PET) can be used. The laminated film can be sealed by heat fusion and molded into the shape of an exterior material. The thickness of the laminated film is preferably 0.2 mm or less, for example.

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

The wound electrode group 2 is formed by further winding a band-shaped laminate in which a band-shaped positive electrode 20, a band-shaped oxide particle layer 21, and a band-shaped 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 preferably exists on the active material layer of the positive electrode 20, 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, and is physically present. It is preferable that they are in contact with each other. 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 on the active material layer of the negative electrode 22, the oxide particle layer 21 is used between the positive electrode active material layer and the negative electrode active material layer and the positive electrode current collector. It is present on the upper or negative electrode current collector. The oxide particle layer 21 existing 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 area where the positive electrode active material layer on the positive electrode current collector or 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. The area where none of the above is provided is defined as the non-coated part. The uncoated portion of the positive electrode current collector becomes the positive electrode current collector tab. The oxide particle layer 21 existing 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 area where the negative electrode active material layer on the negative electrode current collector or 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. The area where none of the above is provided is defined as the non-coated part. The uncoated portion of the negative electrode current collector becomes the 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 developed view of the wound electrode group 2 shown in FIG. 5 and the partial cross-sectional view of the wound electrode group 2 shown in FIG. 6, the wound electrode group 2 having the oxide particle layer 21 is provided. , Will be explained in more detail. The cross-sectional view of FIG. 6 shows a portion in which the positive electrode 20, the oxide particle layer 21, and the negative electrode 22 are laminated in four layers. Although FIGS. 5 and 6 show the electrode group before the current collector tabs are bundled before being pressed, the current collector tabs of the wound electrode group 2 housed in the exterior material 1 are bundled. It is electrically connected to the positive electrode terminal 6 or the negative electrode terminal 7 via a lead. Although the flat-shaped wound electrode group 2 is shown, the present invention is not limited to this, and an electrode group having another shape can be used.

The wound electrode group 2 shown in FIGS. 5 and 6 includes a positive electrode 20 having a positive electrode current collector 20a, a first positive electrode active material layer 20b, a second positive electrode active material layer 20c, and a first oxide particle. A layer 21a, a second oxide particle layer 21b, an oxide particle layer 21 having a third oxide particle layer 21c and a fourth oxide particle layer 21d, a negative electrode current collector 22a, and a first negative electrode active material. It has a layer 22b and a negative electrode 22 having a second negative electrode active material layer 22c. The uncoated portion of the positive electrode 20 is the positive electrode current collecting tab 20d. The uncoated portion of the negative electrode 22 becomes 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, and 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 laminated in this order. This laminate 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 so as to be 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 band shape extending in the first direction (I) and having a width in the second direction (II) orthogonal to the first direction. The winding type electrode group 2 is preferably housed in the exterior material 1 so as to face the direction perpendicular to the winding axis.

One surface of the first oxide particle layer 21a is physically in 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 with each other. The first oxide particle layer 21a may be physically in contact with a 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 The oxide particle layer 21a of 1 is continuous. Then, the first oxide particle layer 21a insulates the second positive electrode active material layer 20c facing the first negative electrode active material layer 22b and the first negative electrode active material layer 22b.

The fourth oxide particle layer 21d is a second in a region where the second positive electrode active material layer 20c is not provided on the surface of the positive electrode current collector 20a on the side where the second positive electrode active material layer 20c is provided. Along the positive electrode active material layer 20c of the above, the positive electrode current collector 20a and the second positive electrode active material layer 20c are physically in contact with each other. The surface of the fourth oxide particle layer 21d facing the positive electrode current collector 20a is the surface of the first oxide particle layer 21a including the end opposite to the negative electrode current collector tab 22d side. opposite. Further, the strip-shaped 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 the non-coated portion, and the positive electrode current collector tab 20d. It becomes. The first oxide particle layer 21a on the outermost periphery 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 physically in 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 with each other. The second oxide particle layer 21b may also be in physical contact with a part of the surface of the negative electrode current collector 22a. When 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 oxide particle layer 21b of 2 is 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 is a first in a region where the first positive electrode active material layer 20b is not provided on the surface of the positive electrode current collector 20a on the side where the first positive electrode active material layer 20b is provided. Along the positive electrode active material layer 20b of the above, the positive electrode current collector 20a and the first positive electrode active material layer 20b are physically in contact with each other. The surface of the third oxide particle layer 21c facing the positive electrode current collector 20a is the surface of the second oxide particle layer 21b including the end opposite to the negative electrode current collector tab 22d side. opposite. Further, the strip-shaped 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 collector tab 20d It becomes.

In the cross-sectional view of FIG. 6, the third oxide particle layer 21c and the fourth oxide particle layer 21d are provided at positions sandwiching the positive electrode current collector 20a, but the third oxide particle layer 21c And the fourth oxide particle layer 21d may be omitted. Further, as shown in the cross-sectional view of FIG. 7, the position where the third oxide particle layer 21c and the fourth oxide particle layer 21d sandwich the negative electrode current collector 22a instead of sandwiching the positive electrode current collector 20a. It may be provided in. Further, 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 facing 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 partially physically in contact with the entire surface of the first negative electrode active material layer 22b and the surface of the fourth oxide particle layer 21d. One surface of the second oxide particle layer 21b is partially physically in 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 is a first in a region where the first negative electrode active material layer 22b is not provided on the surface of the negative electrode current collector 22a on the side where the first negative electrode active material layer 22b is provided. Along the negative electrode active material layer 22b of the above, the negative electrode current collector 22a and the first negative electrode active material layer 22b are physically in contact with each other. The fourth oxide particle layer 21d is a second in a region where the second negative electrode active material layer 22c is not provided on the surface of the negative electrode current collector 22a on the side where the second negative electrode active material layer 22c is provided. Along the negative electrode active material layer 22c of the above, the negative electrode current collector 22a and the second negative electrode active material layer 22c are provided in physical contact with each other. In the form of FIG. 7, the position of the oxide particle layer 21 is different from that of the form of FIG. 6, but since it corresponds to the oxide particle layer 21 of FIG. 6, it is common except for the position of the oxide particle layer 21. To do.

In any of the forms in which the third oxide particle layer 21c and the fourth oxide particle layer 21d are omitted in FIGS. 6, 7 and 7, the entire surface of the facing surface of the positive electrode active material layer and the negative electrode active material layer is covered. If the third oxide particle layer 21c and the fourth oxide particle layer 21d that physically contact 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 facing current collecting tab, and the higher the short-circuit probability due to the contact between the electrode active material layer end and the facing current collecting tab. When the third oxide particle layer 21c and the fourth oxide particle layer 21d are present, they do not come into contact with each other even if the electrode active material layer is thinned, so that the electrode active material layer can be made thin, thereby improving the input / output characteristics. Has the advantage of being able to. In FIGS. 6 and 7, the thicknesses of the third oxide particle layer 21c and the fourth oxide particle layer 21d are equal to or less than the thickness of the active material layers arranged side by side on the current collector. It is preferable to satisfy the following suitable thickness conditions.

The positive electrode 20 and the negative electrode 22 are respectively manufactured and then wound in layers to produce a wound electrode group 2. Therefore, even when the wound electrode group 2 is disassembled, the oxide particle layer 21 formed at the time of producing the positive electrode 20 is present on the positive electrode active material layer, and the oxide particle layer formed at the time of producing the negative electrode 22 is also present. 21 is present on the negative electrode active material layer. The surface of the positive electrode active material layer is rotated so as to face the surface of the negative electrode active material layer, that is, the position of the positive electrode 20 is adjusted so that a non-opposing portion does not occur. The outermost layer of the wound electrode group 2 is preferably fixed with an insulating tape (not shown).

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

The positive electrode 20 typically includes a positive electrode active material layer containing a positive electrode active material, a conductive material and a binder, and a positive electrode current collector. A form in which positive electrode active material layers are present on both sides 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 substance that can be charged and discharged by inserting and removing ions of lithium and other alkali metals can be used. 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 can be used as long as it has appropriate conductivity. For example, carbon black such as acetylene black and carbon such as graphite can be used in combination.

Any of the binders normally used for non-aqueous electrolyte batteries can be used. For example, electrochemically stable polyvinylidene fluoride, polytetrafluoroethylene, or the like is used.

The positive electrode current collector is a conductive thin film provided with a positive electrode active material layer on one side or both sides. As the positive electrode current collector, a non-perforated metal foil, a punched metal having a large number of holes, a metal mesh formed by molding a fine 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 aluminum foil, copper foil, nickel foil and the like. Examples of alloy foils include aluminum alloys, copper alloys, nickel alloys and the like.

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

For the positive electrode 20, for example, the positive electrode active material, the conductive material, and the binder are suspended in an appropriate solvent, the prepared slurry is applied to the positive electrode current collector, dried, and the positive electrode active material layer is rolled. It is produced by. A positive electrode current collector tab is provided in a portion of the positive electrode current collector where the positive electrode active material layer is not formed. The mixing ratio of the positive electrode active material, the conductive material and the binder is 70% by mass or more and 96% by mass or less for the positive electrode active material, 3% by mass or more and 17% by mass or less for the conductive material, and 1% by mass or more and 13% by mass for the binder. It is desirable to make it less than%. The positive electrode density (positive electrode filling 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 ionic conductivity existing between the positive electrode 20 and the negative electrode 22. The oxide particle layer 21 contains 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 as the oxide particles. Carboxymethyl cellulose 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 as the separator, but 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.

In the oxide particle layer 21, for example, the oxide particles, the dispersant, and the binder are suspended in a solvent such as water, and the prepared slurry is placed on the surface of the positive electrode active material layer, on the surface of the negative electrode active material layer, or on the positive electrode. It is formed by applying it on the surface of the active material layer and on the surface of the negative electrode active material layer and drying it. The positive electrode may be coated on a part of the positive electrode current collecting tab and dried to form an oxide particle layer. The oxide particle layer may be formed by applying a slurry on the surface of the electrode before rolling. The mixing ratio of the oxide particles, the dispersant and the binder in the obtained oxide particle layer 21 was 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 5 It is desirable that the content is 0.0% by mass or less and the binder content is 1.0% by mass or more and 10.0% by mass or less. If the ratio of 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 tend to fall off, which is not preferable.

The negative electrode 22 typically includes a negative electrode active material layer containing 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 preferable, and a form in which the negative electrode active material layer is present on both sides of the negative electrode current collector is more preferable. 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.

Examples of the negative electrode active material include _{spinel-type lithium titanate represented by Li 4 + x} Ti ₅ O ₁₂ (x changes in the range of -1 ≦ x ≦ 3 depending on the charge / discharge reaction) and ramsteride-type Li _{2 + x} Ti ₃ O. ₇ (x changes in the range of -1≤x≤3 depending on the 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 composite 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 and 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) can be mentioned. These metal composite oxides are changed to lithium titanium composite oxides by inserting lithium by charging. Of the lithium-titanium composite oxides, spinel-type lithium titanate is preferable because it has excellent cycle characteristics.

The negative electrode active material may contain other active materials, and examples thereof include carbonaceous substances and metal compounds. Examples of carbonaceous materials include natural graphite, artificial graphite, coke, vapor-grown carbon fiber, mesophase pitch-based carbon fiber, spherical carbon, and resin-fired carbon. More preferable carbonaceous materials include vapor-grown carbon fibers, mesophase pitch-based carbon fibers, and spherical carbons. _{For the carbonaceous material, it is preferable that the surface spacing d 002} of the (002) plane by X-ray diffraction is 0.34 nm or less.

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

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

As the binder, any binder usually used for non-aqueous electrolyte batteries can be used. It is preferred to use electrochemically stable materials such as polyvinylidene fluoride and polytetrafluoroethylene, carboxymethyl cellulose, styrene butadiene rubber, and mixtures thereof.

The negative electrode current collector is a conductive thin film provided with a negative electrode active material layer on one side or both sides. As the negative electrode current collector, the same members as the positive electrode current collector can be used.

The negative electrode is produced by suspending, for example, a negative electrode active material, a conductive material, and a binder in an appropriate solvent, applying the prepared slurry to a negative electrode current collector, drying, and rolling. The negative electrode serves as a negative electrode current collector 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 70% by mass or more and 96% by mass or less for the negative electrode active material, 2% by mass or more and 28% by mass or less for the conductive material, and 2% by mass or more and 28% by mass for the binder. It is desirable to keep it below%. 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 enhanced, and excellent cycle characteristics can be expected. On the other hand, it is preferable that the conductive material and the binder are 28% by mass or less, respectively, in order to increase the capacity. The negative electrode density (negative electrode filling density) is preferably 2.0 g / cc or more and 2.3 g / cc or less from the viewpoint of high capacity and input / output characteristics.

The non-aqueous electrolyte battery of the first embodiment has an 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 are log differentials obtained by the mercury intrusion method. It is preferable to have at least two peaks in the pore volume distribution curve.

FIG. 8 is a graph showing the pore size distribution of the negative electrode of the example according to the first embodiment, and FIG. 9 is a graph showing the pore size distribution of the positive electrode of the example 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. In FIGS. 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 and has a pore diameter of D ₁ (first pore diameter), which is larger than that of the first peak and the first pore diameter D _1. It is preferable to have a second peak having a large pore diameter and having a pore diameter in the range of 0.1 μm or more and 3.0 μm or less. The second peak is not limited to one, and may have two or more peaks in the range where the pore diameter is 0.1 μm or more and 3.0 μm or less.

The pore size of the first peak is smaller than the pore size 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. The maximum peak having a pore diameter between 0.03 μm and 0.5 μm is defined as the 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 which 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 the pore distribution curve, and specifically, the maximum value (log differential pore) of each peak included in the pore diameter distribution curve. Volume) is at least twice the minimum value (log differential pore volume) at the base of the peak. Peaks that do not satisfy this condition are treated as noise in the embodiment. 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 has been removed, it is possible to confirm 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 size D 1} having the highest abundance ratio and one peak in the range of the pore size of 0.05 μm or more and 3.0 μm or less. .. The peak with the highest abundance ratio is derived from the electrode active material layer, and one or two peaks having a pore diameter in the range of 0.05 μm or more and 3.0 μm or less and having a smaller pore diameter D ₂ (Second pore diameter) is derived from the oxide particle layer 21, and of the two peaks existing in the range of 0.05 μm or more and 3.0 μm or less, the one having the larger pore diameter (FIGS. 8 and 9). The second peak does not exist in) is derived from the interface between the oxide particle layer 21 and the electrode active material layer.

The average particle size D ₃ of the oxide particles is preferably in the range of 0.2 μm or more and 5.5 μm or less, more preferably 0.31 μm or more and 5.2 μm or less, and further more preferably 0.5 μm or more and 5.0 μm or less. preferable. If the average particle size of the oxide particles is too large or too small, the pore diameter of the oxide particle layer 21 cannot be set in a suitable range. From the same viewpoint, the particle size 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 the 5 cm × 5 cm region are scraped off and determined by laser diffraction. NMP (N-methyl-2-pyrrolidone) was used as the solvent for sample dispersion, the scraped sample was suspended in the solvent, the sample was dispersed by ultrasonic waves at an output of 180 W and a time of 180 sec, and defoaming was performed twice. The measurement was performed later. The measurement was repeated twice and used as the average. The average particle size D ₃ is the volume average diameter of the oxide particles.

_{The second pore diameter D 2} of the oxide particle layer 21 is preferably 0.1 μm or more and 1.8 μm or less. When the second pore diameter D ₂ is smaller than 0.1 μm, the oxide particle layer 21 becomes dense, so that the impregnation property of the electrolytic solution is lowered and the input / output characteristics are lowered. Further, 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 is peeled off, and a short circuit is likely to occur. If the second pore diameter D ₂ is larger than 3.0 μm, pores are formed when the thin film is formed, and a short circuit is likely to occur.

The ratio of the second pore diameter D ₂ derived from the oxide particle layer 21 to the average particle diameter D _{3 of the oxide particles contained in the oxide particle layer 21, D 2} / D _3, is a battery having high input / output characteristics. From the viewpoint of obtaining, 0.1 or more _and 0.7 or less are desirable. When D ₂ / D ₃ is smaller than 0.1, the oxide particle layer 21 becomes dense, so that the impregnation property of the electrolytic solution into the pores of the oxide particle layer 21 deteriorates and the input / output characteristics tend to deteriorate. .. If D ₂ / D ₃ is larger than 0.7, the distance between the oxide particles becomes too large, the binding between the oxide particles is weak, 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 an advantage that it has a sufficient thickness to function as an insulating layer and is not easily cracked at the time of winding. When the oxide particle layer 21 is cracked, the electrodes are short-circuited, and the input / output characteristics and the life characteristics are deteriorated.

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 electrolytic solution is poor, the input / output characteristics are lowered, the gas is hard to escape, and it is easy to fall off 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, the oxide particle layer 21 is easily peeled off, and the life characteristics are deteriorated. If D ₂ / D ₃ is larger than 0.7, the distance between the oxide particles becomes too large, the binding between the oxide particles is weak, the oxide particles fall off, and the battery capacity increases due to vibration or the like. It will drop. 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 an advantage that it has a sufficient thickness to function as an insulating layer and is not easily cracked at the time of 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 longevity 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 an advantage that it has a sufficient thickness to function as an insulating layer and is not easily cracked at the time of winding.

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

The method for measuring the thickness of the oxide particle layer 21 is obtained by observing the cross section of the electrode in the region having the oxide particle layer 21 with respect to the width direction by SEM. The thickness of the oxide particle layer 21 was obtained by dividing the electrode into 5 cm in the flow direction and 10 in the width direction, and for the obtained 10 samples, the region including the central portion was used as the measurement sample, and the magnification was 1000 times. The thickness of the position where the range observed in is divided into 5 is measured, and the average value of 40 points in total is taken as the average value of 50 points obtained by excluding 5 points each of large and small.

By satisfying these physical characteristics, the non-aqueous electrolyte battery of the embodiment can realize the improvement of the input / output characteristics and the life characteristics. The non-aqueous electrolyte battery of the embodiment has preferable pores in the oxide particle layer formed on the electrode surface, so that the impregnation property of the electrolytic solution is improved and the input / output characteristics are improved, so that the input / output characteristics are improved and the battery is used for a long period of time. 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 and a non-aqueous solvent existing in the exterior material 1. It is desirable that the viscosity of the electrolytic solution at −20 ° C. is 50 mPa · s or less. If it is higher than 50 mPa · s, the impregnation property of the electrolytic solution into the pores of the oxide particle layer 21 is lowered. Therefore, even if the physical properties of the oxide particle layer 21 are satisfied, if the viscosity of the electrolytic solution is too high, the battery characteristics. Is 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. Electrolyte salts include, for example, LiPF ₆ , LiBF ₄ , Li (CF ₃ SO ₂ ) ₂ N (bistrifluoromethanesulfonylamide lithium; commonly known as LiTFSI), LiCF ₃ SO ₃ (commonly known as LiTFS), 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 -Oxide-2-trifluoro-methylpropionato _{(2-) -0.0) Lithium borate {LiBF 2} OCOC (CF ₃ ) ₂ , commonly known as; LiBF ₂ (HHIB)} can be used. 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. Examples thereof include lithium hexafluorophosphate (LiPF ₆ ), lithium tetrafluoroborate, and an imide-based supporting salt. The lithium salt may contain one kind or two or more kinds.

The electrolyte salt concentration is preferably in the range of 1 mol / L or more and 3 mol / L or less, and more preferably in the range of 1 mol / L or more and 2 mol / L or less. By defining the electrolyte concentration in this way, it is possible to further improve the performance when a high load current is applied while suppressing the influence of the increase in viscosity due to the increase in the electrolyte salt concentration.

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

As shown in FIGS. 3 and 4, the positive electrode lead 3 is a conductive member that physically connects the positive electrode terminal 6 and the positive electrode backup lead 8. 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.

As shown in FIGS. 3 and 4, the negative electrode lead 4 is a conductive member that physically connects the negative electrode terminal 7 and the negative electrode backup lead 9. 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.

As shown in FIGS. 1 to 4, the lid 5 is a lid of the exterior material 1 accommodating the wound electrode group 2, 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 injection port 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 with a sealing material such as an adhesive resin.

The positive electrode terminal 6 is an electrode terminal for the positive electrode of the secondary battery provided on the lid 5 as shown in FIGS. 1 to 4. 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 the negative electrode of the secondary battery provided on the lid 5 as shown in FIGS. 1 to 4. The negative electrode 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 in which the positive electrode current collecting tabs 20c are bundled 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.

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

As shown in FIG. 2, the positive electrode insulating cover 10 is an insulating member that covers the positive electrode lead 3 and the positive electrode backup lead 8. The positive electrode insulating cover 10 has one end of the wound electrode group 2 including the positive electrode current collecting tab 20d. The positive electrode insulating cover 10 is preferably an insulating and heat-resistant member. As the positive electrode insulating cover 10, a resin molded body, a molded body made of a paper-based material, a member obtained by coating a molded body made of a paper-based material with a resin, or the like is preferable. As the resin, it is preferable to use a polyethylene resin or a fluororesin. 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 an external impact.

As shown in FIG. 2, the negative electrode insulating cover 11 is an insulating member that covers the negative electrode lead 4 and the negative electrode backup lead 9. The negative electrode insulating cover 11 has one end 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. The common description of the positive electrode insulating cover 10 and the negative electrode insulating cover 11 will be omitted.

As shown in FIGS. 1 to 3, the positive electrode gasket 12 is a member that insulates the positive electrode terminal 6 and the exterior material 1. The positive electrode gasket 12 is preferably a solvent-resistant and flame-retardant resin molded body. For the positive electrode gasket 12, for example, polyethylene resin, fluororesin, or the like is used.

As shown in FIGS. 1 to 3, the negative electrode gasket 13 is a member that insulates the negative electrode terminal 7 and the exterior material 1. 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, fluororesin, or the like is used.

The safety valve 14 is provided on the lid as shown in FIGS. 1 to 3, and is a member that functions as a pressure reducing valve that reduces the pressure inside the exterior material 1 when the internal pressure inside the exterior material 1 rises. 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 electrolytic solution injection port 15 is a hole for injecting the electrolytic solution as shown in FIGS. 1 to 3. After injecting 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 by 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 batteries) according to the first embodiment. When the battery module includes a plurality of cells, each cell is electrically connected in series, in parallel, or connected in parallel with the series.

The battery module 200 will be specifically described with reference to the perspective development view of FIG. 10 and the cross-sectional view of FIG. In the battery module 200 shown in FIG. 10, the non-aqueous electrolyte battery 100 shown in FIG. 1 is used as the cell 201. The cross-sectional view of FIG. 11 is a cross-sectional view including the positive electrode terminal 203B and the negative electrode terminal 206B in the perspective development view of FIG.

The plurality of cell cells 201 have positive electrode terminals 203 (203A, 203B) provided on the positive electrode gasket 202, safety valves 204, and negative electrode terminals 206 (206A, 206B) provided on the negative electrode gasket 205 outside the outer can of the battery. Have. The cells 201 shown in FIG. 10 are arranged so as to be aligned in a staggered manner. Although the cells 201 shown in FIG. 10 are connected in series, they may be connected in parallel by changing the arrangement method or the like.

The cell unit 201 is housed in the lower case 207 and the upper case 208. The upper case 208 is provided with power input / output terminals 209 and 210 (positive electrode terminal 209, negative electrode terminal 210) of the battery module. The upper case 208 is provided with an opening 211 aligned with the positions of the positive electrode terminal 203 and the negative electrode terminal 206 of the cell unit 201, and the positive electrode terminal 203 and the negative electrode 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 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 cell 201 on the opposite side to the above. Connected by. The positive electrode terminal 203B not connected by the bus bar 212 is connected to the positive electrode terminal 214A provided on the substrate 213, and the positive electrode terminal 214A is connected to the power input / output terminal 209 of the positive electrode via a circuit on the substrate 213. There is. 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 power input / output terminal 210 of the negative electrode 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) to charge and use the battery module 200. The upper case 208 is sealed with a lid 215. It is preferable that the substrate 213 is provided with a charge / discharge protection circuit. In addition, a configuration such as a configuration in which information such as deterioration of the cell unit 201 can be output from a terminal (not shown) may be added as appropriate.

(Third Embodiment)
The battery module of the embodiment can be mounted on the power storage device 300. The power storage device 300 shown 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 DC-converted by the converter 301, the battery module is charged, AC-converted by the DC power supply inverter 302 from the battery module, and electricity is supplied to the load 304. By using the power storage device 300 having the present configuration having the battery module 200 of the embodiment, a power storage device having excellent battery characteristics is provided.

(Fourth Embodiment)
The battery module 200 of the embodiment can be mounted on the vehicle 400. The 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 supply from the battery module 200 is AC-converted by an inverter, and the motor 402 is driven by the AC power supply. When using a motor driven by direct current, the inverter is omitted. In the figure, the charging mechanism of the battery module and the like are omitted. The driving force of the motor 402 can rotate the wheel 403. The vehicle 400 also 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 the 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 generator 503 such as a motor attached to the axle portion of the wheel 502 is operated at the time of deceleration of the vehicle to obtain regenerative energy, and the obtained regenerative energy is used. It is preferable to charge the battery module 200.

[Example]
The present invention will be described in more detail with reference to the following examples, but the present invention is not limited to the examples described below as long as the gist of the invention is not exceeded.
(Example 1)
1. 1. Production of Non-Aqueous Electrolyte Battery In Example 1, a square non-aqueous 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 the conductive material, and polyvinylidene fluoride PVdF serving as a binder were suspended in N- methylpyrrolidone, positive Slurry for use was obtained. The mixing ratios of lithium manganese oxide, lithium cobalt oxide, acetylene black and PVdF charged into 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 ratios of lithium titanate and PVdF charged into N-methylpyrrolidone were 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 dispersant, 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 put into pure water were 95% by mass, 1% by mass, and 4% by mass, respectively.

[Preparation of positive electrode]
As a positive electrode current collector, an aluminum foil having a thickness of 15 μm was prepared. The positive electrode current collector had a band shape extending in the first direction (I) and having a width in the second direction (II) orthogonal to the first direction. The positive electrode slurry prepared in the above procedure was applied to both sides of the positive electrode current collector so that the thickness of the positive electrode active material layer was 35 μm, and dried. When the positive electrode slurry was applied, a strip-shaped uncoated portion of slurry 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 coating and drying the slurry for the positive electrode, the slurry for the oxide particle layer prepared in the above procedure was applied on the tab of the positive electrode current collector so as to have a width of 4 mm and a thickness of 20 μm after drying, and dried. After drying, the positive electrode active material layer was cut so as to have a width of 90 mm. After cutting, it was rolled to prepare a positive electrode.

[Preparation of negative electrode]
As a negative electrode current collector, an aluminum foil having a thickness of 15 μm was prepared. The negative electrode current collector had a band shape extending in the first direction (I) and having a width in the second direction (II) orthogonal to the first direction. The negative electrode slurry prepared in the above procedure was applied and dried. When the negative electrode slurry was applied, a band-shaped uncoated portion of slurry 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 applying the negative electrode slurry, the oxide particle layer slurry prepared in 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 active material layer of the negative electrode current collector was cut so as to have a width of 95 mm. After cutting, it was rolled to prepare a negative electrode.

[Preparation of winding 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, the positive electrode 40 is adjusted 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 circumference and the negative electrode 41 laps were wound. An insulating tape having a thickness of 50 μm was attached to the surface of the negative electrode active material layer on the outermost periphery of the electrode group to fix the electrode group. A heat press was applied to the electrode group produced by winding as described above to obtain a flat type 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 collectors were bundled.

[Battery assembly]
The flat wound electrode group and the non-aqueous electrolyte thus obtained were housed in an aluminum bottomed square container having an opening. At this time, the positive electrode current collecting tab and the negative electrode current collecting tab extend 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). A prismatic positive electrode terminal was fitted and fixed in one of the three openings. The negative electrode terminal of the prism was fitted and fixed to the other one of the three openings via an insulating gasket. The remaining one of the three openings was an injection port for injecting the 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 electrolytic solution is a non-aqueous solvent prepared by mixing propylene carbonate (PC) and diethyl carbonate (DEC) in a volume ratio of 1: 1 with lithium hexafluorophosphate LiPF ₆ at a concentration of 1.0 mol / L. It was dissolved and prepared by dissolving lithium tetrafluorobolate (LiBF ₄ ) at a concentration of 0.5 mol / L. The viscosity of the prepared electrolytic solution at −20 ° C. was 30 mPa · s.
Next, the electrolytic solution prepared as described above was injected into the container through the electrolytic solution injection port provided on the sealing plate. Next, the battery was assembled by welding a sealing lid to the peripheral edge of the electrolytic solution injection port.

[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 was used as the measuring device. As a sample, the positive electrode ^{was cut into 2} sizes of about 25 × 25 mm, folded and taken in a measurement cell, and measured under the condition of an initial pressure of 20 kPa (about 3 psia, equivalent to a pore diameter of about 60 μm). The average value of the three samples was used as the measurement result. In organizing the data, the pore specific surface area was calculated with the shape of the pores as a cylinder. When one or two peaks exist in the range where the pore diameter of the log differential pore volume distribution curve is 0.1 μm or more and 3.0 μm or less, the peak with the smaller pore diameter is recognized as the second peak. ..

The analysis principle of the mercury intrusion method is based on Washburn's formula (B).
D = -4γcosθ / P (B) formula Here, 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 wall surface of the pores, which is 140. °. 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, and the pore diameter and its volume distribution can be derived by measuring the mercury penetration volume at that time. Can be done. For details on the measurement method and principle, refer to Motoni Jimbo et al .: "Particle Handbook" Asakura Shoten, (1991), edited by Sohachiro Hayakawa: "Measurement Method for Powder Physical Properties" Asakura Shoten (1978).

_{From the pore size distribution, the pore size D 1 of the} pores with the highest abundance ratio derived from the electrode layer was 0.10 μm, and the pore size D _{2 of} the pores 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 rate]
The input / output characteristics were evaluated at a low temperature capacity of 5C. The battery of Example 1 is constantly charged to 2.8 V at 1 C in an environment of 25 ° C., then charged to a constant voltage until the current value reaches 0.1 C, and then paused in an environment of −20 ° C. for 3 hours. After that, constant current discharge was performed at 1C until the voltage became 1.5V. The discharge capacity at this time was defined as a 1C low temperature discharge capacity. After that, it is returned to the environment of 25 ° C., paused for 3 hours, charged with constant current to 2.8 V at 1C, then charged with constant voltage until the current value reaches 0.1C, and paused for 3 hours in the environment of -20 ° C. After that, constant current discharge was performed at 5C until the voltage became 1.5V. The discharge capacity at this time was defined as a 5C low temperature discharge capacity. “(5C discharge capacity / 1C discharge capacity) × 100” was defined as a 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 is discharged at a constant current at 1C until the voltage reaches 1.5V in an environment of 25 ° C., pauses for 10 minutes, and then charged at a constant current of 2.8V at 1C to 100% SOC. And said. Then, it was stored at a high temperature for 2 weeks in an environment of 60 ° C. Then, it was allowed to stand for 2 hours in an environment of 25 ° C., and the voltage was measured. 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 coating the slurry for positive electrode, the slurry for oxide particle layer is applied on the positive electrode active material layer so that the thickness becomes 6 μm after drying, and [Preparation of negative electrode]. In the above, a non-aqueous electrolyte battery was produced in the same manner as in Example 1 except that the oxide particle layer slurry was not applied on the negative electrode active material layer. The 5C low temperature discharge capacity rate and the voltage after high temperature storage were measured in the same manner as in Example 1. The production conditions and results are shown in Table 1.

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

(Examples 4 to 11, 13 to 22)
In Examples 4 to 11 and 13 to 22, non-aqueous electrolyte batteries were produced in the same manner as in Example 1 except for the conditions shown in Table 1. The 5C low temperature discharge capacity rate and the voltage after high temperature storage were measured in the same manner as in Example 1. 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 preparation of the slurry for the oxide particle layer, and a non-aqueous electrolyte battery was prepared in the same manner as in Example 1 except for the conditions shown in Table 1. .. The 5C low temperature discharge capacity rate and the voltage after high temperature storage were measured in the same manner as in Example 1. The production conditions and results are shown in Table 1.

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

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

(Example 24)
In Example 24, in the preparation 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 dissolution, a non-aqueous electrolyte battery was prepared in the same manner as in Example 1 except for the conditions shown in Table 1. The 5C low temperature discharge capacity rate and the voltage after high temperature storage were measured in the same manner as in Example 1. The production conditions and results are shown in Table 1. The viscosity of the prepared electrolytic solution at −20 ° C. was 50 mPa · s.

(Comparative Example 15)
In Comparative Example 15, in the preparation of 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. Using the electrolyte prepared by dissolution, a non-hydrodehydrolytic battery was prepared in the same manner as in Example 1 except for the conditions shown in Table 1. The 5C low temperature discharge capacity rate and the voltage after high temperature storage were measured in the same manner as in Example 1. The production conditions and results are shown in Table 1. The viscosity of the prepared electrolytic solution at −20 ° C. was 82 mPa · s.

It can be seen that, as compared with Examples 1 to 7, Comparative Example 1 has a lower 5C low-temperature discharge capacity ratio and a lower battery voltage after high-temperature storage. Due to the small pore diameter and dense oxide particle layer, the electrolytic solution does not penetrate into the pores of the oxide particle layer, and the input and output are reduced. In high temperature storage, the gas generated during storage is released. It is presumed that the oxide particle layer was separated from the negative electrode due to the retention between the oxide particle layer and the electrode active material layer, causing a short circuit and causing a voltage drop. It can be seen that the battery voltage of Comparative Example 2 after high temperature storage is lower than that of Examples 1 to 7. Since the pore diameter derived from the oxide particle layer was 3.48 μm, it is inferred that pores were formed in the oxide particle layer, a short circuit occurred, and the voltage dropped. It can be seen that the 5C low temperature discharge capacity ratio is lower in Comparative Example 3 than in Examples 1 to 7. Since the viscosity of the electrolytic solution is high, it is presumed that the electrolytic solution did not penetrate into the pores of the oxide particle layer, causing a decrease in input and output.

Comparative Example 3, Example 8, Example 9, and Comparative Example 4 are on the negative electrode active material layer when _{D 2} is 0.64 _{μm, D 3} is 0.95 μm, and D ₂ / D _{3 is 0.67.} This is an example in which the thickness of the oxide particle layer formed in is adjusted to 2.0 μm, 3.0 μm, 10.0 μm, and 12.0 μm. From these examples, if the oxide particle layer is too thin, the voltage after high temperature storage decreases, and if the oxide particle layer is too thick, the voltage after high temperature storage decreases, and the low temperature discharge capacity ratio becomes low. You can see that there is. It is presumed that if the oxide particle layer is too thin, defects occur in the oxide particle layer, resulting in a short circuit in a part and self-discharge. Further, it is presumed that if the oxide particle layer is too thick, the oxide particle layer is cracked at the time of winding, causing self-discharge and a decrease in the low temperature discharge capacity rate due to a short circuit.

In Examples 10 to 13, D ₂ and D ₃ are changed to prepare a wound electrode group so that _{D 2} / D _{3 is between 0.11 and 0.65 or less.} Comparing Comparative Examples 5 and 6 with these Comparative Examples, the low-temperature discharge capacity rate and after high-temperature storage can be obtained by adjusting _{D 2} / D ₃ even if the respective values of _{D 2} and D _{3 are in a suitable range.} It can be seen that it is possible to increase the voltage of. When D ₂ / D ₃ exceeds 0.7, the oxide particle layer becomes sparse, and the distance between the particles becomes too wide, so that it is presumed that the oxide particles fall off. In Example 13, since D ₃ and D ₂ / D ₃ are relatively large, the oxide particle layer becomes sparse as compared with Examples 10 to 12, and the distance between the particles becomes too wide, so that the oxide particles become sparse. It is presumed 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.

In Comparative Example 7, Example 15, Example 16, and Comparative Example 8, D ₂ having a relatively large particle size and pore diameter was 1.21 μm, D ₃ was 1.87 μm, and D ₂ / D ₃ was 0.65. This is an example in which the thickness of the oxide particle layer formed on the negative electrode active material layer is adjusted to 2.0 μm, 4.0 μm, 8.0 μm, and 12.0 μm. From these examples, it can be seen that if the oxide particle layer is too thin, the voltage after high temperature storage is lowered, and if the oxide particle layer is too thick, the low temperature discharge capacity ratio is low. It is presumed that if the oxide particle layer is too thin, a short circuit occurs in a part and self-discharge occurs. Further, it is presumed that if the oxide particle layer is too thick, the impregnation property of the electrolytic solution is lowered or the oxide particle layer is cracked at the time of 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 ratio was lowered, and the voltage after high-temperature storage was lowered. In Comparative Example 9, it is presumed that the gas does not easily escape and the oxide particles are likely to fall off or short-circuit. In Comparative Example 10, since the particle size of the oxide particles was large, it was difficult to thin the oxide particle layer, the low-temperature discharge capacity ratio decreased, and the voltage after high-temperature storage decreased. Since the particle size is too large, the contact area between the particles is small, and the binding between the particles is weak. Therefore, it is presumed that many oxide particles fell off.

In Comparative Example 11, Example 17, Example 18, and Comparative Example 12, D ₂ having a relatively large particle size and pore diameter was 0.07 μm, D ₃ was 0.95 μm, and D ₂ / D ₃ was 0.07. This is an example in which the thickness of the oxide particle layer formed on the negative electrode active material layer is adjusted to 1.0 μm, 3.0 μm, 8.0 μm, and 9.0 μm. From these examples, it can be seen that if the oxide particle layer is too thin, the voltage after high temperature storage is lowered, and if the oxide particle layer is too thick, the low temperature discharge capacity ratio is low. It is presumed that if the oxide particle layer is too thin, a short circuit occurs in a part and self-discharge occurs. Further, if the oxide particle layer is too thick, it is presumed that the oxide particle layer is cracked at the time of winding. Compared with Examples 8 and 15, when D ₂ / D ₃ is a small value, it is presumed that cracks are more 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, the oxide particles having a relatively large particle size are used. When the particle size is large, the contact area between the particles is small, and the binding between the particles is weakened. Therefore, it is presumed that the particles fell off and self-discharged a little. In Example 22, since the pore diameter and the particle size 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 is used as the solvent for the electrolytic solution of Example 22, and in this case as well, a battery having excellent low-temperature discharge capacity ratio and voltage characteristics after high-temperature storage is obtained. Further, in Example 24, since the concentration of the electrolyte in 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 high in this case as well. Batteries with excellent rate and voltage characteristics after high temperature storage have been obtained. In Comparative Example 15, the concentration of the electrolyte in the electrolytic solution is increased, and the viscosity of the electrolytic solution becomes 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 some embodiments of the present invention have been described, these embodiments are presented as examples 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 gist of the invention. These embodiments and modifications thereof are included in the scope and gist of the invention, as well as in the scope of the invention described in the claims and the equivalent scope thereof.

100 ... Secondary battery, 1 ... Exterior can, 2 ... Winding electrode group, 3 ... Positive electrode lead, 4 ... Negative electrode lead, 5 ... Lid, 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 ... Electrode solution 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 ... Cellular 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 case , 209 ... Power input / output terminal (positive electrode terminal), 210 ... Power input / output terminal (negative electrode terminal), 211 ... Opening, 212 ... Bus bar, 213 ... Board, 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 ... wheels, 500 ... vehicle, 501 ... electrical equipment, 502 ... wheels, 503 ... generator

Claims (6)

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,
With electrolyte
The oxide particle layer is provided on the positive electrode active material layer, 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 negative electrode having the oxide particle layer are log differential pore volumes obtained by a mercury intrusion method. It has at least two peaks in the distribution curve and
In the log differential pore volume distribution curve obtained by the mercury intrusion method, the peak having the highest abundance ratio is set as the first peak.
When the pore diameter of the first peak is D ₁ , the pore diameter is larger than that of D _1, and the second peak exists in the range of 0.1 μm or more and 3.0 μm or less.
When the pore diameter of the second peak is D ₂ and the average particle size of the oxide particles contained in the oxide particle layer is D ₃ , D ₂ and D ₃ are 0.1 ≦ D ₂ / D. _{Satisfy 3} ≤ 0.7,
The thickness of the oxide particle layer is 2.5 μm or more and 10.0 μm or less.
A non-aqueous electrolyte battery having a viscosity of the electrolytic solution at −20 ° C. of 50 mPa · s or less. The non-aqueous electrolyte battery according to claim 1, wherein the oxide particle layer has a thickness of 2.5 μm or more and 8.0 μm or less. The non-aqueous electrolyte battery according to claim 1 or 2 _{, wherein D 3} , which is the average particle size of the oxide particles contained in the oxide particle layer, is 0.2 μm or more and 5.5 μm or less. _{D 2} which is the pore diameter of the second peak is the pore diameter of the oxide particle layer, and D ₂ is 0.1 μm or more and 1.8 μm or less, any one of claims 1 to 3. The non-aqueous electrolyte battery described in the section. A battery module using the non-aqueous electrolyte battery according to any one of claims 1 to 4 as a cell. The battery module according to claim 5 and the motor and electrical equipment are included.
A vehicle in which one or both of the motor and the electric device is driven or operated by electric energy from the electric module.

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