JP7134065B2 - Non-aqueous electrolyte secondary battery - Google Patents

Description

The present invention relates to a non-aqueous electrolyte secondary battery.

Non-aqueous electrolyte secondary batteries, especially lithium-ion secondary batteries, have high energy density and are widely used in personal computers, mobile phones, personal digital assistants, etc. Recently, they are also being developed as batteries for vehicles. It is

As a non-aqueous electrolyte secondary battery, for example, a porous layer containing a plate-like inorganic filler as described in Patent Document 1 and having a porosity of 60 to 90% is formed on at least one surface of a porous substrate. A non-aqueous electrolyte secondary battery is known that includes a separator for a non-aqueous secondary battery that is laminated on the substrate.

JP 2010-108753 A

However, the conventional technology as described above has room for improvement from the viewpoint of charge capacity after high-rate discharge.

SUMMARY OF THE INVENTION The present invention has been made in view of the above problems, and an object of the present invention is to realize a non-aqueous electrolyte secondary battery having excellent charge capacity after high-rate discharge.

A non-aqueous electrolyte secondary battery according to aspect 1 of the present invention includes a porous layer containing an inorganic filler and a resin, a non-aqueous electrolyte, a positive electrode and a negative electrode,
The aspect ratio of the projected image of the inorganic filler on the surface of the porous layer is in the range of 1.4 to 4.0,
Peak intensities of arbitrary mutually orthogonal diffraction planes (hkl) and (abc) of the porous layer measured by wide-angle X-ray diffraction: I _(hkl) and I _(abc) satisfy the following formula (1): ,
The range of the maximum value of the peak intensity ratio calculated by the following formula (2) is in the range of 1.5 to 300,
I _(hkl) > I _(abc) (1),
I _(hkl) / I _(abc) (2)
The non-aqueous electrolytic solution contains 0.5 ppm or more and 300 ppm or less of an additive whose ionic conductivity decrease rate L represented by the following formula (A) is 1.0% or more and 6.0% or less.

L=(LA−LB)/LA (A)
(In formula (A), LA is a mixed solvent containing ethylene carbonate, ethylmethyl carbonate and diethyl carbonate at a volume ratio of 3:5:2, and LiPF ₆ was dissolved so that its concentration was 1 mol/L. Represents the ionic conductivity (mS/cm) of the reference electrolyte solution, and LB represents the ionic conductivity (mS/cm) of the electrolyte solution obtained by dissolving 1.0% by weight of an additive in the reference electrolyte solution. .)
Further, in the non-aqueous electrolyte secondary battery according to aspect 2 of the present invention, in aspect 1, the porous layer is laminated on one side or both sides of the polyolefin porous film.

Further, in the non-aqueous electrolyte secondary battery according to aspect 3 of the present invention, in aspect 1 or 2, the porous layer is polyolefin, (meth)acrylate resin, fluorine-containing resin, polyamide resin, polyester It contains one or more resins selected from the group consisting of resins and water-soluble polymers.

Further, in the non-aqueous electrolyte secondary battery according to aspect 4 of the present invention, in aspect 3, the polyamide-based resin is an aramid resin.

Further, the non-aqueous electrolyte secondary battery according to aspect 5 of the present invention is the non-aqueous electrolyte secondary battery according to any one of aspects 1 to 4, wherein the non-aqueous electrolyte contains an electrolyte containing lithium.

Further, in the non-aqueous electrolyte secondary battery according to aspect 6 of the present invention, in any one of aspects 1 to 5, the non-aqueous electrolyte contains an aprotic polar solvent.

According to one aspect of the present invention, a non-aqueous electrolyte secondary battery having excellent 1C charge capacity after high-rate discharge (for example, 3C discharge) can be realized.

FIG. 2 is a schematic diagram showing the structure of a porous layer containing an inorganic filler when the orientation of the inorganic filler is large (left figure) and when the orientation of the inorganic filler is small (right figure). 1 is a schematic diagram showing a projected image of an inorganic filler on the surface of a porous layer for a non-aqueous electrolyte secondary battery in one embodiment of the present invention. FIG.

An embodiment of the invention will be described below, but the invention is not limited thereto. The present invention is not limited to the configurations described below, and can be modified in various ways within the scope of the claims, by appropriately combining technical means disclosed in different embodiments. The resulting embodiment is also included in the technical scope of the present invention. In this specification, unless otherwise specified, "A to B" representing a numerical range means "A or more and B or less".

A nonaqueous electrolyte secondary battery according to an embodiment of the present invention includes a porous layer described later, a positive electrode described later, a negative electrode described later, and a nonaqueous electrolyte described later. Moreover, the non-aqueous electrolyte secondary battery according to one embodiment of the present invention may further include a polyolefin porous film, which will be described later.

Members constituting the non-aqueous electrolyte secondary battery according to one embodiment of the present invention are described in detail below.

[Porous layer]
The porous layer in one embodiment of the present invention is a porous layer containing an inorganic filler and a resin, and the inorganic filler on the surface of the porous layer (hereinafter sometimes referred to as "porous layer surface") The aspect ratio of the projected image of is in the range of 1.4 to 4.0, and the porous layer is measured by a wide-angle X-ray diffraction method. Peak intensity: I _(hkl) and I _(abc) satisfy the following formula (1), and the maximum value range of the peak intensity ratio calculated by the following formula (2) is in the range of 1.5 to 300 characterized by
I _(hkl) > I _(abc) (1),
I _(hkl) / I _(abc) (2).

In one embodiment of the present invention, the porous layer can be arranged between the polyolefin porous film and at least one of the positive electrode and the negative electrode as a member constituting the non-aqueous electrolyte secondary battery. The porous layer may be formed on one side or both sides of the polyolefin porous film. Alternatively, the porous layer may be formed on the active material layer of at least one of the positive electrode and the negative electrode. Alternatively, the porous layer may be arranged between and in contact with the polyolefin porous film and at least one of the positive electrode and the negative electrode. The porous layer arranged between the polyolefin porous film and at least one of the positive electrode and the negative electrode may be one layer or two layers or more. The porous layer is preferably an insulating porous layer containing a resin.

When the porous layer is laminated on one side of the polyolefin porous film, the porous layer is preferably laminated on the surface of the polyolefin porous film facing the positive electrode. More preferably, the porous layer is laminated on the surface in contact with the positive electrode.

Both the above-mentioned "aspect ratio of the projected image of the inorganic filler on the surface of the porous layer" and the above-mentioned "maximum value of the peak intensity ratio calculated by the formula (2)" are the orientation of the inorganic filler in the porous layer It is an index that represents FIG. 1 shows schematic diagrams of the states of the inorganic filler in the porous layer when the orientation is high and when the orientation is low. The left diagram of FIG. 1 is a schematic diagram showing the structure of a porous layer containing an inorganic filler when the orientation of the filler is large and the anisotropy is high, and the right diagram of FIG. FIG. 4 is a schematic diagram showing the structure of the porous layer when the orientation of the filler is small and the anisotropy is low.

A porous layer in one embodiment of the present invention contains an inorganic filler and a resin. The porous layer has a large number of pores inside and has a structure in which these pores are connected, and is a layer that allows gas or liquid to pass from one surface to the other surface. Further, when the porous layer in one embodiment of the present invention is used as a member constituting a laminated separator for a non-aqueous electrolyte secondary battery described later, the porous layer is the outermost layer of the laminated separator, an electrode can be a layer in contact with

The resin contained in the porous layer in one embodiment of the present invention is preferably insoluble in the electrolyte of the battery and electrochemically stable within the range of use of the battery. Specific examples of the resin include polyolefins; (meth)acrylate resins; fluorine-containing resins; polyamide resins; polyimide resins; polyester resins; rubbers; resin; water-soluble polymer; polycarbonate, polyacetal, polyetheretherketone, and the like.

Among the above resins, polyolefins, polyester resins, (meth)acrylate resins, fluorine-containing resins, polyamide resins and water-soluble polymers are preferred.

Preferred polyolefins include polyethylene, polypropylene, polybutene, and ethylene-propylene copolymers.

As polyamide-based resins, aramid resins such as aromatic polyamides and wholly aromatic polyamides are preferred.

Specific examples of aramid resins include poly(paraphenylene terephthalamide), poly(metaphenylene isophthalamide), poly(parabenzamide), poly(methabenzamide), poly(4,4'-benzanilide terephthalate amide), poly(paraphenylene-4,4′-biphenylenedicarboxylic acid amide), poly(metaphenylene-4,4′-biphenylenedicarboxylic acid amide), poly(paraphenylene-2,6-naphthalenedicarboxylic acid amide), Poly(metaphenylene-2,6-naphthalenedicarboxylic acid amide), poly(2-chloroparaphenylene terephthalamide), paraphenylene terephthalamide/2,6-dichloroparaphenylene terephthalamide copolymer, metaphenylene terephthalamide/2 , 6-dichloroparaphenylene terephthalamide copolymer. Among these, poly(paraphenylene terephthalamide) is more preferable.

Aromatic polyesters such as polyarylates and liquid crystalline polyesters are preferable as the polyester-based resin.

Rubbers include styrene-butadiene copolymer and its hydride, methacrylic acid ester copolymer, acrylonitrile-acrylic acid ester copolymer, styrene-acrylic acid ester copolymer, ethylene propylene rubber, polyvinyl acetate, etc. can be mentioned.

Examples of resins having a melting point or glass transition temperature of 180° C. or higher include polyphenylene ether, polysulfone, polyethersulfone, polyphenylene sulfide, polyetherimide, polyamideimide, and polyetheramide.

Examples of water-soluble polymers include polyvinyl alcohol, polyethylene glycol, cellulose ether, sodium alginate, polyacrylic acid, polyacrylamide, and polymethacrylic acid.

Examples of fluorine-containing resins include polyvinylidene fluoride (PVDF), polytetrafluoroethylene, vinylidene fluoride-hexafluoropropylene copolymer, tetrafluoroethylene-hexafluoropropylene copolymer, tetrafluoroethylene-perfluoroalkyl vinyl ether copolymer. coalescence, vinylidene fluoride-tetrafluoroethylene copolymer, vinylidene fluoride-trifluoroethylene copolymer, vinylidene fluoride-trichlorethylene copolymer, vinylidene fluoride-vinyl fluoride copolymer, vinylidene fluoride-hexafluoro Propylene-tetrafluoroethylene copolymers, ethylene-tetrafluoroethylene copolymers, and the like, and fluorine-containing rubbers having a glass transition temperature of 23° C. or lower among the fluorine-containing resins can be mentioned.

The resin contained in the porous layer in one embodiment of the present invention may be of one type or a mixture of two or more types of resin.

Among the above resins, when the porous layer is arranged facing the positive electrode, it is easy to maintain various performances such as rate characteristics and resistance characteristics of the non-aqueous electrolyte secondary battery due to oxidation deterioration during battery operation. Therefore, fluorine-containing resins are preferred.

The porous layer in one embodiment of the invention contains an inorganic filler. The lower limit of the content is preferably 50% by weight or more, and 70% by weight or more, based on the total weight of the filler and the resin constituting the porous layer in one embodiment of the present invention. is more preferable, and 90% by weight or more is even more preferable. On the other hand, the upper limit of the inorganic filler content in the porous layer in one embodiment of the present invention is preferably 99% by weight or less, more preferably 98% by weight or less. The content of the filler is preferably 50% by weight or more from the viewpoint of heat resistance, and the content of the filler is preferably 99% by weight or less from the viewpoint of adhesion between fillers. Containing the inorganic filler can improve the lubricity and heat resistance of the separator including the porous layer. The inorganic filler is not particularly limited as long as it is stable in a non-aqueous electrolyte and electrochemically stable. From the viewpoint of ensuring battery safety, a filler having a heat resistance temperature of 150° C. or higher is preferable.

Although the inorganic filler is not particularly limited, it is usually an insulating filler. The inorganic filler is preferably an inorganic substance containing at least one metal element selected from the group consisting of aluminum element, zinc element, calcium element, zirconia element, silicon element, magnesium element, barium element, and boron element, An inorganic material containing an aluminum element is preferable. Also, the inorganic filler preferably contains an oxide of the metal element.

Specifically, inorganic fillers include titanium oxide, alumina (Al ₂ O ₃ ), zinc oxide (ZnO), calcium oxide (CaO), zirconia oxide (ZrO ₂ ), silica, magnesia, barium oxide, boron oxide, Examples include mica, wollastonite, attapulgite, and boehmite (alumina monohydrate). As the inorganic filler, one type of filler may be used alone, or two or more types of filler may be used in combination.

The inorganic filler in the porous layer in one embodiment of the present invention preferably contains alumina and plate-like filler. Examples of the plate-like filler include one or more fillers selected from the group consisting of zinc oxide (ZnO), mica, and boehmite among the oxides of the metal elements listed above.

The volume average particle size of the inorganic filler is preferably in the range of 0.01 μm to 10 μm from the viewpoint of ensuring good adhesiveness and lubricity and moldability of the laminate. The lower limit thereof is more preferably 0.05 μm or more, more preferably 0.1 μm or more. The upper limit thereof is more preferably 5 μm or less, more preferably 1 μm or less.

The shape of the inorganic filler is arbitrary and not particularly limited. The shape of the inorganic filler can be particulate, for example, spherical, elliptical, plate-like, rod-like, amorphous, fibrous, spherical or columnar single particles such as peanut-like and/or tetrapod-like. is heat-sealed; From the viewpoint of battery short circuit prevention, the inorganic filler is preferably plate-like particles and/or non-agglomerated primary particles, and from the viewpoint of ion permeation, the particles in the porous irregular shapes such as dendritic, coral-like, or tuft-like, having knobs, dents, constrictions, protuberances, or tufts; fibrous; peanut-like and/or tetra A pot-like shape in which single particles are thermally fused is preferred, and a shape in which spherical or columnar single particles are thermally fused, such as a peanut shape and/or a tetrapod shape, is particularly preferred.

The filler can improve slipperiness by forming fine irregularities on the surface of the porous layer. As a result, the irregularities formed on the surface of the porous layer become finer, and the adhesiveness between the porous layer and the electrode becomes better.

The oxygen atomic mass percentage of the metal oxide constituting the inorganic filler contained in the porous layer in one embodiment of the present invention is preferably 10% to 50%, more preferably 20% to 50%. preferable. In the present invention, the "oxygen atom mass percentage" means the ratio of the mass of oxygen atoms in the metal oxide to the total mass of the metal oxide, expressed as a percentage. For example, in the case of zinc oxide, since the atomic weight of zinc is 65.4 and the atomic weight of oxygen is 16.0, the molecular weight of zinc oxide (ZnO) is 65.4 + 16.0 = 81.4. The atomic mass percentage is 16.0/81.4×100=20(%).

The fact that the oxygen atomic mass percentage of the metal oxide is within the above-mentioned range ensures that the affinity between the inorganic filler and the solvent or dispersion medium in the coating liquid used in the method for producing the porous layer described later is suitable. By maintaining an appropriate distance between the inorganic fillers, the dispersibility of the coating liquid can be improved, and as a result, the "aspect ratio of the projected image of the inorganic filler on the surface of the porous layer" and the "orientation degree of the porous layer" can be controlled within an appropriately defined range.

The aspect ratio of the inorganic filler itself contained in the porous layer in one embodiment of the present invention is a state in which the inorganic filler is arranged on a plane, and the SEM image observed from vertically above the arrangement surface overlaps in the thickness direction. It is expressed as the average value of the ratio of the length of the short axis (minor axis diameter) to the length of the long axis (major axis diameter) of 100 particles without particles. The aspect ratio of the inorganic filler itself is preferably 1-10, more preferably 1.1-8, even more preferably 1.2-5. When the aspect ratio of the inorganic filler itself is within the above range, the orientation of the filler and the The uniformity of filler distribution on the surface of the porous layer can be controlled within a preferred range.

The porous layer in one embodiment of the present invention may contain components other than the inorganic filler and resin described above. Examples of the other components include surfactants, waxes, and binder resins. Also, the content of the other components is preferably 0% by weight to 50% by weight with respect to the weight of the entire porous layer.

In one embodiment of the present invention, the average film thickness of the porous layer is preferably in the range of 0.5 μm to 10 μm per one porous layer from the viewpoint of ensuring adhesion to the electrode and high energy density. More preferably, it is in the range of 1 μm to 5 μm.

The basis weight per unit area of the porous layer can be appropriately determined in consideration of the strength, film thickness, weight and handleability of the porous layer. The basis weight per unit area of the porous layer is preferably 0.5 to 20 g/m ² and more preferably 0.5 to 10 g/m ² per one porous layer.

By setting the basis weight per unit area of the porous layer within these numerical ranges, the weight energy density and volume energy density of the non-aqueous electrolyte secondary battery can be increased. If the basis weight of the porous layer exceeds the above range, the non-aqueous electrolyte secondary battery tends to be heavy.

The porosity of the porous layer is preferably 20 to 90% by volume, more preferably 30 to 80% by volume, so as to obtain sufficient ion permeability. Moreover, the pore size of the pores of the porous layer is preferably 1.0 μm or less, more preferably 0.5 μm or less. By setting the pore diameters of the pores to these sizes, the non-aqueous electrolyte secondary battery can obtain sufficient ion permeability.

<Aspect Ratio of Projected Image of Inorganic Filler on Porous Layer Surface>
In one embodiment of the porous layer of the present invention, the aspect ratio of the projected image of the inorganic filler on the surface of the porous layer is in the range of 1.4 to 4.0, and 1.5 to 2.3. A range is preferred. Here, using a scanning electron microscope (SEM), an SEM image, which is an electron micrograph of the surface of the porous layer, is taken from directly above the porous layer, that is, from the vertical direction. It is a value obtained by creating a projected image of the filler and calculating the ratio of the length of the major axis to the length of the minor axis of the projected image of the inorganic filler. The length of the major axis is also referred to as the major axis diameter, and the length of the minor axis is also referred to as the minor axis diameter. That is, the aspect ratio indicates the shape of the inorganic filler observed when the inorganic filler on the surface of the porous layer is observed from directly above the porous layer.

FIG. 2 shows a schematic diagram of a projection image of the inorganic filler created from the SEM image of the surface of the porous layer described above.

A specific method for measuring the aspect ratio includes, for example, a method comprising the following steps (1) to (4). In addition, the "surface" of the porous layer refers to the surface of the porous layer that can be observed by SEM from directly above the porous layer.
(1) In a laminate obtained by laminating a porous layer on a substrate, SEM at an acceleration voltage of 5 kV using a field emission scanning electron microscope JSM-7600F manufactured by JEOL from directly above the porous side of the laminate. A step of performing surface observation (backscattered electron image) and obtaining an SEM image.
(2) An OHP film is placed on the SEM image obtained in step (1), and a projection image is created by spreading along the contours of the inorganic filler particles shown in the SEM image. The process of photographing with a digital still camera.
(3) The photographic data obtained in the step (2) is loaded into a computer, and the filler particles 100 are analyzed using image analysis free software IMAGEJ published by the National Institutes of Health (NIH). Calculating the aspect ratio of each piece. Here, each filler particle is approximated to an elliptical shape, the major axis diameter and the minor axis diameter are calculated, and the value obtained by dividing the major axis diameter by the minor axis diameter is defined as the aspect ratio.
(4) A step of calculating the average value of the aspect ratios of the projected images of the respective particles obtained in step (3), and using that value as the aspect ratio of the projected image of the inorganic filler on the surface of the porous layer.

The aspect ratio of the projected image of the inorganic filler on the surface of the porous layer is an index showing the uniformity of distribution of the inorganic filler on the surface of the porous layer, particularly on the surface. The fact that the aspect ratio is close to 1 means that the shape and distribution of the constituent materials on the surface of the porous layer are uniform, and they are likely to be densely packed. On the other hand, when the aspect ratio is large, the arrangement of constituent components in the surface structure of the porous layer becomes non-uniform, and as a result, the uniformity of the shape and distribution of the openings on the surface of the porous layer deteriorates.

If the aspect ratio is greater than 4.0, the uniformity of the shape and distribution of the porous layer, particularly the openings on the surface thereof, is excessively reduced. In the battery, it is thought that there are places where the ability of the porous layer to accept electrolyte drops during battery operation, and as a result, the rate characteristics of the non-aqueous electrolyte secondary battery deteriorate. On the other hand, when the aspect ratio is less than 1.4, the porous layer, particularly the distribution of the inorganic filler on the surface thereof, becomes an excessively uniform structure, resulting in a surface opening area of the porous layer. Therefore, in a non-aqueous electrolyte secondary battery incorporating the porous layer, the electrolyte-accepting capacity of the porous layer during battery operation is reduced, resulting in a battery rate of the non-aqueous electrolyte secondary battery. It is considered that the characteristics are degraded.

<Orientation degree of porous layer>
The porous layer in one embodiment of the present invention has peak intensities of arbitrary diffraction planes (hkl) and (abc) orthogonal to each other in the porous layer measured by wide-angle X-ray diffraction: I _(hkl) and I _(abc) satisfies the following formula (1), and the range of the maximum value of the peak intensity ratio calculated by the following formula (2) is preferably in the range of 1.5 to 300, and 1.5 to A range of 250 is more preferred.
I _(hkl) > I _(abc) (1),
I _(hkl) / I _(abc) (2).

Hereinafter, in this specification, the maximum value of the peak intensity ratio calculated by the formula (2) is also referred to as "orientation degree of the porous layer".

The method for measuring the peak intensities I _(hkl) and I _(abc) and the peak intensity ratio I _(hkl) / I _(abc) is not particularly limited, but for example, the following (1) to (3) A method consisting of the steps shown can be mentioned.
(1) A step of cutting a laminate (laminated porous film) obtained by laminating a porous layer on a substrate into a 2 cm square to prepare a sample for measurement.
(2) The measurement sample obtained in step (1) is mounted on an Al holder with the porous layer side of the sample as the measurement surface, and an X-ray profile is obtained by a wide-angle X-ray diffraction method (2θ-θ scanning method). the step of measuring The apparatus and measurement conditions for measuring the X-ray profile are not particularly limited. A method of measuring with an output of 50 KV-200 mA and a scan speed of 2°/min can be used.
(3) Based on the X-ray profile obtained in step (2), the peak intensity I _(hkl) of arbitrary diffraction planes (hkl) and (abc) orthogonal to each other in the wide-angle X-ray diffraction measurement of the porous layer When I _(abc) satisfies the above formula (1), the peak intensity ratio calculated by the above formula (2) is calculated, and the maximum value of the peak intensity ratio, that is, the degree of orientation of the porous layer is calculated. process.

In calculating the degree of orientation of the porous layer, it is important to determine both the horizontal direction and the normal direction with respect to the substrate surface by using mutually orthogonal diffraction planes. be.

The maximum value of the peak intensity ratio represented by the formula (2) is an index indicating the degree of orientation inside the porous layer. A small peak intensity ratio represented by the above formula (2) indicates that the degree of orientation in the internal structure of the porous layer is low, and a large peak intensity ratio represented by the above formula (2) indicates that the porous This indicates a high degree of orientation in the internal structure of the layer.

When the maximum value of the peak intensity ratio represented by the formula (2) is greater than 300, the anisotropy of the internal structure of the porous layer becomes excessively high, and the ion permeation channel length inside the porous layer becomes As a result, in a non-aqueous electrolyte secondary battery incorporating the porous layer, the ion permeation resistance of the porous layer increases, and the battery rate characteristics of the non-aqueous electrolyte secondary battery decrease. be done.

On the other hand, when the maximum value of the peak intensity ratio represented by the formula (2) is less than 1.5, compared to the case of using a porous layer having a peak intensity ratio of 1.5 or more, the above In a non-aqueous electrolyte secondary battery incorporating a porous layer, since ions supplied from the electrode are allowed to permeate at high speed, the supply of ions from the electrode becomes rate-determining (that is, ions are depleted on the electrode surface), and the battery operates. Since the limiting current, which is the current value condition, becomes smaller, it is considered that the battery rate characteristics of the non-aqueous electrolyte secondary battery deteriorate as a result.

<Method for producing porous layer>
The method for producing the porous layer in one embodiment of the present invention is not particularly limited. A method of forming a porous layer containing the inorganic filler and the resin can be mentioned. In the case of steps (2) and (3) shown below, the resin can be produced by further drying after precipitating the resin to remove the solvent. The coating liquid in steps (1) to (3) may be in a state in which the inorganic filler is dispersed and the resin is dissolved. The solvent can be said to be a solvent for dissolving the resin and also a dispersion medium for dispersing the resin or the inorganic filler.

(1) A step of coating a substrate with a coating liquid containing the inorganic filler and the fine particles of the resin, and removing the solvent in the coating liquid by drying to form a porous layer.

(2) After coating the surface of the base material with a coating liquid containing the inorganic filler and the resin, the base material is immersed in a deposition solvent that is a poor solvent for the resin. A step of depositing a resin to form a porous layer.

(3) After coating the coating liquid containing the inorganic filler and the resin on the surface of the substrate, using a low boiling point organic acid to acidify the coating liquid, thereby A step of depositing a resin to form a porous layer.

As the substrate, in addition to the polyolefin porous film described later, other films, positive electrodes, negative electrodes, and the like can be used.

The solvent is preferably a solvent that does not adversely affect the substrate, uniformly and stably dissolves the resin, and uniformly and stably disperses the inorganic filler. Examples of the solvent include N-methyl-2-pyrrolidone, N,N-dimethylacetamide, N,N-dimethylformamide, acetone and water.

As the precipitation solvent, for example, isopropyl alcohol or t-butyl alcohol is preferably used.

In the step (3), for example, p-toluenesulfonic acid, acetic acid, etc. can be used as the low-boiling organic acid.

In addition, as a method for controlling the orientation of the porous layer in one embodiment of the present invention, that is, the "aspect ratio of the projected image of the inorganic filler on the surface of the porous layer" and the "degree of orientation of the porous layer", the following are described. As shown, the solid content concentration of the coating liquid containing the inorganic filler and the resin used for producing the porous layer, and the coating shear rate when the coating liquid is applied onto the substrate are adjustment can be mentioned.

A suitable solid content concentration of the coating liquid may vary depending on the type of filler and the like, but generally it is preferably more than 20% by weight and 40% by weight or less. When the solid content concentration is in the above range, the viscosity of the coating liquid is appropriately maintained, and as a result, the "aspect ratio of the projected image of the inorganic filler on the surface of the porous layer" and the "degree of orientation of the porous layer ” can be controlled within the preferred range described above.

The coating shear rate at which the coating liquid is applied onto the substrate may vary depending on the type of filler, but is generally preferably 2 (1/s) or more, and 4 (1/s). s) to 50 (1/s) is more preferable.

Here, for example, the inorganic filler may have a peanut-shaped and/or tetrapod-shaped spherical or columnar single particle thermally fused together, a spherical shape, an elliptical shape, a plate shape, a rod shape, or an irregular shape. When the inorganic filler having the shape of is used, increasing the coating shear rate tends to increase the anisotropy because a high shearing force is applied to the inorganic filler. On the other hand, when the coating shear rate is reduced, the inorganic filler tends to be oriented isotropically because the shear force is not applied to the inorganic filler.

On the other hand, when the inorganic filler is a long fiber diameter inorganic filler such as wollastonite having a long fiber diameter, if the coating shear rate is increased, the long fibers will entangle with each other or the blade of the doctor blade will become long. Since the fibers are caught, the orientation tends to be random and the anisotropy tends to be low. On the other hand, when the coating shear rate is decreased, the long fibers are not caught by each other and by the edge of the doctor blade, so that they are easily oriented and the anisotropy tends to be high.

[Non-aqueous electrolyte]
The non-aqueous electrolyte in one embodiment of the present invention contains an additive whose ionic conductivity decrease rate L represented by the following formula (A) is 1.0% or more and 6.0% or less. contains.
L=(LA−LB)/LA (A)
In formula (A), LA is a mixed solvent containing ethylene carbonate, ethylmethyl carbonate, and diethyl carbonate at a volume ratio of 3:5:2, and LiPF ₆ is dissolved to a concentration of 1 mol/L. represents the ionic conductivity (mS/cm) of the electrolytic solution for LB represents the ionic conductivity (mS/cm) of an electrolytic solution obtained by dissolving 1.0% by weight of an additive in the reference electrolytic solution.

The additive is not particularly limited as long as it is a compound that satisfies that the ionic conductivity decrease rate L represented by formula (A) is 1.0% or more and 6.0% or less. Such compounds include, for example, pentaerythritol tetrakis[3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate], triethyl phosphate, vinylene carbonate, propanesultone, 2,6-di -tert-butyl-4-methylphenol, 6-[3-(3-t-butyl-4-hydroxy-5-methylphenyl)propoxy]-2,4,8,10-tetra-t-butyldibenzo[d , f][1,3,2]dioxaphosphepine, tris(2,4-di-tert-butylphenyl) phosphate, 2-[1-(2-hydroxy-3,5-di-tert- pentylphenyl)ethyl]-4,6-di-tert-pentylphenyl acrylate, dibutylhydroxytoluene, and the like.

The non-aqueous electrolyte contains an electrolyte and an organic solvent. Examples of the electrolyte include an electrolyte containing lithium. Examples of lithium-containing electrolytes include LiClO ₄ , LiPF ₆ , LiAsF ₆ , LiSbF ₆ , LiBF ₄ , LiCF ₃ SO ₃ , LiN(CF ₃ SO ₂ ) ₂ , LiC(CF ₃ SO ₂ ) ₃ , Metal salts such as Li ₂ B ₁₀ Cl ₁₀ , lower aliphatic carboxylic acid lithium salts and lithium salts such as LiAlCl ₄ can be mentioned. Only one type of the electrolyte may be used, or two or more types may be used in combination.

Organic solvents constituting the non-aqueous electrolyte include, for example, carbonates, ethers, esters, nitriles, amides, carbamates, sulfur-containing compounds, and fluorine groups introduced into these organic solvents. Aprotic polar solvents such as fluorine-containing organic solvents are included. Only one type of the organic solvent may be used, or two or more types may be used in combination.

Like the reference electrolyte, the organic solvent is preferably a mixed solvent containing a cyclic compound such as ethylene carbonate and a chain compound such as ethylmethyl carbonate or diethyl carbonate. The mixed solvent contains the cyclic compound and the chain compound preferably in a volume ratio of 2:8 to 4:6, more preferably in a volume ratio of 2:8 to 3:7, and particularly preferably. contains in a volume ratio of 3:7. A mixed solvent in which a cyclic compound and a chain compound are mixed at a volume ratio of 3:7 is an organic solvent that is particularly commonly used for non-aqueous electrolytes in non-aqueous electrolyte secondary batteries.

The additive in one embodiment of the present invention reduces the ionic conductivity of the reference electrolyte. The reason why the addition of the additive to the non-aqueous electrolyte can suppress the decrease in the charge capacity after high-rate discharge is, for example, as follows. By adding the additive, the degree of dissociation of ions in the non-aqueous electrolyte can be lowered. This can reduce the depletion of ions at the separator-electrode interface during charging and discharging, especially when the battery is operated at high speeds. It is considered that this can suppress the decrease in charge capacity after high-rate discharge.

From the viewpoint of reducing depletion of ions in the vicinity of the electrode, the non-aqueous electrolytic solution contains the additive at 0.5 ppm or more, preferably at 20 ppm or more, and more preferably at 45 ppm or more.

On the other hand, when the content of the additive is excessively high, the degree of dissociation of ions in the entire non-aqueous electrolyte is excessively lowered, which is thought to impede the flow of ions in the entire non-aqueous electrolyte secondary battery. be done. Therefore, the battery characteristics such as the charge capacity after high-rate discharge may rather deteriorate. From the viewpoint of suppressing inhibition of ion flow in the entire non-aqueous electrolyte secondary battery, the non-aqueous electrolyte contains the additive at 300 ppm or less, preferably at 250 ppm or less, and at 180 ppm or less. is more preferred.

Here, in the non-aqueous electrolyte secondary battery according to one embodiment of the present invention, the degree of dissociation of ions near the positive electrode when charging and discharging are repeated, particularly when the battery is operated at high speed, is Strongly influenced by the amount of additive.

Therefore, in the non-aqueous electrolyte secondary battery according to one embodiment of the present invention, the dissociation degree of ions in the vicinity of the positive electrode can be suitably reduced regardless of the type of non-aqueous electrolyte. That is, 0.5 ppm or more and 300 ppm or less of the additive is contained regardless of the type and amount of the electrolyte contained in the non-aqueous electrolyte, and the type of the organic solvent contained, thereby dissociating ions near the positive electrode. degree can be suitably reduced. As a result, a decrease in charge capacity after high-rate discharge can be suppressed.

The method for controlling the content of the additive in the non-aqueous electrolyte to 0.5 ppm or more and 300 ppm or less is not particularly limited. A method of dissolving the additive in advance in the non-aqueous electrolyte to be injected into the container serving as the housing of the liquid secondary battery so that the content is 0.5 ppm or more and 300 ppm or less. can.

[Positive electrode]
The positive electrode in one embodiment of the present invention is not particularly limited as long as it is generally used as a positive electrode for non-aqueous electrolyte secondary batteries. For example, a positive electrode sheet having a structure in which an active material layer containing a positive electrode active material and a binder is formed on a positive electrode current collector can be used as the positive electrode. The active material layer may further contain a conductive agent.

Examples of the positive electrode active material include materials that can be doped/dedoped with metal ions such as lithium ions or sodium ions. Specific examples of such materials include lithium composite oxides containing at least one type of transition metal such as V, Mn, Fe, Co and Ni.

Examples of the conductive agent include natural graphite, artificial graphite, cokes, carbon black, pyrolytic carbons, carbon fibers, and carbonaceous materials such as sintered organic polymer compounds. Only one type of the conductive agent may be used, or two or more types may be used in combination.

Examples of the binder include fluorine-based resins such as polyvinylidene fluoride (PVDF), acrylic resins, and styrene-butadiene rubber. In addition, the binder also has a function as a thickener.

Examples of the positive electrode current collector include conductors such as Al, Ni, and stainless steel. Among them, Al is more preferable because it is easy to process into a thin film and is inexpensive.

Methods for producing the positive electrode sheet include, for example, a method of pressure-molding a positive electrode active material, a conductive agent and a binder on a positive electrode current collector; is made into a paste, the paste is applied to the positive electrode current collector, and after drying, pressure is applied to fix it to the positive electrode current collector;

[Negative electrode]
The negative electrode in one embodiment of the present invention is not particularly limited as long as it is generally used as a negative electrode for non-aqueous electrolyte secondary batteries. For example, a negative electrode sheet having a structure in which an active material layer containing a negative electrode active material and a binder is formed on a negative electrode current collector can be used as the negative electrode. The active material layer may further contain a conductive agent.

Examples of the negative electrode active material include materials capable of doping/dedoping metal ions such as lithium ions or sodium ions. Examples of such materials include carbonaceous materials. Examples of carbonaceous materials include natural graphite, artificial graphite, cokes, carbon black and pyrolytic carbons.

Examples of the negative electrode current collector include Cu, Ni, and stainless steel. Cu is more preferable because it is difficult to form an alloy with lithium and is easy to process into a thin film.

Examples of the method for producing the negative electrode sheet include a method of pressure-molding a negative electrode active material on a negative electrode current collector; a method in which the coating is applied to the surface, dried, and then pressed to adhere to the negative electrode current collector; and the like. The paste preferably contains the conductive agent and the binder.

[Polyolefin porous film]
A non-aqueous electrolyte secondary battery in one embodiment of the present invention may include a polyolefin porous film. Hereinafter, the polyolefin porous film may be simply referred to as "porous film". The porous film has a polyolefin resin as a main component and has a large number of interconnected pores therein, allowing gas and liquid to pass from one surface to the other surface. The porous film alone can serve as a separator for a non-aqueous electrolyte secondary battery. It can also be used as a base material of a laminated separator for a non-aqueous electrolyte secondary battery in which the above porous layer is laminated.

A laminate obtained by laminating the porous layer on at least one surface of the polyolefin porous film is also referred to herein as a "laminated separator for a non-aqueous electrolyte secondary battery" or a "laminated separator". . Moreover, the separator for non-aqueous electrolyte secondary batteries in one embodiment of the present invention may further include other layers such as an adhesive layer, a heat-resistant layer, and a protective layer in addition to the polyolefin porous film.

The proportion of polyolefin in the porous film is 50% by volume or more, more preferably 90% by volume or more, and even more preferably 95% by volume or more, of the entire porous film. Further, the polyolefin more preferably contains a high molecular weight component having a weight average molecular weight of 5×10 ⁵ to 15×10 ⁶ . In particular, when the polyolefin contains a high molecular weight component having a weight average molecular weight of 1,000,000 or more, the strength of the separator for non-aqueous electrolyte secondary batteries is improved, which is more preferable.

Specific examples of the polyolefin, which is a thermoplastic resin, include homopolymers obtained by polymerizing monomers such as ethylene, propylene, 1-butene, 4-methyl-1-pentene and 1-hexene. Or a copolymer is mentioned. Examples of the homopolymer include polyethylene, polypropylene, and polybutene. Further, examples of the copolymer include an ethylene-propylene copolymer.

Among these, polyethylene is more preferable because it can prevent the flow of excessive current at a lower temperature. It should be noted that blocking the flow of this excessive current is also called shutdown. Examples of the polyethylene include low-density polyethylene, high-density polyethylene, linear polyethylene (ethylene-α-olefin copolymer), and ultra-high molecular weight polyethylene having a weight average molecular weight of 1,000,000 or more. Among them, ultra-high molecular weight polyethylene having a weight average molecular weight of 1,000,000 or more is more preferable.

The thickness of the porous film is preferably 4 to 40 μm, more preferably 5 to 30 μm, even more preferably 6 to 15 μm.

The basis weight per unit area of the porous film can be appropriately determined in consideration of strength, film thickness, weight and handleability. However, the basis weight is preferably 4 to 20 g/m ² and more preferably 4 to 12 g/m ² so that the weight energy density and volume energy density of the non-aqueous electrolyte secondary battery can be increased. more preferably 5 to 10 g/m ² .

The air permeability of the porous film is preferably 30 to 500 sec/100 mL, more preferably 50 to 300 sec/100 mL in Gurley value. Sufficient ion permeability can be obtained by the porous film having the air permeability. The air permeability of the laminated separator for a non-aqueous electrolyte secondary battery in which the above porous layer is laminated on a porous film is preferably 30 to 1000 sec/100 mL, more preferably 50 to 800 sec/100 mL in Gurley value. is more preferable. The laminated separator for a non-aqueous electrolyte secondary battery can obtain sufficient ion permeability in a non-aqueous electrolyte secondary battery by having the above air permeability.

The porosity of the porous film is preferably 20 to 80% by volume so as to increase the retention amount of the electrolytic solution and to obtain the function of reliably preventing the flow of excessive current at a lower temperature. It is more preferably 30 to 75% by volume. In addition, the pore diameter of the pores of the porous film is 0.3 μm or less so that sufficient ion permeability can be obtained and particles can be prevented from entering the positive electrode and the negative electrode. is preferable, and 0.14 μm or less is more preferable.

[Method for producing polyolefin porous film]
The method for producing the polyolefin porous film is not particularly limited. For example, a sheet-like polyolefin resin composition is produced by kneading a polyolefin resin, a pore-forming agent such as an inorganic filler and a plasticizer, and optionally an antioxidant or the like and then extruding the mixture. After removing the pore-forming agent from the sheet-shaped polyolefin resin composition with an appropriate solvent, the polyolefin porous film can be produced by stretching the polyolefin resin composition from which the pore-forming agent has been removed. can.

The inorganic filler is not particularly limited, and includes inorganic fillers, specifically calcium carbonate and the like. The plasticizer is not particularly limited, and examples thereof include low-molecular-weight hydrocarbons such as liquid paraffin.

Specifically, a method including the steps shown below can be mentioned.
(A) a step of kneading an ultra-high molecular weight polyethylene, a low molecular weight polyethylene having a weight average molecular weight of 10,000 or less, a pore forming agent such as calcium carbonate or a plasticizer, and an antioxidant to obtain a polyolefin resin composition;
(B) A step of rolling the obtained polyolefin resin composition with a pair of rolling rollers, cooling it step by step while pulling it with winding rollers with different speed ratios, and forming a sheet;
(C) removing the pore-forming agent from the obtained sheet with a suitable solvent;
(D) A step of stretching the sheet from which the pore-forming agent has been removed at an appropriate stretching ratio.

[Method for manufacturing laminated separator for non-aqueous electrolyte secondary battery]
As a method for producing a laminated separator for a non-aqueous electrolyte secondary battery in one embodiment of the present invention, for example, in the above-mentioned "method for producing a porous layer", the above-mentioned base material for applying the coating liquid is used. A method using a polyolefin porous film can be mentioned.

In other words, the porous layer is laminated on one side or both sides of the polyolefin porous film to obtain a laminated separator for a non-aqueous electrolyte secondary battery.

[Method for producing non-aqueous electrolyte secondary battery]
As a method for manufacturing the non-aqueous secondary battery according to one embodiment of the present invention, a conventionally known manufacturing method can be adopted. For example, a non-aqueous electrolyte secondary battery member is formed by arranging a positive electrode, a polyolefin porous film and a negative electrode in this order. Here, the porous layer may exist between the polyolefin porous film and at least one of the positive electrode and the negative electrode. Next, the non-aqueous electrolyte secondary battery member is placed in a container that serves as a housing for the non-aqueous electrolyte secondary battery. After filling the inside of the container with the non-aqueous electrolyte, the container is sealed while reducing the pressure. Thereby, a non-aqueous electrolyte secondary battery according to one embodiment of the present invention can be manufactured.

EXAMPLES The present invention will be described in more detail below with reference to Examples and Comparative Examples, but the present invention is not limited to these Examples.

[Measuring method]
Physical properties of the porous layers and polyolefin porous films produced in Examples and Comparative Examples, and charge capacities after high-rate discharge of non-aqueous electrolyte secondary batteries were measured using the following methods.

(1) Film thickness (unit: μm)
The polyolefin porous film and the film thickness of the porous layer were measured using a high-precision digital length measuring machine (VL-50) manufactured by Mitutoyo Corporation. The thickness of the porous layer was obtained by subtracting the thickness of the portion where the porous layer was not formed from the thickness of the portion where the porous layer was formed in each laminate.

(2) Measurement of the aspect ratio of the projected image of the inorganic filler on the surface of the porous layer Using a field-emission scanning electron microscope JSM-7600F manufactured by Manufacture Co., Ltd., SEM surface observation (backscattered electron image) was performed at an acceleration voltage of 5 kV to obtain an electron micrograph (SEM image).

An OHP film was placed on the obtained SEM image, and a projection image was created by spreading along the contours of the particles of the inorganic filler, and the projection image was photographed with a digital still camera. The data of the obtained photograph was loaded into a computer, and the aspect ratio of each of 100 particles was calculated using the image analysis free software IMAGEJ published by the National Institutes of Health (NIH). The average was defined as the aspect ratio of the projected image of the inorganic filler on the surface of the porous layer in the porous layer (hereinafter also referred to as the surface filler aspect ratio). Here, each filler particle was approximated to an elliptical shape, the major axis diameter and the minor axis diameter were calculated, and the value obtained by dividing the major axis diameter by the minor axis diameter was defined as the aspect ratio per filler particle.

(3) Measurement of Maximum Value of Peak Intensity Ratio A 2 cm-square piece was cut from the laminate comprising the polyolefin porous film and the porous layer produced in Examples and Comparative Examples to obtain a sample for measurement. The obtained measurement sample was attached to an Al holder using the porous layer of the sample as a measurement surface, and the X-ray profile was measured by a wide-angle X-ray diffraction method (2θ-θ scanning method). RU-200R (rotating anticathode type) manufactured by Rigaku Denki Co., Ltd. was used as the apparatus, CuKα rays were used as the X-ray source, the output was 50 KV-200 mA, and the scan rate was 2°/min. Based on the obtained X-ray profile, the peak intensities I _(hkl) and I _(abc) of arbitrary orthogonal diffraction planes (hkl) and (abc) in the wide-angle X-ray diffraction measurement of the porous layer are expressed by the following formula (1 ), the peak intensity ratio calculated by I _(hkl) /I _(abc) was calculated, and the maximum value of the peak intensity ratio was calculated.
I _(hkl) >I _(abc) (1).

(4) Decrease rate of ionic conductivity (%)
LiPF ₆ was dissolved in a mixed solvent obtained by mixing ethylene carbonate, ethyl methyl carbonate, and diethyl carbonate in a volume ratio of 3:5:2 to a concentration of 1 mol/L to prepare a reference electrolytic solution. Obtained. After each additive was added to the reference electrolytic solution so as to be 1% and dissolved, the ionic conductivity (mS/cm) was measured. The ionic conductivity was measured using an electrical conductivity meter (ES-71) manufactured by Horiba, Ltd.
The ionic conductivity decrease rate is represented by the following formula (A).

L=(LA−LB)/LA (A)
L: ionic conductivity decrease rate (%),
LA: ionic conductivity (mS/cm) before addition,
LB: ionic conductivity after addition (mS/cm).

(5) Battery characteristics of non-aqueous electrolyte secondary battery A non-aqueous electrolyte secondary battery assembled as described below was charged at 25 ° C. with a voltage range of 4.1 to 2.7 V and a charging current value of 0.2 C. CC-CV charging (final current condition: 0.02C) and CC discharging with a discharge current value of 0.2C were regarded as one cycle, and four cycles of initial charging and discharging were carried out at 25°C.

In addition, the current value for discharging the rated capacity based on the discharge capacity at the rate of 1 hour in 1 hour is assumed to be 1C. Further, CC-CV charging is a charging method in which charging is performed with a set constant current, and after reaching a predetermined voltage, the voltage is maintained while reducing the current. CC discharge is a method of discharging to a predetermined voltage with a set constant current. These are the same as below.

CC-CV charging with a charging current value of 1C (final current condition of 0.02C), discharging current values of 0.2C, 1C, and 3C in the order of CC A discharge was performed. Three cycles of charging and discharging were performed at 55° C. for each rate. At this time, the voltage range was set to 2.7V to 4.2V. At this time, the charge capacity at the time of 1C charge in the third cycle when measuring the 3C discharge rate characteristics was measured and used as the charge capacity after high rate discharge. The design capacity of the non-aqueous electrolyte secondary batteries manufactured in Examples and Comparative Examples was 20.5 mAh.

[Example 1]
[Manufacture of separator for non-aqueous electrolyte secondary battery]
A separator for a non-aqueous electrolyte secondary battery was produced using polyethylene. Specifically, 70 parts by weight of ultra-high molecular weight polyethylene powder (340M, manufactured by Mitsui Chemicals, Inc.) and 30 parts by weight of polyethylene wax (FNP-0115, manufactured by Nippon Seiro Co., Ltd.) having a weight average molecular weight of 1000 are mixed. to obtain a blended polyethylene. To 100 parts by weight of the resulting mixed polyethylene, 0.4 parts by weight of an antioxidant (Irg1010, manufactured by Chiba Specialty Chemicals Co., Ltd.) and 0.4 parts by weight of an antioxidant (P168, manufactured by Chiba Specialty Chemicals Co., Ltd.) were added. 1 part by weight and 1.3 parts by weight of sodium stearate are added, and further calcium carbonate with an average particle size of 0.1 μm (manufactured by Maruo Calcium Co., Ltd.) is added so that the ratio of the total volume is 38% by volume. rice field. This composition as powder was mixed with a Henschel mixer and then melt-kneaded with a twin-screw kneader to obtain a polyethylene resin composition. Next, a sheet was produced by rolling this polyethylene resin composition with a pair of rollers whose surface temperature was set to 150°C. This sheet was immersed in a hydrochloric acid aqueous solution prepared by blending 0.5% by weight of a nonionic surfactant with 4 mol/L hydrochloric acid to dissolve and remove calcium carbonate. Subsequently, the sheet was stretched 6 times at 105° C. to prepare a polyolefin porous film. The polyolefin porous film had a porosity of 53%, a basis weight of 7 g/m ² and a film thickness of 16 µm. This polyolefin porous film was used as a separator 1 for a non-aqueous electrolyte secondary battery.

[Production of porous layer]
(Manufacture of coating liquid)
α-alumina (manufactured by Sumitomo Chemical Co., Ltd., trade name: AKP3000) and hexagonal plate-like zinc oxide (manufactured by Sakai Chemical Industry Co., Ltd., trade name: XZ-100F) are used as raw materials for the inorganic filler, and α-alumina is used as the inorganic filler. A mixture (oxygen atomic mass percentage: 47%) of 99 parts by weight and 1 part by weight of hexagonal plate-like zinc oxide mixed in a mortar was used.

The volume-based particle size distribution of the inorganic filler was calculated by measuring D10, D50, and D90 using a laser diffraction particle size distribution meter SALD2200 manufactured by Shimadzu Corporation. Here, the particle diameter at which the volume-based integrated distribution is 50%, 10%, and 90% are referred to as D50, D10, and D90, respectively.

Further, the specific surface area of the filler was calculated by the BET method after measuring the adsorption/desorption isotherm with nitrogen using the constant volume method.

A vinylidene fluoride-hexafluoropropylene copolymer (manufactured by Arkema Co., Ltd.; trade name “KYNAR2801”) was used as the resin.

The inorganic filler, vinylidene fluoride-hexafluoropropylene copolymer and solvent (N-methyl-2-pyrrolidinone manufactured by Kanto Kagaku Co., Ltd.) were mixed in the following proportions. That is, after mixing 10 parts by weight of the vinylidene fluoride-hexafluoropropylene copolymer with 90 parts by weight of the inorganic filler, the solid content of the inorganic filler and the vinylidene fluoride-hexafluoropropylene copolymer in the resulting mixed solution A mixed solution was prepared by mixing solvents so that the concentration of was 40% by weight. The resulting mixed solution was stirred and mixed with a thin-film rotating high-speed mixer (Filmiku (registered trademark) manufactured by Primix Co., Ltd.) to obtain a uniform coating solution.

(Production of porous layer)
The obtained coating liquid is applied to one side of the non-aqueous electrolyte secondary battery separator 1 by a doctor blade method at a coating shear rate of 39.4 (1 / s), and the non-aqueous electrolysis is performed. A coating film was formed on one side of the liquid secondary battery separator 1 . Thereafter, the coating film was dried at 65° C. for 20 minutes to form a porous layer 1 on one side of the separator 1 for a non-aqueous electrolyte secondary battery. As a result, a laminate 1 including the separator 1 for a non-aqueous electrolyte secondary battery and the porous layer 1 was obtained. The porous layer 1 had a basis weight of 7 g/m ² and a thickness of 4 μm. Using the obtained laminate 1, the maximum value of the aspect ratio and peak intensity ratio (I _(hkl) /I _(abc) ) of the projected image of the inorganic filler on the surface of the porous layer was measured. Table 1 shows the results.

[Preparation of non-aqueous electrolyte secondary battery]
(Preparation of positive electrode)
A commercial positive electrode made by coating LiNi _0.5 Mn _0.3 Co _0.2 O ₂ /conducting agent/PVDF (92/5/3 weight ratio) on aluminum foil was used. The commercially available positive electrode is coated with aluminum foil so that the size of the portion where the positive electrode active material layer is formed is 40 mm × 35 mm, and the portion where the positive electrode active material layer is not formed with a width of 13 mm remains on the outer periphery. A positive electrode was cut off. The positive electrode active material layer had a thickness of 58 μm and a density of 2.50 g/cm ³ .

(Preparation of negative electrode)
A commercial negative electrode prepared by coating a copper foil with graphite/styrene-1,3-butadiene copolymer/sodium carboxymethylcellulose (98/1/1 weight ratio) was used. The commercially available negative electrode is coated with copper foil so that the size of the portion where the negative electrode active material layer is formed is 50 mm × 40 mm, and the portion where the negative electrode active material layer is not formed with a width of 13 mm remains on the outer periphery. A negative electrode was cut off. The negative electrode active material layer had a thickness of 49 μm and a density of 1.40 g/cm ³ .

(Preparation of non-aqueous electrolyte)
LiPF ₆ was dissolved in a mixed solvent of ethylene carbonate, ethyl methyl carbonate, and diethyl carbonate at a volume ratio of 3:5:2 to a concentration of 1 mol/L to obtain an electrolyte stock solution 1. This electrolyte stock solution 1 is an aprotic polar solvent electrolyte containing Li ⁺ ions.

Addition liquid 1 was prepared by adding diethyl carbonate to 10.3 mg of dibutyl hydroxytoluene (BHT, rate of decrease in ionic conductivity: 5.3%) and dissolving it to 5 mL. 300 μL of additive solution 1 and 1700 μL of electrolyte solution undiluted solution 1 were mixed to obtain non-aqueous electrolyte solution 1 . Table 2 shows the content of the additive in the non-aqueous electrolyte 1.

(Assembly of non-aqueous electrolyte secondary battery)
Using the positive electrode, the negative electrode, the laminate 1, and the non-aqueous electrolyte 1, a non-aqueous electrolyte secondary battery was manufactured by the method shown below. The manufactured non-aqueous electrolyte secondary battery was designated as non-aqueous electrolyte secondary battery 1 .

A non-aqueous electrolyte secondary battery member 1 was obtained by laminating the positive electrode, the laminate 1 with the porous layer facing the positive electrode side, and the negative electrode in this order in the laminate pouch. At this time, the positive electrode and the negative electrode were arranged such that the entire main surface of the positive electrode active material layer of the positive electrode was included in the range of the main surface of the negative electrode active material layer of the negative electrode. That is, the positive electrode and the negative electrode were arranged so that the entire main surface of the positive electrode active material layer of the positive electrode overlapped the main surface of the negative electrode active material layer of the negative electrode.

Subsequently, the non-aqueous electrolyte secondary battery member 1 is placed in a prefabricated bag formed by laminating an aluminum layer and a heat seal layer, and 0.23 mL of the non-aqueous electrolyte 1 is added to the bag. I put it in. Then, the non-aqueous electrolyte secondary battery 1 was produced by heat-sealing the bag while decompressing the inside of the bag.

After that, the charge capacity of the non-aqueous electrolyte secondary battery 1 obtained by the above-described method after high-rate discharge was measured. Table 2 shows the results.

[Example 2]
[Preparation of non-aqueous electrolyte secondary battery]
(Preparation of non-aqueous electrolyte)
LiPF ₆ was dissolved in a mixed solvent in which ethylene carbonate and diethyl carbonate were mixed at a volume ratio of 3:7 so as to have a concentration of 1 mol/L.

Addition liquid 2 was prepared by adding diethyl carbonate to 10.0 mg of vinylene carbonate (VC, rate of decrease in ionic conductivity: 1.3%) and dissolving the solution to 5 mL. 200 μL of additive solution 2 and 1800 μL of electrolytic solution undiluted solution 2 were mixed. 50 μL of additive solution 3 and 1950 μL of electrolyte undiluted solution 2 were mixed to obtain non-aqueous electrolyte solution 2 . Table 2 shows the content of the additive in the non-aqueous electrolyte 2.

(Assembly of non-aqueous electrolyte secondary battery)
A non-aqueous electrolyte secondary battery was produced in the same manner as in Example 1, except that the non-aqueous electrolyte 2 was used instead of the non-aqueous electrolyte 1. The fabricated non-aqueous electrolyte secondary battery was designated as a non-aqueous electrolyte secondary battery 2 .

After that, the charge capacity of the non-aqueous electrolyte secondary battery 2 obtained by the above-described method after high-rate discharge was measured. Table 2 shows the results.

[Example 3]
[Production of Laminate Comprising Separator for Non-Aqueous Electrolyte Secondary Battery and Porous Layer]
A laminate 2 including a separator 1 for a non-aqueous electrolyte secondary battery and a porous layer 2 was obtained in the same manner as in Example 1, except for the following.
- Hexagonal tabular zinc oxide (trade name: XZ-100F, manufactured by Sakai Chemical Industry Co., Ltd.) having an oxygen atomic mass percentage of 20% was used as the inorganic filler.
・A solid composed of the inorganic filler and the vinylidene fluoride-hexafluoropropylene copolymer in the mixed liquid obtained after mixing 90 parts by weight of the inorganic filler with 10 parts by weight of the vinylidene fluoride-hexafluoropropylene copolymer. A mixed solution was prepared by mixing solvents so that the concentration of each component was 37% by weight.
- The porous layer 2 was formed instead of the porous layer 1 by applying the coating liquid at a coating shear rate of 3.9 (1/s).

Using the obtained laminate 2, the maximum value of the aspect ratio and peak intensity ratio of the projected image of the inorganic filler on the surface of the porous layer was measured. Table 1 shows the results.

[Preparation of non-aqueous electrolyte secondary battery]
(Preparation of non-aqueous electrolyte)
LiPF ₆ was dissolved in a mixed solvent of ethylene carbonate, ethyl methyl carbonate, and diethyl carbonate in a volume ratio of 4:4:2 to a concentration of 1 mol/L to prepare an electrolytic stock solution 3. .

Diethyl carbonate was added to 11.2 mg of pentaerythritol tetrakis[3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate] (Irg.1010, rate of decrease in ionic conductivity: 4.0%) and dissolved. Addition liquid 4 was prepared by adding 5 mL. 90 μL of additive solution 4 and 1910 μL of electrolyte undiluted solution 3 were mixed to obtain non-aqueous electrolyte solution 3 . Table 2 shows the content of the additive in the non-aqueous electrolyte 3.

(Assembly of non-aqueous electrolyte secondary battery)
In the same manner as in Example 1, except that the laminate 2 was used instead of the laminate 1, and the nonaqueous electrolyte 3 was used instead of the nonaqueous electrolyte 1. A battery was produced. The fabricated non-aqueous electrolyte secondary battery was designated as non-aqueous electrolyte secondary battery 3 .

After that, the charge capacity of the non-aqueous electrolyte secondary battery 3 obtained by the above-described method after high-rate discharge was measured. Table 2 shows the results.

[Example 4]
[Production of Laminate Consisting of Separator for Nonaqueous Electrolyte Secondary Battery and Porous Layer]
A laminate 3 having a separator 1 for a non-aqueous electrolyte secondary battery and a porous layer 3 was obtained in the same manner as in Example 1, except for the following.
・ Obtained by mixing 50 parts by weight of spherical alumina (manufactured by Sumitomo Chemical Co., Ltd., trade name AA03) and 50 parts by weight of synthetic mica (manufactured by Wako Pure Chemical Industries, Ltd., trade name: non-swelling synthetic mica) in a mortar. and a mixture having an oxygen atomic mass percentage of 45% was used as the inorganic filler.
・A solid composed of the inorganic filler and the vinylidene fluoride-hexafluoropropylene copolymer in the mixed liquid obtained after mixing 90 parts by weight of the inorganic filler with 10 parts by weight of the vinylidene fluoride-hexafluoropropylene copolymer. A mixed solution was prepared by mixing solvents so that the concentration of each component was 30% by weight.
- The porous layer 3 was formed instead of the porous layer 1 by applying the coating liquid at a coating shear rate of 7.9 (1/s).

Using the obtained laminate 3, the maximum value of the aspect ratio and peak intensity ratio of the projected image of the inorganic filler on the surface of the porous layer was measured. Table 1 shows the results.

[Preparation of non-aqueous electrolyte secondary battery]
(Preparation of non-aqueous electrolyte)
90 μL of the additive solution 4 and 1910 μL of the undiluted electrolyte solution 1 were mixed to obtain a non-aqueous electrolyte solution 4 . Table 2 shows the content of the additive in the non-aqueous electrolyte 4.

(Assembly of non-aqueous electrolyte secondary battery)
A non-aqueous electrolyte secondary battery was prepared in the same manner as in Example 1 except that the laminate 3 was used instead of the laminate 1 and the non-aqueous electrolyte 4 was used instead of the non-aqueous electrolyte 1. was made. The fabricated non-aqueous electrolyte secondary battery was designated as a non-aqueous electrolyte secondary battery 4 .

After that, the charge capacity of the non-aqueous electrolyte secondary battery 4 obtained by the above-described method after high-rate discharge was measured. Table 2 shows the results.

[Example 5]
[Production of Laminate Comprising Separator for Non-Aqueous Electrolyte Secondary Battery and Porous Layer]
A laminate 4 having a separator 1 for a non-aqueous electrolyte secondary battery and a porous layer 4 was obtained in the same manner as in Example 1 except for the following.
• Wollastonite (manufactured by Hayashi Kasei Co., Ltd., trade name: Wollastonite VM-8N) having an oxygen atomic mass percentage of 41% was used as the inorganic filler.
・A solid composed of the inorganic filler and the vinylidene fluoride-hexafluoropropylene copolymer in the mixed liquid obtained after mixing 90 parts by weight of the inorganic filler with 10 parts by weight of the vinylidene fluoride-hexafluoropropylene copolymer. A mixed solution was prepared by mixing solvents so that the concentration of each component was 40% by weight.
- The porous layer 4 was formed instead of the porous layer 1 by applying the coating liquid at a coating shear rate of 7.9 (1/s).

Using the obtained laminate 4, the maximum value of the aspect ratio and peak intensity ratio of the projected image of the inorganic filler on the surface of the porous layer was measured. Table 1 shows the results.

[Preparation of non-aqueous electrolyte secondary battery]
(Preparation of non-aqueous electrolyte)
LiPF ₆ was dissolved in a mixed solvent obtained by mixing ethylene carbonate, ethylmethyl carbonate, and diethyl carbonate in a volume ratio of 2:5:3 so that the concentration thereof became 1 mol/L, thereby preparing an electrolytic stock solution 4. . 90 μL of additive solution 4 and 1910 μL of electrolyte undiluted solution 4 were mixed to obtain non-aqueous electrolyte solution 5 . Table 2 shows the content of the additive in the non-aqueous electrolyte 5.

(Assembly of non-aqueous electrolyte secondary battery)
A non-aqueous electrolyte secondary battery was prepared in the same manner as in Example 1 except that the laminate 4 was used instead of the laminate 1 and the non-aqueous electrolyte 5 was used instead of the non-aqueous electrolyte 1. was made. The fabricated non-aqueous electrolyte secondary battery was designated as non-aqueous electrolyte secondary battery 5 .

After that, the charge capacity of the non-aqueous electrolyte secondary battery 5 obtained by the above-described method after high-rate discharge was measured. Table 2 shows the results.

[Comparative Example 1]
[Preparation of non-aqueous electrolyte secondary battery]
(Preparation of non-aqueous electrolyte)
Diethyl carbonate was added to 9.7 mg of tris-(4-t-butyl-2,6-dimethyl-3-hydroxybenzyl) isocyanurate (Cyanox 1790, rate of decrease in ionic conductivity: 6.1%) and dissolved. Addition liquid 5 was made up to 5 mL. 90 μL of additive solution 5 and 1910 μL of electrolyte undiluted solution 1 were mixed to obtain non-aqueous electrolyte solution 6 . Table 2 shows the content of the additive in the non-aqueous electrolyte 6.

(Assembly of non-aqueous electrolyte secondary battery)
A non-aqueous electrolyte secondary battery was produced in the same manner as in Example 1, except that non-aqueous electrolyte 6 was used instead of non-aqueous electrolyte 1. The fabricated non-aqueous electrolyte secondary battery was designated as a non-aqueous electrolyte secondary battery 6 .

After that, the charge capacity of the non-aqueous electrolyte secondary battery 6 obtained by the above-described method after high-rate discharge was measured. Table 2 shows the results.

[Comparative Example 2]
[Production of Laminate Comprising Separator for Non-Aqueous Electrolyte Secondary Battery and Porous Layer]
A laminate 5 including a separator 1 for a non-aqueous electrolyte secondary battery and a porous layer 5 was obtained in the same manner as in Example 1 except for the following.
• Borax (manufactured by Wako Pure Chemical Industries, Ltd.) having an oxygen atomic mass percentage of 71% was used as the inorganic filler.
・After mixing 90 parts by weight of the inorganic filler with 10 parts by weight of the vinylidene fluoride-hexafluoropropylene copolymer, the solid content of the inorganic filler and the vinylidene fluoride-hexafluoropropylene copolymer in the resulting mixture A mixed solution was prepared by mixing solvents so that the concentration of was 40% by weight.
- The porous layer 5 was formed instead of the porous layer 1 by applying the coating liquid at a coating shear rate of 7.9 (1/s).

Using the obtained laminate 5, the maximum value of the aspect ratio and peak intensity ratio of the projected image of the inorganic filler on the surface of the porous layer was measured. Table 1 shows the results.

[Preparation of non-aqueous electrolyte secondary battery]
(Assembly of non-aqueous electrolyte secondary battery)
A non-aqueous electrolyte secondary battery was prepared in the same manner as in Example 1 except that the laminate 5 was used instead of the laminate 1 and the non-aqueous electrolyte 4 was used instead of the non-aqueous electrolyte 1. was made. The fabricated non-aqueous electrolyte secondary battery was used as a non-aqueous electrolyte secondary battery 7 .

After that, the charge capacity of the non-aqueous electrolyte secondary battery 7 obtained by the above-described method after high-rate discharge was measured. Table 2 shows the results.

[Comparative Example 3]
[Production of Laminate Comprising Separator for Non-Aqueous Electrolyte Secondary Battery and Porous Layer]
A laminate 6 including a separator 1 for a non-aqueous electrolyte secondary battery and a porous layer 6 was obtained in the same manner as in Example 1, except for the following.
- Hexagonal tabular zinc oxide (trade name: XZ-100F, manufactured by Sakai Chemical Industry Co., Ltd.) having an oxygen atomic mass percentage of 20% was used as the inorganic filler.
・A solid composed of the inorganic filler and the vinylidene fluoride-hexafluoropropylene copolymer in the mixed liquid obtained after mixing 90 parts by weight of the inorganic filler with 10 parts by weight of the vinylidene fluoride-hexafluoropropylene copolymer. A mixed solution was prepared by mixing solvents so that the concentration of each component was 37% by weight.
- The porous layer 6 was formed instead of the porous layer 1 by applying the coating liquid at a coating shear rate of 0.4 (1/s).

Using the obtained laminate 6, the maximum value of the aspect ratio and peak intensity ratio of the projected image of the inorganic filler on the surface of the porous layer was measured. Table 1 shows the results.

[Preparation of non-aqueous electrolyte secondary battery]
(Assembly of non-aqueous electrolyte secondary battery)
A non-aqueous electrolyte secondary battery was prepared in the same manner as in Example 1 except that the laminate 6 was used instead of the laminate 1 and the non-aqueous electrolyte 4 was used instead of the non-aqueous electrolyte 1. was made. The fabricated non-aqueous electrolyte secondary battery was used as a non-aqueous electrolyte secondary battery 8 .

After that, the charge capacity of the non-aqueous electrolyte secondary battery 8 obtained by the above-described method after high-rate discharge was measured. Table 2 shows the results.

[Comparative Example 4]
[Production of Laminate Comprising Separator for Non-Aqueous Electrolyte Secondary Battery and Porous Layer]
A laminate 7 including a separator 1 for a non-aqueous electrolyte secondary battery and a porous layer 7 was obtained in the same manner as in Example 1, except for the following.
- Attapulgite (manufactured by Hayashi Kasei Co., Ltd., trade name: ATTAGEL #50) having an oxygen atomic mass percentage of 48% was used as the inorganic filler.
・A solid composed of the inorganic filler and the vinylidene fluoride-hexafluoropropylene copolymer in the mixed liquid obtained after mixing 90 parts by weight of the inorganic filler with 10 parts by weight of the vinylidene fluoride-hexafluoropropylene copolymer. A mixed solution was prepared by mixing the solvent so that the concentration of each component was 17% by weight.
・By applying the coating liquid on one side of the separator for a non-aqueous electrolyte secondary battery at a coating shear rate of 1.3 (1 / s) by a doctor blade method, a porous layer is formed instead of the porous layer 1. Formation of layer 7;

Using the obtained laminate 7, the maximum value of the aspect ratio and peak intensity ratio of the projected image of the inorganic filler on the surface of the porous layer was measured. Table 1 shows the results.

[Preparation of non-aqueous electrolyte secondary battery]
(Assembly of non-aqueous electrolyte secondary battery)
A non-aqueous electrolyte secondary battery was prepared in the same manner as in Example 1 except that the laminate 7 was used instead of the laminate 1 and the non-aqueous electrolyte 4 was used instead of the non-aqueous electrolyte 1. was made. The fabricated non-aqueous electrolyte secondary battery was used as a non-aqueous electrolyte secondary battery 9 .

After that, the charge capacity of the non-aqueous electrolyte secondary battery 9 obtained by the above-described method after high-rate discharge was measured. Table 2 shows the results.

[Comparative Example 5]
[Production of Laminate Comprising Separator for Non-Aqueous Electrolyte Secondary Battery and Porous Layer]
A laminate 8 having a separator 1 for a non-aqueous electrolyte secondary battery and a porous layer 8 was obtained in the same manner as in Example 1, except for the following.
• Using mica (manufactured by Wako Pure Chemical Industries, trade name: non-swelling mica) having an oxygen atomic mass percentage of 44% as the inorganic filler.
・A solid composed of the inorganic filler and the vinylidene fluoride-hexafluoropropylene copolymer in the mixed liquid obtained after mixing 90 parts by weight of the inorganic filler with 10 parts by weight of the vinylidene fluoride-hexafluoropropylene copolymer. A mixed solution was prepared by mixing a solvent so that the concentration of each component was 20% by weight.
・Porous layer instead of porous layer 1 by applying a coating liquid on one side of the separator for non-aqueous electrolyte secondary batteries at a coating shear rate of 0.4 (1 / s) by a doctor blade method Having formed 8.

Using the obtained laminate 8, the maximum value of the aspect ratio and peak intensity ratio of the projected image of the inorganic filler on the surface of the porous layer was measured. Table 1 shows the results.

[Preparation of non-aqueous electrolyte secondary battery]
(Assembly of non-aqueous electrolyte secondary battery)
A non-aqueous electrolyte secondary battery was prepared in the same manner as in Example 1 except that the laminate 8 was used instead of the laminate 1 and the non-aqueous electrolyte 4 was used instead of the non-aqueous electrolyte 1. was made. The fabricated non-aqueous electrolyte secondary battery was used as a non-aqueous electrolyte secondary battery 10 .

After that, the charge capacity after high-rate discharge of the non-aqueous electrolyte secondary battery 10 obtained by the above method was measured. Table 2 shows the results.

[Comparative Example 6]
[Preparation of non-aqueous electrolyte secondary battery]
(Assembly of non-aqueous electrolyte secondary battery)
A non-aqueous electrolyte secondary battery was produced in the same manner as in Example 1, except that the undiluted electrolyte solution 1 was used instead of the non-aqueous electrolyte solution 1. The fabricated non-aqueous electrolyte secondary battery was used as a non-aqueous electrolyte secondary battery 11 .

After that, the charge capacity of the non-aqueous electrolyte secondary battery 11 obtained by the above-described method after high-rate discharge was measured. Table 2 shows the results.

[result]

From the descriptions in Tables 1 and 2, (i) the requirements for the "surface filler aspect ratio", (ii) the peak intensity of arbitrary mutually orthogonal diffraction planes (hkl) and (abc) measured by the wide-angle X-ray diffraction method The non-aqueous electrolyte secondary battery according to one embodiment of the present invention that satisfies the requirements and (iii) the requirements regarding the ionic conductivity decrease rate and content of the additive contained in the non-aqueous electrolyte is a high rate discharge ( It was shown to be excellent in 1C charge capacity after 3C discharge).

Since the non-aqueous electrolyte secondary battery according to one embodiment of the present invention is excellent in charge capacity after high-rate discharge, it is suitably used as a battery for personal computers, mobile phones, personal digital assistants, etc., and a battery for vehicles. can do.

Claims (6)

Equipped with a porous layer containing an inorganic filler and a resin, a non-aqueous electrolyte, a positive electrode and a negative electrode,
The aspect ratio of the projected image of the inorganic filler on the surface of the porous layer is in the range of 1.4 to 4.0,
Peak intensities of arbitrary mutually orthogonal diffraction planes (hkl) and (abc) of the porous layer measured by wide-angle X-ray diffraction: I _(hkl) and I _(abc) satisfy the following formula (1): ,
The range of the maximum value of the peak intensity ratio calculated by the following formula (2) is in the range of 1.5 to 300,
I _(hkl) > I _(abc) (1),
I _(hkl) / I _(abc) (2)
The non-aqueous electrolytic solution contains 0.5 ppm or more and 300 ppm or less of an additive whose ionic conductivity decrease rate L represented by the following formula (A) is 1.0% or more and 6.0% or less ,
The non-aqueous electrolyte contains an electrolyte and an organic solvent,
The organic solvent is a mixed solvent obtained by mixing a cyclic compound and a chain compound at a volume ratio of 2:8 to 4:6,
Said additives include pentaerythritol tetrakis[3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate], triethyl phosphate, vinylene carbonate, propanesultone, 2,6-di-tert-butyl -4-methylphenol, 6-[3-(3-t-butyl-4-hydroxy-5-methylphenyl)propoxy]-2,4,8,10-tetra-t-butyldibenzo[d,f][ 1,3,2]dioxaphosphepine, tris(2,4-di-tert-butylphenyl) phosphate, 2-[1-(2-hydroxy-3,5-di-tert-pentylphenyl)ethyl phosphate ] A nonaqueous electrolyte secondary battery selected from the group consisting of 4,6-di-tert-pentylphenyl acrylate and dibutylhydroxytoluene .
L=(LA−LB)/LA (A)
(In formula (A), LA is a mixed solvent containing ethylene carbonate, ethylmethyl carbonate and diethyl carbonate at a volume ratio of 3:5:2, and LiPF ₆ was dissolved so that its concentration was 1 mol/L. Represents the ionic conductivity (mS / cm) of the reference electrolyte,
LB represents the ionic conductivity (mS/cm) of an electrolytic solution obtained by dissolving 1.0% by weight of an additive in the reference electrolytic solution. ) 2. The non-aqueous electrolyte secondary battery according to claim 1, wherein said porous layer is laminated on one side or both sides of a polyolefin porous film. Claim 1 or 2, wherein the porous layer contains one or more resins selected from the group consisting of polyolefins, (meth)acrylate resins, fluorine-containing resins, polyamide resins, polyester resins and water-soluble polymers. The non-aqueous electrolyte secondary battery described. 4. The non-aqueous electrolyte secondary battery according to claim 3, wherein said polyamide resin is an aramid resin. 5. The non-aqueous electrolyte secondary battery in accordance with claim 1, wherein said non-aqueous electrolyte contains an electrolyte containing lithium. The non-aqueous electrolyte secondary battery according to any one of claims 1 to 5, wherein the non-aqueous electrolyte contains an aprotic polar solvent.

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