JP2019046587A - Adsorption layer for nonaqueous electrolyte battery, and nonaqueous electrolyte battery separator and nonaqueous electrolyte battery including the same - Google Patents

Abstract

To provide an adsorption layer for a nonaqueous electrolyte battery, capable of providing a nonaqueous electrolyte battery excellent in safety and life characteristics, and a nonaqueous electrolyte battery separator and a nonaqueous electrolyte battery including the adsorption layer for a nonaqueous electrolyte battery.SOLUTION: An adsorption layer for a nonaqueous electrolyte battery includes lithium titanate and an insulating inorganic particle, the insulting inorganic particle being an anion exchanger. A nonaqueous electrolyte battery separator has the adsorption layer for a nonaqueous electrolyte battery at least on one surface thereof, and a nonaqueous electrolyte battery includes the adsorption layer for a nonaqueous electrolyte battery and the nonaqueous electrolyte battery separator.SELECTED DRAWING: None

Description

  The present invention relates to an adsorption layer for a non-aqueous electrolyte battery, a separator for a non-aqueous electrolyte battery using the same, and a non-aqueous electrolyte battery.

  With the recent development of electronic technology or growing interest in environmental technology, various electrochemical devices have been developed. In particular, there are many demands for energy saving, and expectations for electrochemical devices that can contribute to them are increasing.

  A lithium ion secondary battery, which is a typical example of a storage device and is also a typical example of a non-aqueous electrolyte battery, has conventionally been mainly used as a power source for small devices, and in recent years as a power source for hybrid vehicles and electric vehicles It is focused on.

  With lithium ion secondary batteries, with the advancement of devices with higher performance, higher energy density has been developed, and ensuring reliability has become important. In addition, in the case of a medium- or large-sized lithium ion secondary battery such as a vehicle-mounted power source, it is necessary to ensure particularly higher reliability than small-sized devices. Furthermore, as a vehicle-mounted power source, a lithium ion secondary battery capable of maintaining charge and discharge capacity over a long period is required in accordance with a product cycle.

  For example, Patent Document 1 aims to provide a non-aqueous electrolyte secondary battery capable of suppressing deterioration of battery capacity, and is provided with an electrode assembly including a positive electrode and a negative electrode. The electrode body describes a non-aqueous electrolyte secondary battery including a lithium titanate-containing layer disposed between the positive electrode and the negative electrode and spaced apart from the negative electrode. Patent document 2 aims at providing a lithium ion secondary battery etc. which can reduce diffusion resistance and improve the acceptability of lithium, and is formed on the negative electrode main surface facing the negative electrode active material layer of the separator. A lithium ion secondary battery is described, having a LTO conductive layer directly or indirectly conducted to the negative electrode active material layer and containing lithium titanate and a first conductive material.

International Publication No. 2014/020729 JP, 2014-137889, A

In non-aqueous electrolyte batteries, metal ions present or may occur in the system may adversely affect the safety and life characteristics of the battery. For example, in a lithium ion secondary battery, charge and discharge are performed by moving lithium (Li) ions between a positive electrode and a negative electrode. Here, when a trace amount of metal ions other than Li ions, for example, cobalt ions (Co ²⁺ ), nickel ions (Ni ²⁺ ) and manganese ions (Mn ²⁺ ) exist in the battery, these metals are deposited on the negative electrode surface It is known that the battery life may be reduced, or the deposited metal may break the separator to reach the positive electrode, which may cause a short circuit or reduce safety. Such metal ions may generally be derived from impurities of battery constituent materials, and in addition to that, metals contained in battery constituent members such as a positive electrode active material may be non-aqueous due to side reactions in the battery. It may also be derived from elution into the electrolyte. For example, hydrofluoric acid (HF) is generated by a decomposition reaction of a non-aqueous electrolyte or the like, and the metal contained in the positive electrode active material may be eluted by HF. Furthermore, it has been pointed out that the elution of such metals is more pronounced when the cell is exposed to high temperatures.

  One of the problems to be solved by the present invention is to provide an adsorption layer for a non-aqueous electrolyte battery which can provide a non-aqueous electrolyte battery excellent in safety and life characteristics.

The inventors of the present invention conducted extensive studies to solve the above problems, and as a result, it is possible to solve the above problems by using an adsorption layer for a non-aqueous electrolyte battery containing lithium titanate and insulating inorganic particles. It found and came to complete this invention. That is, the present invention is as follows.
[1]
An adsorption layer for a non-aqueous electrolyte battery, comprising lithium titanate and insulating inorganic particles.
[2]
The adsorption layer for non-aqueous electrolyte batteries according to Item 1, wherein the insulating inorganic particle is an anion exchanger.
[3]
The adsorption layer for non-aqueous electrolyte batteries according to Item 1 or 2, wherein lithium titanate is more than 0% by mass and less than 90% by mass, where the total mass of lithium titanate and the insulating inorganic particles is 100% by mass.
[4]
The nonaqueous electrolyte battery which has an adsorption layer for nonaqueous electrolyte batteries as described in any one of the items 1-3.
[5]
A non-aqueous electrolyte battery comprising a positive electrode, a negative electrode, a separator, and the adsorption layer for the non-aqueous electrolyte battery,
The adsorption layer for the non-aqueous electrolyte battery is formed in part or all of at least one selected from the group consisting of the inside of the separator, between the positive electrode and the separator, and between the negative electrode and the separator. The nonaqueous electrolyte battery according to item 4, which has been.
[6]
The separator for non-aqueous electrolyte batteries which has an adsorption layer for non-aqueous electrolyte batteries as described in any one of items 1-3.
[7]
The separator for nonaqueous electrolyte batteries which has an adsorption layer for nonaqueous electrolyte batteries according to any one of Items 1 to 3 on at least one side.
[8]
A laminate, or a wound body of the laminate described above, wherein a positive electrode, an adsorption layer for a non-aqueous electrolyte battery according to any one of items 1 to 3, a separator, and a negative electrode are laminated in this order; Non-aqueous electrolyte battery.

  The adsorption layer for a non-aqueous electrolyte battery of the present invention can efficiently adsorb metal ions present or may occur in the non-aqueous electrolyte battery, thus providing a non-aqueous electrolyte battery excellent in safety and life characteristics. can do.

  Hereinafter, the present invention will be described in detail for the purpose of illustrating an embodiment of the present invention (hereinafter, referred to as “this embodiment”), but the present invention is not limited to the present embodiment. In the present specification, the upper limit value and the lower limit value of each numerical range can be arbitrarily combined.

<< non-aqueous electrolyte battery >>
The non-aqueous electrolyte battery generally has a positive electrode, a negative electrode, a separator, an electrolyte, and an outer package. In the present specification, a lithium ion secondary battery may be mentioned as an example as a non-aqueous electrolyte battery, but such a description is intended only to aid the understanding of the present invention, and the present embodiment The form non-aqueous electrolyte battery is not limited to a lithium ion secondary battery.

  In the specification of the present application, members constituting a lithium ion secondary battery including the positive electrode, the negative electrode, the separator, the non-aqueous electrolyte, and the outer package are collectively referred to as "battery components". As a material which constitutes a battery structural member, for example, aluminum etc. in an exterior body; nickel, cobalt, manganese, iron, zinc, copper, and aluminum etc. in a positive electrode active material; Is typically used. These metals, for example, when in contact with HF, become metal ions and elute into the battery. The eluted metal ions are reduced and precipitated at the negative electrode, and for example, in a lithium ion secondary battery, a Li-containing compound is produced to cause a reduction in capacity. As a result, the safety and life characteristics of the battery may be significantly reduced. The non-aqueous electrolyte battery of the present embodiment can effectively adsorb metal ions present or generated in the battery by having a specific non-aqueous electrolyte battery adsorption layer described later, thereby suppressing metal deposition. The life characteristics of the battery can be improved. In addition, since metal deposition on the negative electrode can be suppressed, and short circuit can be suppressed more effectively, it can contribute to improvement of the safety of the battery. The non-aqueous electrolyte battery of the present embodiment preferably has a specific non-aqueous electrolyte battery adsorption layer described later, and more preferably has a porous layer constituted of the specific non-aqueous electrolyte battery adsorption layer described later . The adsorption layer for a non-aqueous electrolyte battery is preferably formed in part or all of at least one selected from the group consisting of the inside of a separator, between a positive electrode and a separator, and between a negative electrode and a separator. . It is more preferable that the adsorption layer for nonaqueous electrolyte batteries is formed in part or all between the positive electrode and the separator.

<Adsorption layer for non-aqueous electrolyte batteries>
The adsorption layer for non-aqueous electrolyte batteries of this embodiment contains lithium titanate and insulating inorganic particles. The adsorption layer for non-aqueous electrolyte batteries may further contain a binder in addition to lithium titanate and insulating inorganic particles. The adsorption layer for a non-aqueous electrolyte battery of the present embodiment can be preferably a porous layer including the adsorption layer for a non-aqueous electrolyte battery, and more preferably, a porous composed of the adsorption layer for a non-aqueous electrolyte battery It can be a stratum.

(Lithium titanate)
Lithium titanate is an oxide containing titanium (Ti) and lithium (Li). For example, it may be a compound represented by Li _x Ti _y O _z (0 <x ≦ 4, 1 ≦ y ≦ 5, 2 ≦ z ≦ 12). For _{example, Li 4 Ti 5 O 12,} Li 2 Ti 3 O 7, LiTiO 4, Li 0.5 TiO 2 and the like. In the present embodiment, by forming lithium titanate in a layer form with the insulating inorganic particles, metal ions can be efficiently adsorbed, and precipitation of the metal element on the negative electrode can be efficiently suppressed. Thus, a non-aqueous electrolyte battery excellent in safety and life characteristics can be provided. The reason is that although the invention is not limited to the theory, the inventors have found that the inclusion of the insulating inorganic particles increases the dispersibility of lithium titanate and enables metal ions to be adsorbed more efficiently. I guess.

  The lower limit of the amount of lithium titanate is preferably 0% by mass, 40% by mass or more, 60% by mass or more, or 90% by mass, based on 100% by mass of the total mass of lithium titanate and the insulating inorganic particles. The upper limit is preferably 90% by mass or less, less than 90% by mass, 60% by mass or less, or 40% by mass or less. Among these, the amount of lithium titanate is more preferably more than 0% by mass and less than 90% by mass, still more preferably more than 0% by mass and 70% by mass and particularly preferably 40% by mass to 60% by mass. If the lithium titanate content is more than 0% by mass and less than 90% by mass, the energy density of the non-aqueous electrolyte battery is maintained high, and the metal ion adsorption ratio tends to be excellent. In particular, when lithium titanate having a high aspect ratio, for example, lithium titanate having an aspect ratio of 5 or more is used, the effect of making lithium titanate less than 50% by mass becomes more remarkable.

The BET specific surface area of lithium titanate is preferably 3 m ² / g or more and 1000 m ² / g or less. When the BET specific surface area is 3 m ² / g or more, the life characteristics and the safety of the non-aqueous electrolyte battery can be further improved. The BET specific surface area of lithium titanate is preferably 100 m ² / g or less, more preferably 50 m ² / g or less, and still more preferably 30 m ² / g or less. When the BET specific surface area is 1000 m ² / g or less, aggregation of lithium titanate is suppressed, and the energy density of the non-aqueous electrolyte battery tends to be improved.

  The shape of lithium titanate is not particularly limited, but in order to well disperse lithium titanate in the adsorption layer for non-aqueous electrolyte batteries, it is preferable that the shape be excellent in dispersibility, and that it be in the form of particles. preferable. The average secondary particle size (D50) of lithium titanate is preferably 0.05 μm to 5 μm, more preferably 0.1 μm to 3.5 μm, and still more preferably 0.2 μm to 3 μm. When the average secondary particle size is 0.05 μm to 5 μm, the energy density of the non-aqueous electrolyte battery tends to increase.

  The method of controlling the average secondary particle diameter of lithium titanate to be in the range of 0.05 μm to 5 μm is not particularly limited, but any of the conventionally known methods, for example, axial flow type mill method, annular type mill method, roll mill method And ball mill method, bead mill method, jet mill method, container rotary compression shear type mill method, method of pulverizing with a porcelain mortar, and the like.

The crystal system of lithium titanate is not particularly limited, and examples include spinel structure, ram's light structure and anatase structure. Among these, the spinel structure (typically represented as Li ₄ Ti ₅ O ₁₂ ) is preferable.
The preparation method of the above-mentioned lithium titanate is not particularly limited. For example, a lithium compound such as lithium hydroxide or lithium carbonate and titanium dioxide may be wet and / or so that the molar ratio of Li to Ti falls within a predetermined range. It can be produced by dry mixing, drying and firing. The calcination temperature is preferably 550 ° C. to 1500 ° C., more preferably 600 ° C. to 1200 ° C. The firing atmosphere is not particularly limited, but firing in the air is preferable. Moreover, it is preferable to heat-process (anneal) in the temperature range of 400-1000 degreeC after normal baking in air | atmosphere, and to restore an oxygen deficiency. The annealing enhances the crystallinity of lithium titanate and the adsorption performance.
In addition, lithium titanate may contain hydrogen (H). Hydrogen (H) may be contained in place of part of lithium (Li).
Furthermore, lithium titanate has the formula: Li _A Ti _5-B M _B O _{12 + C}
(Wherein, M is V, Mn, Fe, Co, Ni, Cu, Zn, Al, B, Mg, Ca, Sr, Ba, Zr, Nb, Mo, W, Bi, Na and Ga) And at least one selected from A to 3-5, B to 0.005 to 1.5, and C to -1 to 1). M is preferably at least one selected from the group consisting of Mn, Fe, Co, Ni, Cu, Al, B, Mg, Zr, Nb and W.
Moreover, the above-mentioned lithium titanate can be used individually by 1 type, or in mixture of 2 or more types.

(binder)
In the adsorption layer for non-aqueous electrolyte batteries of the present embodiment, the lithium titanate and the insulating inorganic particles may be bound by a binder. This is preferable from the viewpoint of fixing lithium titanate and insulating inorganic particles to prevent dropping off and unsafety in the battery. In addition, it is particularly important that the lithium titanate and the insulating inorganic particles can be kept mixed and dispersed with one another. If the binding by the binder is sufficient, the distance between the lithium titanates narrows and is finely filled, along with the expansion and contraction of the negative electrode due to charge and discharge or with the external stress applied to the battery cell. It is possible to effectively suppress the decrease in metal ion adsorption ability of lithium. Therefore, it is preferable that the binder is contained even when the adsorption layer for non-aqueous electrolyte batteries is installed anywhere in the battery.

  It is preferable that Tg of a binder is -80 degreeC or more and 0 degrees C or less from a viewpoint of maintaining a favorable adsorption | suction characteristic. A more preferable range is −70 ° C. or more and −10 ° C. or less. More preferably, it is -60 degreeC or more and -20 degreeC or less. By being in this range, high stability can be maintained against expansion and contraction of the negative electrode and external stress, and as a result, good adsorption characteristics can be maintained.

  As a binder which fixes lithium titanate, although it is not limited, for example, those insoluble or hardly soluble in the non-aqueous electrolyte to be used and electrochemically stable are preferable. Examples of such a binder include, but are not limited to, for example, polyolefins such as polyethylene and polypropylene; fluorine-containing resins such as vinylidene fluoride and polytetrafluoroethylene; vinylidene fluoride-hexafluoropropylene-tetrafluoroethylene copolymer, ethylene -Fluorine-containing rubber such as tetrafluoroethylene copolymer; styrene-butadiene copolymer and its hydride, acrylonitrile-butadiene copolymer and its hydride, acrylonitrile-butadiene-styrene copolymer and its hydride, methacrylic acid Ester-acrylic acid ester copolymer, styrene-acrylic acid ester copolymer, acrylonitrile-acrylic acid ester copolymer, ethylene propylene rubber, polyvinyl alcohol, polyvinyl acetate, and other rubbers Cellulose derivatives such as ethyl cellulose, methyl cellulose, hydroxyethyl cellulose and carboxymethyl cellulose; at least one selected from the group consisting of polyphenylene ether, polysulfone, polyether sulfone, polyphenyl sulfone, polyphenylene sulfide, polyetherimide, polyamide imide, and polyester Is preferred. The melting point and / or the glass transition temperature of the binder is preferably 180 ° C. or more.

  Among these, as a binder, resin-made latex binders are preferable. In the present specification, “resin latex” refers to a resin in a state of being dispersed in a medium. A separator having a porous non-aqueous electrolyte battery adsorption layer containing lithium titanate and insulating inorganic particles, and a resin-made latex binder tends to have low ion permeability and excellent output characteristics. In addition, even when the temperature rise of the battery is fast such as abnormal heat generation, smooth shutdown performance is exhibited, the heat shrink resistance is high, and the safety tends to be excellent.

  Examples of resin-made latex binders include, but are not limited to, those obtained by emulsion polymerization of aliphatic conjugated diene monomers or unsaturated carboxylic acid monomers, and other monomers copolymerizable therewith. Can be mentioned. By using such a resin-made latex binder, electrochemical stability and binding tend to be further improved. The emulsion polymerization method is not limited, and known methods can be used. Although it does not limit as a method of addition of a monomer and other components, The batch addition method, the division | segmentation addition method, and the continuous addition method can be mentioned, You may use any. Moreover, as a polymerization method, although it is not limited, single-stage polymerization, two-stage polymerization or multi-stage polymerization can be mentioned, and any may be used.

  Examples of the aliphatic conjugated diene monomer include, but are not limited to, 1,3-butadiene, 2-methyl-1,3-butadiene, 2,3-dimethyl-1,3-butadiene, 2-chloro-1, and so on. 3-butadiene, substituted linear conjugated pentadienes, substituted and side chain conjugated hexadienes, and the like can be mentioned. Among these, 1,3-butadiene is preferable as the aliphatic conjugated diene monomer. As the aliphatic conjugated diene-based monomer, one type may be used alone, or two or more types may be used in combination.

  Examples of unsaturated carboxylic acid monomers include, but are not limited to, mono- or dicarboxylic acids (anhydrides) such as acrylic acid, methacrylic acid, crotonic acid, maleic acid, fumaric acid, itaconic acid and the like. Among these, as the unsaturated carboxylic acid monomer, acrylic acid and / or methacrylic acid is preferable. An unsaturated carboxylic acid monomer may be used individually by 1 type, and may use 2 or more types together.

  Examples of the aliphatic conjugated diene monomer or another monomer copolymerizable with the unsaturated carboxylic acid monomer include, but are not limited to, for example, an aromatic vinyl monomer and a vinyl cyanide monomer And unsaturated carboxylic acid alkyl ester monomers, unsaturated monomers containing a hydroxyalkyl group, unsaturated carboxylic acid amide monomers, and the like. Among these, as other monomers, unsaturated carboxylic acid alkyl ester monomers are preferable. The other monomers may be used alone or in combination of two or more.

  Examples of unsaturated carboxylic acid alkyl ester monomers include, but are not limited to, methyl acrylate, methyl methacrylate, ethyl acrylate, ethyl methacrylate, butyl acrylate, glycidyl methacrylate, dimethyl fumarate, diethyl fumarate, dimethyl maleate, diethyl maleate. And amethate, dimethyl itaconate, monomethyl fumarate, monoethyl fumarate, 2-ethylhexyl acrylate and the like. Among these, methyl methacrylate is preferred. The unsaturated carboxylic acid alkyl ester monomers may be used alone or in combination of two or more.

  In addition to the monomers described above, other monomer components may also be used to improve various qualities and properties.

  The average particle size of the resin latex binder is preferably 50 nm to 500 nm, more preferably 60 nm to 460 nm, and still more preferably 70 nm to 420 nm. When the average particle diameter is 50 nm or more, the ion permeability of the adsorption layer containing lithium titanate and the insulating inorganic particles and the resin-made latex binder does not easily decrease, and the output characteristics tend to be excellent. When the average particle diameter of the resin-made latex binder is 500 nm or less, the binding property is further improved, the resistance to expansion and contraction of the negative electrode and the positive electrode is increased, and the preferable adsorption characteristic tends to be maintained.

  Control of the average particle diameter of the resin-made latex binder is possible by adjusting the polymerization time, polymerization temperature, raw material composition ratio, raw material feeding order, pH and the like.

The amount of the resin-made latex binder is, for example, preferably 0.1 g / m ² or more, and more preferably 0.5 g / m ² or more, per unit area, from the viewpoint of securing the effect of the use. Suppressing a decrease in energy density of the battery, from the viewpoint of suppressing the increase in the internal resistance, the amount of the resin latex binder, per unit area, preferably 15 g / m ² or less, more preferably 10 g / m ² or less.

(Insulating inorganic particles)
The adsorption layer for non-aqueous electrolyte batteries of the present embodiment can improve the dispersibility of lithium titanate by including the insulating inorganic particles. In the specification of the application, “insulating inorganic particles” mean particles of an inorganic material having a volume resistivity of 10 ³ Ω · cm or more. The volume resistivity of the insulating inorganic particles may be preferably 10 Ω ⁴ · cm or more, more preferably 10 ⁵ Ω · cm or more, and further preferably 10 ⁶ Ω · cm or more. The insulating inorganic particles preferably have an average longest diameter larger than lithium titanate. The term "longest diameter" as used herein refers to the length of particles in the direction of the longest axis. By containing the insulating inorganic particles having this specific average longest diameter together with lithium titanate, the adsorptive layer for non-aqueous electrolyte batteries particularly enhances the dispersibility of lithium titanate and efficiently adsorbs metal ions. be able to. The ratio of the longest diameter of the insulating inorganic particle to the longest diameter of lithium titanate is not limited, but is preferably 1.01 or more and 1000 or less, more preferably 1.1 or more and 500 or less, and still more preferably 1.2 or more and 300 or less It can be done.

  The method for measuring the average longest diameter of the particles is not particularly limited, but for example, observing the length in the direction of the longest axis of 100 particles with a scanning electron microscope and calculating by calculating the average value Can.

The insulating inorganic particles are preferably, but not limited to, those having a melting point of, for example, 200 ° C. or more and being electrochemically stable in the use range of the non-aqueous electrolyte battery. Such insulating inorganic particles are not particularly limited, but, for example, cation exchangers such as hydroxyapatite, zirconium phosphate, titanium phosphate, titanate, niobate, niobium titanate, zeolite, etc. , Carbonates and sulfates such as calcium sulfate, magnesium sulfate, aluminum sulfate, gypsum and barium sulfate, alumina trihydrate (ATH), fumed silica, precipitated silica, oxide ceramics such as yttria, sodium oxide, oxide Potassium, magnesium oxide, calcium oxide, barium oxide, strontium oxide, vanadium oxide, SiO ₂ -MgO (magnesium silicate), SiO ₂ -CaO (calcium silicate), sodium carbonate, potassium carbonate, magnesium carbonate, calcium carbonate, carbonate Barium, charcoal Lanthanate, cerium carbonate silicon nitride, titanium nitride, nitride nitride ceramics such as boron nitride, magnesium hydroxide, silicon carbide, talc, dicite, nacrite, halloysite, pyrophyllite, montmorillonite, sericite, amesite, bentonite, etc. Synthetic layered silicates, such as layered silicates, asbestos, diatomaceous earth, glass fibers, for example, neutral layered silicates, such as mica or fluoromica, for example, improving intercalation and exfoliation of hectorite, saponite, or vermiculite, nanoclays, etc. And inorganic particles selected from the group consisting of natural or synthetic layered silicates, zinc borates, and anion exchangers containing modifiers.

  The insulating inorganic particle is preferably an anion exchanger. As used herein, "anion exchanger" refers to a material capable of adsorbing anions present or generated in the cell and instead releasing other anions. Since the insulating inorganic particles are an anion exchanger, not only the dispersibility of lithium titanate in the adsorption layer for non-aqueous electrolyte batteries can be improved, but also metal ions can be adsorbed more efficiently. preferable.

  The insulating inorganic particles of the anion exchanger include, but are not limited to, for example, layered double hydroxide (Mg-Al type, Mg-Fe type, Ni-Fe type, Li-Al type), layered double hydroxide -Alumina silica gel complex, boehmite, alumina, zinc oxide, lead oxide, iron oxide, iron oxyhydroxide, hematite, lanthanum oxide, bismuth oxide, tin oxide, titanium oxide, cerium oxide, cerium oxide, zirconium oxide, basic copper acetate and base Lead sulfate etc. From the viewpoint of relatively low water content and preventing battery swelling, as anion exchangers, boehmite, alumina, zinc oxide, lead oxide, iron oxide, iron oxyhydroxide, hematite, lanthanum oxide, bismuth oxide, tin oxide , Titanium oxide, cerium oxide and zirconium oxide are preferable. As the anion exchanger, one type may be used alone, or two or more types may be used in combination.

  The amount of the insulating inorganic particles is preferably 1% or more, more preferably 5% or more, and still more preferably 10% or more, based on 100% by mass of the total weight of the insulating inorganic particles and lithium titanate.

<Porous layer>
The adsorption layer for a non-aqueous electrolyte battery in the present specification is preferably a porous layer including the adsorption layer for a non-aqueous electrolyte battery, and more preferably a porous layer composed of the adsorption layer for a non-aqueous electrolyte battery. preferable.

  The total content of the lithium titanate and the insulating inorganic particles in the porous layer is the total volume of the components of the porous layer (the total volume excluding the void portion) from the viewpoint of securing the effect by the use well. As a standard, it is preferably 1% by volume or more, more preferably 5% by volume or more.

  The porosity of the porous layer is preferably 30% or more and 80% or less. More preferably, it is 40% or more. Moreover, it is preferable that the upper limit is 70% or less.

The volume resistivity of the porous layer is preferably 1 × 10 ³ Ω · cm or more and 1 × 10 ¹² Ω · cm or less. By being in this range, the life characteristics can be improved. A more preferable range is 1 × 10 ⁴ Ω · cm or more and 1 × 10 ¹⁰ Ω · cm or less.

<Separators for non-aqueous electrolyte batteries>
The separator for a non-aqueous electrolyte battery in the present specification (hereinafter, also simply referred to as “separator”) preferably has the adsorption layer for a non-aqueous electrolyte battery of the present embodiment, and more preferably the non-aqueous electrolyte of the present embodiment It has a porous layer comprised from the adsorption layer for electrolyte batteries. More preferably, the non-aqueous electrolyte battery separator has the non-aqueous electrolyte battery adsorption layer of the present embodiment on at least one side, and further has the non-aqueous electrolyte battery adsorption layer on at least one side of the porous substrate. preferable. The porous substrate is not limited as long as it has high ion permeability and has a function of electrically separating the positive electrode and the negative electrode. Known porous substrates used for non-aqueous electrolyte batteries can be used.

  When the porous substrate has an adsorption layer for a non-aqueous electrolyte battery, the thickness of the adsorption layer for a non-aqueous electrolyte battery is preferably 1 μm to 10 μm. The thickness of the non-aqueous electrolyte battery adsorption layer is more preferably 1 μm or more and less than 5 μm because the energy density of the non-aqueous electrolyte battery tends to increase.

<Porous base material>
Materials for the porous substrate include, but are not limited to, materials that are stable to non-aqueous electrolytes in batteries and electrochemically stable, such as polyolefins such as polyethylene (PE), polypropylene (PP), etc. Polyester; polyimide; polyamide; polyurethane. Although it does not limit as a form of a separator, For example, a microporous film, a nonwoven fabric, etc. are mentioned.

  The porous substrate preferably has a property (also referred to as a “shutdown function”) at which the pores are clogged at preferably 80 ° C. to 180 ° C., more preferably 100 ° C. to 150 ° C. Therefore, as a porous substrate, the melting temperature measured using a differential scanning calorimeter (DSC) according to the definition of JIS K 7121 is preferably 80 ° C. to 180 ° C., more preferably 100 ° C. to 150 ° C. It is more preferable to use a microporous membrane or non-woven fabric containing a polyolefin having a temperature of at most ° C.

  The microporous membrane or non-woven fabric as the porous substrate may be made of, for example, PE, may be made of PP, or may contain two or more kinds of materials. The porous substrate may be a laminate of a microporous film composed of PE and a microporous film composed of PP, for example, a three-layer laminate in which PP, PE, and PP are laminated in this order.

  As the microporous film, for example, an ion-permeable porous film having a large number of pores formed by a conventionally known solvent extraction method, dry method or wet drawing method can be used. It may be a microporous membrane generally used as a separator.

  In the specification of the present application, the porous substrate “based on polyolefin” means that the content of the polyolefin in the total volume of the constituent components (total volume excluding the void portion) is 30% by volume or more. , Preferably 70% by volume or more.

  The porous base material mainly made of polyolefin, especially the microporous membrane, is easily thermally shrunk due to the high temperature in the battery. However, since the non-aqueous electrolyte battery adsorption layer of the present embodiment functions as a heat-resistant layer and thermal contraction of the whole porous substrate is suppressed, a non-aqueous electrolyte battery having higher safety at high temperatures is obtained. be able to.

  The amount of the inorganic particles in the adsorption layer for a non-aqueous electrolyte battery is preferably, based on the total volume of the components of the porous layer (the total volume excluding the void portion), from the viewpoint of securing the effect by its use well. It is 1% by volume or more, more preferably 5% by volume or more.

  The porous substrate may have resin particles in addition to the lithium titanate and the insulating inorganic particles of the present embodiment. The porous base material having resin particles can further enhance, for example, the shape stability of the entire separator under high temperature.

  The resin particles are composed of an electrochemically stable resin which has heat resistance and electrical insulation, is stable to the non-aqueous electrolyte in the battery, and is not easily oxidized or reduced in the operating voltage range of the battery. Is preferred. Materials for forming such resin particles include styrene resin (polystyrene etc.), styrene butadiene rubber, acrylic resin (polymethyl methacrylate etc.), polyalkylene oxide (polyethylene oxide etc.), fluorocarbon resin (polyvinylidene fluoride etc.) And crosslinked products of at least one resin selected from the group consisting of these derivatives; urea resins; polyurethanes and the like. The resin particles may be used alone or in combination of two or more. In addition, the resin particles may contain, if necessary, known additives that can be added to the resin, such as an antioxidant.

  The form of the resin particles may be any form independently, such as plate, scale, needle, column, sphere, polyhedron, block, etc. From the viewpoint of permeability improvement, a plurality of surfaces may be used. The polyhedron shape is preferable.

  The average particle diameter (D50) of the resin particles is preferably independently 0.1 μm to 4.0 μm, more preferably 0.2 μm to 3.5 μm, and still more preferably 0.4 μm to 3.0 μm. When the average particle size is 0.1 μm to 4.0 μm, the thermal contraction of the separator at high temperatures tends to be further suppressed.

  When the porous substrate has resin particles, these particles may be, for example, (i) the adsorption layer for the non-aqueous electrolyte battery of the present embodiment, or (ii) the adsorption layer for the non-aqueous electrolyte battery and the substrate It may be contained in another porous layer (hereinafter, also simply referred to as “other porous layer”).

  When the resin particles are contained in (i) an adsorption layer for a non-aqueous electrolyte battery, the content of the resin particles is adjusted so that the content of lithium titanate falls within the preferable range described above. Is preferred.

  When the resin particles are contained in (ii) another porous layer, the other porous layer is, for example: on a non-woven fabric as a substrate or on one side of a microporous membrane, and the non-aqueous electrolyte of the present embodiment It may be disposed on the side opposite to the side on which the battery adsorption layer is provided; it may be disposed between the non-aqueous electrolyte battery adsorption layer and the substrate; or for non-aqueous electrolyte batteries You may arrange | position on the surface opposite to the surface which contact | connects a base material among the surfaces of an adsorption layer.

  The other porous layer containing the resin particles may be integral with the substrate and / or the adsorption layer for the non-aqueous electrolyte battery, and they are present as a separate membrane and superposed on them in the battery It may constitute a separator.

  When resin particles are contained in (ii) another porous layer, the content of the resin particles in the other porous layer is the total volume of the other porous layer (the total volume excluding the void portion), It is preferably 5% by volume or more, more preferably 10% by volume or more, and still more preferably 50% by volume or more.

  When resin particles are contained in (ii) another porous layer, the porous layer preferably contains a binder. The content of resin particles in the other porous layer is preferably 99.5% by volume or less in the total volume of the other porous layer (the total volume excluding the pore portion). As a binder, the thing similar to the binder illustrated as what can be used for the porous layer containing the inorganic particle for nonaqueous electrolyte batteries of this embodiment can be used.

  Even if the porous substrate does not have the porous layer containing the inorganic particles for non-aqueous electrolyte batteries of the present embodiment, the separator has the above-mentioned nonwoven fabric or microporous film as the substrate, and one side thereof Alternatively, it may be a porous substrate having another porous layer containing other inorganic particles or resin particles on both sides.

The porosity of the non-aqueous electrolyte battery separator is preferably 30% or more, more preferably 40% or more in the dried state of the separator, in order to secure the amount of non-aqueous electrolyte retained and to improve the ion permeability. It is. From the viewpoint of securing the separator strength and preventing the internal short circuit, the porosity of the separator is preferably 80% or less, more preferably 70% or less in the dried state of the separator. In the specification of the present application, the porosity P (%) of the separator can be calculated from the thickness of the separator, the mass per unit area, and the density of the constituent components by determining the sum for each component i using the following formula .
P = {1- (m / t ) / (Σa i · ρ i)} × 100
{Wherein, a _i is the ratio of component i when the overall mass is 1, ρ _i is the density of component i (g / cm ³ ), and m is the unit area of the separator It is mass (g / cm ² ), and t is the thickness of the separator (cm). }

  The total thickness of the non-aqueous electrolyte battery separator is preferably 2 μm or more and 200 μm or less, more preferably 5 μm or more and 100 μm or less, and still more preferably 7 μm or more and 30 μm or less, in both cases with and without the porous layer described above. It is. When the total thickness of the separator is 2 μm or more, the mechanical strength of the separator tends to be further improved. In addition, when the total thickness of the separator is 200 μm or less, the volume occupied by the separator in the battery is reduced, so the capacity of the non-aqueous electrolyte battery tends to be higher, and the ion permeability tends to be further improved.

  The air permeability of the non-aqueous electrolyte battery separator is preferably 10 seconds / 100 cc or more and 500 seconds / 100 cc or less, more preferably 20 seconds / 100 cc or more and 450 seconds / 100 cc or less, still more preferably 30 seconds / 100 cc or more and 450 seconds / cc. It is less than 100 cc. When the air permeability is 10 seconds / 100 cc or more, the self-discharge tends to be less when the separator is used in a non-aqueous electrolyte battery. When the air permeability is 500 seconds / 100 cc or less, better charge / discharge characteristics tend to be obtained.

  When the porous substrate has a porous layer containing the inorganic particles for non-aqueous electrolyte batteries of the present embodiment, the thickness of the porous layer is preferably 1 μm to 10 μm.

  When the porous substrate has another porous layer containing resin particles, the thickness of the other porous layer is preferably 1 μm to 10 μm.

  The thickness of the porous base material itself, for example, the nonwoven fabric or the porous membrane itself, is preferably 5 μm to 40 μm.

  The porous layer containing the inorganic particles for a non-aqueous electrolyte battery of the present embodiment is prepared by dispersing or dissolving the inorganic particles for a non-aqueous electrolyte battery of the present embodiment, a binder and the like in water or an organic solvent. It may be formed by applying and drying (for example, paste, slurry, etc.) on the place where the porous layer is desired to be formed, and the composition is applied on a substrate such as a resin film and dried and then peeled off. It may be formed as an independent film. Other porous layers containing other inorganic particles or resin particles can also be formed as described above.

<Positive electrode>
The positive electrode generally has a current collector and a positive electrode mixture layer formed thereon, and the positive electrode mixture layer preferably contains a positive electrode active material, a conductive auxiliary, and a binder.

As the positive electrode active material, known materials capable of absorbing and releasing lithium ions electrochemically can be used. As a positive electrode active material, a material containing lithium is preferable. As a positive electrode active material, for example,
Following formula (1):
Li _x Mn _2-y M _y O _z (1)
{Wherein, M represents at least one element selected from the group consisting of transition metal elements, and 0 <x ≦ 1.3, 0.2 <y <0.8, and 3.5 <z <4. .5. }
An oxide represented by
Following formula (2):
Li _x M _y O _z (2)
{Wherein, M represents at least one element selected from the group consisting of transition metal elements, and 0 <x ≦ 1.3, 0.8 <y <1.2, and 1.8 <z <2 .2. }
Layered oxide represented by
Following formula (3):
LiMn _2-x Ma _x O ₄ (3)
{Wherein, Ma represents at least one element selected from the group consisting of transition metal elements, and 0.2 ≦ x ≦ 0.7. }
Spinel type oxide represented by
Following formula (4):
Li ₂ McO ₃ (4)
{Wherein, Mc represents at least one element selected from the group consisting of transition metal elements. } And the following formula (5):
LiMdO ₂ (5)
{Wherein M d represents at least one element selected from the group consisting of transition metal elements. Or a composite oxide with the oxide represented by
zLi ₂ McO _3- (1-z) LiMdO ₂ (6)
{Wherein, Mc and Md have the same meanings as Mc and Md in the above formulas (4) and (5), respectively, and 0.1 ≦ z ≦ 0.9. }
A layered oxide positive electrode active material having an excess of Li;
Following formula (7):
LiMb _1-y Fe _y PO ₄ (7)
In the formula, Mb represents at least one element selected from the group consisting of Mn and Co, and 0 ≦ y ≦ 1.0. }
An olivine type positive electrode active material represented by the following formula; and the following formula (8):
Li ₂ MePO ₄ F (8)
{Wherein, Me represents at least one element selected from the group consisting of transition metal elements. The compound represented by} is mentioned. The positive electrode active material may be used singly or in combination of two or more.

  The positive electrode active material is preferably one that can be operated at a higher potential to increase the energy density of the battery. The non-aqueous electrolyte battery according to the present embodiment can effectively adsorb metal ions that degrade the battery characteristics or cause a short circuit by being eluted from the positive electrode active material and deposited on the negative electrode. Since a decrease can be suppressed, at least one selected from the group consisting of a spinel lithium manganese complex oxide represented by the above formula (3) and a layered compound represented by the above formula (2) as the positive electrode active material It is preferred to use a seed.

  Known conductive aids and current collectors can be used in the positive electrode.

  The positive electrode may have the adsorption layer for the non-aqueous electrolyte battery of the present embodiment. When a positive electrode has the adsorption layer for non-aqueous electrolyte batteries of this embodiment, it is not limited as the aspect, For example, (i) The adsorption layer for non-aqueous electrolyte batteries of this embodiment is contained in a positive electrode mixture layer Or (ii) a method of forming a porous layer containing the adsorption layer for a non-aqueous electrolyte battery of the present embodiment on the surface of the positive electrode mixture layer. In the case of the former method, the adsorption layer for a non-aqueous electrolyte battery of this embodiment may be in a state of being mixed with the positive electrode active material, or may be coated on the surface of the positive electrode active material. In the case of the latter method, the porous layer containing the adsorption layer for a non-aqueous electrolyte battery of the present embodiment can be formed by the same method as the porous layer described above, and the configuration thereof is also the above-mentioned porous The configuration of the stratum can be used.

  The content of the adsorption layer for non-aqueous electrolyte batteries in the positive electrode is, for example, the total volume of the components of the adsorption layer for non-aqueous electrolyte batteries excluding the current collector (the void portion It is preferable that it is 0.5 volume% or more in total volume except for, and it is more preferable that it is 1 volume% or more. Further, from the viewpoint of the energy density and internal resistance of the battery, the content of the adsorption layer for non-aqueous electrolyte batteries in the positive electrode is the total volume of the components of the positive electrode excluding the current collector (total volume excluding holes) It is preferably 10% by volume or less, more preferably 6% by volume or less.

  When the positive electrode does not contain an adsorption layer for non-aqueous electrolyte batteries, the content of the positive electrode active material is preferably 87% by mass to 97% by mass, based on the total mass of the positive electrode mixture layer, The content of is preferably 1.5% by mass to 6.5% by mass, and the content of the binder is preferably 1.5% by mass to 6.5% by mass.

  When the positive electrode contains an adsorption layer for a non-aqueous electrolyte battery, the content of the positive electrode active material is preferably 79.4% by mass to 96.4% by mass based on the total mass of the positive electrode mixture layer The content of the conductive additive is preferably 1.4% by mass to 6.5% by mass, and the content of the binder is preferably 1.4% by mass to 6.5% by mass.

<Negative electrode>
The negative electrode generally has a current collector and a negative electrode mixture layer formed thereon, and the negative electrode mixture layer preferably contains a negative electrode active material and a binder.

  Examples of the current collector in the negative electrode include, but are not limited to, foils of metals such as copper, nickel, and stainless steel, expanded metals, punched metals, foamed metals; carbon materials such as carbon cloth and carbon paper. The current collectors in the negative electrode may be used alone or in combination of two or more.

  As the negative electrode active material, a known material capable of electrochemically absorbing and desorbing lithium ions can be used. Negative electrode active materials include, but are not limited to, for example, carbon materials such as graphite powder, mesophase carbon fibers, and mesophase microspheres; and metals, alloys, oxides and nitrides. One type of negative electrode active material may be used alone, or two or more types may be used in combination.

  The negative electrode may include the adsorption layer for a non-aqueous electrolyte battery of the present embodiment. When a negative electrode has an adsorption layer for nonaqueous electrolyte batteries of this embodiment, although it is not limited as the mode, for example, (i) A adsorption layer for nonaqueous electrolyte batteries of this embodiment is contained in a cathode mixture layer. Or (ii) a method of forming a porous layer containing the adsorption layer for a non-aqueous electrolyte battery of the present embodiment on the surface of the negative electrode mixture layer. In the case of the former method, the adsorption layer for a non-aqueous electrolyte battery of the present embodiment may be mixed with the negative electrode active material, or may be coated on the surface of the negative electrode active material. In the case of the latter method, the porous layer containing the adsorption layer for a non-aqueous electrolyte battery of the present embodiment can be formed by the same method as the porous layer described above, and the configuration thereof is also the above-mentioned porous The configuration of the stratum can be used.

  The content of the adsorption layer for a non-aqueous electrolyte battery in the negative electrode is, for example, the total volume of the components of the negative electrode excluding the current collector (the total volume excluding the void portion) from the viewpoint The content is preferably 1.5% by volume or more, more preferably 2% by volume or more. Further, in view of the energy density and internal resistance of the battery, the content of the adsorption layer for a non-aqueous electrolyte battery in the negative electrode is the total volume of the components of the negative electrode (excluding the void portion) It is preferable that it is 25 volume% or less, and it is more preferable that it is 15 volume% or less.

  When the negative electrode does not contain the adsorption layer for non-aqueous electrolyte batteries, the content of the negative electrode active material is preferably 88% by mass to 99% by mass based on the total mass of the negative electrode mixture layer, and the binder is contained. The amount is preferably 1% by mass to 12% by mass, and when a conductive auxiliary is used, the content of the conductive auxiliary is preferably 0.5% by mass to 6% by mass.

  When the negative electrode contains an adsorption layer for a non-aqueous electrolyte battery, the content of the negative electrode active material is preferably 68% by mass to 98% by mass, based on the total mass of the negative electrode mixture layer. The content is preferably 0.8% by mass to 11.8% by mass, and in the case of using a conduction aid, the content of the conduction aid is 0.9% by mass to 5.9% by mass Is preferred.

  As a binder in the negative electrode, a known material capable of binding at least two of a negative electrode active material, a conductive additive, and a material constituting the negative electrode of the current collector can be used. It may be the same as or different from the binder of the non-aqueous electrolyte battery adsorption layer. Examples of the binder in the negative electrode include, but are not limited to, carboxymethyl cellulose, a crosslinked rubber latex of styrene-butadiene, an acrylic latex, and polyvinylidene fluoride. A binder may be used individually by 1 type, or may use 2 or more types together.

<Non-aqueous electrolyte>
The non-aqueous electrolyte may be, for example but not limited to, a solution in which a lithium salt is dissolved in an organic solvent. Examples of the lithium salt include, but are not limited to, LiPF ₆ (lithium hexafluorophosphate), LiClO ₄ , LiBF ₄ , LiBF ₄ , LiAsF ₆ , Li ₂ SiF ₆ , LiOSO ₂ C _k F _{2k + 1} , wherein k is 1 to LiN (SO ₂ C _k F _{2 k + 1} ) ₂ (wherein, k is an integer of 1 to 8), LiPF _n (C _k F _{2 k + 1} ) _6-n (where n is 1) And an integer of 1 to 5 and k is an integer of 1 to 8), LiPF ₄ (C ₂ O ₄ ), LiPF ₂ (C ₂ O ₄ ) _{2 and the} like. Among these, LiPF ₆ is preferable as the lithium salt. The use of LiPF ₆ tends to be more excellent in battery characteristics and safety even at high temperatures. The lithium salts may be used alone or in combination of two or more.

  The non-aqueous solvent used for the non-aqueous electrolyte is not limited, and known solvents can be used, and for example, an aprotic polar solvent is preferable.

  The aprotic polar solvent includes, but is not limited to, ethylene carbonate, propylene carbonate, 1,2-butylene carbonate, 2,3-butylene carbonate, 1,2-pentylene carbonate, 2,3-pentylene carbonate, for example. Cyclic carbonates such as trifluoromethyl ethylene carbonate, fluoroethylene carbonate and 4,5-difluoroethylene carbonate; lactones such as γ-butyrolactone and γ-valerolactone; cyclic sulfones such as sulfolane; cyclic ethers such as tetrahydrofuran and dioxane; ethyl methyl carbonate, dimethyl Carbonate, diethyl carbonate, methyl propyl carbonate, methyl isopropyl carbonate, dipropyl carbonate, methyl butyl carbo Linear carbonates such as dibutyl carbonate, ethyl propyl carbonate and methyl trifluoroethyl carbonate; nitriles such as acetonitrile; linear ethers such as dimethyl ether; linear carboxylic esters such as methyl propionate; and linear chains such as dimethoxyethane Ether carbonate compounds are mentioned. The non-aqueous electrolytes may be used alone or in combination of two or more.

  The concentration of the lithium salt contained in the non-aqueous electrolyte is preferably 0.5 mol / L to 1.5 mol / L, more preferably 0.9 mol / L to 1.25 mol / L.

  The non-aqueous electrolyte may be a liquid electrolyte (non-aqueous electrolyte) or may be a solid electrolyte.

  The non-aqueous electrolyte may contain the lithium titanate of the present embodiment. The content of lithium titanate in the non-aqueous electrolyte is preferably 5 mg or more, and more preferably 10 mg or more, per 1 mL of the non-aqueous electrolyte, from the viewpoint of securing the effect of the use.

<Exterior body>
As an exterior body, although not limited, metal cans, such as a steel can and an aluminum can, are mentioned, for example. Examples of the form of the exterior body include a cylinder, for example, a square cylinder, a cylinder and the like. A non-aqueous electrolyte battery can also be formed by using a laminated film on which metal is vapor-deposited as an outer package.

<< Production method of non-aqueous electrolyte battery >>
The manufacturing method of the non-aqueous electrolyte battery of the present embodiment is not limited. For example, the positive electrode and the negative electrode are stacked via the separator of the present embodiment to obtain a stacked body, or the stacked body is further wound and wound. A roll can be obtained, and the obtained laminate or wound body can be manufactured by containing the non-aqueous electrolyte in an outer package.

  Preferably, a laminate is obtained such that the positive electrode, the adsorption layer for a non-aqueous electrolyte battery according to the present embodiment, the separator, and the negative electrode are laminated in this order, or this laminate is wound to obtain a wound body. The obtained laminated body or winding body and the non-aqueous electrolyte may be contained in an outer package. It is preferable to laminate the positive electrode, the separator of the present embodiment, and the negative electrode so that the porous layer faces the positive electrode. When the non-aqueous electrolyte battery is, for example, a lithium ion secondary battery, the migration of lithium ions in the battery is secured by arranging the plurality of components of the lithium ion secondary battery in such a procedure, And, the adsorption of metal ions, which affects the life characteristics or safety of the battery, becomes remarkable.

  EXAMPLES Hereinafter, the embodiments of the present invention will be specifically described by Examples and Comparative Examples, but the present invention is not limited to these Examples and Comparative Examples. In addition, unless otherwise indicated, various measurement and evaluation were performed on the conditions of room temperature 23 degreeC, 1 atmosphere, and 50% of relative humidity conditions.

Example 1
<Preparation of lithium titanate>
Lithium carbonate and titanium dioxide were wet mixed in the form of a slurry dispersed in water. Thereafter, it was dried, calcined at 900 ° C. in the atmosphere, and heat-treated at 700 ° C. Thereafter, the mixture was crushed to obtain a lithium titanate (Li ₄ Ti ₅ O ₁₂ ) powder. It was confirmed by X-ray diffraction measurement that the obtained lithium titanate was a single phase having a spinel structure and that there was no hetero phase. The specific surface area of the obtained lithium titanate was 10 m ² / g. In addition, the average longest diameter of 100 particles observed with a scanning electron microscope was 500 nm.

<Preparation of Separator>
47.5 parts by weight of a homopolymer of viscosity average molecular weight (Mv) 700,000, 47.5 parts by weight of a homopolymer of Mv 250,000, and 5 parts by weight of polypropylene of a homopolymer of Mv 400,000 It dry-blended using the tumbler blender, and obtained the polyolefin resin mixture. To 99% by mass of the obtained polyolefin resin mixture, 1% by mass of pentaerythrityl-tetrakis- [3- (3,5-di-t-butyl-4-hydroxyphenyl) propionate] is added as an antioxidant. The polyolefin resin composition was obtained by dry blending again using a tumbler blender.
The resulting polyolefin resin composition was replaced with nitrogen and then fed to a twin-screw extruder by a feeder under a nitrogen atmosphere. Also, liquid paraffin (kinetic viscosity at 37.78 ° C .: 7.59 × 10 ⁻⁵ m ² / s) was injected into the extruder cylinder by a plunger pump. The feeder and the pump were adjusted so that the mass ratio of liquid paraffin occupied in the entire mixture extruded by melt-kneading with a twin-screw extruder was 66% by mass (the resin composition concentration is 34% by mass). Melt-kneading conditions were a preset temperature of 200 ° C., a screw rotation speed of 100 rpm, and a discharge amount of 12 kg / h.
Subsequently, the melt-kneaded product was extruded and cast on a cooling roll controlled to have a surface temperature of 25 ° C. through a T-die to obtain a gel sheet having a thickness of 1600 μm. Next, the obtained gel sheet was introduced into a simultaneous biaxial tenter stretching machine, and biaxial stretching was performed. The set stretching conditions were an MD magnification of 7.0 times, a TD magnification of 6.1 times, and a set temperature of 123 ° C. Next, the gel sheet after biaxial stretching was introduced into a methyl ethyl ketone tank and thoroughly immersed in methyl ethyl ketone to extract and remove liquid paraffin, and then the methyl ethyl ketone was dried and removed. Finally, the dried gel sheet was introduced into a TD tenter, and stretching and thermal relaxation were performed to obtain a microporous polyolefin membrane. The stretching temperature was 125 ° C., the thermal relaxation temperature was 133 ° C., the maximum TD magnification was 1.65, and the relaxation rate was 0.9. The resulting microporous polyolefin membrane had a thickness of 12 μm and a porosity of 40%.
In 100 parts by mass of ion-exchanged water, 29 parts by mass of the above-mentioned inorganic particles of lithium titanate: alumina (average longest diameter: 900 m) = 90: 10 (mass ratio), an aqueous solution of ammonium polycarboxylate (manufactured by Sannopco SN Dispersant 5468) 0.29 parts by mass were mixed. After mixing, bead milling was performed to adjust the average particle size (D50) to 1.5 μm, and a dispersion was obtained. Furthermore, 100 parts by mass of the obtained dispersion liquid is mixed with 2.2 parts by mass of acrylic latex suspension (solid content concentration 40%, average particle diameter 150 nm) as a binder to form a uniform porous layer Prepared. The average particle diameter of the inorganic particles in the above-mentioned dispersion liquid is a particle whose particle size distribution is measured using a laser type particle size distribution measuring device (Microtrac MT3300EX manufactured by Nikkiso Co., Ltd.) and the volume cumulative frequency becomes 50%. The diameter was taken as the average particle diameter (μm). In addition, the average particle diameter of the resin-made latex binder was determined as an average particle diameter by measuring a volume average particle diameter (nm) using a particle diameter measurement apparatus (MICROTRACTMUPA 150 manufactured by LEED & NORTHRUP) by a light scattering method.
Next, the composition for forming a porous layer is applied to the surface of the microporous polyolefin membrane using a microgravure coater, dried at 60 ° C. to remove water, and a 4 μm thick on the microporous polyolefin membrane. An adsorption layer containing lithium titanate and alumina was disposed to obtain a separator having an adsorption layer. The volume ratio of the inorganic particles in the adsorption layer containing lithium titanate and alumina in the separator was 95 volume%.

<Fabrication of positive electrode>
LiNi _{0.5 Co 0.2} Mn _0.3 O ₂ as a positive electrode active material, powder of acetylene black as a conductive additive, and polyvinylidene fluoride solution as a binder in a solid content ratio of 93.9: 3.3: It mixed by the mass ratio of 2.8. To the obtained mixture, N-methyl-2-pyrrolidone was added as a dispersion solvent so as to have a solid content of 35% by mass, and they were further mixed to prepare a slurry-like solution. This slurry-like solution was applied to both sides of a 10 μm thick aluminum foil. At this time, a part of the aluminum foil was exposed. Thereafter, the solvent was removed by drying and rolled by a roll press. The rolled sample is cut so that the size of the coated part is 30 mm × 50 mm and includes the exposed part of the aluminum foil, and further, an aluminum lead piece is welded to the exposed part of the aluminum foil for extracting current. The positive electrode was obtained.

<Fabrication of negative electrode>
Graphite powder as a negative electrode active material, and styrene butadiene rubber and carboxymethyl cellulose aqueous solution as a binder were mixed at a solid content mass ratio of 97.5: 1.5: 1.0. The resulting mixture was added to water as a dispersion solvent so that the solid content concentration was 45% by mass, to prepare a slurry-like solution. This slurry-like solution was applied to one side and both sides of a 10 μm thick copper foil. At this time, part of the copper foil was exposed. Thereafter, the solvent was removed by drying and rolled by a roll press. Cut the rolled sample so that the size of the coated part is 32 mm × 52 mm and includes the exposed part of the copper foil, and further weld the nickel lead piece to the exposed part of the copper foil to extract the current. The negative electrode was obtained.

<Preparation of non-aqueous electrolyte>
In a mixed solvent of ethylene carbonate (EC) and ethyl methyl carbonate (EMC) mixed at a volume ratio of 1: 2 under an argon gas atmosphere, LiPF ₆ is dissolved to 1 mol / L to obtain a non-aqueous electrolyte ( A non-aqueous electrolyte was obtained.

<Fabrication of non-aqueous electrolyte battery>
The positive electrode and the negative electrode were stacked with the separator interposed therebetween to form a laminated electrode body. The separator was disposed so that the non-aqueous electrolyte battery adsorption layer faced the positive electrode. This laminated electrode body was inserted into an 80 × 60 mm aluminum laminate outer package. Next, the non-aqueous electrolyte (non-aqueous electrolyte solution) is injected into the outer package, and then the opening of the outer package is sealed, and a non-aqueous electrolyte battery (lithium ion secondary battery having the laminated electrode inside) ) Was produced. The rated capacity of the obtained non-aqueous electrolyte battery was 90 mAh.

<Evaluation of metal adsorption capacity>
Manganese trifluoromethanesulfonate [Mn (CF ₃ SO ₃ ) ₂ ] was dissolved in the non-aqueous electrolyte used in the non-aqueous electrolyte battery under an argon gas atmosphere so that the concentration of Mn was 5 ppm. In an argon gas atmosphere, 100 parts by mass of the non-aqueous electrolyte in which this Mn is dissolved and 0.035 parts by mass of lithium titanate are placed in a closed container made of polypropylene, and Variable Mix Rotor VMR-5R (manufactured by As One Corporation) is used. The mixture was shaken and stirred at 100 rpm for 6 hours under an atmosphere of 23.degree. Thereafter, it was filtered through a PTFE membrane filter with a pore size of 0.2 μm. The concentration (Mx) (unit: ppm) of Mn in this filtrate was measured, and the adsorption rate (Ax) (unit:%) was calculated from the following equation.
Ax = [(5-Mx) / 5] × 100
The concentration of Mn was measured by ICP emission spectrometry (ICP emission spectrometry: Optima 8300 (manufactured by Perkin Elmer)). In addition, acid decomposition (microwave method) was performed for pretreatment of the measurement sample. The adsorption rate was evaluated as less than 10%: “x”, 10 to 20%: “Δ”, more than 20%: “o”.

<Life characteristics / safety test>
-Initial charge and discharge The obtained non-aqueous electrolyte secondary battery (hereinafter, also simply referred to as "battery") is housed in a thermostatic chamber (thermostatic chamber PLM-73S manufactured by Two Leaf Science Co., Ltd., set at 25 ° C) and charged. The discharge device was connected to a charge / discharge device ACD-01 manufactured by Aska Electronics Co., Ltd. The cell was then charged with a constant current of 0.05 C, reached 4.35 V, charged for 2 hours with a constant voltage of 4.35 V, and discharged to 3.0 V with a constant current of 0.2 C. Here, 1 C is a current value at which the battery is discharged in one hour.
-Float test The battery after the above initial charge is housed in a thermostatic chamber (constant temperature tank PLM-73S manufactured by Futaba Scientific Co., Ltd.) set at 50 ° C, and a charge / discharge device (manufactured by Aska Electronics Co., Ltd., charge / discharge device ACD- Connected to 01). The cell was then charged to 4.35 V with a constant current of 0.5 C and charged to a constant voltage of 4.35 V after reaching 4.35 V. At this time, the time until reaching a slight short circuit was evaluated.
The time until the slight short circuit is measured is the time until the charge capacity is twice the rated capacity in the above charging process, less than 30 days: "×", 30 days or more but less than 60 days: "Δ" , 60 days or more: rated as "○".

Example 2
A separator having an adsorption layer containing lithium titanate and boehmite in the same manner as in Example 1 except that lithium titanate: boehmite (average longest diameter: 1000 nm) = 90: 10 (weight ratio) was used as the inorganic particles. I got The volume ratio of the inorganic particles in the adsorption layer containing lithium titanate and boehmite in this separator was 95 volume%. Further, the life characteristics / safety evaluation was performed in the same manner as in Example 1. In addition, the value of Example 1 was used for the measurement result of metal adsorption capacity.

[Example 3]
An adsorption layer containing lithium titanate and alumina was obtained by the same method as Example 1, except that lithium titanate: alumina (average longest diameter: 900 nm) = 60: 40 (weight ratio) was used as the inorganic particles. . The volume ratio of the inorganic particles in the adsorption layer containing lithium titanate and alumina in this separator was 93%. Further, the life characteristics / safety evaluation was performed in the same manner as in Example 1. In addition, the value of Example 1 was used for the measurement result of metal adsorption capacity.

Example 4
An adsorption layer containing lithium titanate and boehmite was obtained in the same manner as in Example 1 except that lithium titanate: boehmite (average longest diameter: 1000 nm) = 60: 40 (weight ratio) was used as the inorganic particles. . The volume ratio of the inorganic particles in the adsorption layer containing lithium titanate and boehmite in this separator was 93%. Further, the life characteristics / safety evaluation was performed in the same manner as in Example 1. In addition, the value of Example 1 was used for the measurement result of metal adsorption capacity.

[Example 5]
An adsorption layer containing lithium titanate and alumina was obtained in the same manner as in Example 1 except that lithium titanate: alumina (average longest diameter: 900 nm) = 40: 60 (weight ratio) was used as the inorganic particles. . The volume ratio of the inorganic particles in the adsorption layer containing lithium titanate and alumina in the separator was 91%. Further, the life characteristics / safety evaluation was performed in the same manner as in Example 1. In addition, the value of Example 1 was used for the measurement result of metal adsorption capacity.

[Example 6]
An adsorption layer containing lithium titanate and boehmite was obtained in the same manner as in Example 1 except that lithium titanate: boehmite (average longest diameter: 1000 nm) = 40: 60 (weight ratio) was used as the inorganic particles. . The volume ratio of the inorganic particles in the adsorption layer containing lithium titanate and boehmite in this separator was 91%. Further, the life characteristics / safety evaluation was performed in the same manner as in Example 1. In addition, the value of Example 1 was used for the measurement result of metal adsorption capacity.

Comparative Example 1
An adsorption layer containing lithium titanate was obtained in the same manner as in Example 1 except that only lithium titanate was used as the inorganic particles. The volume ratio of the inorganic particles in the adsorption layer containing lithium titanate in the separator was 90%. Further, the life characteristics / safety evaluation was performed in the same manner as in Example 1. In addition, the value of Example 1 was used for the measurement result of metal adsorption capacity.

Comparative Example 2
An adsorption layer containing boehmite was obtained in the same manner as in Example 1 except that only boehmite (average longest diameter: 900 nm) was used as the inorganic particles. In addition, the volume ratio of the inorganic particles in the adsorption layer containing boehmite of this separator was 97%. Further, in the same manner as in Example 1, metal adsorption capacity and life characteristics / safety evaluation were performed.

Comparative Example 3
An adsorption layer containing alumina was obtained in the same manner as in Example 1 except that only alumina (average longest diameter: 900 nm) was used as the inorganic particles. The volume ratio of the inorganic particles in the adsorption layer containing alumina of this separator was 97%. Further, in the same manner as in Example 1, metal adsorption capacity and life characteristics / safety evaluation were performed.

  The adsorption layer for non-aqueous electrolyte batteries of the present invention can be used for a non-aqueous electrolyte battery separator, and the non-aqueous electrolyte battery separator of the present invention can be used for non-aqueous electrolyte batteries such as lithium ion secondary batteries it can.

Claims (8)

  An adsorption layer for a non-aqueous electrolyte battery, comprising lithium titanate and insulating inorganic particles.   The adsorption layer for non-aqueous electrolyte batteries according to claim 1, wherein the insulating inorganic particles are an anion exchanger.   The adsorption layer for nonaqueous electrolyte batteries according to claim 1 or 2 whose lithium titanate is more than 0 mass% and less than 90 mass% when the total mass of lithium titanate and insulating inorganic particles is 100 mass%.   The nonaqueous electrolyte battery which has an adsorption layer for nonaqueous electrolyte batteries as described in any one of Claims 1-3. A non-aqueous electrolyte battery comprising a positive electrode, a negative electrode, a separator, and the adsorption layer for the non-aqueous electrolyte battery,
The non-aqueous electrolyte battery adsorption layer is formed in part or all of at least one selected from the group consisting of the inside of the separator, between the positive electrode and the separator, and between the negative electrode and the separator. The non-aqueous electrolyte battery according to claim 4.   The separator for non-aqueous electrolyte batteries which has an adsorption layer for non-aqueous electrolyte batteries as described in any one of Claims 1-3.   The separator for non-aqueous electrolyte batteries which has an adsorption layer for non-aqueous electrolyte batteries as described in any one of Claims 1-3 in at least single side | surface.   A laminated body or a wound body of the laminated body, in which a positive electrode, an adsorption layer for a non-aqueous electrolyte battery according to any one of claims 1 to 3, a separator, and a negative electrode are laminated in this order; Non-aqueous electrolyte battery.