JP7330231B2 - Laminated separator for non-aqueous electrolyte secondary battery - Google Patents

Description

TECHNICAL FIELD The present invention relates to a laminated separator for a non-aqueous electrolyte secondary battery.

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

Non-aqueous electrolyte secondary batteries are required to be chargeable under high voltage conditions. Therefore, the laminated separator for a non-aqueous electrolyte secondary battery is required to be not degraded even after the charging, and to be excellent in heat resistance and deterioration resistance.

Patent Document 1 discloses that a wholly aromatic polyamide in which the aromatic ring at the end of the polymer chain does not have an amino group and the aromatic ring has an electron-withdrawing substituent is applied with a high voltage. It is also stated that there is little discoloration.

Japanese Patent Application Laid-Open No. 2003-40999 (published on February 13, 2003)

Patent Document 1 shows that when constant-current and constant-voltage charging is performed under the condition that the state of 4.5 V is maintained for one day, the discoloration of the laminated separator used as a member of the flat plate battery is small. .

However, in the case of trickle charging, for example, charging is often performed under high voltage for a considerably longer time than one day. It is not shown at all that it is excellent in deterioration resistance.

Accordingly, one aspect of the present invention provides a laminated separator for a non-aqueous electrolyte secondary battery that does not deteriorate even after being charged for a long time under high voltage conditions and has excellent heat resistance and deterioration resistance. The purpose is to realize

The present invention includes the inventions shown in [1] to [12] below.

[1] A laminated separator for a non-aqueous electrolyte secondary battery comprising a polyolefin porous film and a porous layer,
The porous layer contains a binder resin and a filler,
Laminated separator for non-aqueous electrolyte secondary battery, having an opening area of 7.0 mm ² or less when subjected to the following heat resistance test:
Step 1. A positive electrode containing a positive electrode active material capable of doping and dedoping lithium ions, the laminated separator for a non-aqueous electrolyte secondary battery, and a negative electrode containing a negative electrode active material capable of being doped and dedoped with lithium ions, in this order. and impregnating a laminate in which the porous layer and the positive electrode active material layer provided in the positive electrode are in contact with each other are impregnated with a non-aqueous electrolyte to prepare a test battery;
Step 2. After constant current charging to 4.6 V (vs Li/Li ⁺ ) at 25 ° C. and 1 ^C of the test battery, 168 impose a time trickle charge;
Step 3. Taking out the laminated separator for the non-aqueous electrolyte secondary battery from the test battery that has undergone step 2;
Step 4. A metal core having a diameter of 2.2 mm at 450° C. is penetrated from the porous layer side of the laminated separator for a non-aqueous electrolyte secondary battery, which was in contact with the positive electrode active material layer.
(Here, the positive electrode is a positive electrode in which lithium nickel cobalt manganese oxide (LiNi _0.5 Co _0.2 Mn _0.3 O ₂ ) is laminated on an aluminum foil,
The negative electrode is a negative electrode in which natural graphite is laminated on a copper foil,
The above non-aqueous electrolyte is prepared by dissolving LiPF ₆ to 1 mol/L in a mixed solvent of ethylene carbonate, ethylmethyl carbonate, and diethyl carbonate at a volume ratio of 3:5:2. It is a non-aqueous electrolyte. ).

[2] The content of the filler in the porous layer is 40% by weight or more and 70% by weight or less when the weight of the porous layer is 100% by weight. Laminated separator for secondary batteries.

[3] The filler is a metal oxide filler,
The binder resin contains one or more selected from the group consisting of (meth)acrylate resins, fluorine-containing resins, polyamide resins, polyimide resins, polyamideimide resins, polyester resins and water-soluble polymers. , [1] or [2] for a non-aqueous electrolyte secondary battery laminated separator.

[4] The laminated separator for a non-aqueous electrolyte secondary battery according to any one of [1] to [3], wherein the porous layer contains an aramid resin.

[5] The aramid resin contained in the porous layer satisfies the relationship of (X2/X1) × 100 ≥ 80 (%), for a non-aqueous electrolyte secondary battery according to [4] Laminated separator. (In the formula, X1 is (a) in the range of 1490 to 1530 ^cm when the IR intensity on the surface of the porous layer is measured by the ATR-IR method before starting trickle charging in step 2 above. maximum peak intensity; or (b) after trickle charging in step 2, among the surfaces of the porous layer, ATR the IR intensity of the surface that was not in contact with the positive electrode active material layer of the positive electrode during the trickle charging. - is the maximum peak intensity in the range of 1490-1530 cm ^-1 as measured by the IR method,
X2 is 1490 when the IR intensity of the surface of the porous layer that was in contact with the positive electrode active material layer of the positive electrode during the trickle charge was measured by the ATR-IR method after the trickle charge in step 2. is the maximum peak intensity in the range of ∼1530 cm ⁻¹ ).

[6] The aramid resin is
(i) having an electron-withdrawing group in the aromatic ring in the main chain,
(ii) at least one end of the molecule is an amino group;
(iii) The laminated separator for a non-aqueous electrolyte secondary battery according to [4] or [5], wherein more than 90% of the bonds connecting the aromatic rings contained in the main chain are amide bonds.

[7] The laminated separator for a non-aqueous electrolyte secondary battery according to [6], wherein the aramid resin does not have an ether bond as a bond connecting the aromatic rings contained in the main chain.

[8] The aramid resin is
(iv) 40% or more of the aromatic diamine-derived units have an electron-withdrawing group,
(v) The laminated separator for a non-aqueous electrolyte secondary battery according to [6] or [7], wherein 20% or less of the acid chloride-derived units have an electron-withdrawing group.

[9] The non-aqueous electrolyte secondary battery according to any one of [6] to [8], wherein the electron-withdrawing group is one or more selected from the group consisting of halogen, cyano group and nitro group. Laminated separator for

[10] The laminated separator for a nonaqueous electrolyte secondary battery according to any one of [4] to [8], wherein the aramid resin has an intrinsic viscosity of 1.4 to 4.0 dL/g.

[11] a positive electrode;
A laminated separator for a non-aqueous electrolyte secondary battery according to any one of [1] to [10];
a negative electrode;
is laminated in this order, a member for a nonaqueous electrolyte secondary battery.

[12] The laminated separator for a non-aqueous electrolyte secondary battery according to any one of [1] to [10], or the member for a non-aqueous electrolyte secondary battery according to [11], Non-aqueous electrolyte secondary battery.

ADVANTAGE OF THE INVENTION According to one aspect of the present invention, a laminated separator for a non-aqueous electrolyte secondary battery that does not deteriorate even after being charged for a long time under high voltage conditions and has excellent heat resistance and deterioration resistance can be realized.

It is a figure which shows an example of the procedure of step 4 of the heat resistance test in Embodiment 1 of this invention. FIG. 4 is an explanatory diagram of a method for interpreting the results of a heat resistance test in Embodiment 1 of the present invention.

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

[Embodiment 1: Laminated separator for non-aqueous electrolyte secondary battery]
A laminated separator for a non-aqueous electrolyte secondary battery according to one embodiment of the present invention comprises a polyolefin porous film (hereinafter also simply referred to as "porous film") and a porous layer. A laminated separator for a secondary battery,
The porous layer contains a binder resin and a filler,
A laminated separator for a non-aqueous electrolyte secondary battery having an opening area of 7.0 mm ² or less when subjected to the following heat resistance test.
Step 1. A positive electrode containing a positive electrode active material capable of doping and dedoping lithium ions, the laminated separator for a non-aqueous electrolyte secondary battery, and a negative electrode containing a negative electrode active material capable of being doped and dedoped with lithium ions, in this order. step 2. impregnate the laminate in which the porous layer and the positive electrode active material layer of the positive electrode are in contact with each other are impregnated with a non-aqueous electrolyte to prepare a test battery; After constant current charging to ^4.6 V (vs Li/Li ⁺ ) at 25 ° C. and 1 C of the test battery, 168 impose a time trickle charge;
Step 3. Taking out the laminated separator for the non-aqueous electrolyte secondary battery from the test battery that has undergone step 2;
Step 4. A metal core having a diameter of 2.2 mm at 450° C. is penetrated from the porous layer side of the laminated separator for a non-aqueous electrolyte secondary battery, which was in contact with the positive electrode active material layer.
(Here, the positive electrode is a positive electrode in which lithium nickel cobalt manganese oxide (LiNi _0.5 Co _0.2 Mn _0.3 O ₂ ) is laminated on an aluminum foil,
The negative electrode is a negative electrode in which natural graphite is laminated on a copper foil,
The above non-aqueous electrolyte is prepared by dissolving LiPF ₆ to 1 mol/L in a mixed solvent of ethylene carbonate, ethylmethyl carbonate, and diethyl carbonate at a volume ratio of 3:5:2. It is a non-aqueous electrolyte. ).

(1. Heat resistance test)
A laminated separator for a non-aqueous electrolyte secondary battery according to an embodiment of the present invention has an opening area of 7.0 mm ² or less when subjected to the heat resistance test. In order to satisfy the above configuration, the laminated separator for a non-aqueous electrolyte secondary battery does not deteriorate even after being charged for a long time under high voltage conditions, as shown in the examples described later. In addition, it has the effect of being excellent in heat resistance and deterioration resistance.

(1-1. Step 1)
The positive electrode constituting the test battery used in step 1 contains a positive electrode active material capable of doping and dedoping lithium ions, and the positive electrode active material is lithium nickel cobalt manganese oxide (LiNi _0.5 Co _0.2 Mn _0.3 O ₂ ). Lithium nickel cobalt manganese oxide is preferred because of its high average discharge potential.

The positive electrode active material is preferably laminated on a current collector together with, for example, a binder, a conductive aid, and the like to form a positive electrode active material layer. The current collector is an aluminum foil.

Examples of the method for producing the positive electrode include a method of pressure-molding a positive electrode active material, a conductive aid, and a binder on a positive electrode current collector; A method of making an adhesive into a paste, applying the paste to the positive electrode current collector, drying it, and applying pressure to fix it to the positive electrode current collector; and the like.

The negative electrode constituting the test battery used in step 1 includes a negative electrode active material capable of doping and dedoping lithium ions, and the negative electrode active material is natural graphite.

The negative electrode active material is preferably laminated on a current collector together with, for example, a binder, a conductive aid, and the like to form a negative electrode active material layer. The current collector is copper foil.

The above natural graphite has a negative electrode potential that hardly changes during charging from an uncharged state to a fully charged state (good potential flatness), a low average discharge potential, and a high capacity retention rate when repeatedly charged and discharged (cycle It is preferably used for reasons such as good characteristics.

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

In step 1, the positive electrode, the laminated separator for a non-aqueous electrolyte secondary battery, and the negative electrode are laminated in this order such that the porous layer and the positive electrode active material layer of the positive electrode are in contact with each other. to obtain a laminate. “The porous layer and the positive electrode active material layer are in contact with each other” means that the surface of the positive electrode active material layer of the positive electrode and the surface of the porous layer that face each other overlap at least partially.

When the test battery is subjected to trickle charge, a high voltage is applied for a long time to the portion of the porous layer that is in contact with the positive electrode active material layer. Therefore, the above portion is a portion where deterioration of the laminated separator for a non-aqueous electrolyte secondary battery due to high voltage can be easily determined. Therefore, lamination is performed so that the porous layer and the positive electrode active material layer are in contact with each other.

At this time, it is preferable that the surface of the positive electrode active material layer and the surface of the porous layer facing each other are in contact with the surface of the porous layer over the entire surface of the positive electrode active material layer. Further, the surface of the porous layer has a larger surface area than the surface of the positive electrode active material layer, and part of the surface of the porous layer is not in contact with the surface of the positive electrode active material layer. preferable. The surface of the porous layer that does not overlap the surface of the positive electrode active material layer may be in contact with the surface of the current collector.

A portion of the surface of the porous layer that is not in contact with the surface of the positive electrode active material layer does not deteriorate even when trickle charging is applied. Therefore, it can be said that the portion is in the same state as the porous layer before trickle charging is started. Therefore, this portion can be regarded as the surface of the porous layer before trickle charging is started.

A test battery can be produced by impregnating the laminate with a non-aqueous electrolyte. The impregnation method is not particularly limited. For example, there is a method in which the laminate is placed in a container that serves as a housing for the test battery, the container is then filled with a non-aqueous electrolyte, and then the container is sealed while reducing the pressure.

The above non-aqueous electrolyte is prepared by dissolving LiPF ₆ to 1 mol/L in a mixed solvent of ethylene carbonate, ethylmethyl carbonate, and diethyl carbonate at a volume ratio of 3:5:2. It is a non-aqueous electrolyte. The non-aqueous electrolyte is preferable because it has a wide operating temperature range, does not easily deteriorate even when charged and discharged at a high current rate, and does not easily deteriorate even when used for a long time.

(1-2. Step 2)
In step 2, the test battery obtained in step 1 is subjected to constant current charging at 25 ° C. and 1 C current to 4.6 V (vs Li/Li ⁺ ), then 25 ° C. and 4.6 V (vs Li / Li ⁺ ) is a step of imposing trickle charge for 168 hours.

A high voltage is applied to the porous layer for a long time by imposing the trickle charge under the above conditions. At this time, if the porous layer has poor heat resistance, deterioration such as discoloration appears in the porous layer, and large cracks occur in step 4 described later. Therefore, it can be said that step 2 is a step that deliberately promotes deterioration of the porous layer in order to ascertain the heat resistance of the porous layer.

(1-3. Step 3)
Step 3 is a step of taking out the laminated separator for the non-aqueous electrolyte secondary battery from the test battery that has undergone step 2 . The method for taking out the laminated separator for the non-aqueous electrolyte secondary battery is not particularly limited. good.

(1-4. Step 4)
In step 4, a metal core with a diameter of 2.2 mm at 450 ° C. is taken out from the test battery, and the porous layer in contact with the positive electrode active material layer of the laminated separator for the non-aqueous electrolyte secondary battery. This is the process of penetrating from the side. As described above, a high voltage is applied to the portion of the porous layer that contacts the positive electrode active material layer for a long period of time. , the metal core is penetrated from the porous layer side in contact with the positive electrode active material layer.

FIG. 1 is a diagram showing an example of the procedure of step 4. As shown in FIG. The left side of FIG. 1 is a diagram showing the appearance of a solder testing apparatus used to carry out step 4. FIG. As a solder testing device, for example, RX-802AS manufactured by Taiyo Electric Industry Co., Ltd. can be used. Also, a to d shown in FIG. 1 indicate that step 4 progresses from a to d.

The laminated separator for a non-aqueous electrolyte secondary battery is placed with the porous layer side up on a stand indicated by a dotted frame in the left side of FIG. 1 . Next, a metal core having a temperature of 450° C. and a diameter of 2.2 mm placed above the table is brought close to the porous layer, and the tip is brought into contact with the surface of the porous layer as shown in FIG. 1a.

At this time, the metal core holds the tip portion in a position in contact with the surface of the porous layer without applying a downward load. As the metal core, for example, a soldering iron as shown in FIG. 1 can be used. The 450° C. is the temperature of the entire metal core, and the diameter of 2.2 mm is the diameter of the tip of the metal core.

FIG. 1a shows the state immediately after the tip is brought into contact with the surface of the porous layer. By holding the tip portion at the above position, heat from the metal core propagates to the laminated separator for a non-aqueous electrolyte secondary battery, and as shown in FIG. A substantially concentric region (hereinafter referred to as “region 1”) is generated. This is a region produced by melting the polyolefin (polyethylene) that constitutes the polyolefin porous film.

FIG. 1b shows the state when time has passed from FIG. 1a. Due to the thermal history, the area 1 is larger than the area a in FIG. 1, and a new circular area is also formed outside the tip.

FIG. 1c shows the state when time has passed from FIG. 1b. A black opening is formed around the tip portion, and the tip portion penetrates the laminated separator for the non-aqueous electrolyte secondary battery. Outside the opening, a distinct circular region (hereinafter referred to as "region 2") occurs adjacent to the opening. This is a region generated by melting the polyolefin (polyethylene) constituting the polyolefin porous film to the inside of the binder resin contained in the porous layer. Furthermore, on the outer side, there is a region where the polyolefin is melted as shown in FIG. 1a.

FIG. 1d is a diagram showing a state immediately after step 4 is completed after separating the metal core from the laminated separator for a non-aqueous electrolyte secondary battery. The time required from a to d in FIG. 1 is 10 seconds. In d, a protruding pattern can be seen from the aperture towards the circle adjacent to the outside of the aperture. This is a crack generated in the laminated separator for the non-aqueous electrolyte secondary battery.

FIG. 2 is an explanatory diagram of how to interpret the results of the heat resistance test. 1 shown in "result analysis" in FIG. 2 is the region 1, which is a translucent region in which the polyethylene constituting the base material is melted. Reference numeral 2 denotes the region 2, which is a transparent region generated by melting the polyethylene to the inside of the binder resin contained in the porous layer. 3 is a brownish-white area that is believed to be caused by oxidative degradation of the polyethylene. 4 is a region where the porous layer is curled. 5 is a crack and 6 is an opening. "MD" is an abbreviation for Machine Direction.

When all cracks stopped in region 2, it can be judged as a good result, as indicated by "(good)" in FIG. If there are cracks beyond region 2 and cracks that stop at region 2, it can be determined that the result is rather poor. Also, if all the cracks cross region 2 and reach region 1, it can be determined as a bad result.

In the laminated separator for a non-aqueous electrolyte secondary battery according to one embodiment of the present invention, the area of the opening is 7.0 mm ² or less when subjected to the above heat resistance test. That is, the area of the opening measured after step 4 is 7.0 mm ² or less.

The configuration "the area of the opening is 7.0 mm ² or less" corresponds to the result shown in "(Good)" in FIG. With the above configuration, it can be said that deterioration of the laminated separator for non-aqueous electrolyte secondary batteries is sufficiently suppressed. Therefore, at this time, it can be said that the laminated separator for a non-aqueous electrolyte secondary battery is excellent in heat resistance and deterioration resistance under high voltage conditions.

The area of the opening is more preferably 7.0 mm ² or less, more preferably 5.0 mm ² or less, from the viewpoint of providing a laminated separator for a non-aqueous electrolyte secondary battery with more excellent heat resistance. Especially preferred. The smaller the area, the better, but in practice, the lower limit is about 1.0 mm ² . The area can be measured by an optical microscope image analysis method.

The area of the opening can be controlled to 7.0 mm ² or less by coating the polyolefin porous film with a heat-resistant aramid resin, for example.

(2. Porous layer)
The porous layer is laminated on at least one surface of the porous film to constitute a laminated separator for a non-aqueous electrolyte secondary battery according to one embodiment of the present invention. The porous layer is preferably an insulating porous layer.

The porous layer has a large number of pores inside, and has a structure in which these pores are connected, and is a layer that allows gas or liquid to pass from one surface to the other surface. . The porous layer contains a binder resin and a filler.

The filler is preferably a heat-resistant filler. The heat-resistant filler may be an inorganic filler or an organic filler, and preferably contains an inorganic filler. The heat-resistant filler means a filler having a melting point of 150° C. or higher.

From the viewpoint of improving the heat resistance of the porous layer, the content of the filler in the porous layer is 40% by weight or more and 70% by weight or less when the weight of the porous layer is 100% by weight. preferable. More preferably, the content is 50% by weight or more and less than 70% by weight.

Examples of the filler include calcium carbonate, talc, clay, kaolin, silica, hydrotalcite, diatomaceous earth, magnesium carbonate, barium carbonate, calcium sulfate, magnesium sulfate, barium sulfate, aluminum hydroxide, boehmite, magnesium hydroxide, oxide One or more inorganic fillers selected from inorganic substances such as calcium, magnesium oxide, titanium oxide, titanium nitride, alumina (aluminum oxide), aluminum nitride, mica, zeolite, and glass can be used.

Among them, the filler is preferably a metal oxide filler from the viewpoint of improving the heat resistance of the porous layer. A "metal oxide filler" is an inorganic filler composed of a metal oxide. Examples of metal oxide fillers include inorganic fillers made of aluminum oxide and/or magnesium oxide.

Organic substances constituting the organic filler include homopolymers or copolymers of two or more monomers such as styrene, vinyl ketone, acrylonitrile, methyl methacrylate, ethyl methacrylate, glycidyl methacrylate, glycidyl acrylate, and methyl acrylate; Fluorine-containing resins such as polytetrafluoroethylene, tetrafluoroethylene/hexafluoropropylene copolymer, tetrafluoroethylene/ethylene copolymer, polyvinylidene fluoride; melamine resin; urea resin; polyethylene; polypropylene; polyacrylic acid , polymethacrylic acid; and resorcinol resin.

The average particle diameter (D50) of the filler is preferably 0.001 μm or more and 10 μm or less, more preferably 0.01 μm or more and 8 μm or less, and further preferably 0.05 μm or more and 5 μm or less. preferable. The average particle size of the filler is a value measured using MICROTRAC (MODEL: MT-3300EXII) manufactured by Nikkiso Co., Ltd.

The shape of the filler varies depending on the manufacturing method of the organic or inorganic raw material, the dispersion conditions of the filler when preparing the coating liquid for forming the porous layer, and the like. Any shape may be used, such as a shape such as a shape, or an irregular shape that does not have a specific shape.

The binder resin is preferably insoluble in the electrolyte of the battery and electrochemically stable within the range of use of the battery. From such a viewpoint, the binder resin is one or more selected from the group consisting of (meth)acrylate resins, fluorine-containing resins, polyamide resins, polyimide resins, polyamideimide resins, polyester resins and water-soluble polymers. preferably contains

The porous layer preferably contains an aramid resin. In other words, the polyamide-based resin is preferably an aramid resin from the viewpoint of improving the safety against internal short circuit of the battery.

Aramid resins include aromatic polyamides and wholly aromatic polyamides. As the aromatic polyamide, at least one resin selected from the group consisting of para-(p)-aromatic polyamide and meta-(m)-aromatic polyamide is preferred.

Specific examples of aramid resins include poly(paraphenylene terephthalamide), poly(metaphenylene isophthalamide), poly(metaphenylene terephthalamide), poly(parabenzamide), poly(methabenzamide), poly(4, 4'-benzanilide terephthalamide), poly(paraphenylene-4,4'-biphenylenedicarboxylic acid amide), poly(metaphenylene-4,4'-biphenylenedicarboxylic acid amide), poly(paraphenylene-2,6- naphthalenedicarboxylic acid amide), poly(metaphenylene-2,6-naphthalenedicarboxylic acid amide), poly(2-chloroparaphenylene terephthalamide), paraphenylene terephthalamide/metaphenylene terephthalamide copolymer, paraphenylene terephthalamide/ At least one selected from 2,6-dichloroparaphenylene terephthalamide copolymers, metaphenylene terephthalamide/2,6-dichloroparaphenylene terephthalamide copolymers, and the like.

Among these, poly(paraphenylene terephthalamide), poly(metaphenylene terephthalamide) and paraphenylene terephthalamide/metaphenylene terephthalamide copolymer are preferred.

The aramid resin contained in the porous layer preferably satisfies the relationship of (X2/X1)×100≧80(%).
(In the formula, X1 is (a) in the range of 1490 to 1530 ^cm when the IR intensity on the surface of the porous layer is measured by the ATR-IR method before starting trickle charging in step 2 above. maximum peak intensity; or (b) after trickle charging in step 2, among the surfaces of the porous layer, ATR the IR intensity of the surface that was not in contact with the positive electrode active material layer of the positive electrode during the trickle charging. - is the maximum peak intensity in the range of 1490-1530 cm ^-1 as measured by the IR method,
X2 is 1490 when the IR intensity of the surface of the porous layer that was in contact with the positive electrode active material layer of the positive electrode during the trickle charge was measured by the ATR-IR method after the trickle charge in step 2. is the maximum peak intensity in the range of ~1530 cm ^-1 )
A peak derived from an amide group appears in the above range of 1490 to 1530 cm ^-1 . The fact that the aramid resin satisfies the above relationship means that the residual rate of amide groups in the aramid resin contained in the porous layer is high even after the trickle test. That is, even after a high voltage is applied for a long period of time, the retention of the structure of the aramid resin is high. Therefore, it can be said that the laminated separator for a non-aqueous electrolyte secondary battery according to an embodiment of the present invention that satisfies the above relationship has high heat resistance and deterioration resistance.

As described in (1-1. Step 1) above, the portion of the surface of the porous layer that is not in contact with the surface of the positive electrode active material layer does not deteriorate even when trickle charging is applied. This portion can be regarded as the surface of the porous layer before trickle charging is started. Therefore, since the maximum peak intensity of (a) of X1 and the maximum peak intensity of (b) are substantially the same, X1 may be any of (a) and (b) above. do not have.

The surface of the porous layer that is in contact with the positive electrode active material layer during trickle charging undergoes a step that promotes deterioration of the porous layer, as described in (1-2. Step 2) above. . Therefore, when the aramid resin satisfies the relationship of (X2/X1)×100≧80(%), the laminated separator for a non-aqueous electrolyte secondary battery according to one embodiment of the present invention performs the above steps. It can be said that it exhibited good resistance to deterioration in spite of the aging.

The intensity of the maximum peak can be obtained by subjecting the laminated separator for a non-aqueous electrolyte secondary battery to an apparatus capable of performing an ATR-IR method and measuring the IR intensity of the surface of the porous layer. . As the apparatus, for example, Cary600 FTIR manufactured by Agilent can be used.

Methods for controlling the aramid resin to satisfy the above relationship include controlling the molecular structure of the aramid resin so that the aramid resin satisfies the following (i) to (iii).

In the laminated separator for a non-aqueous electrolyte secondary battery according to one embodiment of the present invention, the aramid resin has (i) an electron-withdrawing group in the aromatic ring in the main chain, and (ii) the molecule is an amino group, and (iii) more than 90% of the bonds connecting the aromatic rings contained in the main chain are preferably amide bonds.

When the binder resin contained in the porous layer is an aramid resin, it tends to be more difficult to maintain heat resistance than the other binder resins described above, such as discoloration when used in a high voltage environment. There is However, the present inventor can improve the oxidation resistance of the aramid resin by satisfying the above (i) to (iii), and as a result, the non-aqueous electrolyte secondary battery using the aramid resin It has been found that the heat resistance of the laminated separator for use can be greatly improved.

The main chain of the aramid resin is, for example, the structure shown in parentheses in the following chemical formula. However, in the chemical formula below, the bond connecting the aromatic rings contained in the main chain is only an amide bond, but this is not necessarily the case. Just do it. Other above-mentioned bonds include an ether bond, a sulfonyl bond, and the like.

The proportion of amide bonds in the above bonds is more preferably 95% or more, most preferably 100%. Moreover, the aramid resin preferably does not have an ether bond as a bond connecting the aromatic rings contained in the main chain.

Examples of the electron withdrawing groups include halogen, -CN, -NO ₂ , - ⁺ NH ₃ , -CF ₃ , -CCl ₃ , -CHO, -COCH ₃ , -CO ₂ C ₂ H ₅ , -CO ₂ H, -SO ₂ CH ₃ , -SO ₃ H, -OCH ₃ and the like can be mentioned. The electron-withdrawing group may be of one type, or may be of two or more types.

Above all, the electron-withdrawing group is preferably one or more selected from the group consisting of halogen, cyano group and nitro group, which are commonly available from the viewpoint of price.

Both ends or at least one end of the molecule of the aramid resin are amino groups. That is, at least one of the terminal aromatic rings of the molecule has an amino group.

An aramid resin satisfying the above (i) to (iii) can be produced by reacting an aromatic diamine and an acid chloride in a solvent.

In the aramid resin, (iv) 40% or more of the units derived from the aromatic diamine have an electron-withdrawing group, and (v) 20% or less of the units derived from the acid chloride have an electron-withdrawing group. preferably.

The "aromatic diamine-derived unit" is a structural unit represented by -(NH-Ar-NH)-. The structural units also include NH ₂ —Ar—NH— and —NH—Ar—NH ₂ , which are structural units having amino groups at their ends. "40% or more of the units have an electron-withdrawing group" means that 40% or more of the aromatic rings (Ar) in the above-mentioned units present in the molecule of the aramid resin have an electron-withdrawing group. .

The proportion of the aromatic diamine-derived units having an electron-withdrawing group is more preferably 50% or more, more preferably 75% or more, and most preferably 100%.

The above-mentioned "acid chloride-derived unit" is a structural unit represented by -(CO-Ar-CO)-. "20% or less of the units have an electron-withdrawing group" means that 20% or less of the aromatic rings (Ar) in the above-mentioned units present in the molecule of the aramid resin have an electron-withdrawing group. means The proportion of the acid chloride-derived units having an electron-withdrawing group is preferably as low as possible, more preferably 10% or less, and most preferably 0%.

Since the aramid resin satisfies the above (iv) and (v), the area of the opening tends to be smaller when subjected to the heat resistance test described above, which is preferable.

The aramid resin satisfying the above (iv) and (v) in addition to the above (i) to (iii) is the raw material aromatic diamine and acid chloride, the ratio of the aromatic diamine and acid chloride having an electron-withdrawing group can be produced by controlling

In the laminated separator for a non-aqueous electrolyte secondary battery according to one embodiment of the present invention, the intrinsic viscosity of the aramid resin is 1.4 to 4.0 dL / g from the viewpoint of improving the heat resistance of the porous layer. Preferably. The intrinsic viscosity can be confirmed, for example, by the method described in International Publication 2016/002785. That is, 0.5 g of aramid resin can be dissolved in 100 mL of concentrated sulfuric acid and measured using a capillary viscometer. Examples of the method for controlling the intrinsic viscosity include a method for controlling the charging ratio of the monomers during polymerization of the aramid resin.

(3. Production of laminated separator for non-aqueous electrolyte secondary battery)
A laminated separator for a non-aqueous electrolyte secondary battery according to one embodiment of the present invention comprises a step of laminating a coating liquid containing the binder resin and filler described above on one or both sides of a polyolefin porous film, and the coating and removing the solvent in the liquid.

The coating liquid can be obtained by mixing a binder resin, a filler, and a solvent. From the viewpoint of improving the heat resistance of the porous layer, the content of the filler is preferably 40 to 70% by weight, preferably 50 to 70%, when the weight of the binder resin and the filler is 100% by weight. % by weight is more preferred.

Examples of the solvent include nonpolar solvents described in International Publication 2016/002785. Specific examples include N-methylpyrrolidone, N,N-dimethylacetamide, N,N-dimethylformamide and the like. Only one type of these solvents may be used, or two or more types may be used in combination.

The step of laminating the coating liquid can be performed by laminating the coating liquid on one or both sides of the porous film by, for example, a gravure coater method, a dip coater method, a bar coater method, or a die coater method. can.

The step of removing the solvent in the coating liquid can be performed by drying and removing the solvent. As a result, a porous layer is formed on one side or both sides of the porous film (substrate) to obtain a laminated separator for a non-aqueous electrolyte secondary battery.

Removal of the solvent can also be carried out, for example, by the following method.

(1) After the composition is applied to one or both sides of a substrate, the substrate is immersed in a deposition solvent that is a poor solvent for the binder resin, thereby depositing the binder and forming a porous layer. After forming, it is dried and the solvent is removed.

(2) After coating the above composition on one or both sides of a substrate, a binder resin is precipitated using a low boiling point solvent to form a porous layer, followed by drying to remove the solvent.

Examples of the precipitation solvent that can be used include water, ethyl alcohol, isopropyl alcohol, and acetone.

The porous film is mainly composed of polyolefin and has a large number of interconnected pores therein, allowing gas and liquid to pass from one surface to the other surface. The porous film serves as a base material of the laminate having the porous layer formed thereon. The porous layer has a large number of pores inside, and has a structure in which these pores are connected, and is a layer that allows gas or liquid to pass from one surface to the other surface. .

The proportion of polyolefin in the porous film is 50% by volume or more, more preferably 90% by volume or more, and even more preferably 95% by volume or more, of the entire porous film.

Further, the polyolefin more preferably contains a high molecular weight component having a weight average molecular weight of 5×10 ⁵ to 15×10 ⁶ . In particular, it is more preferable that the polyolefin contains a high-molecular-weight component having a weight-average molecular weight of 1,000,000 or more, because the strength of the laminate is improved.

Examples of the polyolefin include homopolymers and copolymers obtained by polymerizing monomers such as ethylene, propylene, 1-butene, 4-methyl-1-pentene and 1-hexene. Examples of the homopolymer include polyethylene, polypropylene, and polybutene. Further, examples of the copolymer include an ethylene/propylene copolymer.

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

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

The weight per unit area of the porous film can be appropriately determined in consideration of strength, film thickness, weight and handleability. However, in order to increase the weight energy density and volume energy density of the non-aqueous electrolyte secondary battery, the weight per unit area is preferably 4 to 15 g/m ² , and 4 to 12 g/m2. m ² is more preferred, and 5 to 10 g/m ² is even more preferred.

The air permeability of the porous film is preferably 30 to 500 sec/100 mL, more preferably 50 to 300 sec/100 mL in Gurley value. Sufficient ion permeability can be obtained by the porous film having the above air permeability.

The air permeability of the laminated separator for a non-aqueous electrolyte secondary battery according to one embodiment of the present invention is preferably 30 to 1000 sec/100 mL, more preferably 50 to 800 sec/100 mL in Gurley value. The laminated separator for a non-aqueous electrolyte secondary battery can obtain sufficient ion permeability in the non-aqueous electrolyte secondary battery by having the above air permeability.

The porosity of the porous film is preferably 20 to 80% by volume, such as 30 to 75%, so as to increase the amount of electrolyte retained and to reliably prevent the flow of excessive current at a lower temperature. % by volume is more preferred. In addition, the pore diameter of the pores of the porous film is 0.30 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 preferred, 0.14 µm or less is more preferred, and 0.10 µm or less is even more preferred.

The method for producing the porous film is not particularly limited. For example, a method including the steps shown below can be mentioned.

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

[Embodiment 2: Non-aqueous electrolyte secondary battery member, non-aqueous electrolyte secondary battery]
A non-aqueous electrolyte secondary battery member according to an embodiment of the present invention comprises a positive electrode, a laminated separator for a non-aqueous electrolyte secondary battery according to an embodiment of the present invention, and a negative electrode laminated in this order. there is

Since the non-aqueous electrolyte secondary battery member includes the laminated separator for a non-aqueous electrolyte secondary battery, the non-aqueous electrolyte secondary battery incorporating the non-aqueous electrolyte secondary battery member can be operated at a high voltage. When used in an environment, the heat resistance and deterioration resistance of the non-aqueous electrolyte secondary battery can be improved.

The positive electrode, the laminated separator for the non-aqueous electrolyte secondary battery, and the negative electrode are already described in the first embodiment. The member for a non-aqueous electrolyte secondary battery can be produced by laminating a positive electrode, a laminated separator for a non-aqueous electrolyte secondary battery according to one embodiment of the present invention, and a negative electrode in this order. .

<Positive electrode>
As the positive electrode, for example, a positive electrode sheet having a structure in which an active material layer containing a positive electrode active material and a binder is formed on a current collector can be used. The active material layer may further contain a conductive agent.

Examples of the positive electrode active material include materials capable of doping and dedoping lithium ions.

Examples of such materials include lithium composite oxides containing at least one transition metal such as V, Ti, Cr, Mn, Fe, Co, Ni, and Cu. Lithium composite oxides include, for example, a lithium composite oxide having a layered structure, a lithium composite oxide having a spinel structure, and a solid solution lithium-containing transition metal oxide composed of a lithium composite oxide having both a layered structure and a spinel structure. things are mentioned. Lithium-cobalt composite oxides and lithium-nickel composite oxides are also included. Furthermore, some of the transition metal atoms that are the main constituents of these lithium composite oxides are Na, K, B, F, Al, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, Mg, Ca , Ga, Zr, Si, Nb, Mo, Sn and W, and the like.

Lithium composite oxides in which some of the transition metal atoms that are the main constituent of the lithium composite oxide are replaced with other elements include, for example, lithium cobalt composite oxides having a layered structure represented by the following formula (2), Lithium nickel composite oxide represented by formula (3), lithium manganese composite oxide having a spinel structure represented by formula (4) below, transition metal oxide containing solid solution lithium represented by formula (5) below, etc. is mentioned.

Li[Li _x (Co _1-a M ¹ _a ) _1-x ]O ₂ (2)
(In formula (2), M ¹ is Na, K, B, F, Al, Ti, V, Cr, Mn, Fe, Ni, Cu, Zn, Mg, Ga, Zr, Si, Nb, Mo, Sn and At least one metal selected from the group consisting of W, and satisfies −0.1≦x≦0.30 and 0≦a≦0.5.)
Li[Li _y (Ni _1-b M ² _b ) _1-y ]O ₂ (3)
(In formula (3), ^M2 is Na, K, B, F, Al, Ti, V, Cr, Mn, Fe, Co, Cu, Zn, Mg, Ga, Zr, Si, Nb, Mo, Sn and At least one metal selected from the group consisting of W, satisfying -0.1 ≤ y ≤ 0.30 and 0 ≤ b ≤ 0.5.)
Li _z Mn _2-c M ³ _c O ₄ (4)
(In formula (4), ^M3 is Na, K, B, F, Al, Ti, V, Cr, Fe, Co, Ni, Cu, Zn, Mg, Ga, Zr, Si, Nb, Mo, Sn and At least one metal selected from the group consisting of W, satisfying 0.9≦z and 0≦c≦1.5.)
_{Li1 +} ^wM4dM5eO2 ₍ ⁵ ₎
(In formula (5), ^M4 and ^M5 are at least one metal selected from the group consisting of Al, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, Mg and Ca, satisfy 0<w≦1/3, 0≦d≦2/3, 0≦e≦2/3, and w+d+e=1.)
Specific examples of the lithium composite oxides represented by the above formulas (2) to (5) include LiCoO ₂ , LiNiO ₂ , LiMnO ₂ , LiNi _0.8 Co _0.2 O ₂ , LiNi _0.5 Mn _{0.5. 5O2 , LiNi0.85Co0.10Al0.05O2 , LiNi0.8Co0.15Al0.05O2 , LiNi0.5Co0.2Mn0.3O2 , LiNi _ _ _ _ _ 0.6Co0.2Mn0.2O2 , LiNi0.33Co0.33Mn0.33O2 , LiMn2O4 , LiMn1.5Ni0.5O4 , LiMn1.5Fe _ _ _ _ _ 0.5O4 , LiCoMnO4 , Li1.21Ni0.20Mn0.59O2 , Li1.22Ni0.20Mn0.58O2 , Li1.22Ni0.15Co0 . _ _ _ _ 10Mn0.53O2 , Li1.07Ni0.35Co0.08Mn0.50O2 , Li1.07Ni0.36Co0.08Mn0.49O2 and the like . _ _ _ _}

Lithium composite oxides other than the lithium composite oxides represented by the above formulas (2) to (5) can also be preferably used as the positive electrode active material. Examples of such lithium composite oxides include LiNiVO ₄ , LiV ₃ O ₆ , Li _1.2 Fe _0.4 Mn _0.4 O ₂ and the like.

Materials other than lithium composite oxides that can be preferably used as positive electrode active materials include, for example, phosphates having an olivine type structure, and phosphoric acid having an olivine type structure represented by the following formula (6): salt.

Li _v (M ⁶ _f M ⁷ _g M ⁸ _h M ⁹ _i ) _j PO ₄ (6)
(In formula (6), ^M6 is Mn, Co, or Ni, ^M7 is Ti, V, Cr, Mn, Fe, Co, Ni, Zr, Nb, or Mo, and ^M8 is , a transition metal or main group element arbitrarily excluding elements of groups VIA and VIIA, M ⁹ is a transition metal or main group element arbitrarily excluding elements of groups VIA and VIIA, 1.2 ≥ a ≧0.9, 1≧b≧0.6, 0.4≧c≧0, 0.2≧d≧0, 0.2≧e≧0, 1.2≧f≧0.9.) .

The positive electrode active material preferably has a coating layer on the surface of the lithium metal composite oxide particles that constitute the positive electrode active material. Examples of materials constituting the coating layer include metal composite oxides, metal salts, boron-containing compounds, nitrogen-containing compounds, silicon-containing compounds, sulfur-containing compounds, etc. Among these, metal composite oxides are preferably used. be done.

As the metal composite oxide, an oxide having lithium ion conductivity is preferably used. Such metal composite oxides include, for example, Li and at least one selected from the group consisting of Nb, Ge, Si, P, Al, W, Ta, Ti, S, Zr, Zn, V and B. Metal composite oxides with elements can be mentioned. When the positive electrode active material has a coating layer, the coating layer suppresses a side reaction at the interface between the positive electrode active material and the electrolyte under high voltage, and the resulting secondary battery can have a long life. In addition, formation of a high-resistance layer at the interface between the positive electrode active material and the electrolyte can be suppressed, and the output of the resulting secondary battery can be increased.

<Non-aqueous electrolyte>
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 lithium _salts include _LiClO4 , _LiPF6 , _LiAsF6 , _LiSbF6 , _LiBF4 , _{LiSO3F , LiCF3SO3 ,} LiN( _SO2CF3 ) ₂ , LiN( _SO2C2F5 ) ₂ , LiN ( _{SO2CF3 )} ( _COCF3 ), Li _{( C4F9SO3} ), _LiC ( _{SO2CF3 ) 3} , _Li2B10Cl10 , LiBOB (where BOB is _bis (oxalato) _borate ), lower aliphatic carboxylic acid lithium salt, _LiAlCl4 , and the like. These may be used alone or as a mixture of two or more. Lithium salts include LiPF ₆ , LiAsF ₆ , LiSbF ₆ , LiBF ₄ , LiSO ₃ F, LiCF ₃ SO ₃ , LiN(SO ₂ CF ₃ ) ₂ and LiC(SO ₂ CF ₃ ) ₃ containing fluorine. It is preferable to use one containing at least one selected from the group.

Examples of organic solvents include propylene carbonate, ethylene carbonate, dimethyl carbonate, diethyl carbonate, ethylmethyl carbonate, 4-trifluoromethyl-1,3-dioxolan-2-one, 1,2-di(methoxycarbonyloxy)ethane, and the like. carbonates; ethers such as 1,2-dimethoxyethane, 1,3-dimethoxypropane, pentafluoropropylmethyl ether, 2,2,3,3-tetrafluoropropyldifluoromethyl ether, tetrahydrofuran, and 2-methyltetrahydrofuran; esters such as methyl formate, methyl acetate and γ-butyrolactone; nitriles such as acetonitrile and butyronitrile; amides such as N,N-dimethylformamide and N,N-dimethylacetamide; carbamates such as 3-methyl-2-oxazolidone Groups; sulfur-containing compounds such as sulfolane, dimethyl sulfoxide, 1,3-propanesultone, or those obtained by further introducing a fluoro group into these organic solvents (one or more of the hydrogen atoms of the organic solvent are substituted with fluorine atoms things) can be used.

As the organic solvent, it is preferable to use a mixture of two or more of these. Among them, a mixed solvent containing carbonates is preferable, and a mixed solvent of a cyclic carbonate and a non-cyclic carbonate and a mixed solvent of a cyclic carbonate and an ether are more preferable. A mixed solvent containing ethylene carbonate, dimethyl carbonate and ethyl methyl carbonate is preferable as the mixed solvent of the cyclic carbonate and the non-cyclic carbonate. A non-aqueous electrolyte using such a mixed solvent has a wide operating temperature range, does not easily deteriorate even when used at a high voltage, and does not easily deteriorate even when used for a long time. It has the advantage of being resistant to decomposition even when a graphite material such as artificial graphite is used.

In addition, as the non-aqueous electrolyte, a non-aqueous electrolyte containing a fluorine-containing lithium salt such as _LiPF6 and an organic solvent having a fluorine substituent is used because the safety of the obtained non-aqueous electrolyte secondary battery is increased. is preferred. A mixed solvent containing ethers having fluorine substituents such as pentafluoropropylmethyl ether and 2,2,3,3-tetrafluoropropyldifluoromethyl ether and dimethyl carbonate has a capacity retention rate even when discharged at a high voltage. It is more preferable because it is expensive.

<Negative Electrode>
As the negative electrode, for example, a negative electrode sheet having a structure in which an active material layer containing a negative electrode active material and a binder is formed on a current collector can be used. The active material layer may further contain a conductive agent.

<Negative electrode active material>
Examples of the negative electrode active material include carbon materials, chalcogen compounds (oxides, sulfides, etc.), nitrides, metals or alloys, which are capable of doping and dedoping lithium ions at a potential lower than that of the positive electrode. is mentioned.

Examples of carbon materials that can be used as the negative electrode active material include graphite such as natural graphite and artificial graphite, cokes, carbon black, pyrolytic carbons, carbon fibers, and baked organic polymer compounds.

Examples of oxides that can be used as the negative electrode active material include oxides of silicon represented by the formula SiO _x (where x _is a positive real number) such as SiO ₂ and SiO _; (where x is a positive real number); V ₂ O ₅ , VO _{2 ,} etc., represented by the formula V _x O _y (where x and y are positive real numbers); Oxides; _Fe3O4 , _Fe2O3 , _FeO , etc. Iron oxides represented by the formula _FexOy (where x and y are positive real numbers); _SnO2 , SnO _{, etc.} Formula _SnOx ( where x is a positive real number); tin oxides represented by the general formula WO _x (where x is a positive real number), such as WO ₃ and WO ₂ ; Li ₄ Ti composite metal oxides containing lithium and titanium or vanadium, such as ₅ O ₁₂ and LiVO ₂ ;

Examples of sulfides that can be used as negative electrode active materials include titanium sulfides represented by the formula Ti _{x Sy} (where x and y are positive real numbers) such as Ti ₂ S ₃ , TiS ₂ and TiS; Vanadium sulfide represented by _the formula VS _x ( _where x is a positive real _{number) such as V 3 S 4 ,} VS ₂ , _VS ; , x and y are positive real numbers); sulfides of molybdenum represented by _the formula _MoxSy (where x and y _are positive real numbers) such as _Mo2S3 , _MoS2, etc. tin sulfide represented by the formula SnS _x (where x is a positive real number) such as SnS ₂ and SnS; tungsten represented by the formula WS _x (where x is a positive real number) such as WS ₂ sulfides of antimony represented by the formula _SbxSy (where x and y are positive real numbers) _{, such} as _Sb2S3 ; _{formulas SexSy} , such as _Se5S3 , _SeS2 , _SeS (here, x and y are positive real numbers).

Nitrides that can be used as negative electrode active materials include, for example, Li ₃ N and Li _3-x A _x N (where A is either one or both of Ni and Co and 0<x<3 .) and other lithium-containing nitrides.

These carbon materials, oxides, sulfides and nitrides may be used alone or in combination of two or more. Moreover, these carbon materials, oxides, sulfides and nitrides may be either crystalline or amorphous. These carbon materials, oxides, sulfides, and nitrides are mainly used as electrodes by being carried on a negative electrode current collector.

Metals that can be used as the negative electrode active material include lithium metal, silicon metal, and tin metal.

Composite materials containing Si or Sn as a first constituent element and additionally containing second and third constituent elements can also be mentioned. The second constituent element is, for example, at least one of cobalt, iron, magnesium, titanium, vanadium, chromium, manganese, nickel, copper, zinc, gallium and zirconium. The third constituent element is, for example, at least one of boron, carbon, aluminum and phosphorus.

In particular, since a high battery capacity and excellent battery characteristics can be obtained, as the metal material, silicon or tin alone (which may contain trace amounts of impurities), SiO _v (0 < v ≤ 2), SnO _w (0 ≤w≤2), Si--Co--C composite materials, Si--Ni--C composite materials, Sn--Co--C composite materials, and Sn--Ni--C composite materials are preferred.

A non-aqueous electrolyte secondary battery according to one embodiment of the present invention includes a laminated separator for a non-aqueous electrolyte secondary battery according to one embodiment of the present invention, or a non-aqueous electrolyte solution according to one embodiment of the present invention. A secondary battery member is provided.

As a method for manufacturing the non-aqueous electrolyte secondary battery, for example, after forming the non-aqueous electrolyte secondary battery member by the above method, the non-aqueous electrolyte secondary battery is placed in a container that will be the housing of the non-aqueous electrolyte secondary battery. A method of putting the member for an aqueous electrolyte secondary battery into the container, then filling the inside of the container with the non-aqueous electrolyte, and sealing the container while reducing the pressure can be mentioned.

The present invention is not limited to the above-described embodiments, but can be modified in various ways within the scope of the claims, and can be obtained by appropriately combining technical means disclosed in different embodiments. is also included in the technical scope of the present invention.

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

<Test method>
(1. Heat resistance test)
(1-1. Positive electrode of test battery)
The positive electrode contains 92 parts by weight of LiNi _0.5 Co _0.2 Mn _0.3 O ₂ as a positive electrode active material, 5 parts by weight of a conductive material, and 3 parts by weight of a binder, and has a thickness of 58 μm and a density of 2.5 g. / cm ³ electrode hoop was purchased from Hachiyama Co., Ltd. and used.

(1-2. Regarding negative electrode of test battery)
For the negative electrode, an electrode hoop containing 98 parts by weight of natural graphite, 1 part by weight of binder, and 1 part by weight of carboxymethyl cellulose, having a thickness of 48 μm and a density of 1.5 g/cm ³ was purchased from Hachiyama Co., Ltd. and used. .

(1-3. Preparation of test battery)
In the laminated pouch, the porous layer of the laminated separator for non-aqueous electrolyte secondary batteries prepared in Examples and Comparative Examples described later and the positive electrode active material layer of the positive electrode are in contact, and the non-aqueous electrolysis The positive electrode, the laminated separator for the non-aqueous electrolyte secondary battery, and the negative electrode are laminated in this order such that the polyethylene porous film of the laminated separator for the liquid secondary battery and the negative electrode active material layer of the negative electrode are in contact with each other ( Arrangement) to obtain a member for a non-aqueous electrolyte secondary battery.

At this time, the entire surface of the positive electrode active material layer of the positive electrode is in contact with the surface of the porous layer, and the portion of the surface of the porous layer that is not in contact with the surface of the positive electrode active material layer is the positive electrode active material layer of the positive electrode. The positive electrode and the negative electrode were arranged so as to be in contact with the portion where the substance layer was not formed. As a result, the portion of the surface of the porous layer that did not contact the surface of the positive electrode active material layer was arranged to surround the positive electrode active material layer in a frame shape.

Subsequently, the non-aqueous electrolyte secondary battery member was placed in a bag formed by laminating an aluminum layer and a heat seal layer, and 230 μL of a non-aqueous electrolyte was added to the bag. The above non-aqueous electrolyte was prepared by dissolving LiPF ₆ to 1 mol/L in a mixed solvent obtained by mixing ethylene carbonate, ethyl methyl carbonate, and diethyl carbonate at a volume ratio of 3:5:2. .

A non-aqueous electrolyte secondary battery was produced by heat-sealing the bag while decompressing the inside of the bag.

(1-4. Trickle charge)
Non-aqueous electrolyte secondary batteries prepared using the laminated separators for non-aqueous electrolyte secondary batteries prepared in Examples and Comparative Examples were tested at 25 ° C. and 1 C using a charge-discharge test device manufactured by Toyo System Co., Ltd. After constant current charging to 4.5 V (that is, 4.6 V (vs Li/Li ⁺ )) at a current of 25 ° C., 4.5 V (that is, 4.6 V (vs Li/Li ⁺ )), A trickle charge was imposed for 168 hours.

After completion of trickle charging, the test battery was disassembled, the laminated separator for non-aqueous electrolyte secondary battery was taken out, and the color of the surface of the porous layer before trickle charging and the positive electrode active material layer after trickle charging The color of the surface of the porous layer that was in contact was visually observed and compared.

(1-5. Metal core penetration test)
As described in step 4 of Embodiment 1, using the solder test apparatus shown in FIG. , from the side of the porous layer that was in contact with the positive electrode active material layer. The time from the contact of the tip of the metal core to the surface of the porous layer to the separation of the tip from the surface was 10 seconds. After completion of the metal core penetration test, the area of the opening of the laminated separator for non-aqueous electrolyte secondary battery was determined. The area of the opening was measured using a Digital Microscope VHX-5000 manufactured by KEYENCE CORPORATION using attached image analysis software.

(2. Measurement of IR Intensity)
The IR intensity of the porous layer surface of the laminated separator for non-aqueous electrolyte secondary batteries prepared in Examples and Comparative Examples was measured by the ATR-IR method, and the maximum peak intensity (X1) in the range of 1490 to 1530 cm ^-1 . asked for As a device, Cary 600 manufactured by Agilent
FTIR was used.

After the completion of the trickle charge, the IR intensity of the surface of the porous layer that was in contact with the positive electrode active material layer was measured for the laminated separator for the non-aqueous electrolyte secondary battery taken out from the disassembled test battery. It was measured by the ATR-IR method and the maximum peak intensity (X2) in the range of 1490 to 1530 cm ^-1 was obtained. Furthermore, the value of (X2/X1)×100 was calculated.

[Example 1]
(1. Preparation of coating liquid)
A 500 mL separable flask with a stirrer, thermometer, nitrogen inlet tube and powder addition port was used. After sufficiently drying the flask by flowing nitrogen, 409.2 g of N-methyl-2-pyrrolidone (hereinafter abbreviated as NMP) as an organic solvent is placed in the flask, and calcium chloride ( (200° C. for 2 hours, vacuum dried for use) was added, and the temperature was raised to 100° C. to completely dissolve calcium chloride. After that, the temperature of the obtained solution was returned to room temperature (25° C.), and the water content of the solution was adjusted to 500 ppm.
Then, 18.11 g of 2-chloro-1,4-phenylenediamine as an aromatic diamine was added and dissolved completely. 25.19 g of terephthaloyl dichloride (hereinafter abbreviated as TPC) as an acid chloride was added while stirring the solution while maintaining the temperature at 20±2°C.

In the above method, the aromatic ring in the main chain has a chloro group as an electron-withdrawing group, has amino groups at both ends of the molecule, and has 100 bonds connecting the aromatic rings in the main chain. % is an amide bond, 100% of the aromatic diamine-derived units have an electron-withdrawing group, the acid chloride-derived units do not have an electron-withdrawing group, and the intrinsic viscosity is 2.28 dL / g Aramid resin 1 was obtained.

100 parts by weight of alumina powder having an average particle size of 0.02 μm and 100 parts by weight of alumina powder having an average particle size of 0.7 μm were added to the obtained solution of aramid resin 1 . Subsequently, NMP was added to the above solution to dilute it, and a coating liquid 1 having a total concentration of aramid resin 1 and filler of 6% by weight was prepared. At this time, since the content of the filler in the porous layer is 66% by weight, when the weight of the aramid resin 1 and the filler is 100% by weight, the aramid is added so that the content of the filler is 66% by weight. Resin 1, a filler and a solvent were mixed to obtain Coating Liquid 1.

(2. Preparation of laminated separator for non-aqueous electrolyte secondary battery)
Coating liquid 1 is applied to one side of a porous film substrate obtained by stretching a polyolefin resin composition made of ultra-high molecular weight polyethylene using a gravure coater, dried, and contained in coating liquid 1. Aramid resin 1 was deposited. As a result, a laminated separator 1 for a non-aqueous electrolyte secondary battery was obtained in which a porous layer was laminated on the substrate surface.

(3. Heat resistance test, etc.)
The laminated separator 1 for a non-aqueous electrolyte secondary battery was subjected to the test described in <Test Method> above. Tables 1 and 2 show the results.

[Example 2]
(1. Preparation of coating liquid)
In the same manner as in Example 1, except that the amount of 2-chloro-1,4-phenylenediamine added as the aromatic diamine was 7.46 g and the amount of TPC added as the acid chloride was 10.30 g. , to obtain aramid resin 2. Aramid resin 2 has a chloro group as an electron-withdrawing group in the aromatic ring in the main chain, amino groups at both ends of the molecule, and 100% of the bonds connecting the aromatic rings in the main chain. is an amide bond, 100% of the aromatic diamine-derived units have an electron-withdrawing group, the acid chloride-derived units do not have an electron-withdrawing group, and the intrinsic viscosity is 1.47 dL / g. there were.

100 parts by weight of alumina powder having an average particle size of 0.02 μm and 100 parts by weight of alumina powder having an average particle size of 0.7 μm were added to the obtained solution of aramid resin 2 . Subsequently, the solution was diluted by adding NMP to prepare a coating solution 2 in which the total concentration of the aramid resin 2 and the filler was 6% by weight. At this time, since the content of the filler in the porous layer is 66% by weight, when the weight of the aramid resin 2 and the filler is 100% by weight, the aramid is added so that the content of the filler is 66% by weight. Resin 2, filler and solvent were mixed to obtain coating liquid 2.

(2. Preparation of laminated separator for non-aqueous electrolyte secondary battery, heat resistance test, etc.)
A laminated separator 2 for a non-aqueous electrolyte secondary battery was obtained in the same manner as in Example 1 except that Coating Liquid 2 was used instead of Coating Liquid 1, and subjected to the test described in <Test Method> above. provided. Tables 1 and 2 show the results.

[Example 3]
(1. Preparation of coating liquid)
In the same manner as in Example 1, except that the amount of 2-chloro-1,4-phenylenediamine added as the aromatic diamine was 2.49 g and the amount of TPC added as the acid chloride was 3.51 g. , to obtain aramid resin 3. Aramid resin 3 has a chloro group as an electron-withdrawing group in the aromatic ring in the main chain, amino groups at both ends of the molecule, and 100% of the bonds connecting the aromatic rings in the main chain. is an amide bond, 100% of the aromatic diamine-derived units have an electron-withdrawing group, the acid chloride-derived units do not have an electron-withdrawing group, and the intrinsic viscosity is 3.85 dL / g. there were.

100 parts by weight of alumina powder having an average particle size of 0.02 μm and 100 parts by weight of alumina powder having an average particle size of 0.7 μm were added to the obtained solution of aramid resin 3 . Subsequently, the solution was diluted by adding NMP to prepare a coating solution 3 in which the total concentration of the aramid resin 3 and the filler was 2.87% by weight. At this time, since the content of the filler in the porous layer is 66% by weight, when the weight of the aramid resin 3 and the filler is 100% by weight, the aramid is added so that the content of the filler is 66% by weight. A coating liquid 3 was obtained by mixing resin 3, a filler and a solvent.

(2. Preparation of laminated separator for non-aqueous electrolyte secondary battery, heat resistance test, etc.)
A laminated separator 3 for a non-aqueous electrolyte secondary battery was obtained in the same manner as in Example 1 except that Coating Solution 3 was used instead of Coating Solution 1, and subjected to the test described in <Test Method> above. provided. Tables 1 and 2 show the results.

[Example 4]
(1. Preparation of coating liquid)
In the same manner as in Example 1 except that the amount of 2-cyano-1,4-phenylenediamine added as the aromatic diamine was 5.40 g and the amount of TPC added as the acid chloride was 8.15 g, Aramid resin 4 was obtained. Aramid resin 4 has a cyano group as an electron-withdrawing group in the aromatic ring in the main chain, amino groups at both ends of the molecule, and 100% of the bonds connecting the aromatic rings in the main chain. is an amide bond, 100% of the aromatic diamine-derived units have an electron-withdrawing group, the acid chloride-derived units do not have an electron-withdrawing group, and the intrinsic viscosity is 2.62 dL / g. there were.

100 parts by weight of alumina powder with an average particle size of 0.02 μm and 100 parts by weight of alumina powder with an average particle size of 0.7 μm were added to the obtained solution of the aramid resin 4 . Subsequently, NMP was added to the solution to dilute it, and a coating liquid 4 having a total concentration of the aramid resin 4 and the filler of 3.00% by weight was prepared. At this time, since the content of the filler in the porous layer is 66% by weight, when the weight of the aramid resin 4 and the filler is 100% by weight, the aramid is added so that the content of the filler is 66% by weight. A coating liquid 4 was obtained by mixing resin 4, a filler and a solvent.

(2. Preparation of laminated separator for non-aqueous electrolyte secondary battery, heat resistance test, etc.)
A laminated separator 4 for a non-aqueous electrolyte secondary battery was obtained in the same manner as in Example 1 except that Coating Solution 4 was used instead of Coating Solution 1, and subjected to the test described in <Test Method> above. provided. Tables 1 and 2 show the results.

[Example 5]
(1. Preparation of coating liquid)
The amount of 2-chloro-1,4-phenylenediamine added as the aromatic diamine was 5.53 g, the amount of paraphenylenediamine added was 5.53 g, and the amount of TPC added as the acid chloride was 9.38 g. Aramid resin 5 was obtained in the same manner as in Example 1, except for the above. Aramid resin 5 has a chloro group as an electron-withdrawing group in the aromatic ring in the main chain, amino groups at both ends of the molecule, and 100% of the bonds connecting the aromatic rings in the main chain. is an amide bond, 75% of the aromatic diamine-derived units have an electron-withdrawing group, the acid chloride-derived units do not have an electron-withdrawing group, and the intrinsic viscosity is 1.55 dL / g. there were.

100 parts by weight of alumina powder with an average particle size of 0.02 μm and 100 parts by weight of alumina powder with an average particle size of 0.7 μm were added to the obtained solution of the aramid resin 5 . Subsequently, the solution was diluted by adding NMP to prepare a coating solution 5 in which the total concentration of the aramid resin 5 and the filler was 2.21% by weight. At this time, since the content of the filler in the porous layer is 66% by weight, when the weight of the aramid resin 5 and the filler is 100% by weight, the aramid is added so that the content of the filler is 66% by weight. A coating liquid 5 was obtained by mixing resin 5, a filler and a solvent.

(2. Preparation of laminated separator for non-aqueous electrolyte secondary battery, heat resistance test, etc.)
A laminated separator 5 for a non-aqueous electrolyte secondary battery was obtained in the same manner as in Example 1 except that Coating Liquid 5 was used instead of Coating Liquid 1, and subjected to the test described in <Test Method> above. provided. Tables 1 and 2 show the results.

[Example 6]
(1. Preparation of coating liquid)
The amount of 2-chloro-1,4-phenylenediamine added as the aromatic diamine was 3.72 g, the amount of paraphenylenediamine added was 2.81 g, and the amount of TPC added as the acid chloride was 10.48 g. Aramid resin 6 was obtained in the same manner as in Example 1, except for the above. Aramid resin 6 has a chloro group as an electron-withdrawing group in the aromatic ring in the main chain, amino groups at both ends of the molecule, and 100% of the bonds connecting the aromatic rings in the main chain. is an amide bond, 50% of the aromatic diamine-derived units have an electron-withdrawing group, the acid chloride-derived units do not have an electron-withdrawing group, and the intrinsic viscosity is 3.67 dL / g. there were.

100 parts by weight of alumina powder having an average particle size of 0.02 μm and 100 parts by weight of alumina powder having an average particle size of 0.7 μm were added to the obtained solution of the aramid resin 6 . Subsequently, the solution was diluted by adding NMP to prepare a coating solution 6 in which the total concentration of the aramid resin 6 and the filler was 2.15% by weight. At this time, since the content of the filler in the porous layer is 66% by weight, when the weight of the aramid resin 6 and the filler is 100% by weight, the aramid is added so that the content of the filler is 66% by weight. A coating liquid 6 was obtained by mixing resin 6, a filler and a solvent.

(2. Preparation of laminated separator for non-aqueous electrolyte secondary battery, heat resistance test, etc.)
A laminated separator 6 for a non-aqueous electrolyte secondary battery was obtained in the same manner as in Example 1 except that the coating liquid 6 was used instead of the coating liquid 1, and the test described in the above <Test method> was performed. provided. Tables 1 and 2 show the results.

[Example 7]
(1. Preparation of coating liquid)
In the same manner as in Example 1, except that the amount of 2-chloro-1,4-phenylenediamine added as the aromatic diamine was 84.83 g and the amount of TPC added as the acid chloride was 117.05 g. , to obtain aramid resin 7. Aramid resin 7 has a chloro group as an electron-withdrawing group in the aromatic ring in the main chain, amino groups at both ends of the molecule, and 100% of the bonds connecting the aromatic rings in the main chain. is an amide bond, 100% of the aromatic diamine-derived units have an electron-withdrawing group, the acid chloride-derived units do not have an electron-withdrawing group, and the intrinsic viscosity is 2.40 dL / g. there were.

Alumina powder having an average particle size of 0.02 μm was added to the obtained solution of aramid resin 7 . Subsequently, the solution was diluted by adding NMP to prepare a coating liquid 7 in which the total concentration of the aramid resin 7 and the filler was 4.00% by weight. At this time, in order to make the content of the filler in the porous layer 50% by weight, when the weight of the aramid resin 7 and the filler is 100% by weight, the aramid is added so that the content of the filler is 50% by weight. A coating liquid 7 was obtained by mixing the resin 7, the filler and the solvent.

(2. Preparation of laminated separator for non-aqueous electrolyte secondary battery, heat resistance test, etc.)
A laminated separator 7 for a non-aqueous electrolyte secondary battery was obtained in the same manner as in Example 1 except that Coating Solution 7 was used instead of Coating Solution 1, and subjected to the test described in <Test Method> above. provided. Tables 1 and 2 show the results.

[Example 8]
(1. Preparation of coating liquid)
The amount of 2-chloro-1,4-phenylenediamine added as the aromatic diamine was 6.98 g, the amount of paraphenylenediamine added was 5.15 g, and the amount of TPC added as the acid chloride was 19.06 g. Aramid resin 8 was obtained in the same manner as in Example 1, except for the above. Aramid resin 8 has a chloro group as an electron-withdrawing group in the aromatic ring in the main chain, amino groups at both ends of the molecule, and 100% of the bonds connecting the aromatic rings in the main chain. is an amide bond, 50% of the aromatic diamine-derived units have an electron-withdrawing group, the acid chloride-derived units do not have an electron-withdrawing group, and the intrinsic viscosity is 1.90 dL / g. there were.

Alumina powder having an average particle size of 0.02 μm was added to the obtained solution of aramid resin 8 . Subsequently, the solution was diluted by adding NMP to prepare a coating solution 8 in which the total concentration of the aramid resin 8 and the filler was 3.00% by weight. At this time, since the content of the filler in the porous layer is 40% by weight, when the weight of the aramid resin 8 and the filler is 100% by weight, the aramid is added so that the content of the filler is 40% by weight. A coating liquid 8 was obtained by mixing resin 8, a filler and a solvent.

(2. Preparation of laminated separator for non-aqueous electrolyte secondary battery, heat resistance test, etc.)
A laminated separator 8 for a non-aqueous electrolyte secondary battery was obtained in the same manner as in Example 1 except that the coating liquid 8 was used instead of the coating liquid 1, and the test described in the above <Test method> was performed. provided. Tables 1 and 2 show the results.

[Comparative Example 1]
(1. Preparation of coating liquid)
The amount of 2-chloro-1,4-phenylenediamine added as the aromatic diamine was 3.72 g, the amount of paraphenylenediamine added was 2.79 g, and the amount of TPC added as the acid chloride was 9.45 g. Aramid resin 1 for comparison was obtained in the same manner as in Example 1 except for the above. Comparative aramid resin 1 has a chloro group as an electron-withdrawing group in the aromatic ring in the main chain, amino groups at both ends of the molecule, and a bond connecting the aromatic rings in the main chain. 100% are amide bonds, 50% of the aromatic diamine-derived units have electron-withdrawing groups, the acid chloride-derived units do not have electron-withdrawing groups, and the intrinsic viscosity is 1.10 dL/ was g.

100 parts by weight of alumina powder having an average particle size of 0.02 μm and alumina powder having an average particle size of 0.7 μm were added to the obtained solution of aramid resin 1 for comparison. Subsequently, the solution was diluted by adding NMP to prepare a comparative coating solution 1 in which the total concentration of the comparative aramid resin 1 and the filler was 4.51% by weight. At this time, in order to make the content of the filler in the porous layer 66% by weight, when the weight of the comparative aramid resin 1 and the filler is 100% by weight, the content of the filler is 66% by weight. , a comparative aramid resin 1, a filler and a solvent were mixed to obtain a comparative coating liquid 1.

(2. Preparation of laminated separator for non-aqueous electrolyte secondary battery, heat resistance test, etc.)
A laminated separator 1 for a comparative non-aqueous electrolyte secondary battery was obtained in the same manner as in Example 1, except that the comparative coating liquid 1 was used instead of the coating liquid 1. Subjected to the test described. Tables 1 and 2 show the results.

[Comparative Example 2]
(1. Preparation of coating liquid)
Except that the amount of 2-chloro-1,4-phenylenediamine added as the aromatic diamine was 1.86 g, the amount of paraphenylenediamine added was 4.24 g, and the amount of TPC as the acid chloride was 9.50 g. Aramid resin 2 for comparison was obtained in the same manner as in Example 1. Comparative aramid resin 2 has a chloro group as an electron-withdrawing group in the aromatic ring in the main chain, amino groups at both ends of the molecule, and a bond connecting the aromatic rings in the main chain. 100% are amide bonds, 25% of the aromatic diamine-derived units have an electron-withdrawing group, the acid chloride-derived units do not have an electron-withdrawing group, and the intrinsic viscosity is 0.66 dL/ was g.

100 parts by weight of alumina powder having an average particle size of 0.02 μm and alumina powder having an average particle size of 0.7 μm were added to the obtained solution of aramid resin 2 for comparison. Subsequently, the solution was diluted by adding NMP to prepare a comparative coating solution 2 in which the total concentration of the comparative aramid resin 2 and the filler was 4.51% by weight. At this time, in order to make the content of the filler in the porous layer 66% by weight, when the weight of the comparative aramid resin 2 and the filler is 100% by weight, the content of the filler is 66% by weight. , Aramid resin 2 for comparison, a filler and a solvent were mixed to obtain a coating liquid 2 for comparison.

(2. Preparation of laminated separator for non-aqueous electrolyte secondary battery, heat resistance test, etc.)
A laminated separator 2 for a comparative non-aqueous electrolyte secondary battery was obtained in the same manner as in Example 1, except that the comparative coating liquid 2 was used instead of the coating liquid 1. Subjected to the test described. Tables 1 and 2 show the results.

[Comparative Example 3]
It has no electron-withdrawing group in the aromatic ring in the main chain, has amino groups at both ends of the molecule, and 100% of the bonds connecting the aromatic rings in the main chain are amide bonds. Group diamine-derived units do not have electron-withdrawing groups, acid chloride-derived units do not have electron-withdrawing groups, and a comparative aramid resin 3 having an intrinsic viscosity of 1.90 dL/g was used. .

Alumina powder having an average particle size of 0.7 μm was added to the solution of aramid resin 3 for comparison. Subsequently, NMP was added to the above solution to dilute it, and Comparative Coating Solution 3 was prepared. At this time, in order to make the content of the filler in the porous layer 90% by weight, when the weight of the comparative aramid resin 3 and the filler is 100% by weight, the content of the filler is 90% by weight. , Aramid resin 3 for comparison, a filler and a solvent were mixed to obtain a coating liquid 3 for comparison.

(2. Preparation of laminated separator for non-aqueous electrolyte secondary battery, heat resistance test, etc.)
A laminated separator 3 for a comparative non-aqueous electrolyte secondary battery was obtained in the same manner as in Example 1, except that the comparative coating liquid 3 was used instead of the coating liquid 1. Subjected to the test described. Tables 1 and 2 show the results.

[Comparative Example 4]
(1. Preparation of coating liquid)
In the same manner as in Example 1, except that the amount of 2-chloro-1,4-phenylenediamine added as the aromatic diamine was 7.44 g and the amount of TPC added as the acid chloride was 10.29 g. Aramid resin 4 for comparison was obtained. Comparative aramid resin 4 has a chloro group as an electron-withdrawing group in the aromatic ring in the main chain, amino groups at both ends of the molecule, and a bond connecting the aromatic rings in the main chain. 100% are amide bonds, 100% of the aromatic diamine-derived units have electron-withdrawing groups, the acid chloride-derived units do not have electron-withdrawing groups, and the intrinsic viscosity is 2.40 dL/ was g.

Alumina powder having an average particle size of 0.7 μm was added to the obtained solution of aramid resin 4 for comparison. Subsequently, NMP was added to the solution to dilute it, and Comparative Coating Solution 4 was prepared. At this time, in order to make the content of the filler in the porous layer 90% by weight, when the weight of the comparative aramid resin 4 and the filler is 100% by weight, the content of the filler is 90% by weight. , Aramid resin 4 for comparison, a filler and a solvent were mixed to obtain a coating liquid 4 for comparison.

(2. Preparation of laminated separator for non-aqueous electrolyte secondary battery, heat resistance test, etc.)
A laminated separator 4 for a comparative non-aqueous electrolyte secondary battery was obtained in the same manner as in Example 1, except that the comparative coating liquid 4 was used instead of the coating liquid 1. Subjected to the test described. Tables 1 and 2 show the results.

[Comparative Example 5]
(1. Preparation of coating liquid)
Except that the amount of p-phenylenediamine added as the aromatic diamine was set to 13.25 g, the amount of TPC added as the acid chloride was set to 24.27 g, and 5.09 g of benzoyl chloride for terminal blocking was added last. obtained comparative aramid resin 5 in the same manner as in Example 1. Comparative aramid resin 5 does not have an electron-withdrawing group in the aromatic ring in the main chain, does not have an amino group at both ends of the molecule, and has 100 of the bond connecting the aromatic rings in the main chain. % is an amide bond, the aromatic diamine-derived unit does not have an electron-withdrawing group, the acid chloride-derived unit does not have an electron-withdrawing group, and the intrinsic viscosity is 1.78 dL / g. Ta.

100 parts by weight of alumina powder having an average particle size of 0.02 μm and 100 parts by weight of alumina powder having an average particle size of 0.7 μm were added to the obtained solution of aramid resin 5 for comparison. Subsequently, the solution was diluted by adding NMP to prepare a comparative coating liquid 5 in which the total concentration of the comparative aramid resin 5 and the filler was 6.0% by weight. At this time, in order to make the content of the filler in the porous layer 66% by weight, when the weight of the comparative aramid resin 5 and the filler is 100% by weight, the content of the filler is 66% by weight. , a comparative aramid resin 5, a filler and a solvent were mixed to obtain a comparative coating liquid 5.

(2. Preparation of laminated separator for non-aqueous electrolyte secondary battery, heat resistance test, etc.)
A laminated separator 5 for a comparative non-aqueous electrolyte secondary battery was obtained in the same manner as in Example 1 except that the comparative coating liquid 5 was used instead of the coating liquid 1, and the above <test method> was performed. Subjected to the test described. Tables 1 and 2 show the results.

[Comparative Example 6]
(1. Preparation of coating liquid)
Except that the amount of paraphenylenediamine added as the aromatic diamine was 12.77 g, the amount of TPC added as the acid chloride was 24.71 g, and 0.85 g of 4-aminobenzonitrile was used as the terminal-capping aniline. obtained comparative aramid resin 6 in the same manner as in Example 1. Comparative aramid resin 6 does not have an electron-withdrawing group in the aromatic ring in the main chain, does not have an amino group at both ends of the molecule, and has 100 of the bond connecting the aromatic rings in the main chain. % is an amide bond, the aromatic diamine-derived unit does not have an electron-withdrawing group, the acid chloride-derived unit does not have an electron-withdrawing group, and the intrinsic viscosity is 0.73 dL / g. Ta.

100 parts by weight of alumina powder having an average particle size of 0.02 μm and alumina powder having an average particle size of 0.7 μm were added to the obtained solution of aramid resin 6 for comparison. Subsequently, the solution was diluted by adding NMP to prepare a comparative coating solution 6 in which the total concentration of the comparative aramid resin 6 and the filler was 6.0% by weight. At this time, in order to make the content of the filler in the porous layer 66% by weight, when the weight of the comparative aramid resin 6 and the filler is 100% by weight, the content of the filler is 66% by weight. , a comparative aramid resin 6, a filler and a solvent were mixed to obtain a comparative coating liquid 6.

(2. Preparation of laminated separator for non-aqueous electrolyte secondary battery, heat resistance test, etc.)
A laminated separator 6 for a comparative non-aqueous electrolyte secondary battery was obtained in the same manner as in Example 1, except that the comparative coating liquid 6 was used instead of the coating liquid 1. Subjected to the test described. Tables 1 and 2 show the results.

[Comparative Example 7]
(1. Preparation of coating liquid)
The amount of 2-chloro-1,4-phenylenediamine added as the aromatic diamine was 1.87 g, the amount of paraphenylenediamine added was 4.22 g, and the amount of TPC added as the acid chloride was 10.51 g. Aramid resin 7 for comparison was obtained in the same manner as in Example 1 except for the above. Comparative aramid resin 7 has a chloro group as an electron-withdrawing group in the aromatic ring in the main chain, amino groups at both ends of the molecule, and a bond connecting the aromatic rings in the main chain. 100% are amide bonds, 25% of the aromatic diamine-derived units have electron-withdrawing groups, the acid chloride-derived units do not have electron-withdrawing groups, and the intrinsic viscosity is 3.55 dL/ was g.

100 parts by weight of alumina powder with an average particle size of 0.02 μm and alumina powder with an average particle size of 0.7 μm were added to the obtained solution of the aramid resin 7 for comparison. Subsequently, the solution was diluted by adding NMP to prepare a comparative coating solution 7 in which the total concentration of the comparative aramid resin 7 and the filler was 2.21% by weight. At this time, in order to make the content of the filler in the porous layer 66% by weight, when the weight of the comparative aramid resin 7 and the filler is 100% by weight, the content of the filler is 66% by weight. , a comparative aramid resin 7, a filler and a solvent were mixed to obtain a comparative coating liquid 7.

(2. Preparation of laminated separator for non-aqueous electrolyte secondary battery, heat resistance test, etc.)
A laminated separator 7 for a comparative non-aqueous electrolyte secondary battery was obtained in the same manner as in Example 1, except that the comparative coating liquid 7 was used instead of the coating liquid 1. Subjected to the test described. Tables 1 and 2 show the results.

[Comparative Example 8]
(1. Preparation of coating liquid)
Except that the amount of 2-chloro-1,4-phenylenediamine added as the aromatic diamine was 11.20 g and the amount of 4,4'-oxybis(benzoyl chloride) added as the acid chloride was 10.51 g. Aramid resin 8 for comparison was obtained in the same manner as in Example 1. Comparative aramid resin 8 has a chloro group as an electron-withdrawing group in the aromatic ring in the main chain, amino groups at both ends of the molecule, and a bond connecting the aromatic rings in the main chain. 66% are amide bonds, 100% of the aromatic diamine-derived units have an electron-withdrawing group, the acid chloride-derived units do not have an electron-withdrawing group, and the intrinsic viscosity is 1.50 dL/ was g.

Alumina powder having an average particle size of 0.02 μm was added to the obtained solution of aramid resin 8 for comparison. Subsequently, the solution was diluted by adding NMP to prepare a comparative coating solution 8 in which the total concentration of the comparative aramid resin 8 and the filler was 6.00% by weight. At this time, in order to make the content of the filler in the porous layer 50% by weight, when the weight of the comparative aramid resin 8 and the filler is 100% by weight, the content of the filler is 50% by weight. , a comparative aramid resin 8, a filler and a solvent were mixed to obtain a comparative coating liquid 8.

(2. Preparation of laminated separator for non-aqueous electrolyte secondary battery, heat resistance test, etc.)
A laminated separator 8 for a comparative non-aqueous electrolyte secondary battery was obtained in the same manner as in Example 1, except that the comparative coating liquid 8 was used instead of the coating liquid 1. Subjected to the test described. Tables 1 and 2 show the results.

[Comparative Example 9]
(1. Preparation of coating liquid)
For comparison, in the same manner as in Example 1, except that the amount of 4,4′-diaminodiphenyl ether added as the aromatic diamine was 17.31 g, and the amount of TPC added as the acid chloride was 17.38 g. Aramid resin 9 was obtained. Comparative aramid resin 9 does not have an electron-withdrawing group in the aromatic ring in the main chain, has amino groups at both ends of the molecule, and has 66% of the bonds connecting the aromatic rings in the main chain. is an amide bond, the aromatic diamine-derived unit does not have an electron-withdrawing group, the acid chloride-derived unit does not have an electron-withdrawing group, and the intrinsic viscosity is 1.65 dL / g. .

Alumina powder having an average particle size of 0.02 μm was added to the obtained solution of aramid resin 9 for comparison. Subsequently, NMP was added to the solution to dilute it, and a comparative coating solution 9 was prepared in which the total concentration of the comparative aramid resin 9 and the filler was 6.00% by weight. At this time, in order to make the content of the filler in the porous layer 50% by weight, when the weight of the comparative aramid resin 9 and the filler is 100% by weight, the content of the filler is 50% by weight. , Comparative Aramid Resin 9, a filler and a solvent were mixed to obtain Comparative Coating Liquid 9.

(2. Preparation of laminated separator for non-aqueous electrolyte secondary battery, heat resistance test, etc.)
A laminated separator 9 for a comparative non-aqueous electrolyte secondary battery was obtained in the same manner as in Example 1, except that the comparative coating liquid 9 was used instead of the coating liquid 1. Subjected to the test described. Tables 1 and 2 show the results.

[Comparative Example 10]
(1. Preparation of coating liquid)
Aramid resin 10 was obtained in the same manner as in Example 1, except that the amount of paraphenylenediamine added was 5.15 g and the amount of TPC added as acid chloride was 19.06 g. Comparative aramid resin 10 has a chloro group as an electron-withdrawing group in the aromatic ring in the main chain, amino groups at both ends of the molecule, and a bond connecting the aromatic rings in the main chain. 100% are amide bonds, 50% of the aromatic diamine-derived units have electron-withdrawing groups, the acid chloride-derived units do not have electron-withdrawing groups, and the intrinsic viscosity is 1.90 dL/ was g.

Alumina powder having an average particle size of 0.02 μm was added to the obtained solution of aramid resin 10 . Subsequently, the solution was diluted by adding NMP to prepare a coating liquid 10 in which the total concentration of the aramid resin 10 and the filler was 3.00% by weight. At this time, in order to make the content of the filler in the porous layer 20% by weight, when the weight of the aramid resin 10 and the filler is 100% by weight, the aramid is added so that the content of the filler is 20% by weight. A coating liquid 10 was obtained by mixing resin 10, a filler and a solvent.

(2. Preparation of laminated separator for non-aqueous electrolyte secondary battery, heat resistance test, etc.)
A laminated separator 10 for a comparative non-aqueous electrolyte secondary battery was obtained in the same manner as in Example 1, except that the comparative coating liquid 10 was used instead of the coating liquid 1. However, the pores of the porous layer were not sufficiently formed, and the test described in the above <Test method> could not be carried out. Tables 1 and 2 show the results.

In Table 1, "Main chain aromatic ring electron-withdrawing group" is the type of electron-withdrawing group in the aromatic ring in the main chain; "Diamine unit withdrawing group content" is derived from the aromatic diamine in the aramid resin. Of the units, the ratio of those having an electron-withdrawing group; "Acid chloride unit withdrawing group content" is the ratio of those having an electron-withdrawing group among the acid chloride-derived units in the aramid resin; "Presence or absence" indicates whether or not the aramid resin has an amino group at the end of the molecule (circle if it has, x if it does not); "Aromatic ring-linked amide group ratio" is contained in the main chain The ratio of the bond connecting the aromatic rings to have an amide group; "filler content in the porous layer" is the filler content when the weight of the porous layer is 100% by weight; "aramid intrinsic viscosity" is the aramid The intrinsic viscosity of the resin and the “basis weight” each represent the weight per square meter of the laminated separator for a non-aqueous electrolyte secondary battery.

In Table 2, "Discoloration after trickle test" refers to the color of the porous layer surface before trickle charging and the color of the surface of the porous layer before trickle charging when the laminated separator for non-aqueous electrolyte secondary battery is taken out from the test battery after trickle charging. After visually observing and comparing the color of the surface of the porous layer that was in contact with the positive electrode active material layer; X1) × 100” is X1, X2, (X2/X1) × 100 described in (2. Measurement of IR intensity) above; “Area of opening” is above (1-5. Metal core penetration test) 2 represents the area of the opening of the laminated separator for a non-aqueous electrolyte secondary battery described in 1, respectively.

The laminated separators 1 to 8 for non-aqueous electrolyte secondary batteries according to Examples 1 to 8 all had an opening area of 7.0 mm ² or less after the heat resistance test, had little discoloration, and had an amide group. had a high survival rate. Therefore, it can be seen that the laminated separators 1 to 8 for non-aqueous electrolyte secondary batteries are excellent in heat resistance and deterioration resistance even when charged at high voltage for a long time.

On the other hand, in the laminated separators 1 to 9 for comparative non-aqueous electrolyte secondary batteries according to Comparative Examples 1 to 9, the areas of the openings after the heat resistance test all greatly exceeded 7.0 mm ² . Moreover, in the laminated separator 10 for a comparative non-aqueous electrolyte secondary battery according to Comparative Example 10, a suitable porous layer was not formed. Based on the results of Examples and Comparative Examples, we designed an aromatic polyamide with high oxidation resistance and added an appropriate amount of heat-resistant filler to create a non-aqueous electrolyte secondary electrolyte with excellent heat resistance and deterioration resistance. It is believed that a laminated separator for batteries can be obtained.

INDUSTRIAL APPLICABILITY The laminated separator for non-aqueous electrolyte secondary batteries according to one embodiment of the present invention can be suitably used in various industries dealing with non-aqueous electrolyte secondary batteries.

Claims (8)

A laminated separator for a non-aqueous electrolyte secondary battery comprising a polyolefin porous film and a porous layer,
The porous layer contains a binder resin and a filler,
When subjected to the following heat resistance test, the area of the opening is 7.0 mm ² or less ,
The content of the filler in the porous layer is 40% by weight or more and 70% by weight or less when the weight of the porous layer is 100% by weight,
The binder resin contains an aramid resin,
The aramid resin is
(i) having an electron-withdrawing group in the aromatic ring in the main chain,
(ii) at least one end of the molecule is an amino group;
(iii) more than 90% of the bonds connecting the aromatic rings contained in the main chain are amide bonds;
(iv) 40% or more of the aromatic diamine-derived units have an electron-withdrawing group,
(v) A laminated separator for a non-aqueous electrolyte secondary battery, in which 20% or less of the acid chloride-derived units have an electron-withdrawing group :
Step 1. A positive electrode containing a positive electrode active material capable of doping and dedoping lithium ions, the laminated separator for a non-aqueous electrolyte secondary battery, and a negative electrode containing a negative electrode active material capable of being doped and dedoped with lithium ions, in this order. and impregnating a laminate in which the porous layer and the positive electrode active material layer provided in the positive electrode are in contact with each other are impregnated with a non-aqueous electrolyte to prepare a test battery;
Step 2. After constant current charging to 4.6 V (vs Li/Li ⁺ ) at 25 ° C. and 1 ^C of the test battery, 168 impose a time trickle charge;
Step 3. Taking out the laminated separator for the non-aqueous electrolyte secondary battery from the test battery that has undergone step 2;
Step 4. Contact a metal core with a diameter of 2.2 mm at 450° C. with the positive electrode active material layer of the laminated separator for a non-aqueous electrolyte secondary battery without applying a downward load. The metal core is held at a position in contact with the surface of the porous layer side, and the metal core is brought into contact with the positive electrode active material layer of the laminated separator for a non-aqueous electrolyte secondary battery. It penetrates from the said porous layer side which had been carried out.
(Here, the positive electrode is a positive electrode in which lithium nickel cobalt manganese oxide (LiNi _0.5 Co _0.2 Mn _0.3 O ₂ ) is laminated on an aluminum foil,
The negative electrode is a negative electrode in which natural graphite is laminated on a copper foil,
The above non-aqueous electrolyte is prepared by dissolving LiPF ₆ to 1 mol/L in a mixed solvent of ethylene carbonate, ethylmethyl carbonate, and diethyl carbonate at a volume ratio of 3:5:2. It is a non-aqueous electrolyte. ) The laminated separator for a non-aqueous electrolyte secondary battery according to claim 1 , wherein the filler is a metal oxide filler. The laminate for a non-aqueous electrolyte secondary battery according to claim 1 or 2 , wherein the aramid resin contained in the porous layer satisfies the relationship of (X2/X1) × 100 ≥ 80 (%) separator.
(In the formula, X1 is (a) in the range of 1490 to 1530 ^cm when the IR intensity on the surface of the porous layer is measured by the ATR-IR method before starting trickle charging in step 2 above. maximum peak intensity; or (b) after trickle charging in step 2, among the surfaces of the porous layer, ATR the IR intensity of the surface that was not in contact with the positive electrode active material layer of the positive electrode during the trickle charging. - is the maximum peak intensity in the range of 1490-1530 cm ^-1 as measured by the IR method,
X2 is 1490 when the IR intensity of the surface of the porous layer that was in contact with the positive electrode active material layer of the positive electrode during the trickle charge was measured by the ATR-IR method after the trickle charge in step 2. is the maximum peak intensity in the range of ~1530 cm ^-1 ) The laminated separator for a non-aqueous electrolyte secondary battery according to any one of claims 1 to 3 , wherein the aramid resin does not have an ether bond as a bond connecting aromatic rings contained in the main chain. The laminated separator for a non-aqueous electrolyte secondary battery according to any one of claims 1 to 4 , wherein the electron-withdrawing group is one or more selected from the group consisting of halogen, cyano group and nitro group. . The laminated separator for a non-aqueous electrolyte secondary battery according to any one of claims 1 to 5 , wherein the aramid resin has an intrinsic viscosity of 1.4 to 4.0 dL/g. a positive electrode;
A laminated separator for a non-aqueous electrolyte secondary battery according to any one of claims 1 to 6 ,
a negative electrode;
is laminated in this order, a member for a nonaqueous electrolyte secondary battery. Non-aqueous electrolysis comprising the laminated separator for non-aqueous electrolyte secondary batteries according to any one of claims 1 to 6 or the member for non-aqueous electrolyte secondary batteries according to claim 7 Liquid secondary battery.