JP2020072038A - Non-aqueous electrolyte secondary battery - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a non-aqueous electrolyte secondary battery having an excellent charge capacity after high-rate discharge. SOLUTION: A porous layer containing an inorganic filler and a resin, and a positive and negative electrode plates having a capacitance per measurement area of 900 mm2 within a predetermined range are provided, and a projected image of the inorganic filler on the surface of the porous layer is provided. Non-aqueous electrolysis in which the peak intensity ratio (I (hkl) / I (abc)) of arbitrary orthogonal diffraction planes (hkl) and (abc) as measured by the aspect ratio and wide-angle X-ray diffraction method is in a predetermined range. Liquid secondary battery. [Selection diagram] None

Description

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

  Non-aqueous electrolyte secondary batteries, especially lithium-ion secondary batteries, are widely used as batteries for personal computers, mobile phones, personal digital assistants, etc. because of their high energy density, and recently they have been developed as in-vehicle batteries. Has been.

  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 provided on at least one surface of a porous substrate. There is known a non-aqueous electrolyte secondary battery including a non-aqueous secondary battery separator that is laminated on.

JP, 2010-108753, A

  However, the above-described conventional techniques have room for improvement in terms of charge capacity after high-rate discharge.

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

The non-aqueous electrolyte secondary battery according to Aspect 1 of the present invention is a porous layer containing an inorganic filler and a resin, a positive electrode plate having a capacitance per measurement area 900 mm ^{2 of} 1 nF or more and 1000 nF or less, A negative electrode plate having a capacitance per measurement area 900 mm ^{2 of 4} nF or more and 8500 nF or less, and an aspect ratio of a projected image of the inorganic filler on the surface of the porous layer is 1.4 to 4.0. And the peak intensities I _(hkl) and I _{(abc) of} arbitrary diffraction planes (hkl) and (abc) orthogonal to each other measured by the wide-angle X-ray diffraction method of the porous layer are The range of the maximum value of the peak intensity ratio that satisfies the following formula (1) and is 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).

  Further, in the non-aqueous electrolyte secondary battery according to Aspect 2 of the present invention, in the Aspect 1, the porous layer includes a polyolefin, a (meth) acrylate resin, a fluorine-containing resin, a polyamide resin, a polyester resin, and It includes a resin selected from the group consisting of water-soluble polymers.

  Further, in the non-aqueous electrolyte secondary battery according to Aspect 3 of the present invention, in the Aspect 2, the polyamide resin is an aramid resin.

  Further, in the non-aqueous electrolyte secondary battery according to Aspect 4 of the present invention, in any one of Aspects 1 to 3, the porous layer is laminated on one side or both sides of a polyolefin porous film.

  Further, in the non-aqueous electrolyte secondary battery according to Aspect 5 of the present invention, in any one of Aspects 1 to 4, the positive electrode plate contains a transition metal oxide and the negative electrode plate contains graphite.

  The non-aqueous electrolyte secondary battery according to the embodiment of the present invention is excellent in charge capacity after high rate discharge of the battery.

It is a schematic diagram showing the structure of the said porous layer when the orientation of an inorganic filler is large in the porous layer containing an inorganic filler (left figure), and when the orientation of an inorganic filler is small (right figure). It is a schematic diagram which shows the projected image of the inorganic filler of the surface of the porous layer in one Embodiment of this invention. FIG. 3 is a schematic diagram showing a measurement target electrode which is a target of measurement of capacitance in an example of the present application. FIG. 3 is a schematic diagram showing a probe electrode used for measuring capacitance in an example of the present application.

  One embodiment of the present invention will be described below, but the present invention is not limited thereto. The present invention is not limited to each configuration described below, various modifications are possible within the scope shown in the claims, and the technical means disclosed in different embodiments are appropriately combined. The obtained embodiments are also included in the technical scope of the present invention. Unless otherwise specified in the present specification, “A to B” representing a numerical range means “A or more and B or less”.

  A non-aqueous electrolyte secondary battery according to an embodiment of the present invention includes a porous layer described below, a positive electrode plate and a negative electrode plate described below. The non-aqueous electrolyte secondary battery according to the exemplary embodiment of the present invention may further include a polyolefin porous film described below.

  The members constituting the non-aqueous electrolyte secondary battery according to the embodiment of the present invention will be 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 is an inorganic material on the surface of the porous layer (hereinafter, may be referred to as “porous layer surface”). The aspect ratio of the projected image of the filler is in the range of 1.4 to 4.0, and arbitrary diffraction planes (hkl) and (abc) of the porous layer, which are measured by a wide-angle X-ray diffraction method and are orthogonal to each other. The peak intensities of I _(hkl) and I _(abc) satisfy the following formula (1), and the maximum value of the peak intensity ratio calculated by the following formula (2) is in the range of 1.5 to 300. is there.
I _(hkl) > I _(abc) ... (1),
I _(hkl) / I _(abc) (2).

  In one embodiment of the present invention, the porous layer may be disposed between the polyolefin porous film and at least one of the positive electrode plate and the negative electrode plate 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 plate and the negative electrode plate. Alternatively, the porous layer may be disposed between the polyolefin porous film and at least one of the positive electrode plate and the negative electrode plate so as to be in contact with them. The porous layer disposed between the polyolefin porous film and at least one of the positive electrode plate and the negative electrode plate may be one layer or two or more layers. The porous layer is preferably an insulating porous layer containing a resin.

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

  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 both the orientation of the inorganic filler in the porous layer. Is an index representing. Here, FIG. 1 shows a schematic diagram of the state 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 the 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. 1 is the inorganic layer. It is a schematic diagram showing the structure of the said porous layer in case the orientation of a filler is small and anisotropy is low.

  The 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 through which gas or liquid can 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 non-aqueous electrolyte secondary battery laminated separator described below, the porous layer is an electrode as an outermost layer of the laminated separator. It can be a layer in contact with the plate.

  The resin contained in the porous layer in one embodiment of the present invention is preferably insoluble in the electrolytic solution of the battery and is electrochemically stable in the usage range of the battery. Specific examples of the resin include polyolefins; (meth) acrylate resins; fluorine-containing resins; polyamide resins; polyimide resins; polyester resins; rubbers; melting points or glass transition temperatures of 180 ° C. or higher. Resins; water-soluble polymers; polycarbonates, polyacetals, polyether ether ketones and the like.

  Among the above resins, polyolefin, (meth) acrylate resin, fluorine-containing resin, polyamide resin, polyester resin and water-soluble polymer are preferable.

  As the polyolefin, polyethylene, polypropylene, polybutene, ethylene-propylene copolymer and the like are preferable.

  As a fluorine-containing resin, Polyvinylidene fluoride (PVDF), Polytetrafluoroethylene, Vinylidene fluoride-hexafluoropropylene copolymer, Tetrafluoroethylene-hexafluoropropylene copolymer, Tetrafluoroethylene-perfluoroalkyl vinyl ether copolymer, Vinylidene fluoride-tetrafluoroethylene copolymer, Vinylidene fluoride-trifluoroethylene copolymer, Vinylidene fluoride-trichloroethylene copolymer, Vinylidene fluoride-vinyl fluoride copolymer, Vinylidene fluoride-hexafluoropropylene-tetrafluoroethylene copolymer, And ethylene-tetrafluoroethylene copolymer, And Among the above-mentioned fluorine-containing resins, a fluorine-containing rubber having a glass transition temperature of 23 ° C. or lower can be mentioned.

  As the polyamide resin, aramid resins such as aromatic polyamide and wholly aromatic polyamide are preferable.

  Specific examples of the aramid resin include poly (paraphenylene terephthalamide), poly (metaphenylene isophthalamide), poly (parabenzamide), poly (metabenzamide), 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-naphthalene dicarboxylic acid amide), poly (2-chloroparaphenylene terephthalamide), paraphenylene terephthalamide / 2,6-dichloroparaphenylene terephthalamide copolymer, metaphenylene terephthalamide / 2 , 6-dichloro La-phenylene terephthalamide copolymer and the like. Of these, poly (paraphenylene terephthalamide) is more preferable.

  As the polyester resin, aromatic polyesters such as polyarylate and liquid crystal polyesters are preferable.

  As the rubbers, 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 and the like. Can be mentioned.

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

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

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

  Among the resins, when the porous layer is arranged to face the positive electrode plate, various performances such as rate characteristics and resistance characteristics of the non-aqueous electrolyte secondary battery are maintained due to oxidative deterioration during battery operation. A fluorine-containing resin is preferable because it is easy.

  The porous layer in one embodiment of the present 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 the embodiment of the present invention. More preferably, it is more preferably 90% by weight or more. On the other hand, the upper limit of the content of the inorganic filler in the porous layer in the embodiment of the present invention is preferably 99% by weight or less, and 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 the fillers. By containing the inorganic filler, the slipperiness and heat resistance of the separator including the porous layer can be improved. The inorganic filler is not particularly limited as long as it is a filler that is stable in a non-aqueous electrolytic solution and is electrochemically stable. From the viewpoint of ensuring battery safety, a filler having a heat resistant temperature of 150 ° C. or higher is preferable.

  The inorganic filler is not particularly limited, but is usually an insulating filler. The inorganic filler is preferably an inorganic material containing at least one element selected from the group consisting of aluminum element, zinc element, calcium element, zirconium element, silicon element, magnesium element, barium element, and boron element, and preferably Is an inorganic substance containing an aluminum element. The inorganic filler preferably contains an oxide of the above element.

Specifically, as the inorganic filler, titanium oxide, alumina (Al ₂ O ₃ ), zinc oxide (ZnO), calcium oxide (CaO), zirconia oxide (ZrO ₂ ), silica, magnesia, barium oxide, boron oxide, Examples thereof include mica, wollastonite, attapulgite, and boehmite (alumina monohydrate). As the inorganic filler, one kind of filler may be used alone, or two or more kinds 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 a 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 oxides of the above-mentioned elements.

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

  The shape of the inorganic filler is arbitrary and is not particularly limited. The shape of the inorganic filler may be a particle shape, for example, a spherical shape; an elliptical shape; a plate shape; a rod shape; an irregular shape; a fibrous shape; a spherical or columnar single particle such as a peanut shape and / or a tetrapot shape. The shape may be any of the above. From the viewpoint of battery short-circuit prevention, the inorganic filler is preferably plate-like particles and / or non-aggregated primary particles, and from the viewpoint of ion permeation, the particles in the porous layer are closest packed. Difficult to form, voids are easily formed between particles, bumps, dents, constrictions, bumps or bulges, dendritic, coral-shaped, or tuft-like irregular shapes; fibrous; peanut-shaped and / or tetra-shaped A shape in which single particles are heat-fused like a pot is preferable, and a shape in which spherical or columnar single particles are heat-fused like a peanut and / or tetrapot is more preferable.

  The filler can improve the slipperiness by forming fine irregularities on the surface of the porous layer, but when the filler is plate-like particles and / or primary particles that are not aggregated, the filler is 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 plate becomes better.

  The oxygen atom mass percentage of the oxide of the element that constitutes the inorganic filler contained in the porous layer in one embodiment of the present invention is preferably 10% to 50%, and 20% to 50%. Is more preferable. In the present invention, the "oxygen atom mass percentage" means the ratio of the mass of oxygen atoms in the oxide to the total mass of the entire oxide of the element, 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 oxygen atom mass percentage of the oxide of the element is in the above range, the solvent or dispersion medium in the coating liquid used in the method for producing a porous layer described later, and the affinity of the inorganic filler. It is possible to improve the dispersibility of the coating liquid by keeping the suitable distance between the inorganic fillers and maintaining a suitable distance, and as a result, "the aspect ratio of the projected image of the inorganic filler on the surface of the porous layer is improved." And “the orientation degree of the porous layer” can be controlled within an appropriate specified range.

  The aspect ratio of the inorganic filler itself contained in the porous layer in the embodiment of the present invention is such that, in a state where the inorganic filler is arranged on a plane, in an SEM image observed from vertically above the arrangement surface, overlapping in the thickness direction occurs. It is expressed as the average value of the ratio of the length of the short axis to the length of the long axis of 100 particles that are not present. In the present specification, 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. The aspect ratio of the inorganic filler itself is preferably 1 to 10, more preferably 1.1 to 8, and even more preferably 1.2 to 5. By the aspect ratio of the inorganic filler itself is in the above range, when the porous layer in one embodiment of the present invention is formed by the method described below, in the resulting porous layer, the orientation of the filler, The uniformity of the distribution of the filler on the surface of the porous layer can be controlled within a preferable range.

  The porous layer in one embodiment of the present invention may contain other components other than the above-mentioned inorganic filler and resin. Examples of the other components include a surfactant, a wax, and a binder resin. Further, the content of the other components is preferably 0% by weight to 50% by weight based on the weight of the entire porous layer.

  The average film thickness of the porous layer in one embodiment of the present invention is preferably in the range of 0.5 μm to 10 μm per porous layer from the viewpoint of securing adhesiveness to the electrode plate 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. Basis weight per unit area of the porous layer, the porous per Soisso is preferably 0.5 to 20 g / ^{m 2,} and more preferably 0.5 to 10 g / ^{m 2.}

  By setting the basis weight per unit area of the porous layer within these numerical ranges, the weight energy density and the volume energy density of the non-aqueous electrolyte secondary battery can be increased. When 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, and more preferably 30 to 80% by volume so that sufficient ion permeability can be obtained. 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 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 the porous layer in one embodiment 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 is 1.5 to 2.3. It is preferably in the range. Here, for the aspect ratio, a scanning electron microscope (SEM) is used to take an SEM image, which is an electron micrograph of the surface, immediately above the porous layer, that is, from above the vertical direction. It is a value obtained by creating a projected image of the filler and calculating the ratio of the major axis length / minor axis length of the projected image of the inorganic filler. That is, the aspect ratio refers to 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.

  In addition, the schematic diagram of the projected image of the inorganic filler created from the SEM image of the above-mentioned porous layer surface is shown in FIG.

As a specific measuring method of the aspect ratio, for example, a method including the following steps (1) to (4) can be mentioned. The “surface” of the porous layer means 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, an SEM at an accelerating voltage of 5 kV using a field emission scanning electron microscope JSM-7600F manufactured by JEOL Ltd. from directly above the porous side of the laminate. A step of observing the surface (reflected electron image) to obtain an SEM image.
(2) An OHP film is placed on the SEM image obtained in the step (1), a projection image laid along the contour of the particles of the inorganic filler shown in the SEM image is created, and the projection image is obtained. The process of shooting 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 filled with the image analysis free software IMAGEJ issued by the National Institutes of Health (NIH). Calculating the aspect ratio of each of the pieces. Here, each of the filler particles is approximated to an ellipse one by one, 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 an aspect ratio.
(4) A step of calculating the average value of the aspect ratios of the projected images of the respective particles obtained in the 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 the distribution of the inorganic filler on the porous layer, especially on the surface thereof. When the aspect ratio is close to 1, the shape and distribution of the constituent material on the surface of the porous layer are uniform, and it is easy to be densely packed. On the other hand, when the aspect ratio is large, the arrangement of the 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 of 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, especially the surface openings thereof, is excessively reduced, so that a non-aqueous electrolyte secondary electrode incorporating the porous layer is used. It is considered that in the battery, a portion where the capacity of the porous layer to receive the electrolyte solution during the operation of the battery is reduced, and as a result, the rate characteristic of the non-aqueous electrolyte secondary battery is reduced. On the other hand, when the aspect ratio is less than 1.4, the porous layer, in particular, the distribution of the inorganic filler on the surface thereof has an excessively uniform structure, and as a result, the surface opening area of the porous layer is small. In the non-aqueous electrolyte secondary battery incorporating the porous layer, the electrolyte receiving capacity of the porous layer during the operation of the battery decreases, and as a result, the battery rate of the non-aqueous electrolyte secondary battery decreases. It is considered that the characteristics are degraded.

<Orientation of porous layer>
The porous layer in one embodiment of the present invention has peak intensity I _{(hkl) of} arbitrary diffraction planes (hkl) and (abc) orthogonal to each other in the porous layer measured by a wide-angle X-ray diffraction method, and It is preferable that I _(abc) satisfies the following formula (1), and that 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. It is more preferably in the range of 250.
I _(hkl) > I _(abc) ... (1),
I _(hkl) / I _(abc) (2).

  Hereinafter, in the present specification, the maximum value of the peak intensity ratio calculated by the formula (2) is also referred to as “the degree of orientation 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) are used. A method comprising the steps shown can be mentioned.
(1) A step of preparing a measurement sample by cutting a 2 cm square laminate (laminated porous film) obtained by laminating a porous layer on a substrate.
(2) The measurement sample obtained in step (1) was attached to an Al holder with the porous layer side of the sample as the measurement surface, and an X-ray profile was obtained by a wide-angle X-ray diffraction method (2θ-θ scan method). Measuring step. The device for measuring the X-ray profile and the measurement conditions are not particularly limited, but for example, RU-200R (rotating anticathode type) manufactured by Rigaku Denki Co., Ltd. is used as the device, and CuKα rays are used as the X-ray source. The output may be measured at 50 KV-200 mA and a scanning speed of 2 ° / min.
(3) Based on the X-ray profile obtained in the step (2), peak intensity I _{(hkl) of} arbitrary diffractive surfaces (hkl) and (abc) orthogonal to each other in wide-angle X-ray diffraction measurement of the porous layer. A step of calculating the peak intensity ratio calculated by the equation (2) when I _(abc) satisfies the equation (1), and calculating the maximum value of the peak intensity ratio, that is, the degree of orientation of the porous layer. ..

  In the calculation of the degree of orientation of the porous layer, it is important to determine both the orientation in the horizontal direction and the orientation in the normal direction with respect to the substrate surface by using the diffractive surfaces orthogonal to each other. is there.

  The maximum value of the peak intensity ratio shown by the formula (2) is an index showing the degree of orientation inside the porous layer. A small peak intensity ratio represented by the formula (2) means that the degree of orientation in the internal structure of the porous layer is low, and a large peak intensity ratio represented by the formula (2) means that It shows that the internal structure of the texture layer has a high degree of orientation.

  When the maximum value of the peak intensity ratio represented by the formula (2) is larger than 300, the anisotropy of the internal structure of the porous layer becomes excessively high, and the ion permeation flow channel length inside the porous layer is increased. Therefore, as a result, in the non-aqueous electrolyte secondary battery incorporating the porous layer, the ion permeation resistance of the porous layer is increased, and the battery rate characteristic of the non-aqueous electrolyte secondary battery is considered to deteriorate. Be done.

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

<Method for producing porous layer>
The method for producing the porous layer according to the embodiment of the present invention is not particularly limited, but, for example, one of the following steps (1) to (3) is used on the substrate, A method of forming a porous layer containing the inorganic filler and the resin can be mentioned. In the case of the step (2) and the step (3) shown below, the resin can be produced by precipitating the resin and then drying 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 a dispersion medium for dispersing the resin or the inorganic filler.

  (1) A step of forming a porous layer by applying a coating liquid containing the inorganic filler and the resin onto a substrate and drying and removing the solvent in the coating liquid.

  (2) After applying a coating liquid containing the inorganic filler and the resin to the surface of the base material, 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 base material, the liquid property of the coating liquid is made acidic by using a low-boiling organic acid. A step of depositing a resin to form a porous layer.

  As the base material, other than the polyolefin porous film described later, other films, a positive electrode plate, a negative electrode plate, and the like can be used.

  It is preferable that the solvent does not adversely affect the base material, dissolves the resin uniformly and stably, 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 deposition solvent, for example, isopropyl alcohol or t-butyl alcohol is preferably used.

  In the step (3), as the low boiling point organic acid, for example, paratoluenesulfonic acid, acetic acid or the like can be used.

  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 orientation degree of the porous layer", As shown, used in the production of the porous layer, the solid content concentration of the coating liquid containing the inorganic filler and the resin, and the coating shear rate when coating the coating liquid on the substrate The adjustment can be mentioned.

  The suitable solid content concentration of the coating liquid may vary depending on the kind of the filler and the like, but it is generally preferably more than 20% by weight and 40% by weight or less. That the solid content concentration is within 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 "orientation degree of the porous layer". Is preferable because it can be controlled within the above-mentioned preferable range.

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

  Here, for example, as the inorganic filler, spherical or columnar single particles such as peanut-like and / or tetrapot-like particles are heat-sealed, spherical, elliptical, plate-like, rod-like, or irregular shape. When an inorganic filler having the above-mentioned shape is used, if the coating shear rate is increased, a high shearing force is applied to the inorganic filler, so that the anisotropy tends to increase. On the other hand, when the coating shear rate is reduced, the shearing force is not applied to the inorganic filler, so that the inorganic filler tends to be oriented isotropically.

  On the other hand, when the inorganic filler is a long fiber diameter inorganic filler such as long wollastonite having a large fiber diameter, when the coating shear rate is increased, the long fibers are entangled with each other, or the length of the doctor blade is long. Since the fibers are caught, the fibers tend to be in a random orientation, and the anisotropy tends to decrease. On the other hand, when the coating shear rate is decreased, the long fibers do not get caught on each other and the blade of the doctor blade, so that they tend to be oriented and the anisotropy tends to increase.

[Positive plate, negative plate]
The positive electrode plate in an embodiment of the present invention, the capacitance of the measurement area 900 mm ² per are, 1nF or more, or less 1000 nF, negative plates, the capacitance of the measurement area 900 mm ² per are, 4nF above, 8500NF less Is.

<Capacitance>
In the present specification, the “measurement area” is in contact with the measurement target (positive electrode plate or negative electrode plate) in the measurement electrode (upper (main) electrode, probe electrode) of the LCR meter in the capacitance measuring method described later. It means the area of the part. Therefore, the value of the capacitance per measurement area Xmm ² means that the area of the measurement electrode in the LCR meter where the measurement object and the measurement electrode overlap is Xmm ² . It means a measured value when the capacitance is measured by contacting.

  In the present invention, the capacitance of the positive electrode plate is a value measured by bringing a measurement electrode (probe electrode) into contact with the positive electrode active material layer side surface of the positive electrode plate in the method for measuring the capacitance of the electrode plate described later. And mainly represents the polarization state of the positive electrode active material layer of the positive electrode plate.

  Further, in the present invention, the capacitance of the negative electrode plate is a value measured by bringing a measurement electrode into contact with the negative electrode active material layer side surface of the negative electrode plate in the method for measuring the capacitance of the electrode plate described later. , Mainly represents the polarization state of the negative electrode active material layer of the negative electrode plate.

In the non-aqueous electrolyte secondary battery, ions as charge carriers are released from the negative electrode plate during discharge. The ions pass through the separator for non-aqueous electrolyte secondary battery, and are then taken into the positive electrode plate. At this time, the ions are solvated by the electrolyte solvent in the negative electrode plate and the surface of the negative electrode plate, and desolvated in the positive electrode plate and the surface of the positive electrode plate. The ions are Li ⁺ when the non-aqueous electrolyte secondary battery is a lithium ion secondary battery, for example.

  Therefore, the degree of solvation of the above ions is influenced by the polarization state of the negative electrode active material layer of the negative electrode plate, and the degree of desolvation of the above ions is determined by the polarization state of the positive electrode active material layer of the positive electrode plate. To be affected.

Therefore, by controlling the electrostatic capacities of the negative electrode plate and the positive electrode plate within a suitable range, that is, by adjusting the polarization state of the negative electrode active material layer and the positive electrode active material layer to a suitable state, the above-mentioned solvation and desolvation can be performed. Solvation can be moderately promoted. As a result, the permeability of ions as charge carriers can be improved, and the discharge output characteristics of the non-aqueous electrolyte secondary battery can be improved especially when a large discharge current with a time rate of 10 C or more is applied. Can be made From the above viewpoint, in the negative electrode plate of the non-aqueous electrolyte secondary battery according to the embodiment of the present invention, the capacitance per measurement area 900 mm ² is 4 nF or more and 8500 nF or less, and 4 nF or more and 3000 nF or less. Is preferable and 4nF or more and 2600nF or less is more preferable. The lower limit value of the capacitance may be 100 nF or more, 200 nF or more, and 1000 nF or more.

Specifically, when the capacitance of the negative electrode plate per measured area of 900 mm ² is less than 4 nF, the polarizability of the negative electrode plate is low, so that it hardly contributes to the promotion of solvation. Therefore, no improvement in output characteristics occurs in the non-aqueous electrolyte secondary battery incorporating the negative electrode plate. On the other hand, when the capacitance per measured area 900 mm ² in the negative electrode plate is larger than 8500 nF, the polarizability of the negative electrode plate becomes too high, and the affinity between the inner wall of the void of the negative electrode plate and the ions becomes high. Pass. Therefore, the movement (release) of ions from the negative electrode plate is hindered. Therefore, the output characteristics of the non-aqueous electrolyte secondary battery incorporating the negative electrode plate are rather deteriorated.

From the above viewpoint, the positive electrode plate in one embodiment of the present invention has a capacitance per measurement area 900 mm ^{2 of} 1 nF or more and 1000 nF or less, preferably ² nF or more and 600 nF or less, and ² nF or more. , 400 nF or less is more preferable. Further, the lower limit value of the capacitance may be 3 nF or more.

Specifically, in the positive electrode plate, when the capacitance per 900 mm ² of the measurement area is less than 1 nF, the positive electrode plate has a low polarizability and thus hardly contributes to the desolvation. Therefore, the improvement of the output characteristics does not occur in the non-aqueous electrolyte secondary battery incorporating the positive electrode plate. On the other hand, in the positive electrode plate, when the capacitance per 900 mm ^{2 of} measured area is larger than 1000 nF, the polarizability of the positive electrode plate becomes too high, so that the desolvation proceeds excessively. Therefore, the solvent for moving inside the positive electrode plate is desolvated, and the affinity between the inner wall of the void inside the positive electrode plate and the desolvated ions becomes too high. Therefore, the movement of ions inside the positive electrode plate is hindered. Therefore, the output characteristics of the non-aqueous electrolyte secondary battery incorporating the positive electrode plate are rather deteriorated.

<Control method of capacitance>
The capacitances of the positive electrode plate and the negative electrode plate can be controlled by adjusting the surface areas of the positive electrode active material layer and the negative electrode active material layer, respectively. Specifically, for example, the surfaces of the positive electrode active material layer and the negative electrode active material layer are ground with sandpaper or the like to increase the surface area, thereby increasing the capacitance. Alternatively, the electrostatic capacities of the positive electrode plate and the negative electrode plate can be controlled by adjusting the relative permittivity of the material forming each of the positive electrode plate and the negative electrode plate. The relative permittivity can be adjusted by changing the shape of voids, the void ratio, and the distribution of voids in each of the positive electrode plate and the negative electrode plate. The relative permittivity can also be adjusted by adjusting the materials forming each of the positive electrode plate and the negative electrode plate.

<Method of measuring capacitance>
The capacitance of the electrode plate (positive electrode plate or negative electrode plate) per measurement area 900 mm ² in one embodiment of the present invention is CV: 0.010V, SPEED: SLOW2, AVG: 8, CABLE using an LCR meter. 1 m, OPEN: All, SHORT: All DCBIAS 0.00V, and the frequency is 300 KHz.

  In the measurement of the electrostatic capacity, the electrostatic capacity of the electrode plate before being incorporated in the non-aqueous electrolyte secondary battery is measured. The capacitance is a unique value determined by the shape (surface area) of the solid insulating material (electrode plate), the constituent material, the shape of voids, the void ratio, the distribution of voids, and the like. Therefore, the capacitance of the electrode plate after being incorporated in the non-aqueous electrolyte secondary battery is also the same value as the capacitance value measured before being incorporated in the non-aqueous electrolyte secondary battery.

  It is also possible to take out the positive electrode plate and the negative electrode plate from the battery that has undergone charge / discharge history after being incorporated into the non-aqueous electrolyte secondary battery, and measure the capacitance of the positive electrode plate and the negative electrode plate. Specifically, for example, after taking out the electrode laminate (member for non-aqueous electrolyte secondary battery) from the exterior member of the non-aqueous electrolyte secondary battery, it is expanded to form one electrode plate ( Take out the positive electrode plate or the negative electrode plate). A sample piece is obtained by cutting out this electrode plate into the same size as the electrode plate to be measured in the above-described capacitance measuring method. Then, the test piece is washed several times (for example, three times) in diethyl carbonate (hereinafter sometimes referred to as DEC). The above-mentioned cleaning is performed by adding a test piece to DEC and then cleaning the test piece by replacing the DEC with a new DEC and cleaning the test piece several times (for example, three times) to adhere to the surface of the electrode plate. This is a step of removing the electrolytic solution, the electrolytic solution decomposition product, the lithium salt, and the like. The obtained washed electrode plate is sufficiently dried and then used as an electrode to be measured. There is no limitation on the type of exterior member or laminated structure of the battery to be taken out.

<Orientation of inorganic filler in porous layer and capacitance of electrode plate>
As described above, 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 when the porous layer is measured by the wide-angle X-ray diffraction method. When I _(hkl) and I _(abc) satisfy the above expression and the range of the maximum value of the peak intensity ratio calculated by the above expression (2) is in the range of 1.5 to 300 (condition 1) The porous layer has a structure that easily retains the electrolytic solution, and the migration path of ions as charge carriers is optimized, so that the permeability of ions is promoted.

Moreover, when the capacitance per 900 mm ² of the measurement area of the positive electrode plate is 1 nF or more and 1000 nF or less and the capacitance per 900 mm ² of the measurement area of the negative electrode plate is 4 nF or more and 8500 nF or less (condition 2). In addition, since the polarization of the electrode active material layer becomes appropriate, desolvation / solvation of ions as charge carriers is promoted, and the permeability of the ions is improved.

  When the degree of orientation of the inorganic filler in the porous layer satisfies the above condition 1 and the electrode plate satisfies the above condition 2, the pores of the porous layer have an appropriate dense structure, and the ions as charge carriers are The permeability and the acceptability of the electrolytic solution are compatible with each other, and the polarization of the electrode active material layer is appropriate. Therefore, solvation and desolvation of ions as charge carriers also proceed smoothly. As a result, the non-uniformity of the capacity in the electrode surface direction due to the high rate discharge is suppressed, that is, the uneven concentration of ions as charge carriers is eliminated. As a result, it becomes possible to correct nonuniformity in the surface direction during recharging (reuniformization). As a result, it is considered that the charge capacity after high rate discharge of the battery can be improved.

  The charge capacity of the non-aqueous electrolyte secondary battery according to one embodiment of the present invention at 1 C charge after high rate discharge (10 C discharge) is preferably 14.5 mAh or more, and more preferably 15 mAh or more. preferable.

  The charge capacity during 1C charging after high-rate discharge (10C discharge) is a value measured by the measuring method described in the examples.

<Positive plate>
The positive electrode plate in one embodiment of the present invention is not particularly limited as long as the capacitance per measurement area 900 mm ² is within the above range. For example, as the positive electrode active material layer, a sheet-shaped positive electrode plate in which a positive electrode mixture containing a positive electrode active material, a conductive agent and a binder is carried on a positive electrode current collector is used. The positive electrode plate may carry the positive electrode mixture on both surfaces of the positive electrode current collector, or may carry the positive electrode mixture on one surface of the positive electrode current collector.

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

  Examples of the conductive agent include natural graphite, artificial graphite, cokes, carbon black, pyrolytic carbons, carbon fibers, and carbonaceous materials such as organic polymer compound fired bodies. The conductive agent may be used alone or in combination of two or more kinds.

  Examples of the binder include polyvinylidene fluoride, vinylidene fluoride copolymer, polytetrafluoroethylene, tetrafluoroethylene-hexafluoropropylene copolymer, tetrafluoroethylene-perfluoroalkyl vinyl ether copolymer. , Ethylene-tetrafluoroethylene copolymer, vinylidene fluoride-hexafluoropropylene copolymer, vinylidene fluoride-hexafluoropropylene-tetrafluoroethylene copolymer, thermoplastic polyimide, thermoplastic resin such as polyethylene and polypropylene , Acrylic resin, and styrene-butadiene rubber. 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 easily processed into a thin film and is inexpensive.

  Examples of the method for producing a sheet-shaped positive electrode plate include a method in which a positive electrode active material, a conductive agent, and a binder are pressure-molded on a positive electrode current collector; a positive electrode active material, a conductive agent, and A method of fixing the binder to the positive electrode current collector by applying the paste to the positive electrode current collector, applying the paste to the positive electrode current collector, and then drying and pressing the paste, and the like.

<Negative electrode plate>
The negative electrode plate in one embodiment of the present invention is not particularly limited as long as the capacitance per measurement area 900 mm ² is within the above range. For example, as the negative electrode active material layer, a sheet-shaped negative electrode plate in which a negative electrode mixture containing a negative electrode active material, a conductive agent and a binder is carried on a negative electrode current collector is used. The negative electrode plate may carry the negative electrode mixture on both surfaces of the negative electrode current collector, or may carry the negative electrode mixture on one surface of the negative electrode current collector.

  As the conductive agent and the binder, those described as the conductive agent and the binder contained in the positive electrode active material layer can be used.

  Examples of the negative electrode active material include materials that can be doped / dedoped with lithium ions, lithium metal, lithium alloys, and the like. Specific examples of the material include carbonaceous materials such as natural graphite, artificial graphite, cokes, carbon black, pyrolytic carbons, carbon fibers, and organic polymer compound calcined materials; at a potential lower than that of the positive electrode. Examples thereof include chalcogen compounds such as oxides and sulfides, which are doped and dedoped with lithium ions. Among the negative electrode active materials, the potential flatness is high, and since a large energy density can be obtained when combined with the positive electrode because the average discharge potential is low, those containing graphite are preferable, such as natural graphite and artificial graphite. A carbonaceous material containing a graphite material as a main component is more preferable. Further, the negative electrode active material may contain graphite as a main component and additionally contain silicon.

  Examples of the negative electrode current collector include Cu, Ni, and stainless steel. Particularly, in a lithium ion secondary battery, Cu is more preferable because it is difficult to form an alloy with lithium and is easily processed into a thin film.

  Examples of the method for producing the sheet-shaped negative electrode plate include, for example, a method in which the negative electrode active material is pressure-molded on a negative electrode current collector; the negative electrode active material is made into a paste using an appropriate organic solvent, and then the paste is used as a negative electrode. A method of coating the current collector, then drying and then applying pressure to fix the current collector to the negative electrode current collector, and the like. The paste preferably contains the conductive agent and the binder.

[Polyolefin porous film]
The non-aqueous electrolyte secondary battery in one embodiment of the present invention may include a polyolefin porous film. Below, a polyolefin porous film may only be called a "porous film." The porous film contains a polyolefin-based resin as a main component and has a large number of pores connected to the inside thereof, so that a gas and a liquid can 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 a base material of the laminated separator for a non-aqueous electrolyte secondary battery in which the above-mentioned porous layer is laminated.

  On at least one surface of the polyolefin porous film, a laminate in which the porous layer is laminated, in the present specification, also referred to as "non-aqueous electrolyte secondary battery laminated separator" or "laminated separator" .. Further, the separator for a non-aqueous electrolyte secondary battery 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 of the entire porous film, more preferably 90% by volume or more, and further preferably 95% by volume or more. Further, it is more preferable that the polyolefin 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 a non-aqueous electrolyte secondary battery is improved, which is more preferable.

  Specific examples of the polyolefin that is a thermoplastic resin include homopolymers obtained by polymerizing monomers such as ethylene, propylene, 1-butene, 4-methyl-1-pentene and 1-hexene. Alternatively, a copolymer may be used. Examples of the homopolymer include polyethylene, polypropylene and polybutene. Moreover, as said copolymer, an ethylene-propylene copolymer can be mentioned, for example.

  Of these, polyethylene is more preferable because it can prevent an excessive current from flowing at a lower temperature. Note that blocking the flow of this excessive current is also referred to as shutdown. Examples of the polyethylene include low density polyethylene, high density polyethylene, linear polyethylene (ethylene-α-olefin copolymer), and ultrahigh molecular weight polyethylene having a weight average molecular weight of 1,000,000 or more. Among these, ultrahigh 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, and further 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, to be able to increase the weight energy density and volume energy density of the nonaqueous electrolyte secondary battery, wherein the basis weight is preferably 4~20g / ^{m 2,} is 4~12g / ^{m 2} More preferably, it is more preferably 5 to 10 g / m ² .

  The air permeability of the porous film is preferably 30 to 500 sec / 100 mL as a Gurley value, and more preferably 50 to 300 sec / 100 mL. When the porous film has the above-mentioned air permeability, sufficient ion permeability can be obtained. The air permeability of the laminated separator for a non-aqueous electrolyte secondary battery in which the above-mentioned porous layer is laminated on the porous film is preferably 30 to 1000 sec / 100 mL in terms of Gurley value, and is 50 to 800 sec / 100 mL. Is more preferable. Since the laminated separator for a non-aqueous electrolyte secondary battery has the above-mentioned air permeability, it is possible to obtain sufficient ion permeability in the non-aqueous electrolyte secondary battery.

  The porosity of the porous film is preferably 20 to 80% by volume so as to increase the holding amount of the electrolytic solution and to surely prevent the flow of an excessive current at a lower temperature. It is more preferably 30 to 75% by volume. The pore size 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-shaped polyolefin resin composition is prepared by kneading a polyolefin resin, a pore-forming agent such as an inorganic filler and a plasticizer, and optionally an antioxidant and the like and then extruding the kneaded product. After removing the pore-forming agent from the sheet-shaped polyolefin resin composition with an appropriate solvent, the polyolefin resin composition from which the pore-forming agent has been removed may be stretched to produce a polyolefin porous film. it can.

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

Specifically, a method including the following steps can be mentioned.
(A) a step of kneading an ultrahigh 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 and gradually cooling it while pulling it with a take-up roller having a different speed ratio to form a sheet,
(C) a step of 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 producing laminated separator for non-aqueous electrolyte secondary battery]
Examples of the method for producing a laminated separator for a non-aqueous electrolyte secondary battery in one embodiment of the present invention include, for example, in the above-mentioned “method for producing a porous layer”, as the base material to which the coating liquid is applied, The method of using a polyolefin porous film can be mentioned.

[Non-aqueous electrolyte]
The non-aqueous electrolyte that can be included in the non-aqueous electrolyte secondary battery according to the embodiment of the present invention is not particularly limited as long as it is a non-aqueous electrolyte that is generally used in non-aqueous electrolyte secondary batteries. As the non-aqueous electrolyte, for example, a non-aqueous electrolyte obtained by dissolving a lithium salt in an organic solvent can be used. Examples of the lithium salt 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 , Li ₂ B ₁₀ Cl. ₁₀ , lower aliphatic carboxylic acid lithium salt, LiAlCl _{4 and the} like. The lithium salt may be used alone or in combination of two or more kinds.

  Examples of the organic solvent that constitutes the non-aqueous electrolytic solution include carbonates, ethers, esters, nitriles, amides, carbamates and sulfur-containing compounds, and fluorine-containing compounds introduced into these organic solvents. Fluorine organic solvents and the like can be mentioned. The organic solvent may be used alone or in combination of two or more.

[Method for producing non-aqueous electrolyte secondary battery]
As a method for manufacturing the non-aqueous secondary battery according to the embodiment of the present invention, a conventionally known manufacturing method can be adopted. For example, a positive electrode plate, a polyolefin porous film, and a negative electrode plate are arranged in this order to form a member for a non-aqueous electrolyte secondary battery. Here, the porous layer may be present between the polyolefin porous film and at least one of the positive electrode plate and the negative electrode plate. Then, the member for a non-aqueous electrolyte secondary battery is put in a container which is a casing of 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, the non-aqueous electrolyte secondary battery according to the embodiment of the present invention can be manufactured.

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

[Measuring method]
Each measurement in Examples and Comparative Examples was performed by the following methods.

(1) Film thickness (unit: μm)
The film thickness of the polyolefin porous film and the porous layer, and the thickness of the positive electrode plate and the negative electrode plate were measured using a high precision digital length measuring machine (VL-50) manufactured by Mitutoyo Corporation. The thickness of the electrode active material layer was a value obtained by subtracting the thickness of the uncoated portion from the thickness of the coated portion of each electrode plate.

(2) Measurement of Aspect Ratio of Projection Image of Inorganic Filler on Surface of Porous Layer From the porous layer side of the laminate of the polyolefin porous film and the porous layer produced in Examples and Comparative Examples, manufactured by JEOL Ltd. Using a field emission scanning electron microscope JSM-7600F, SEM surface observation (backscattered electron image) was performed at an accelerating voltage of 5 kV, and an electron microscope photograph (SEM image) was obtained.

  An OHP film was placed on the obtained SEM image to form a projection image spread along the contours of the particles of the inorganic filler, and the projection image was photographed with a digital still camera. The obtained photograph data was imported into a computer, and the aspect ratio of each of 100 particles was calculated using free image analysis software IMAGEJ issued 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 ellipse, 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.

(3) Measurement of maximum value of peak intensity ratio (I _(hkl) / I _(abc) ) The laminate of the polyolefin porous film and the porous layer produced in Examples and Comparative Examples was cut into 2 cm squares, A measurement sample was obtained. 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 the wide-angle X-ray diffraction method (2θ-θ scan method). RU-200R (rotating anticathode type) manufactured by Rigaku Denki Co., Ltd. was used as an apparatus, CuKα rays were used as an X-ray source, and the output was measured at 50 KV-200 mA and a scan speed of 2 ° / min. Based on the obtained X-ray profile, the peak intensities I _(hkl) and I _{(abc) of} arbitrary diffraction planes (hkl) and (abc) orthogonal to each other 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) in the case of satisfying ₍₁₎ is calculated, and the maximum value of the peak intensity ratio is calculated.
I _(hkl) > I _(abc) ... (1).

(4) Measurement of Electrostatic Capacity of Electrode Plate The electrostatic capacity per 900 mm ² of the measurement area of the positive electrode plate and the negative electrode plate obtained in Examples and Comparative Examples was measured by using an LCR meter (model number: IM3536) manufactured by Hioki Electric. It was measured using. At this time, the measurement conditions were set to CV: 0.010V, SPEED: SLOW2, AVG: 8, CABLE: 1m, OPEN: All, SHORT: All DCBIAS 0.00V, and the frequency was 300 KHz. The absolute value of the measured capacitance was defined as the capacitance.

  From the electrode plate to be measured, the site where the 3 cm × 3 cm square electrode active material layer was formed and the site where the 1 cm × 1 cm square electrode active material layer was not formed were cut out as one piece. A tab lead having a length of 6 cm and a width of 0.5 cm was ultrasonically welded to a portion of the cut electrode plate where the electrode active material layer was not formed to obtain an electrode plate for measuring capacitance (Fig. 3). The tab lead of the positive electrode plate was made of aluminum, and the tab lead of the negative electrode plate was made of nickel.

  From the current collector, a 5 cm × 4 cm square and a 1 cm × 1 cm square for tab lead welding were cut out as one piece. A tab lead having a length of 6 cm and a width of 0.5 cm was ultrasonically welded to the tab lead welding portion of the cut current collector to obtain a probe electrode (measurement electrode) (FIG. 4). A 20 μm thick aluminum probe electrode is used as the probe electrode for measuring the capacitance of the positive electrode plate, and a 20 μm thick copper probe electrode is used as the probe electrode for measuring the capacitance of the negative electrode plate. Using.

  The probe electrode and a portion of the electrode plate for measurement on which the electrode active material layer was formed (a square portion of 3 cm × 3 cm) were overlapped with each other to produce a laminate. The obtained laminated body was sandwiched between two silicone rubbers, and further sandwiched between each of the silicone rubbers with two SUS plates at a pressure of 0.7 MPa to obtain a laminated body for measurement. The tab lead was taken out from the laminate used for the measurement, and the voltage terminal and the current terminal of the LCR meter were connected from the side closer to the electrode plate of the tab lead.

(5) Measurement of Porosity of Positive Electrode Active Material Layer The porosity of the positive electrode active material layer included in the positive electrode plate 1 in Example 1 below was measured by the following method. The porosities of the positive electrode active material layers included in the other positive electrode plates in the following Examples and Comparative Examples were also measured by the same method.

Positive electrode mixture (LiNi _0.5 Mn _0.3 Co _0.2 O ₂ / conductive agent / PVDF (weight ratio 92
/ 5/3)), the positive electrode plate supported on one surface of the positive electrode current collector (aluminum foil) was cut into a size of 14.5 cm ² (4.5 cm × 3 cm + 1 cm × 1 cm). The cut-out positive electrode plate had a mass of 0.215 g and a thickness of 58 μm. When the positive electrode current collector was cut into the same size, the mass was 0.078 g and the thickness was 20 μm.

The positive electrode active material layer density ρ was calculated to be (0.215-0.078) / {(58-20) /10000×14.5} = 2.5 g / cm ³ .

Each true density of the material constituting the positive electrode _{mixture, LiNi 0.5 Mn 0.3 Co 0.2 O} 2 is 4.68 g / cm ^3, the conductive agent is 1.8g / cm ^3, PVDF Was 1.8 g / cm ³ .

The porosity ε of the positive electrode active material layer calculated based on the following formula using these values was 40%.
ε = [1- {2.5 × (92/100) /4.68+2.5× (5/100) /1.8+2.5× (3/100) /1.8}] × 100 = 40%
(6) Measurement of Porosity of Negative Electrode Active Material Layer The porosity of the negative electrode active material layer included in the negative electrode plate 1 in Example 1 below was measured by the following method. The porosities of the negative electrode active material layers included in the other negative electrode plates in the following Examples and Comparative Examples were also measured by the same method.

A negative electrode plate (graphite / styrene-1,3-butadiene copolymer / sodium carboxymethyl cellulose (weight ratio 98/1/1)) was carried on one surface of a negative electrode current collector (copper foil) to form a negative electrode plate 18 It was cut into a size of 0.5 cm ² (5 cm × 3.5 cm + 1 cm × 1 cm). The cut negative electrode plate had a mass of 0.266 g and a thickness of 48 μm. When the negative electrode current collector was cut into the same size, the mass was 0.162 g and the thickness was 10 μm.

The negative electrode active material layer density ρ was calculated as (0.266-0.162) / {(48-10) /10000×18.5} = 1.49 g / cm ³ .

The true densities of the materials forming the negative electrode mixture are 2.2 g / cm ³ for graphite, 1 g / cm ³ for styrene-1,3-butadiene copolymer, and 1.6 g / cm ³ for sodium carboxymethyl cellulose. It was cm ³ .

The porosity ε of the negative electrode active material layer calculated based on the following formula using these values was 31%.
ε = [1- {1.49 × (98/100) /2.2+1.49× (1/100) /1+1.49× (1/100) /1.6}] × 100 = 31%
(7) Charge capacity after high-rate discharge of non-aqueous electrolyte secondary battery Non-aqueous electrolyte secondary battery manufactured in Examples and Comparative Examples by the method shown in the following steps (A) and (B) The charge capacity during 1C charging after high rate discharge (10C discharge) was measured.

(A) Initial charge / discharge test With respect to the new non-aqueous electrolyte secondary battery that has not been subjected to charge / discharge cycles manufactured in the examples and comparative examples, voltage range: 2.7 to 4.1 V, charging current value CC-CV charge of 0.2C (end current condition 0.02C) and CC discharge of discharge current value 0.2C were set as one cycle, and initial charge and discharge of 4 cycles were carried out at 25 ° C.

  It should be noted that the current value for discharging the rated capacity based on the discharge capacity of 1 hour rate in 1 hour is 1C. CC-CV charging is a charging method in which charging is performed with a set constant current, and after reaching a predetermined voltage, the current is reduced while maintaining the voltage. CC discharge is a method of discharging to a predetermined voltage with a set constant current. The same applies to the following.

(B) Charge capacity (mAh) at 1C charge after high-rate discharge (10C discharge)
For the non-aqueous electrolyte secondary battery that has been subjected to the initial charge / discharge, CC-CV charge with a charge current value of 1C (end current condition 0.02C), discharge current value of 0.2C, 1C, 5C, 10C in this order. CC discharge was carried out. Charging / discharging was performed for 3 cycles at 55 ° C. for each rate. At this time, the voltage range was 2.7V to 4.2V.

  At this time, the charge capacity at the time of 1C charge of the 3rd cycle at the time of 10C discharge rate characteristic measurement was measured, and it was set as the charge capacity (mAh) after high rate discharge. The designed capacity of the non-aqueous electrolyte secondary batteries manufactured in Examples and Comparative Examples was 20.5 mAh.

[Example 1]
<Production of polyolefin porous film>
A polyolefin porous film 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 having a weight average molecular weight of 1000 (FNP-0115, manufactured by Nippon Seiro Co., Ltd.) are mixed. To obtain mixed polyethylene. With respect to 100 parts by weight of the obtained mixed polyethylene, 0.4 parts by weight of an antioxidant (Irg1010, manufactured by Ciba Specialty Chemicals Co., Ltd.), and an antioxidant (P168, manufactured by Ciba Specialty Chemicals Co., Ltd.) 0. 1 part by weight and 1.3 parts by weight of sodium stearate were added, and further, calcium carbonate having an average particle diameter of 0.1 μm (manufactured by Maruo Calcium Co., Ltd.) was added so that the ratio to the total volume was 38% by volume. It was This composition as a powder was mixed with a Henschel mixer and then melt-kneaded with a biaxial kneader to obtain a polyethylene resin composition. Then, this polyethylene resin composition was rolled with a pair of rolls whose surface temperature was set to 150 ° C. to prepare a sheet. This sheet was immersed in an aqueous hydrochloric acid solution (containing 4 mol / L of hydrochloric acid and 0.5% by weight of a nonionic surfactant) to dissolve and remove calcium carbonate. Then, the said sheet | seat was stretched 6 times at 105 degreeC, and the polyolefin porous film was produced. The porosity of the polyolefin porous film was 53%, the basis weight was 7 g / m ² , and the film thickness was 16 μm. This polyolefin porous film was used as a polyolefin porous film 1.

<Production of porous layer>
(Production of coating liquid)
As the inorganic filler, hexagonal plate-shaped zinc oxide having an oxygen atomic mass percentage of 20% (manufactured by Sakai Chemical Industry Co., Ltd., trade name: XZ-100F) was used.

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

The inorganic filler, vinylidene fluoride-hexafluoropropylene copolymer, and solvent (N-methyl-2-pyrrolidinone manufactured by Kanto Chemical Co., Inc.) were mixed in the following proportions. That is, while mixing 10 parts by weight of vinylidene fluoride-hexafluoropropylene copolymer with 90 parts by weight of inorganic filler, the solid content (inorganic filler and vinylidene fluoride-hexafluoropropylene copolymer) in the resulting mixed liquid is The solvent was mixed so that the concentration would be 37% by weight. The resulting mixed liquid was stirred and mixed with a thin film swivel type high speed mixer (Filmiku (registered trademark) manufactured by PRIMIX Corporation) to obtain a uniform coating liquid.
(Production of porous layer)
The obtained coating liquid was applied to one side of the polyolefin porous film 1 by a doctor blade method at a coating shear rate of 3.9 (1 / s), and was applied to one side of the polyolefin porous film 1. A coating film was formed. Then, the coating film was dried at 65 ° C. for 20 minutes to form the porous layer 1 on one surface of the polyolefin porous film 1. Thereby, a laminate 1 of the polyolefin porous film 1 and the porous layer 1 was obtained. The basis weight of the porous layer 1 was 7 g / m ² and the thickness was 4 μm. Using the obtained laminate 1, the maximum values of the aspect ratio and the peak intensity ratio of the projected image of the inorganic filler on the surface of the porous layer were measured. The results are shown in Table 1.

<Preparation of non-aqueous electrolyte secondary battery>
(Preparation of positive electrode plate)
A positive electrode plate manufactured by applying LiNi _0.5 Mn _0.3 Co _0.2 O ₂ / conductive agent / PVDF (weight ratio 92/5/3) to an aluminum foil was used. The positive electrode plate is cut out of an aluminum foil so that the size of the part where the positive electrode active material layer is formed is 45 mm × 30 mm, and the part where the width of 13 mm is not formed and the positive electrode active material layer is not formed remains on the outer periphery. To obtain a positive electrode plate 1. 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 plate)
A negative electrode plate manufactured by applying graphite / styrene-1,3-butadiene copolymer / sodium carboxymethyl cellulose (weight ratio 98/1/1) to a copper foil was used. A copper foil was applied to the negative electrode plate so that the size of the portion on which the negative electrode active material layer was formed was 50 mm × 35 mm, and the portion on the outer periphery of which the width was 13 mm and the negative electrode active material layer was not formed remained. It was cut out to obtain a negative electrode plate 1. The negative electrode active material layer had a thickness of 49 μm and a density of 1.40 g / cm ³ .

(Assembly of non-aqueous electrolyte secondary battery)
A non-aqueous electrolyte secondary battery was manufactured by the following method using the positive electrode plate, the negative electrode plate, and the laminated body 1.

  By stacking (arranging) the positive electrode plate 1, the laminated body 1 in which the porous layers are opposed to the positive electrode side, and the negative electrode plate 1 in this order in a laminated pouch, a member 1 for non-aqueous electrolyte secondary battery Got At this time, the positive electrode plate 1 and the negative electrode plate 1 are so arranged that the entire main surface of the positive electrode active material layer of the positive electrode plate 1 is included in the range of the main surface of the negative electrode active material layer of the negative electrode plate 1 (overlaps with the main surface). Was placed.

Then, the non-aqueous electrolyte secondary battery member 1 was placed in a pre-made bag formed by laminating an aluminum layer and a heat-sealing layer, and 0.25 mL of the non-aqueous electrolyte solution was placed in this bag. It was The non-aqueous electrolyte solution was prepared by dissolving LiPF _{6 in a} mixed solvent prepared by mixing ethylene carbonate, ethyl methyl carbonate and diethyl carbonate in a volume ratio of 3: 5: 2 so that the concentration of LiPF ₆ was 1 mol / L. Prepared. Then, the inside of the bag was depressurized and the bag was heat-sealed to manufacture the non-aqueous electrolyte secondary battery 1.

[Example 2]
<Production of laminate of polyolefin porous film and porous layer>
As a raw material of the inorganic filler, Zirkondioxid / Calciumoxid (ZrO ₂ / CaO = 95/5) fused (manufactured by Ceram) having an oxygen atomic mass percentage of 26% was used. The raw material of this inorganic filler was subjected to vibration mill pulverization for 4 hours using a 3.3 L alumina pot and a 15 mmφ alumina ball to pulverize the Zirkondioxid / Calciumoxid (ZrO ₂ / CaO = 95/5) fused (Ceram). I got a thing. The ground product was used as an inorganic filler. Here _{Zirkondioxid / Calciumoxid (ZrO 2 / CaO} = 95/5) fused is, ZrO 295 parts by weight of CaO 5 parts by weight to form a solid solution formed by melting.

The inorganic filler used for the preparation of the porous layer was changed to the crushed product of Zirkondioxid / Calciumoxid (ZrO ₂ / CaO = 95/5) fused mentioned above, and the coating was applied at a coating shear rate of 7.9 (1 / s). A laminate 2 of a polyolefin porous film 1 and a porous layer 2 was obtained in the same manner as in Example 1 except that the porous layer 2 was formed by working. Using the obtained laminate 2, the maximum values of the aspect ratio and the peak intensity ratio of the projected image of the inorganic filler on the surface of the porous layer were measured. The results are shown in Table 1.

<Preparation of non-aqueous electrolyte secondary battery>
A non-aqueous electrolyte secondary battery 2 was produced in the same manner as in Example 1 except that the laminate 2 was used instead of the laminate 1.

[Example 3]
<Production of laminate of polyolefin porous film and porous layer>
Α-alumina (Sumitomo Chemical Co., Ltd., trade name: AKP3000) and hexagonal plate-shaped zinc oxide (Sakai Chemical Industry Co., Ltd., trade name: XZ-1000F) were used as raw materials for the inorganic filler, and α-alumina was used as the inorganic filler. A mixture of 99 parts by weight and 1 part by weight of hexagonal plate-shaped zinc oxide in a mortar (oxygen atom mass percentage 47%) was used, and 90 parts by weight of an inorganic filler, vinylidene fluoride-hexafluoropropylene. 10 parts by weight of the copolymer is mixed, and a solvent is mixed so that the concentration of the solid content (inorganic filler and vinylidene fluoride-hexafluoropropylene copolymer) in the resulting mixed solution is 40% by weight, and coating is performed. Polyol was prepared in the same manner as in Example 1 except that a liquid was prepared and coated at a coating shear rate of 39.4 (1 / s) to form the porous layer 3. A laminate 3 of the fin porous film 1 and the porous layer 3 was obtained. Using the obtained laminate 3, the maximum values of the aspect ratio and the peak intensity ratio of the projected image of the inorganic filler on the surface of the porous layer were measured. The results are shown in Table 1.

<Preparation of non-aqueous electrolyte secondary battery>
A non-aqueous electrolyte secondary battery 3 was produced in the same manner as in Example 1 except that the laminate 3 was used instead of the laminate 1.

[Example 4]
<Production of laminate of polyolefin porous film and porous layer>
Spherical alumina (Sumitomo Chemical Co., Ltd., trade name AA03) and synthetic mica (Wako Pure Chemical Industries, Ltd., trade name: non-swelling synthetic mica) are used as raw materials for the inorganic filler, and spherical alumina is used as the inorganic filler. A mixture of 50 parts by weight and 50 parts by weight of synthetic mica in a mortar (oxygen atom mass percentage 45%) was used, and vinylidene fluoride-hexafluoropropylene copolymer with respect to 90 parts by weight of inorganic filler. Is mixed with 10 parts by weight, and a solvent is mixed so that the concentration of the solid content (inorganic filler and vinylidene fluoride-hexafluoropropylene copolymer) in the resulting mixed solution is 30% by weight to prepare a coating solution. Then, the polyolefin porous film was prepared in the same manner as in Example 1 except that the porous layer 4 was formed by coating at a coating shear rate of 7.9 (1 / s). To obtain a 1 and laminate 4 of the porous layer 4. Using the obtained laminate 4, the maximum values of the aspect ratio and the peak intensity ratio of the projected image of the inorganic filler on the surface of the porous layer were measured. The results are shown in Table 1.

<Preparation of non-aqueous electrolyte secondary battery>
A non-aqueous electrolyte secondary battery 4 was produced in the same manner as in Example 1 except that the laminate 4 was used instead of the laminate 1.

[Example 5]
<Production of laminate of polyolefin porous film and porous layer>
As the inorganic filler, wollastonite (Hayashi Kasei Co., Ltd., trade name: Wollastonite VM-8N) having an oxygen atomic mass percentage of 41% was used, and 90 parts by weight of the inorganic filler was vinylidene fluoride-. 10 parts by weight of the hexafluoropropylene copolymer was mixed, and a solvent was mixed so that the concentration of the solid content (inorganic filler and vinylidene fluoride-hexafluoropropylene copolymer) in the obtained mixed liquid was 40% by weight. And a polyolefin porous film 1 were prepared in the same manner as in Example 1 except that the coating liquid was prepared by applying the coating liquid at a coating shear rate of 7.9 (1 / s) to form the porous layer 5. A laminate 5 with the porous layer 5 was obtained. Using the obtained laminate 5, the maximum values of the aspect ratio and the peak intensity ratio of the projected image of the inorganic filler on the surface of the porous layer were measured. The results are shown in Table 1.

<Preparation of non-aqueous electrolyte secondary battery>
A non-aqueous electrolyte secondary battery 5 was produced in the same manner as in Example 1 except that the laminate 5 was used instead of the laminate 1.

[Example 6]
<Production of laminate of polyolefin porous film and porous layer>
The same layered product 3 as in Example 3 was used.

<Preparation of non-aqueous electrolyte secondary battery>
(Preparation of positive electrode plate)
The surface of the same positive electrode plate as the positive electrode plate 1 on the positive electrode active material layer side was polished three times using a polishing cloth sheet (model number TYPE PE A GRIT No100) manufactured by Nagatsuka Industry Co., Ltd. to obtain a positive electrode plate 2. The positive electrode active material layer of the positive electrode plate 2 had a thickness of 38 μm and a porosity of 40%.

(Preparation of negative electrode plate)
The negative electrode plate 1 was used as the negative electrode plate.

(Assembly of non-aqueous electrolyte secondary battery)
A non-aqueous electrolyte secondary battery 6 was produced in the same manner as in Example 1 except that the laminate 3 was used instead of the laminate 1 and the positive electrode plate 2 was used.

[Example 7]
<Production of laminate of polyolefin porous film and porous layer>
The same layered product 3 as in Example 3 was used.

<Preparation of non-aqueous electrolyte secondary battery>
(Preparation of positive electrode plate)
The surface of the same positive electrode plate as the positive electrode plate 1 on the positive electrode active material layer side was polished 5 times using a polishing cloth sheet (model number TYPE AA GRIT No100) manufactured by Nagatsuka Industry Co., Ltd. to obtain a positive electrode plate 3. The positive electrode active material layer of the positive electrode plate 3 had a thickness of 38 μm and a porosity of 40%.

(Preparation of negative electrode plate)
The negative electrode plate 1 was used as the negative electrode plate.

(Assembly of non-aqueous electrolyte secondary battery)
A non-aqueous electrolyte secondary battery 7 was produced in the same manner as in Example 1 except that the laminate 3 was used instead of the laminate 1 and the positive electrode plate 3 was used.

[Example 8]
<Production of laminate of polyolefin porous film and porous layer>
The same layered product 3 as in Example 3 was used.

<Preparation of non-aqueous electrolyte secondary battery>
(Preparation of positive electrode plate)
The positive electrode plate 1 was used as the positive electrode plate.

(Preparation of negative electrode plate)
The surface of the same negative electrode plate as the negative electrode plate 1 on the negative electrode active material layer side was polished three times using a polishing cloth sheet (model number TYPE AA GRIT No100) manufactured by Nagatsuka Industry Co., Ltd. to obtain a negative electrode plate 2. The negative electrode active material layer of the negative electrode plate 2 had a thickness of 38 μm and a porosity of 31%.

(Assembly of non-aqueous electrolyte secondary battery)
A non-aqueous electrolyte secondary battery 8 was produced in the same manner as in Example 1 except that the laminate 3 was used instead of the laminate 1 and the negative electrode plate 2 was used.

[Example 9]
<Production of laminate of polyolefin porous film and porous layer>
The same layered product 3 as in Example 3 was used.

<Preparation of non-aqueous electrolyte secondary battery>
(Preparation of positive electrode plate)
The positive electrode plate 1 was used as the positive electrode plate.

(Preparation of negative electrode plate)
The surface of the same negative electrode plate as the negative electrode plate 1 on the negative electrode active material layer side was polished seven times using a polishing cloth sheet (model number TYPE AA GRIT No100) manufactured by Nagatsuka Industry Co., Ltd. to obtain a negative electrode plate 3. The thickness of the negative electrode active material layer of the negative electrode plate 3 was 38 μm, and the porosity was 31%.

(Assembly of non-aqueous electrolyte secondary battery)
A non-aqueous electrolyte secondary battery 9 was produced in the same manner as in Example 1 except that the laminate 3 was used instead of the laminate 1 and the negative electrode plate 3 was used.

[Comparative Example 1]
<Production of laminate of polyolefin porous film and porous layer>
Borax (manufactured by Wako Pure Chemical Industries, Ltd.) having an oxygen atomic mass percentage of 71% was used as the inorganic filler, and 10 parts by weight of a vinylidene fluoride-hexafluoropropylene copolymer was mixed with 90 parts by weight of the inorganic filler. At the same time, the solvent was mixed so that the concentration of the solid content (inorganic filler and vinylidene fluoride-hexafluoropropylene copolymer) in the obtained mixed liquid was 40% by weight to prepare a coating liquid, and a coating shear rate. A laminate 6 of the polyolefin porous film 1 and the porous layer 6 was obtained in the same manner as in Example 1 except that the porous layer 6 was formed by coating at 7.9 (1 / s). Using the obtained layered product 6, the maximum values of the aspect ratio and the peak intensity ratio of the projected image of the inorganic filler on the surface of the porous layer were measured. The results are shown in Table 1.

<Preparation of non-aqueous electrolyte secondary battery>
A non-aqueous electrolyte secondary battery 10 was produced in the same manner as in Example 1 except that the laminate 6 was used instead of the laminate 1.

[Comparative example 2]
<Production of laminate of polyolefin porous film and porous layer>
As an inorganic filler, hexagonal plate-shaped zinc oxide having a mass percentage of oxygen atoms of 20% (manufactured by Sakai Chemical Industry Co., Ltd., trade name: XZ-100F) was used, and a coating liquid was applied to one side of the polyolefin porous film. Lamination of the polyolefin porous film 1 and the porous layer 7 in the same manner as in Example 1 except that the porous layer 7 was formed by applying a coating shear rate of 0.4 (1 / s) by the blade method. I got body 7. Using the obtained laminate 7, the maximum values of the aspect ratio and the peak intensity ratio of the projected image of the inorganic filler on the surface of the porous layer were measured. The results are shown in Table 1.

<Preparation of non-aqueous electrolyte secondary battery>
A non-aqueous electrolyte secondary battery 11 was produced in the same manner as in Example 1 except that the laminate 7 was used instead of the laminate 1.

[Comparative Example 3]
<Production of laminate of polyolefin porous film and porous layer>
As the inorganic filler, attapulgite (Hayashi Kasei Co., Ltd., trade name: ATTAGEL # 50) having an oxygen atomic mass percentage of 48% was used, and vinylidene fluoride-hexafluoropropylene co-weight with respect to 90 parts by weight of the inorganic filler. The coating liquid was prepared by mixing 10 parts by weight of the coalescence and mixing a solvent so that the concentration of the solid content (inorganic filler and vinylidene fluoride-hexafluoropropylene copolymer) in the resulting mixed liquid is 17% by weight. The same procedure as in Example 1 was performed except that the porous layer 8 was formed by applying a coating shear rate of 1.3 (1 / s) to one surface of the polyolefin porous film by the doctor blade method. A laminate 8 of the porous film 1 and the porous layer 8 was obtained. Using the obtained laminate 8, the maximum values of the aspect ratio and the peak intensity ratio of the projected image of the inorganic filler on the surface of the porous layer were measured. The results are shown in Table 1.

<Preparation of non-aqueous electrolyte secondary battery>
A non-aqueous electrolyte secondary battery 12 was produced in the same manner as in Example 1 except that the laminate 8 was used instead of the laminate 1.

[Comparative Example 4]
<Production of laminate of polyolefin porous film and porous layer>
As the inorganic filler, mica (manufactured by Wako Pure Chemical Industries, trade name: non-swelling mica) having an oxygen atom mass percentage of 44% was used, and vinylidene fluoride-hexafluoropropylene copolymer weight was used for 90 parts by weight of the inorganic filler. The coating liquid was prepared by mixing 10 parts by weight of the coalescence and mixing a solvent so that the concentration of the solid content (inorganic filler and vinylidene fluoride-hexafluoropropylene copolymer) in the resulting mixed liquid is 20% by weight. In the same manner as in Example 1, except that the porous layer 9 was formed by applying a coating shear rate of 0.4 (1 / s) to one side of the polyolefin porous film by the doctor blade method. A laminate 9 of the high quality film 1 and the porous layer 9 was obtained. Using the obtained laminate 9, the maximum values of the aspect ratio and the peak intensity ratio of the projected image of the inorganic filler on the surface of the porous layer were measured. The results are shown in Table 1.

<Preparation of non-aqueous electrolyte secondary battery>
A non-aqueous electrolyte secondary battery 13 was produced in the same manner as in Example 1 except that the laminate 9 was used instead of the laminate 1.

[Comparative Example 5]
<Production of laminate of polyolefin porous film and porous layer>
The same layered product 3 as in Example 3 was used.

<Preparation of non-aqueous electrolyte secondary battery>
(Preparation of positive electrode plate)
The surface of the same positive electrode plate as the positive electrode plate 1 on the positive electrode active material layer side was polished 10 times using a polishing cloth sheet (model number TYPE AA GRIT No100) manufactured by Nagatsuka Kogyo Co., Ltd. to obtain a positive electrode plate 4. The positive electrode active material layer of the positive electrode plate 4 had a thickness of 38 μm and a porosity of 40%.

(Preparation of negative electrode plate)
The negative electrode plate 1 was used as the negative electrode plate.

(Assembly of non-aqueous electrolyte secondary battery)
A non-aqueous electrolyte secondary battery 14 was produced in the same manner as in Example 1 except that the laminate 3 was used instead of the laminate 1 and the positive electrode plate 4 was used.

[Comparative Example 6]
<Production of laminate of polyolefin porous film and porous layer>
The same layered product 3 as in Example 3 was used.

<Preparation of non-aqueous electrolyte secondary battery>
(Preparation of positive electrode plate)
The positive electrode plate 1 was used as the positive electrode plate.

(Preparation of negative electrode plate)
The surface of the same negative electrode plate as the negative electrode plate 1 on the negative electrode active material layer side was polished 10 times using a polishing cloth sheet (model number TYPE PE A GRIT No100) manufactured by Nagatsuka Industry Co., Ltd. to obtain a negative electrode plate 4. The thickness of the negative electrode active material layer of the negative electrode plate 4 was 38 μm, and the porosity was 31%.

(Assembly of non-aqueous electrolyte secondary battery)
A non-aqueous electrolyte secondary battery 15 was produced in the same manner as in Example 1 except that the laminate 3 was used instead of the laminate 1 and the negative electrode plate 4 was used.

[Evaluation results of non-aqueous electrolyte secondary batteries 1 to 15]
Table 1 shows the results of measurement of the charge capacities of the non-aqueous electrolyte secondary batteries 1 to 15 obtained in Examples and Comparative Examples after high rate discharge.

[Conclusion]
From the description in Table 1, 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 the maximum value of the peak intensity ratio (I _(hkl) / I _(abc) ) is , 1.5 to 300, the capacitance per 900 mm ² of the measurement area of the positive electrode plate is 1 nF or more and 1000 nF or less, and the capacitance per 900 mm ² of the measurement area of the negative electrode plate is 4 nF or more, The non-aqueous electrolyte secondary batteries obtained in Examples 1 to 9 which are 8500 nF or less are compared with the non-aqueous electrolyte secondary batteries obtained in Comparative Examples 1 to 6 which do not satisfy any of the conditions. It was also shown to exhibit excellent charge capacity after high rate discharge.

  The non-aqueous electrolyte secondary battery according to the present invention has excellent charge capacity after high rate discharge. Therefore, the non-aqueous electrolyte secondary battery according to the present invention can be widely used in the field of manufacturing non-aqueous electrolyte secondary batteries.

Claims (5)

A porous layer containing an inorganic filler and a resin,
A positive electrode plate having a capacitance per measurement area 900 mm ^{2 of} 1 nF or more and 1000 nF or less;
A negative electrode plate having a capacitance per measurement area 900 mm ^{2 of 4} nF or more and 8500 nF or less,
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,
I _(hkl) and I _(abc) , which are peak intensities of arbitrary diffraction planes (hkl) and (abc) orthogonal to each other, measured by a wide-angle X-ray diffraction method, of the porous layer are represented by the following formula (1). The filling,
The non-aqueous electrolyte secondary battery in which 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)   2. The porous layer according to claim 1, wherein the porous layer contains a resin selected from the group consisting of polyolefins, (meth) acrylate resins, fluorine-containing resins, polyamide resins, polyester resins and water-soluble polymers. Non-aqueous electrolyte secondary battery.   The non-aqueous electrolyte secondary battery according to claim 2, wherein the polyamide resin is an aramid resin.   The non-aqueous electrolyte secondary battery according to claim 1, wherein the porous layer is laminated on one side or both sides of a polyolefin porous film.   The non-aqueous electrolyte secondary battery according to claim 1, wherein the positive electrode plate contains a transition metal oxide and the negative electrode plate contains graphite.

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