JP2022013778A - Laminate separator for nonaqueous electrolyte secondary battery - Google Patents

Abstract

To realize a laminate separator for a nonaqueous electrolyte secondary battery, which is superior in heat resistance and which is never changed in quality even after being charged under a high-voltage condition for a long time.SOLUTION: A laminate separator for a nonaqueous electrolyte secondary battery comprises a polyolefin porous film and a porous layer. The porous layer contains a binder resin and filler. When having gone through a given heat resistance test, the laminate separator for a nonaqueous electrolyte secondary battery is 7.0 mm2 or smaller in opening area.SELECTED DRAWING: None

Description

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, are widely used as batteries for personal computers, mobile phones, mobile information terminals, etc. due to their high energy density, and have recently been developed as in-vehicle batteries. Has been done.

The non-aqueous electrolyte secondary battery is required to be able to be charged under high voltage conditions. Therefore, the laminated separator for a non-aqueous electrolytic solution secondary battery is required to have excellent heat resistance and deterioration resistance without being deteriorated even after being charged.

Patent Document 1 describes a case where a high voltage is applied to a total 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. It is also stated that there is little discoloration.

Japanese Unexamined Patent Publication 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, for example, when trickle charging is performed, charging is often performed under a high voltage for a time considerably longer than one day, but even in such a case, the laminated separator does not deteriorate, and heat resistance and resistance. Nothing has been shown to be excellent in deterioration.

Therefore, one aspect of the present invention is a laminated separator for a non-aqueous electrolytic solution 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 the following [1] to [12].

[1] A laminated separator for a non-aqueous electrolytic solution secondary battery provided with a polyolefin porous film and a porous layer.
The porous layer contains a binder resin and a filler, and 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 the following heat resistance test is imposed:
Step 1. A positive electrode containing a positive electrode active material that can be doped with and dedoped with lithium ions, a laminated separator for the non-aqueous electrolyte secondary battery, and a negative electrode containing a negative electrode active material that can be doped with and dedoped with lithium ions are arranged in this order. Then, the non-aqueous electrolytic solution is impregnated with the laminated body laminated so that the porous layer and the positive electrode active material layer provided in the positive electrode are in contact with each other to prepare a test battery;
Step 2. The test battery was charged to a constant current of 4.6 V (vs Li / Li ⁺ ) at 25 ° C. and 1 C, and then 168 under the conditions of 25 ° C. and 4.6 V (vs Li / Li ⁺ ). Imposing time trickle charge;
Step 3. From the test battery that has undergone step 2, the laminated separator for the non-aqueous electrolytic solution secondary battery is taken out;
Step 4. A metal core having a diameter of 2.2 mm at 450 ° C. is passed through the porous layer side of the laminated separator for a non-aqueous electrolytic solution secondary battery, which is 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 non-aqueous electrolytic solution is prepared by dissolving LiPF ₆ in a mixed solvent prepared by mixing ethylene carbonate, ethyl methyl carbonate, and diethyl carbonate at a ratio of 3: 5: 2 (volume ratio) so as to be 1 mol / L. It is a non-aqueous electrolyte solution. ).

[2] The non-aqueous electrolyte solution 2 according to [1], wherein 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 next battery.

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

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

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

[6] The above-mentioned aramid resin is
(I) It has 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 electrolytic solution 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 electrolytic solution 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 above-mentioned aramid resin is
(Iv) More than 40% of the units derived from aromatic diamines have electron-withdrawing groups.
(V) The laminated separator for a non-aqueous electrolytic solution 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 electrolytic solution 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 a halogen, a cyano group and a nitro group. For laminated separators.

[10] The laminated separator for a non-aqueous electrolytic solution 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] Positive electrode and
The laminated separator for a non-aqueous electrolytic solution secondary battery according to any one of [1] to [10],
With the negative electrode
Is a member for a non-aqueous electrolyte secondary battery, which is laminated in this order.

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

According to one aspect of the present invention, a laminated separator for a non-aqueous electrolytic solution 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. It is explanatory drawing about the interpretation method of the result of the heat resistance test in Embodiment 1 of this invention.

An embodiment of the present invention will be described below, but the present invention is not limited thereto. The present invention is not limited to the configurations described below, and various modifications can be made within the scope of the claims, and the technical means disclosed in the different embodiments may be appropriately combined. The obtained embodiments are also included in the technical scope of the present invention. Unless otherwise specified in the present specification, "A to B" representing a numerical range means "A or more and B or less".

[Embodiment 1: Laminated Separator for Non-Aqueous Electrolyte Secondary Battery]
The laminated separator for a non-aqueous electrolytic solution secondary battery according to an embodiment of the present invention is a non-aqueous electrolytic solution 2 comprising a polyolefin porous film (hereinafter, also simply referred to as “porous film”) and a porous layer. Laminated separator for next battery
The porous layer contains a binder resin and a filler, and contains a binder resin and a filler.
A laminated separator for a non-aqueous electrolytic solution secondary battery having an opening area of 7.0 mm ² or less when the following heat resistance test is imposed.
Step 1. A positive electrode containing a positive electrode active material that can be doped with and dedoped with lithium ions, a laminated separator for the non-aqueous electrolyte secondary battery, and a negative electrode containing a negative electrode active material that can be doped with and dedoped with lithium ions are arranged in this order. Then, the non-aqueous electrolytic solution is impregnated with the laminated body laminated so that the porous layer and the positive electrode active material layer provided in the positive electrode are in contact with each other to prepare a test battery; step 2. The test battery was charged to a constant current of 4.6 V (vs Li / Li ⁺ ) at 25 ° C. and 1 C, and then 168 under the conditions of 25 ° C. and 4.6 V (vs Li / Li ⁺ ). Imposing time trickle charge;
Step 3. From the test battery that has undergone step 2, the laminated separator for the non-aqueous electrolytic solution secondary battery is taken out;
Step 4. A metal core having a diameter of 2.2 mm at 450 ° C. is passed through the porous layer side of the laminated separator for a non-aqueous electrolytic solution secondary battery, which is 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 non-aqueous electrolytic solution is prepared by dissolving LiPF ₆ in a mixed solvent prepared by mixing ethylene carbonate, ethyl methyl carbonate, and diethyl carbonate at a ratio of 3: 5: 2 (volume ratio) so as to be 1 mol / L. It is a non-aqueous electrolyte solution. ).

(1. Heat resistance test)
The laminated separator for a non-aqueous electrolytic solution secondary battery according to the embodiment of the present invention has an opening area of 7.0 mm ² or less when the heat resistance test is applied. In order to satisfy the configuration, the laminated separator for a non-aqueous electrolytic solution secondary battery does not deteriorate even after being charged for a long time under high voltage conditions, as shown in Examples described later. Moreover, 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 preferable because it has a high average discharge potential.

It is preferable that the positive electrode active material is laminated on the current collector together with, for example, a binder, a conductive auxiliary agent, etc., and formed as 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 auxiliary agent and a binder on a positive electrode current collector; a positive electrode active material, a conductive auxiliary agent and a binder using an appropriate organic solvent. Examples thereof include a method of forming a paste into a paste, applying the paste to the positive electrode current collector, drying the paste, and then pressurizing the paste to fix the paste to the positive electrode current collector.

The negative electrode constituting the test battery used in step 1 contains a negative electrode active material that can be doped with lithium ions and dedoped, and the negative electrode active material is natural graphite.

It is preferable that the negative electrode active material is laminated on the current collector together with, for example, a binder, a conductive auxiliary agent, etc., and formed as a negative electrode active material layer. The current collector is a copper foil.

The natural graphite has almost no change in the potential of the negative electrode from an uncharged state to a fully charged state during charging (good potential flatness), has a low average discharge potential, and has a high capacity retention rate when repeatedly charged and discharged (cycle). It is preferably used for reasons such as (good characteristics).

As a method for manufacturing the negative electrode, for example, a method of pressure molding a negative electrode active material on a negative electrode current collector; after making a negative electrode active material into a paste using an appropriate organic solvent, the paste is used as a negative electrode current collector. A method of applying the paste to the negative electrode, drying it, and then pressurizing it to fix it to the negative electrode current collector; The paste preferably contains the conductive aid and the binder.

In step 1, the positive electrode, the laminated separator for a non-aqueous electrolytic solution secondary battery, and the negative electrode are laminated in this order so that the porous layer and the positive electrode active material layer provided in the positive electrode are in contact with each other. And obtain a laminate. "The porous layer and the positive electrode active material layer come into contact with each other" means that the surface of the positive electrode active material layer of the positive electrode facing each other and the surface of the porous layer overlap each other at least in a part.

When the test battery is subjected to trickle charging, a high voltage is applied to the portion of the porous layer in contact with the positive electrode active material layer for a long time. Therefore, the above-mentioned portion is a portion where deterioration due to a high voltage of the above-mentioned laminated separator for a non-aqueous electrolytic solution secondary battery can be easily determined. Therefore, the 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 such that the entire surface of the positive electrode active material layer is in contact with the surface of the porous layer. Further, the surface area of the porous layer is larger than the surface of the positive electrode active material layer, and a 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 with the surface of the positive electrode active material layer may be in contact with the surface of the current collector.

Of the surface of the porous layer, the portion 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 the trickle charge is started. Therefore, the portion can be regarded as the surface of the porous layer before the trickle charge is started.

A test battery can be manufactured by impregnating the laminate with a non-aqueous electrolytic solution. The impregnation method is not particularly limited. For example, a method may be mentioned in which the laminate is placed in a container serving as a housing of a test battery, the inside of the container is filled with a non-aqueous electrolytic solution, and then the container is sealed while reducing the pressure.

The non-aqueous electrolytic solution is prepared by dissolving LiPF ₆ in a mixed solvent prepared by mixing ethylene carbonate, ethyl methyl carbonate, and diethyl carbonate at a ratio of 3: 5: 2 (volume ratio) so as to be 1 mol / L. It is a non-aqueous electrolyte solution. The non-aqueous electrolyte solution is preferable because it has a wide operating temperature range, is not easily deteriorated even when charged and discharged at a high current rate, and is not easily deteriorated even when used for a long time.

(1-2. Step 2)
In step 2, the test battery obtained in step 1 is constantly charged to 4.6 V (vs Li / Li ⁺ ) with a current of 25 ° C. and 1 C, and then charged at 25 ° C. to 4.6 V (vs Li / Li +). It is a process of imposing trickle charge for 168 hours under the condition of ⁺ ).

By imposing trickle charge under the above conditions, a high voltage is applied to the porous layer for a long time. 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 intentionally promotes deterioration of the porous layer in order to determine 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 electrolytic solution secondary battery from the test battery that has undergone step 2. The method for taking out the laminated separator for the non-aqueous electrolytic solution secondary battery is not particularly limited, and if the test battery is disassembled according to a conventional method and the laminated separator for the non-aqueous electrolytic solution secondary battery is taken out. good.

(1-4. Step 4)
In step 4, the porous layer in which the metal core having a diameter of 2.2 mm at 450 ° C. was in contact with the positive electrode active material layer of the laminated separator for the non-aqueous electrolytic solution secondary battery taken out from the test battery. It is a process of penetrating from the side. As described above, since a high voltage is applied to the portion of the porous layer in contact with the positive electrode active material layer for a long time, when the porous layer is formed on both sides of the polyolefin porous film, the porous layer is formed on both sides. , The metal core is penetrated from the porous layer side that was in contact with the positive electrode active material layer.

FIG. 1 is a diagram showing an example of the procedure of step 4. The left side of FIG. 1 is a diagram showing the appearance of a solder test apparatus used for carrying out step 4. As the solder test apparatus, for example, RX-802AS manufactured by Taiyo Denki Sangyo can be used. Further, a to d shown in FIG. 1 indicate that step 4 proceeds from a to d.

The laminated separator for a non-aqueous electrolytic solution secondary battery is placed on a table shown by a dotted line frame in the left side of FIG. 1 with the porous layer side facing up. Next, a metal core having a diameter of 2.2 mm at 450 ° C. installed above the table is brought close to the porous layer, and the tip portion 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 end portion in contact with the surface of the porous layer without applying a downward load. As the metal core, for example, a soldering iron can be used as shown in FIG. 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 a state immediately after the tip portion is brought into contact with the surface of the porous layer. By holding the tip portion at the position, the heat from the metal core propagates to the laminated separator for the non-aqueous electrolytic solution secondary battery, and as shown in FIG. 1a, the tip portion is centered. A substantially concentric region (hereinafter referred to as "region 1") is generated. This is a region generated by melting the polyolefin (polyethylene) constituting the polyolefin porous film.

FIG. 1b shows a state when a time has elapsed more than that of FIG. 1a. Along with the thermal history, the region 1 is larger than a in FIG. 1, and a new circular region is also formed on the outside of the tip portion.

FIG. 1c shows a state when a time has elapsed more than that of 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. On the outside of the opening, a clear circular region (hereinafter referred to as “region 2”) is formed 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. Further, on the outer side, there is a region where the polyolefin shown in FIG. 1a is melted.

FIG. 1d is a diagram showing a state immediately after the metal core is separated from the laminated separator for a non-aqueous electrolytic solution secondary battery and step 4 is completed. The time required from a to d in FIG. 1 is 10 seconds. In d, a protrusion-like pattern is seen from the opening toward the circle adjacent to the outside of the opening. This is a crack generated in the laminated separator for the non-aqueous electrolytic solution secondary battery.

FIG. 2 is an explanatory diagram of a method of interpreting the results of the heat resistance test. 1 shown in the "result analysis" of FIG. 2 is the above-mentioned region 1, which is a translucent region in which the polyethylene constituting the base material is melted. Reference numeral 2 is the above-mentioned region 2, which is a transparent region formed by melting polyethylene to the inside of the binder resin contained in the above-mentioned porous layer. Reference numeral 3 is a brownish-white region which is considered to be caused by the deterioration of polyethylene due to oxidation. Reference numeral 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 the cracks stop in the region 2, it can be judged as a good result as shown in "(Good)" in FIG. If there is a crack that exceeds the region 2 and a crack that stops in the region 2, it can be determined that the result is slightly worse. Further, if all the cracks exceed the region 2 and reach the region 1, it can be determined that the result is bad.

The laminated separator for a non-aqueous electrolytic solution secondary battery according to the embodiment of the present invention has an opening area of 7.0 mm ² or less when the above heat resistance test is applied. That is, the area of the opening measured after the end of step 4 is 7.0 mm ² or less.

The configuration that "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 the deterioration of the laminated separator for the non-aqueous electrolyte secondary battery is sufficiently suppressed. Therefore, at this time, it can be said that the laminated separator for the non-aqueous electrolytic solution 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, and more preferably 5.0 mm ² or less, from the viewpoint of providing a laminated separator for a non-aqueous electrolytic solution secondary battery having more excellent heat resistance. Especially preferable. The smaller the area is, the more preferable it is, but in practice, the lower limit is about 1.0 mm ² . The area can be measured by an image analysis method of an optical microscope.

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

(2. Porous layer)
The porous layer is laminated on at least one surface of the porous film to form a laminated separator for a non-aqueous electrolytic solution secondary battery according to an 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, so that gas or liquid can pass from one surface to the other. .. 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.

The content of the filler in the porous layer may be 40% by weight or more and 70% by weight or less when the weight of the porous layer is 100% by weight from the viewpoint of improving the heat resistance of the porous layer. preferable. The content is more preferably 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, and oxidation. 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.

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

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

The average particle size (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 JGC Holdings Corporation.

Since the shape of the filler changes depending on the method for producing the organic or inorganic material as a raw material, the dispersion conditions of the filler when preparing the coating liquid for forming the porous layer, etc., it is spherical, oval, rectangular, or gourd. It may have any shape such as a shape or an irregular shape that does not have a specific shape.

It is preferable that the binder resin is insoluble in the electrolytic solution of the battery and is electrochemically stable in the range of use of the battery. From this point of view, the binder resin is one or more selected from the group consisting of (meth) acrylate-based resin, fluorine-containing resin, polyamide-based resin, polyimide-based resin, polyamide-imide-based resin, polyester-based resin and water-soluble polymer. Is preferably contained.

The porous layer preferably contains an aramid resin. That is, the polyamide resin is preferably an aramid resin from the viewpoint of improving safety when a short circuit occurs inside the battery.

Aramid resins include aromatic polyamides and all aromatic polyamides. As the aromatic polyamide, a resin selected from the group consisting of para (p) -aromatic polyamide and meta (m) -aromatic polyamide is preferable.

Specific examples of the aramid resin include poly (paraphenylene terephthalamide), poly (metaphenylene isophthalamide), poly (metaphenylene terephthalamide), poly (parabenzamide), poly (metabenzamide), and 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 / One or more selected from 2,6-dichloroparaphenylene terephthalamide copolymer, metaphenylene terephthalamide / 2,6-dichloroparaphenylene terephthalamide copolymer and the like can be mentioned.

Of these, poly (paraphenylene terephthalamide), poly (metaphenylene terephthalamide) and paraphenylene terephthalamide / metaphenylene terephthalamide copolymers are preferable.

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 ^-1 when the IR strength of the surface of the porous layer is measured by the ATR-IR method before starting the trickle charge in step 2. Maximum peak intensity; or (b) After the trickle charge in step 2, the IR intensity of the surface of the porous layer that was not in contact with the positive electrode active material layer of the positive electrode during the trickle charge is ATR. -The maximum peak intensity in the range of 1490 to 1530 cm ^-1 as measured by the IR method.
In X2, after the trickle charge in step 2, the IR strength 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, 1490. Maximum peak intensity in the range of ~ 1530 cm ^-1 )
A peak derived from an amide group appears in the range of 1490 to 1530 cm ^-1 . The fact that the aramid resin satisfies the above relationship means that the residual ratio of the amide group of 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 time, the retention rate of the structure of the aramid resin is high. Therefore, it can be said that the laminated separator for a non-aqueous electrolytic solution secondary battery according to the embodiment of the present invention satisfying 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. The portion can be regarded as the surface of the porous layer before the trickle charge is started. Therefore, since the maximum peak intensity of (a) and the maximum peak intensity of (b) of X1 are substantially the same, X1 may be either (a) or (b). not.

As described in (1-2. Step 2), the surface of the porous layer that was in contact with the positive electrode active material layer during trickle charging has undergone a step of daringly promoting deterioration of the porous layer. .. Therefore, when the aramid resin satisfies the relationship of (X2 / X1) × 100 ≧ 80 (%), the laminated separator for a non-aqueous electrolytic solution secondary battery according to the embodiment of the present invention performs the above step. Despite the fact that it has passed, it can be said that it exhibited good resistance to deterioration.

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

As a method of controlling the aramid resin so as to satisfy the above relationship, it can be mentioned that the molecular structure of the aramid resin is controlled so that the aramid resin satisfies the following (i) to (iii).

In the laminated separator for a non-aqueous electrolytic solution secondary battery according to an embodiment of the present invention, the above-mentioned aramid resin has (i) an electron-withdrawing group in an aromatic ring in the main chain, and (ii) a molecule. At least one end of the above is an amino group, and it is preferable that more than 90% of the bonds linking the aromatic rings contained in (iii) the main chain are amide bonds.

When the binder resin contained in the porous layer is an aramid resin, discoloration is likely to occur when used in a high voltage environment, and it tends to be more difficult to maintain heat resistance than the other binder resins described above. 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 above-mentioned non-aqueous electrolytic solution secondary battery using the aramid resin. It has been found that the heat resistance of the laminated separator for plastic use can be greatly improved.

The main chain of the aramid resin is, for example, the structure shown in parentheses of the following chemical formula. However, in the following chemical formula, the bond connecting the aromatic rings contained in the main chain is only an amide bond, but the bond is not necessarily limited to this, and more than 90% of the above bonds may be an amide bond. Just do it. Examples of the other bonds include ether bonds, sulfonyl bonds and the like.

The ratio of the amide bond to the above bonds is more preferably 95% or more, and most preferably 100%. Further, it is preferable that the aramid resin does not have an ether bond as a bond for connecting the aromatic rings contained in the main chain.

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

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 generally distributed 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 aromatic rings at the end of the molecule has an amino group.

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

In the above-mentioned aramid resin, (iv) 40% or more of the units derived from aromatic diamines have electron-withdrawing groups, and (v) 20% or less of the units derived from acid chloride have electron-withdrawing groups. It is preferable to do so.

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

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

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

When the above-mentioned aramid resin satisfies the above-mentioned (iv) and (v), the area of the opening tends to be smaller when the above-mentioned heat resistance test is imposed, which is preferable.

The aramid resin satisfying the above (iv) and (v) in addition to the above (i) to (iii) is the ratio of the aromatic diamine and the acid chloride having an electron-withdrawing group in the aromatic diamine and the acid chloride which are the raw materials. Can be manufactured by controlling.

The laminated separator for a non-aqueous electrolytic solution secondary battery according to an embodiment of the present invention has an intrinsic viscosity of the aramid resin of 1.4 to 4.0 dL / g from the viewpoint of improving the heat resistance of the porous layer. It is preferable to have. 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. As a method of controlling the intrinsic viscosity, a method of controlling the charging ratio of the monomer at the time of polymerization of the aramid resin can be mentioned.

(3. Manufacture of laminated separators for non-aqueous electrolyte secondary batteries)
The laminated separator for a non-aqueous electrolytic solution secondary battery according to an embodiment of the present invention includes a step of laminating a coating liquid containing the above-mentioned binder resin and filler on one or both sides of a polyolefin porous film, and the above-mentioned coating. It can be produced by a method including a step of removing a solvent in a liquid.

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

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

The step of laminating the coating liquid can be performed by laminating the coating liquid on one side 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 (base material), and a laminated separator for a non-aqueous electrolytic solution secondary battery can be obtained.

The removal of the solvent can also be performed by, for example, the following method.

(1) After applying the above composition to one side or both sides of the base material, the base material is immersed in a precipitation solvent which is a poor solvent for the binder resin to precipitate the binder and form a porous layer. After formation, it is dried and the solvent is removed.

(2) After applying the above composition to one side or both sides of the base material, a binder resin is precipitated using a low boiling point solvent, a porous layer is formed, and then the mixture is dried to remove the solvent.

As the precipitation solvent, for example, water, ethyl alcohol, isopropyl alcohol, acetone and the like can be used.

The porous film contains polyolefin as a main component and has a large number of pores connected to the inside thereof, so that gas and liquid can pass from one surface to the other. The porous film serves as a base material for the laminate on which the porous layer is formed. The porous layer has a large number of pores inside and has a structure in which these pores are connected, so that gas or liquid can pass from one surface to the other. ..

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

Further, it is more preferable that the polyolefin contains a high molecular weight component having a weight average molecular weight of ⁵ × 10 ⁵ to 15 × 106. In particular, it is more preferable that the polyolefin contains a high molecular weight component having a weight average molecular weight of 1 million or more because the strength of the laminate is improved.

Examples of the polyolefin include homopolymers or 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. Moreover, as the said copolymer, for example, an ethylene / propylene copolymer can be mentioned.

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

The film thickness of the porous film is preferably 4 to 40 μm, more preferably 5 to 30 μm, and 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, the weight per unit area is preferably 4 to 15 g / m ² so that the weight energy density and the volume energy density of the non-aqueous electrolyte secondary battery can be increased. It is more preferably m ² and even more preferably 5 to 10 g / m ² .

The air permeability of the porous film is preferably 30 to 500 sec / 100 mL in terms of Gale value, and more preferably 50 to 300 sec / 100 mL. When the porous film has the above-mentioned air permeability, sufficient ion permeability can be obtained.

The air permeability of the laminated separator for a non-aqueous electrolytic solution secondary battery according to the embodiment of the present invention is preferably 30 to 1000 sec / 100 mL, more preferably 50 to 800 sec / 100 mL in terms of Gale value. Since the laminated separator for a non-aqueous electrolytic solution secondary battery has the above-mentioned air permeability, sufficient ion permeability can be obtained in the non-aqueous electrolytic solution secondary battery.

The porosity of the porous film is preferably 20 to 80% by volume, preferably 30 to 75%, so that the holding amount of the electrolytic solution can be increased and the excessive current can be reliably prevented from flowing at a lower temperature. More preferably, it is by volume. Further, the pore diameter of the pores of the porous film should be 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 more preferable, 0.14 μm or less is more preferable, and 0.10 μm or less is further preferable.

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

(A) A step of kneading ultra-high molecular weight polyethylene, low molecular weight polyethylene having a weight average molecular weight of 10,000 or less, a pore-forming agent such as calcium carbonate or a plasticizer, and an antioxidant to obtain a polyolefin resin composition.
(B) A step of rolling the obtained polyolefin resin composition with a pair of rolling rollers and gradually cooling the obtained polyolefin resin composition while pulling it with winding rollers having different speed ratios to form a sheet.
(C) A step of removing the pore-forming agent from the obtained sheet with an appropriate solvent.
(D) A step of stretching a 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]
In the member for a non-aqueous electrolytic solution secondary battery according to an embodiment of the present invention, a positive electrode, a laminated separator for a non-aqueous electrolytic solution secondary battery according to an embodiment of the present invention, and a negative electrode are laminated in this order. There is.

Since the non-aqueous electrolyte secondary battery member includes the laminated separator for the non-aqueous electrolyte secondary battery, the non-aqueous electrolyte secondary battery incorporating the non-aqueous electrolyte secondary battery member has 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 electrolytic solution secondary battery, and the negative electrode are as described in the first embodiment. The non-aqueous electrolytic solution secondary battery member can be manufactured by laminating a positive electrode, a laminated separator for a non-aqueous electrolytic solution secondary battery according to an 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 the material include a lithium composite oxide containing at least one transition metal such as V, Ti, Cr, Mn, Fe, Co, Ni, and Cu. Examples of the lithium composite oxide include a solid solution lithium-containing transition metal oxidation composed of a lithium composite oxide having a layered structure, a lithium composite oxide having a spinel structure, and a lithium composite oxide having both a layered structure and a spinel structure. Things can be mentioned. Further, a lithium cobalt composite oxide and a lithium nickel composite oxide can also be mentioned. 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 substituted with other elements.

The lithium composite oxide obtained by substituting a part of the transition metal atom which is the main component of the lithium composite oxide with another element is, for example, a lithium cobalt composite oxide having a layered structure represented by the following formula (2), the following. Lithium-nickel composite oxide represented by the formula (3), lithium manganese composite oxide having a spinel structure represented by the following formula (4), solid solution lithium-containing transition metal oxide represented by the following formula (5), etc. Can be mentioned.

Li [Li _x (Co _1-a M ¹ _a ) _1-x ] O ₂ ... (2)
(In the 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 It is at least one metal selected from the group consisting of W and satisfies −0.1 ≦ x ≦ 0.30, 0 ≦ a ≦ 0.5).
Li [Li _y (Ni _1-b M ² _b ) _1-y ] O ₂ ... (3)
(In the formula (3), M ² is Na, K, B, F, Al, Ti, V, Cr, Mn, Fe, Co, Cu, Zn, Mg, Ga, Zr, Si, Nb, Mo, Sn and It is at least one metal selected from the group consisting of W and satisfies −0.1 ≦ y ≦ 0.30, 0 ≦ b ≦ 0.5).
Li _z Mn _2-c M ³ _c O ₄ ... (4)
(In the formula (4), M ³ is Na, K, B, F, Al, Ti, V, Cr, Fe, Co, Ni, Cu, Zn, Mg, Ga, Zr, Si, Nb, Mo, Sn and It is at least one metal selected from the group consisting of W and satisfies 0.9 ≦ z and 0 ≦ c ≦ 1.5.)
Li _{1 + w} M ⁴ _d M ⁵ _e O ₂ ... (5)
(In the formula (5), M ⁴ and M ⁵ 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, w + d + e = 1)
Specific examples of the lithium composite oxide represented by the above formulas (2) to (5) include LiCoO ₂ , LiNiO ₂ , LiMnO ₂ , LiNi _0.8 Co _0.2 O ₂ , and LiNi _0.5 Mn _{0. 5} O ₂ , LiNi _0.85 Co _0.10 Al _0.05 O ₂ , LiNi _0.8 Co _0.15 Al _0.05 O ₂ , LiNi _0.5 Co _0.2 Mn _0.3 O ₂ , LiNi _0.6 Co _0.2 Mn _0.2 O ₂ , LiNi _0.33 Co _0.33 Mn _0.33 O ₂ , LiMn ₂ O ₄ , LiMn _1.5 Ni _0.5 O ₄ , LiMn _1.5 Fe _0.5 O ₄ , LiCoMnO ₄ , Li _1.21 Ni _0.20 Mn _0.59 O ₂ , Li _1.22 Ni _0.20 Mn _0.58 O ₂ , Li _1.22 Ni _0.15 Co _0. Examples thereof include ₁₀ Mn _0.53 O ₂ , Li _1.07 Ni _0.35 Co _0.08 Mn _0.50 O ₂ , Li _1.07 Ni _0.36 Co _0.08 Mn _0.49 O ₂ .

Further, 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 a lithium composite oxide include LiNiVO ₄ , LiV ₃ O ₆ , Li _1.2 Fe _0.4 Mn _0.4 O ₂ , and the like.

Examples of materials other than the lithium composite oxide that can be preferably used as the positive electrode active material include phosphate having an olivine-type structure, and phosphoric acid having an olivine-type structure represented by the following formula (6). Salt is mentioned.

Li _v (M ⁶ _f M ⁷ _g M ⁸ _h M ⁹ _i ) _j PO ₄ ... (6)
(In formula (6), M ⁶ is Mn, Co, or Ni, M ⁷ is Ti, V, Cr, Mn, Fe, Co, Ni, Zr, Nb, or Mo, and M ⁸ is. , VIA and VIIA elements are arbitrarily excluded from the transition metal or typical element, and M ⁹ is a transition metal or typical element from which the VIA and VIIA elements are arbitrarily excluded, 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 particles of the lithium metal composite oxide constituting the positive electrode active material. Examples of the material constituting the coating layer include metal composite oxides, metal salts, boron-containing compounds, nitrogen-containing compounds, silicon-containing compounds, sulfur-containing compounds, and the like, and among these, the metal composite oxide is preferably used. Be done.

As the metal composite oxide, an oxide having lithium ion conductivity is preferably used. As such a metal composite oxide, for example, at least one selected from the group consisting of Li and Nb, Ge, Si, P, Al, W, Ta, Ti, S, Zr, Zn, V and B. A metal composite oxide with an element can be mentioned. When the positive electrode active material has a coating layer, the coating layer can suppress side reactions at the interface between the positive electrode active material and the electrolyte under high voltage, and can realize a long life of the obtained secondary battery. Further, it is possible to suppress the formation of a high resistance layer at the interface between the positive electrode active material and the electrolyte, and to realize high output of the obtained secondary battery.

<Non-water electrolyte>
As the non-aqueous electrolyte solution, for example, a non-aqueous electrolyte solution obtained by dissolving a lithium salt in an organic solvent can be used. Lithium salts include LiClO ₄ , LiPF ₆ , LiAsF ₆ , LiSbF ₆ , LiBF ₄ , LiSO ₃ F, LiCF ₃ SO ₃ , LiN (SO ₂ CF ₃ ) ₂ , LiN (SO ₂ C ₂ F ₅ ) ₂ , LiN. (SO ₂ CF ₃ ) (COCF ₃ ), Li (C ₄ F ₉ SO ₃ ), LiC (SO ₂ CF ₃ ) ₃ , Li ₂ B ₁₀ Cl ₁₀ , LiBOB (where BOB is bis (oxalato) boronate) ), Lower aliphatic carboxylic acid lithium salt, LiAlCl ₄ and the like. These may be used alone or as a mixture of two or more. Among them, the lithium salt is composed of 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 the organic solvent 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, 2-methyltetraoxide; Esters such as methyl formate, methyl acetate, γ-butyrolactone; nitriles such as acetonitrile and butyronitrile; amides such as N, N-dimethylformamide, N, N-dimethylacetamide; carbamates such as 3-methyl-2-oxazolidone. Class: Sulfur-containing compounds such as sulfolane, dimethylsulfoxide, 1,3-propanesartone, or those in which a fluoro group is further introduced into these organic solvents (one or more of the hydrogen atoms of the organic solvent are replaced with fluorine atoms). Things) can be used.

As the organic solvent, it is preferable to use a mixture of two or more of these. Of these, a mixed solvent containing carbonates is preferable, and a mixed solvent of cyclic carbonate and acyclic carbonate and a mixed solvent of cyclic carbonate and ethers are more preferable. As the mixed solvent of the cyclic carbonate and the acyclic carbonate, a mixed solvent containing ethylene carbonate, dimethyl carbonate and ethyl methyl carbonate is preferable. A non-aqueous electrolytic solution using such a mixed solvent has a wide operating temperature range, is not easily deteriorated even when used at a high voltage, is not easily deteriorated even when used for a long time, and is made of natural graphite as an active material for a negative electrode. It has the advantage of being persistently decomposable even when a graphite material such as artificial graphite is used.

Further, as the non-aqueous electrolyte solution, in order to enhance the safety of the obtained non-aqueous electrolyte secondary battery, a non-aqueous electrolyte solution containing a lithium salt containing fluorine such as LiPF ₆ and an organic solvent having a fluorine substituent should be used. Is preferable. A mixed solvent containing ethers having a fluorine substituent 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, alloys, and materials capable of doping and dedoping lithium ions at a lower potential than the positive electrode. Can be mentioned.

Examples of the carbon material 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 calcined organic polymer compounds.

Examples of the oxide that can be used as the negative electrode active material include an oxide of silicon represented by the _formula SiO _x (where _x is a positive real number) such as SiO ₂ , SiO; Titanium oxide represented by (where x is a positive real number); V ₂ O ₅ , VO ₂ , etc. Formula V _x Oy (where x and _y are positive real numbers) of vanadium Oxide; Fe ₃ O ₄ , Fe ₂ O ₃ , FeO, etc. Formula Fe x Oy (where x and y are positive real numbers), iron oxide represented by the formula Fe _x O _y (where _x and y are positive real numbers); SnO ₂ , SnO, etc. Here, x is an oxide of tin represented by a positive real number); an oxide of tungsten represented by the general formula WO _x (where x is a positive real number) such as WO ₃ and WO ₂ ; Li ₄ Ti. ₅ O ₁₂ , a composite metal oxide containing lithium such as LiVO ₂ and titanium or vanadium; and the like.

Examples of the sulfide that can be used as the negative electrode active material include Titanium sulfide represented by the formula Ti _x S _y (where x and y are positive real numbers) such as Ti ₂ S ₃ , TiS ₂ , and TiS; V ₃ S ₄ , VS ₂ , VS, etc. Formula VS _x (where x is a positive real number), vanadium sulfide; Fe ₃ S ₄ , FeS ₂ , Fe S, etc. Formula Fe _x S _y (here, x is a positive real number) , X and y are positive real numbers); Sulfide of molybdenum represented by the formula Mo _x S _y (where x and y are positive real numbers) such as Mo ₂ S ₃ and Mo S ₂ . Object; Sulfide of tin represented by the formula SnS _x (where x is a positive real number) such as SnS ₂ , SnS; tungsten represented by the formula WS _x (where x is a positive real number) such as WS ₂ . Sulfide of Sb ₂ S ₃ etc. Antimony sulfide represented by the formula Sb _x S _y (where x and y are positive real numbers); the formula Se _x S _y such as Se ₅ S ₃ , Se S ₂ , Se S and the like. (Here, x and y are positive real numbers), a sulphide of selenium; can be mentioned.

Nitridees that can be used as the negative electrode active material include, for example, Li ₃ N, Li _3-x A _x N (where A is either or both of Ni and Co, and 0 <x <3. ) And the like can be mentioned.

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

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

Further, a composite material containing Si or Sn as the first constituent element and the second and third constituent elements in addition thereof may 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 high battery capacity and excellent battery characteristics can be obtained, as the metal material, silicon or tin alone (may contain a trace amount of impurities), SiO _v (0 <v ≦ 2), SnO _w (0). ≦ w ≦ 2), Si—Co—C composite material, Si—Ni—C composite material, Sn—Co—C composite material, Sn—Ni—C composite material are preferable.

The non-aqueous electrolytic solution secondary battery according to the embodiment of the present invention is the laminated separator for the non-aqueous electrolytic solution secondary battery according to the embodiment of the present invention, or the non-aqueous electrolytic solution according to the embodiment of the present invention. It is equipped with a member for a secondary battery.

As a method for manufacturing the non-aqueous electrolyte secondary battery, for example, after forming a member for the non-aqueous electrolyte secondary battery by the above method, the non-aqueous electrolyte secondary battery is placed in a container which is a housing of the non-aqueous electrolyte secondary battery. A method of inserting a member for a water electrolytic solution secondary battery, then filling the inside of the container with a non-aqueous electrolytic solution, and then sealing the container while reducing the pressure can be mentioned.

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

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

<Test method>
(1. Heat resistance test)
(1-1. Positive electrode of test battery)
_The positive electrode contains LiNi _0.5 Co _0.2 Mn _0.3 O 292 parts by weight, which is 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. An electrode hoop of / ^cm3 was purchased from Yayama Co., Ltd. and used.

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

(1-3. Preparation of test battery)
In the laminated pouch, the porous layer of the laminated separator for a non-aqueous electrolytic solution secondary battery prepared in Examples and Comparative Examples described later is in contact with the positive electrode active material layer of the positive electrode, and the non-aqueous electrolysis is performed. The positive electrode, the laminated separator for the non-aqueous electrolytic solution secondary battery, and the negative electrode are laminated in this order so 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. By arranging), a member for a non-aqueous electrolyte secondary battery was obtained.

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 activity in the positive electrode. The positive electrode and the negative electrode were arranged so as to be in contact with the portion where the material layer was not formed. As a result, the portion of the surface of the porous layer that does not come into contact with the surface of the positive electrode active material layer was arranged so as to surround the positive electrode active material layer in a frame shape.

Subsequently, the non-aqueous electrolytic solution secondary battery member was placed in a bag in which an aluminum layer and a heat seal layer were laminated, and 230 μL of the non-aqueous electrolytic solution was further contained in this bag. The non-aqueous electrolyte solution was prepared by dissolving LiPF ₆ in a mixed solvent prepared by mixing ethylene carbonate, ethyl methyl carbonate, and diethyl carbonate at a ratio of 3: 5: 2 (volume ratio) so as to be 1 mol / L. ..

Then, the non-aqueous electrolyte secondary battery was produced by heat-sealing the bag while reducing the pressure inside the bag.

(1-4. Trickle charge)
For the non-aqueous electrolyte secondary battery produced by using the laminated separator for the non-aqueous electrolyte secondary battery prepared in Examples and Comparative Examples, a charge / discharge test device manufactured by Toyo System Co., Ltd. was used at 25 ° C. and 1C. After constant current charging to 4.5V (ie 4.6V (vs Li / Li ⁺ )) with the current of, under the conditions of 25 ° C. and 4.5V (ie 4.6V (vs Li / Li ⁺ )). Trickle charge was imposed for 168 hours.

After the trickle charge is completed, the test battery is disassembled, the laminated separator for the non-aqueous electrolyte secondary battery is taken out, and the color of the surface of the porous layer before the trickle charge and the positive electrode active material layer after the trickle charge are obtained. 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 the first embodiment, using the solder test apparatus shown in FIG. 1, a metal core having a diameter of 2.2 mm at 450 ° C. is subjected to the trickle charge of the laminated separator for a non-aqueous electrolytic solution secondary battery. , Penetrated from the porous layer side that was in contact with the positive electrode active material layer. The time from when the tip of the metal core came into contact with the surface of the porous layer until the tip was separated from the surface was 10 seconds. After the completion of the metal core penetration test, the area of the opening of the laminated separator for the non-aqueous electrolytic solution secondary battery was determined. The area of the opening was measured using the digital microscope VHX-5000 manufactured by KEYENCE CORPORATION and the attached image analysis software.

(2. Measurement of IR intensity)
The IR strength of the surface of the porous layer of the laminated separator for a non-aqueous electrolyte secondary battery prepared in Examples and Comparative Examples was measured by the ATR-IR method, and the maximum peak strength (X1) in the range of 1490 to 1530 cm ^-1 . Asked. As a device, Agilent's Cary600
FTIR was used.

Further, regarding the laminated separator for a non-aqueous electrolyte secondary battery taken out from the disassembled test battery after the trickle charge is completed, the IR strength of the surface of the porous layer that was in contact with the positive electrode active material layer was determined. The maximum peak intensity (X2) in the range of 1490 to 1530 cm ^-1 was determined by measurement by the ATR-IR method. Further, a value of (X2 / X1) × 100 was calculated.

[Example 1]
(1. Preparation of coating liquid)
A 500 mL separable flask with a stirring blade, thermometer, nitrogen inflow tube and powder addition port was used. After sufficiently drying by flowing nitrogen into the flask, 409.2 g of N-methyl-2-pyrrolidone (hereinafter abbreviated as NMP) as an organic solvent is added to the flask, and calcium chloride (hereinafter abbreviated as NMP) is added as a chloride. 30.8 g) was added (used after vacuum drying at 200 ° C. for 2 hours), and the temperature was raised to 100 ° C. to completely dissolve calcium chloride. Then, 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 completely dissolved. While stirring while maintaining the temperature of this solution at 20 ± 2 ° C., 25.19 g of terephthalic acid dichloride (hereinafter abbreviated as TPC) as an acid chloride was added.

By the above method, 100 of bonds having 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 connecting the aromatic rings contained in the main chain. % Is an amide bond, 100% of the aromatic diamine-derived unit has an electron-withdrawing group, the acid chloride-derived unit has no electron-withdrawing group, and the intrinsic viscosity is 2.28 dL / g. The aramid resin 1 was obtained.

To the obtained solution of aramid resin 1, 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. Subsequently, NMP was added to the solution and diluted to prepare a coating liquid 1 in which the total concentration of the aramid resin 1 and the filler was 6% by weight. At this time, since the content of the filler in the porous layer is 66% by weight, the content of the filler is 66% by weight when the weight of the aramid resin 1 and the filler is 100% by weight. The resin 1, the filler and the solvent were mixed to obtain a coating liquid 1.

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

(3. Heat resistance test, etc.)
The laminated separator 1 for a non-aqueous electrolytic solution secondary battery was subjected to the test described in the above <test method>. The results are shown in Tables 1 and 2.

[Example 2]
(1. Preparation of coating liquid)
By the same method as in Example 1 except that the amount of 2-chloro-1,4-phenylenediamine added as an aromatic diamine was 7.46 g and the amount of TPC added as an acid chloride was 10.30 g. , Aramid resin 2 was obtained. The 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 contained in the main chain. Is an amide bond, 100% of the aromatic diamine-derived units have an electron-withdrawing group, the acid chloride-derived unit has no electron-withdrawing group, and the intrinsic viscosity is 1.47 dL / g. there were.

To the obtained solution of the aramid resin 2, 100 parts by weight of an alumina powder having an average particle size of 0.02 μm and 100 parts by weight of an alumina powder having an average particle size of 0.7 μm were added. Subsequently, NMP was added to the solution and diluted to prepare a coating liquid 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, the content of the filler is 66% by weight when the weight of the aramid resin 2 and the filler is 100% by weight. The resin 2, the filler and the solvent were mixed to obtain a 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 electrolytic solution secondary battery was obtained in the same manner as in Example 1 except that the coating liquid 2 was used instead of the coating liquid 1, and the test described in the above <test method> was performed. Served. The results are shown in Tables 1 and 2.

[Example 3]
(1. Preparation of coating liquid)
By the same method as in Example 1 except that the amount of 2-chloro-1,4-phenylenediamine added as an aromatic diamine was 2.49 g and the amount of TPC added as an acid chloride was 3.51 g. , Aramid resin 3 was obtained. The 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 contained in the main chain. Is an amide bond, 100% of the aromatic diamine-derived units have an electron-withdrawing group, the acid chloride-derived unit has no electron-withdrawing group, and the intrinsic viscosity is 3.85 dL / g. there were.

To the obtained solution of aramid resin 3, 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. Subsequently, NMP was added to the solution and diluted to prepare a coating liquid 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, the content of the filler is 66% by weight when the weight of the aramid resin 3 and the filler is 100% by weight. The resin 3, the filler and the solvent were mixed to obtain a coating liquid 3.

(2. Preparation of laminated separator for non-aqueous electrolyte secondary battery, heat resistance test, etc.)
A laminated separator 3 for a non-aqueous electrolytic solution secondary battery was obtained in the same manner as in Example 1 except that the coating liquid 3 was used instead of the coating liquid 1, and the test described in the above <test method> was performed. Served. The results are shown in Tables 1 and 2.

[Example 4]
(1. Preparation of coating liquid)
By the same method as in Example 1 except that the amount of 2-cyano-1,4-phenylenediamine added as an aromatic diamine was 5.40 g and the amount of TPC added as an acid chloride was 8.15 g. An aramid resin 4 was obtained. The 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 contained in the main chain. Is an amide bond, 100% of the aromatic diamine-derived units have an electron-withdrawing group, the acid chloride-derived unit has no electron-withdrawing group, and the intrinsic viscosity is 2.62 dL / g. there were.

To the obtained solution of the aramid resin 4, 100 parts by weight of an alumina powder having an average particle size of 0.02 μm and 100 parts by weight of an alumina powder having an average particle size of 0.7 μm were added. Subsequently, NMP was added to the solution and diluted to prepare a coating liquid 4 in which the total concentration of the aramid resin 4 and the filler was 3.00% by weight. At this time, since the content of the filler in the porous layer is 66% by weight, the content of the filler is 66% by weight when the weight of the aramid resin 4 and the filler is 100% by weight. The resin 4, the filler and the solvent were mixed to obtain a coating liquid 4.

(2. Preparation of laminated separator for non-aqueous electrolyte secondary battery, heat resistance test, etc.)
A laminated separator 4 for a non-aqueous electrolytic solution secondary battery was obtained in the same manner as in Example 1 except that the coating liquid 4 was used instead of the coating liquid 1, and the test described in the above <test method> was performed. Served. The results are shown in Tables 1 and 2.

[Example 5]
(1. Preparation of coating liquid)
The amount of 2-chloro-1,4-phenylenediamine added as an aromatic diamine was 5.53 g, the amount of para-phenylenediamine added was 5.53 g, and the amount of TPC added as an acid chloride was 9.38 g. The aramid resin 5 was obtained by the same method as in Example 1 except for the above. The 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 contained in the main chain. Is an amide bond, 75% of the aromatic diamine-derived units have an electron-withdrawing group, the acid chloride-derived unit has no electron-withdrawing group, and the intrinsic viscosity is 1.55 dL / g. there were.

To the obtained solution of the aramid resin 5, 100 parts by weight each of an alumina powder having an average particle size of 0.02 μm and an alumina powder having an average particle size of 0.7 μm were added. Subsequently, NMP was added to the solution and diluted to prepare a coating liquid 5 having a total concentration of the aramid resin 5 and the filler of 2.21% by weight. At this time, since the content of the filler in the porous layer is 66% by weight, the content of the filler is 66% by weight when the weight of the aramid resin 5 and the filler is 100% by weight. The resin 5, the filler and the solvent were mixed to obtain a coating liquid 5.

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

[Example 6]
(1. Preparation of coating liquid)
The amount of 2-chloro-1,4-phenylenediamine added as an aromatic diamine was 3.72 g, the amount of para-phenylenediamine added was 2.81 g, and the amount of TPC added as an acid chloride was 10.48 g. The aramid resin 6 was obtained by the same method as in Example 1 except for the above. The 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 contained in the main chain. Is an amide bond, 50% of the aromatic diamine-derived units have an electron-withdrawing group, the acid chloride-derived unit has no electron-withdrawing group, and the intrinsic viscosity is 3.67 dL / g. there were.

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

(2. Preparation of laminated separator for non-aqueous electrolyte secondary battery, heat resistance test, etc.)
A laminated separator 6 for a non-aqueous electrolytic solution 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. Served. The results are shown in Tables 1 and 2.

[Example 7]
(1. Preparation of coating liquid)
By the same method as in Example 1 except that the amount of 2-chloro-1,4-phenylenediamine added as an aromatic diamine was 84.83 g and the amount of TPC added as an acid chloride was 117.05 g. , Aramid resin 7 was obtained. The 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 contained in the main chain. Is an amide bond, 100% of the aromatic diamine-derived units have an electron-withdrawing group, the acid chloride-derived unit has no 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, NMP was added to the solution to dilute it to prepare a coating liquid 7 having a total concentration of the aramid resin 7 and the filler of 4.00% by weight. At this time, since the content of the filler in the porous layer is 50% by weight, the content of the filler is 50% by weight when the weight of the aramid resin 7 and the filler is 100% by weight. The resin 7, the filler and the solvent were mixed to obtain a coating liquid 7.

(2. Preparation of laminated separator for non-aqueous electrolyte secondary battery, heat resistance test, etc.)
A laminated separator 7 for a non-aqueous electrolytic solution secondary battery was obtained in the same manner as in Example 1 except that the coating liquid 7 was used instead of the coating liquid 1, and the test described in the above <test method> was performed. Served. The results are shown in Tables 1 and 2.

[Example 8]
(1. Preparation of coating liquid)
The amount of 2-chloro-1,4-phenylenediamine added as an aromatic diamine was 6.98 g, the amount of para-phenylenediamine added was 5.15 g, and the amount of TPC added as an acid chloride was 19.06 g. The aramid resin 8 was obtained by the same method as in Example 1 except for the above. The 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 contained in the main chain. Is an amide bond, 50% of the aromatic diamine-derived units have an electron-withdrawing group, the acid chloride-derived unit has no 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, NMP was added to the solution to dilute it to prepare a coating liquid 8 having a total concentration of the aramid resin 8 and the filler of 3.00% by weight. At this time, since the content of the filler in the porous layer is 40% by weight, the content of the filler is 40% by weight when the weight of the aramid resin 8 and the filler is 100% by weight. The resin 8, the filler and the solvent were mixed to obtain a coating liquid 8.

(2. Preparation of laminated separator for non-aqueous electrolyte secondary battery, heat resistance test, etc.)
A laminated separator 8 for a non-aqueous electrolytic solution 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. Served. The results are shown in Tables 1 and 2.

[Comparative Example 1]
(1. Preparation of coating liquid)
The amount of 2-chloro-1,4-phenylenediamine added as an aromatic diamine was 3.72 g, the amount of para-phenylenediamine added was 2.79 g, and the amount of TPC added as an acid chloride was 9.45 g. Aramid resin 1 for comparison was obtained by the same method as in Example 1 except for the above. The 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 contained in the main chain. 100% is an amide bond, 50% of the aromatic diamine-derived units have an electron-withdrawing group, the acid chloride-derived unit has no electron-withdrawing group, and the intrinsic viscosity is 1.10 dL /. It was g.

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

(2. Preparation of laminated separator for non-aqueous electrolyte secondary battery, heat resistance test, etc.)
A laminated separator 1 for a comparative non-aqueous electrolytic solution 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, and the above <test method> was applied. It was subjected to the described test. The results are shown in Tables 1 and 2.

[Comparative Example 2]
(1. Preparation of coating liquid)
Except that the amount of 2-chloro-1,4-phenylenediamine added as an aromatic diamine was 1.86 g, the amount of para-phenylenediamine added was 4.24 g, and the TPC as an acid chloride was 9.50 g. A comparative aramid resin 2 was obtained by the same method as in Example 1. The 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 contained in the main chain. 100% are amide bonds, 25% of aromatic diamine-derived units have electron-withdrawing groups, acid chloride-derived units do not have electron-withdrawing groups, and the intrinsic viscosity is 0.66 dL / It was g.

To the obtained solution of the comparative aramid resin 2, 100 parts by weight of an alumina powder having an average particle size of 0.02 μm and 100 parts by weight of an alumina powder having an average particle size of 0.7 μm were added. Subsequently, NMP was added to the solution to dilute it to prepare a comparative coating liquid 2 in which the total concentration of the comparative aramid resin 2 and the filler was 4.51% by weight. At this time, since the content of the filler in the porous layer is 66% by weight, the content of the filler is 66% by weight when the weights of the comparative aramid resin 2 and the filler are 100% by weight. , The comparative aramid resin 2, the filler and the solvent were mixed to obtain a comparative coating liquid 2.

(2. Preparation of laminated separator for non-aqueous electrolyte secondary battery, heat resistance test, etc.)
A laminated separator 2 for a comparative non-aqueous electrolytic solution 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, and the above <test method> was applied. It was subjected to the described test. The results are shown in Tables 1 and 2.

[Comparative Example 3]
The aromatic ring in the main chain does not have an electron-withdrawing group, has amino groups at both ends of the molecule, and 100% of the bonds connecting the aromatic rings contained in the main chain are amide bonds, which are aromatic. A comparative aramid resin 3 having a group diamine-derived unit having no electron-withdrawing group, an acid chloride-derived unit having no electron-withdrawing group, and 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 the comparative aramid resin 3. Subsequently, NMP was added to the solution and diluted to prepare a comparative coating liquid 3. At this time, since the content of the filler in the porous layer is 90% by weight, the content of the filler is 90% by weight when the weights of the comparative aramid resin 3 and the filler are 100% by weight. , The comparative aramid resin 3, the filler and the solvent were mixed to obtain a comparative coating liquid 3.

(2. Preparation of laminated separator for non-aqueous electrolyte secondary battery, heat resistance test, etc.)
A laminated separator 3 for a comparative non-aqueous electrolytic solution 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, and the above <test method> was applied. It was subjected to the described test. The results are shown in Tables 1 and 2.

[Comparative Example 4]
(1. Preparation of coating liquid)
By the same method as in Example 1 except that the amount of 2-chloro-1,4-phenylenediamine added as an aromatic diamine was 7.44 g and the amount of TPC added as an acid chloride was 10.29 g. A comparative aramid resin 4 was obtained. The 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 contained in the main chain. 100% is an amide bond, 100% of the aromatic diamine-derived unit has an electron-withdrawing group, the acid chloride-derived unit has no electron-withdrawing group, and the intrinsic viscosity is 2.40 dL /. It was g.

Alumina powder having an average particle size of 0.7 μm was added to the obtained solution of the comparative aramid resin 4. Subsequently, NMP was added to the solution and diluted to prepare a comparative coating liquid 4. At this time, since the content of the filler in the porous layer is 90% by weight, the content of the filler is 90% by weight when the weights of the comparative aramid resin 4 and the filler are 100% by weight. , The comparative aramid resin 4, the filler and the solvent were mixed to obtain a comparative coating liquid 4.

(2. Preparation of laminated separator for non-aqueous electrolyte secondary battery, heat resistance test, etc.)
A laminated separator 4 for a comparative non-aqueous electrolytic solution 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, and the above <test method> was applied. It was subjected to the described test. The results are shown in Tables 1 and 2.

[Comparative Example 5]
(1. Preparation of coating liquid)
Except for the fact that the amount of para-phenylenediamine added as an aromatic diamine was 13.25 g, the amount of TPC added as an acid chloride was 24.27 g, and the last addition of benzoyl chloride for end sealing was 5.09 g. Obtained a comparative aramid resin 5 by the same method as in Example 1. The comparative aramid resin 5 has no electron-withdrawing group in the aromatic ring in the main chain, does not have amino groups at both ends of the molecule, and has 100 bonds connecting the aromatic rings contained in the main chain. % Is an amide bond, the aromatic diamine-derived unit has no electron-withdrawing group, the acid chloride-derived unit has no electron-withdrawing group, and the intrinsic viscosity is 1.78 dL / g. rice field.

To the obtained solution of the comparative aramid resin 5, 100 parts by weight of an alumina powder having an average particle size of 0.02 μm and 100 parts by weight of an alumina powder having an average particle size of 0.7 μm were added. Subsequently, NMP was added to the solution and diluted 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, since the content of the filler in the porous layer is 66% by weight, the content of the filler is 66% by weight when the weights of the comparative aramid resin 5 and the filler are 100% by weight. , The comparative aramid resin 5, the filler and the 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 electrolytic solution 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 applied. It was subjected to the described test. The results are shown in Tables 1 and 2.

[Comparative Example 6]
(1. Preparation of coating liquid)
Except for the fact that the amount of para-phenylenediamine added as an aromatic diamine was 12.77 g, the amount of TPC added as an acid chloride was 24.71 g, and 0.85 g of 4-aminobenzonitrile was used as the terminal encapsulating aniline. Obtained a comparative aramid resin 6 by the same method as in Example 1. The comparative aramid resin 6 has no electron-withdrawing group in the aromatic ring in the main chain, does not have amino groups at both ends of the molecule, and has 100 bonds connecting the aromatic rings contained in the main chain. % Is an amide bond, the aromatic diamine-derived unit has no electron-withdrawing group, the acid chloride-derived unit has no electron-withdrawing group, and the intrinsic viscosity is 0.73 dL / g. rice field.

To the obtained solution of the comparative aramid resin 6, 100 parts by weight of an alumina powder having an average particle size of 0.02 μm and 100 parts by weight of an alumina powder having an average particle size of 0.7 μm were added. Subsequently, NMP was added to the solution and diluted to prepare a comparative coating liquid 6 in which the total concentration of the comparative aramid resin 6 and the filler was 6.0% by weight. At this time, since the content of the filler in the porous layer is 66% by weight, the content of the filler is 66% by weight when the weights of the comparative aramid resin 6 and the filler are 100% by weight. , The comparative aramid resin 6, the filler and the 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 electrolytic solution 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, and the above <test method> was applied. It was subjected to the described test. The results are shown in Tables 1 and 2.

[Comparative Example 7]
(1. Preparation of coating liquid)
The amount of 2-chloro-1,4-phenylenediamine added as an aromatic diamine was 1.87 g, the amount of para-phenylenediamine added was 4.22 g, and the amount of TPC added as an acid chloride was 10.51 g. Aramid resin 7 for comparison was obtained by the same method as in Example 1 except for the above. The 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 contained in the main chain. 100% are amide bonds, 25% of aromatic diamine-derived units have electron-withdrawing groups, acid chloride-derived units do not have electron-withdrawing groups, and the intrinsic viscosity is 3.55 dL / It was g.

To the obtained solution of the comparative aramid resin 7, 100 parts by weight of an alumina powder having an average particle size of 0.02 μm and 100 parts by weight of an alumina powder having an average particle size of 0.7 μm were added. Subsequently, NMP was added to the solution and diluted to prepare a comparative coating liquid 7 having a total concentration of the comparative aramid resin 7 and the filler of 2.21% by weight. At this time, since the content of the filler in the porous layer is 66% by weight, the content of the filler is 66% by weight when the weights of the comparative aramid resin 7 and the filler are 100% by weight. , The comparative aramid resin 7, the filler and the 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 electrolytic solution 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, and the above <test method> was applied. It was subjected to the described test. The results are shown in Tables 1 and 2.

[Comparative Example 8]
(1. Preparation of coating liquid)
Except that the amount of 2-chloro-1,4-phenylenediamine added as an aromatic diamine was 11.20 g, and the amount of 4,4'-oxybis (benzoyl chloride) added as an acid chloride was 10.51 g. Aramid resin 8 for comparison was obtained by the same method as in Example 1. The 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 contained in the main chain. 66% 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 1.50 dL / It was g.

Alumina powder having an average particle size of 0.02 μm was added to the obtained solution of the comparative aramid resin 8. Subsequently, NMP was added to the solution to dilute it to prepare a comparative coating liquid 8 in which the total concentration of the comparative aramid resin 8 and the filler was 6.00% by weight. At this time, since the content of the filler in the porous layer is 50% by weight, the content of the filler is 50% by weight when the weights of the comparative aramid resin 8 and the filler are 100% by weight. , The comparative aramid resin 8, the filler and the 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 electrolytic solution 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, and the above <test method> was applied. It was subjected to the described test. The results are shown in Tables 1 and 2.

[Comparative Example 9]
(1. Preparation of coating liquid)
For comparison, the same method as in Example 1 was used 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. An aramid resin 9 was obtained. The comparative aramid resin 9 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 contained in the main chain. 66% are amide bonds, aromatic diamine-derived units do not have electron-withdrawing groups, acid chloride-derived units do not have electron-withdrawing groups, and the intrinsic viscosity is 1.65 dL / g. there were.

Alumina powder having an average particle size of 0.02 μm was added to the obtained solution of the comparative aramid resin 9. Subsequently, NMP was added to the solution and diluted to prepare a comparative coating liquid 9 in which the total concentration of the comparative aramid resin 9 and the filler was 6.00% by weight. At this time, since the content of the filler in the porous layer is 50% by weight, the content of the filler is 50% by weight when the weights of the comparative aramid resin 9 and the filler are 100% by weight. , The comparative aramid resin 9, the filler and the solvent were mixed to obtain a 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 electrolytic solution 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, and the above <test method> was applied. It was subjected to the described test. The results are shown in Tables 1 and 2.

[Comparative Example 10]
(1. Preparation of coating liquid)
The aramid resin 10 was obtained by the same method as in Example 1 except that the amount of para-phenylenediamine added was 5.15 g and the amount of TPC as an acid chloride was 19.06 g. The 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 contained in the main chain. 100% is an amide bond, 50% of the aromatic diamine-derived units have an electron-withdrawing group, the acid chloride-derived unit has no electron-withdrawing group, and the intrinsic viscosity is 1.90 dL /. It was g.

Alumina powder having an average particle size of 0.02 μm was added to the obtained solution of the aramid resin 10. Subsequently, NMP was added to the solution and diluted to prepare a coating liquid 10 having a total concentration of the aramid resin 10 and the filler of 3.00% by weight. At this time, since the content of the filler in the porous layer is 20% by weight, the content of the filler is 20% by weight when the weight of the aramid resin 10 and the filler is 100% by weight. The resin 10, the filler and the solvent were mixed to obtain a coating liquid 10.

(2. Preparation of laminated separator for non-aqueous electrolyte secondary battery, heat resistance test, etc.)
A laminated separator 10 for a comparative non-aqueous electrolytic solution 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 performed. The results are shown in Tables 1 and 2.

In Table 1, the "main chain aromatic ring electron-withdrawing group" is the type of electron-withdrawing group contained in the aromatic ring in the main chain; and the "diamine unit attraction group content" is derived from the aromatic diamine in the aramid resin. Percentage of units having an electron-withdrawing group; "acid chloride unit withdrawing group content" is the ratio of acid chloride-derived units in the aramid resin having an electron-withdrawing group; "terminal amino group". "Presence / absence" indicates whether or not the aramid resin has an amino group at the molecular terminal (circle indicates that it has, and x indicates that it does not exist); "Aromatic ring-linked amide group ratio" is included in the main chain. The ratio of the bond connecting the aromatic rings having 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 aramid. The intrinsic viscosity of the resin and the "grain" represent the weight per square meter of the laminated separator for a non-aqueous electrolyte secondary battery.

In Table 2, for "discoloration after trickle test", the laminated separator for the non-aqueous electrolyte secondary battery is taken out from the test battery after the trickle charge, and the color of the surface of the porous layer before the trickle charge and the trickle charge are performed. Later, the color of the surface of the porous layer that was in contact with the positive electrode active material layer was visually observed and compared; "IR strength before trickle test", "IR strength after trickle test", "(X2 / "X1) x 100" is X1, X2, (X2 / X1) x 100 described in the above (2. Measurement of IR intensity); "Area of opening" is the above (1-5. Metal core penetration test). Represents the area of the opening of the laminated separator for the non-aqueous electrolytic solution secondary battery described in the above.

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

On the other hand, in each of the laminated separators 1 to 9 for the comparative non-aqueous electrolytic solution secondary battery according to Comparative Examples 1 to 9, the area of the opening after the heat resistance test greatly exceeded 7.0 mm ² . Further, the laminated separator 10 for a comparative non-aqueous electrolytic solution secondary battery according to Comparative Example 10 did not form a suitable porous layer. From the results of Examples and Comparative Examples, a non-aqueous electrolytic solution secondary having excellent heat resistance and deterioration resistance was designed by designing an aromatic polyamide having high oxidation resistance and containing an appropriate amount of heat-resistant filler. It is considered that a laminated separator for a battery can be obtained.

The laminated separator for a non-aqueous electrolytic solution secondary battery according to an embodiment of the present invention can be suitably used in various industries dealing with a non-aqueous electrolytic solution secondary battery.

[Comparative Example 9]
(1. Preparation of coating liquid)
For comparison, the same method as in Example 1 was used 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. An aramid resin 9 was obtained. The 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 66% of the bonds connecting the aromatic rings contained in the main chain. Was an amide bond, the aromatic diamine-derived unit had no electron-withdrawing group, the acid chloride-derived unit had no electron-withdrawing group, and the intrinsic viscosity was 1.65 dL / g. ..

Claims (12)

A laminated separator for a non-aqueous electrolytic solution secondary battery provided with a polyolefin porous film and a porous layer.
The porous layer contains a binder resin and a filler, and 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 the following heat resistance test is imposed:
Step 1. A positive electrode containing a positive electrode active material that can be doped with and dedoped with lithium ions, a laminated separator for the non-aqueous electrolyte secondary battery, and a negative electrode containing a negative electrode active material that can be doped with and dedoped with lithium ions are arranged in this order. Then, the non-aqueous electrolytic solution is impregnated with the laminated body laminated so that the porous layer and the positive electrode active material layer provided in the positive electrode are in contact with each other to prepare a test battery;
Step 2. The test battery was charged to a constant current of 4.6 V (vs Li / Li ⁺ ) at 25 ° C. and 1 C, and then 168 under the conditions of 25 ° C. and 4.6 V (vs Li / Li ⁺ ). Imposing time trickle charge;
Step 3. From the test battery that has undergone step 2, the laminated separator for the non-aqueous electrolytic solution secondary battery is taken out;
Step 4. A metal core having a diameter of 2.2 mm at 450 ° C. is passed through the porous layer side of the laminated separator for a non-aqueous electrolytic solution secondary battery, which is 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 non-aqueous electrolytic solution is prepared by dissolving LiPF ₆ in a mixed solvent prepared by mixing ethylene carbonate, ethylmethyl carbonate, and diethyl carbonate at a ratio of 3: 5: 2 (volume ratio) so as to be 1 mol / L. It is a non-aqueous electrolyte solution. ) The non-aqueous electrolytic solution secondary battery according to claim 1, wherein 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. The above filler is a metal oxide filler and is
The binder resin contains one or more selected from the group consisting of (meth) acrylate-based resin, fluorine-containing resin, polyamide-based resin, polyimide-based resin, polyamide-imide-based resin, polyester-based resin, and water-soluble polymer. , The laminated separator for a non-aqueous electrolyte secondary battery according to claim 1 or 2. The laminated separator for a non-aqueous electrolytic solution secondary battery according to any one of claims 1 to 3, wherein the porous layer contains an aramid resin. The laminated separator for a non-aqueous electrolytic solution secondary battery according to claim 4, wherein the aramid resin contained in the porous layer satisfies the relationship of (X2 / X1) × 100 ≧ 80 (%).
(In the formula, X1 is (a) in the range of 1490 to 1530 cm ^-1 when the IR intensity of the surface of the porous layer is measured by the ATR-IR method before starting the trickle charge in step 2. Maximum peak intensity; or (b) After the trickle charge in step 2, the IR intensity of the surface of the porous layer that was not in contact with the positive electrode active material layer of the positive electrode during the trickle charge is ATR. -The maximum peak intensity in the range of 1490 to 1530 cm ^-1 as measured by the IR method.
X2 is 1490 when the IR strength 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 after the trickle charge in step 2 was measured by the ATR-IR method. Maximum peak intensity in the range of ~ 1530 cm ^-1 ) The above aramid resin is
(I) It has 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 electrolytic solution secondary battery according to claim 4 or 5, wherein more than 90% of the bonds connecting the aromatic rings contained in the main chain are amide bonds. The laminated separator for a non-aqueous electrolytic solution secondary battery according to claim 6, wherein the aramid resin does not have an ether bond as a bond connecting the aromatic rings contained in the main chain. The above aramid resin is
(Iv) More than 40% of the units derived from aromatic diamines have electron-withdrawing groups.
(V) The laminated separator for a non-aqueous electrolyte secondary battery according to claim 6 or 7, wherein 20% or less of the acid chloride-derived units have an electron-withdrawing group. The laminated separator for a non-aqueous electrolytic solution secondary battery according to any one of claims 6 to 8, wherein the electron-withdrawing group is one or more selected from the group consisting of a halogen, a cyano group and a nitro group. .. The laminated separator for a non-aqueous electrolytic solution secondary battery according to any one of claims 4 to 8, wherein the aramid resin has an intrinsic viscosity of 1.4 to 4.0 dL / g. With the positive electrode
The laminated separator for a non-aqueous electrolytic solution secondary battery according to any one of claims 1 to 10.
With the negative electrode
Is a member for a non-aqueous electrolyte secondary battery, which is laminated in this order. Non-aqueous electrolysis comprising the non-aqueous electrolytic solution secondary battery laminated separator according to any one of claims 1 to 10 or the non-aqueous electrolytic solution secondary battery member according to claim 11. Liquid secondary battery.

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