JP2011014379A - Nonaqueous electrolyte secondary battery, and method of manufacturing the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a nonaqueous electrolyte secondary battery and a method of manufacturing the same which can sufficiently achieve swelling suppression effect when stored at high temperature.SOLUTION: The nonaqueous electrolyte secondary battery includes: an electrode body formed by winding or laminating a positive electrode and a negative electrode through a separator; an electrolyte; and an external package member for housing them. The positive electrode contains positive electrode active material coated with phosphate. The electrolyte includes an electrolyte containing: nonaqueous solvent; electrolyte salt; and an isocyanate compound represented by general formula (2). In the formula (2), N is nitride, C is carbon, and O is oxygen, Ris a 1-22C chain hydrocarbon group, or a 1-22C chain hydrocarbon group in which at least a part of carbon and/or hydrogen is substituted with at least one selected from a group of halogen, oxygen, sulfur, nitrogen and silicon.

Description

The present invention relates to a nonaqueous electrolyte secondary battery and a method for manufacturing the same.
More specifically, the present invention includes an electrode body formed by winding or laminating a positive electrode and a negative electrode with a separator interposed therebetween, an electrolyte, and an exterior member that accommodates them, and the positive electrode is coated with phosphate. The present invention relates to a nonaqueous electrolyte secondary battery containing a positive electrode active material and an electrolyte containing an electrolyte solution containing a predetermined isocyanate compound, and a method for manufacturing the same.

In recent years, many portable electronic devices such as a camera-integrated video tape recorder, a digital still camera, a mobile phone, a personal digital assistant, and a notebook computer have appeared, and their size and weight have been reduced.
In addition, as a portable power source for these portable electronic devices, research and development for improving the energy density of batteries, particularly secondary batteries, are being actively promoted.
Among them, a lithium ion secondary battery using a carbon material as a negative electrode active material, a composite material of lithium (Li) and a transition metal as a positive electrode active material, and a carbonate ester mixture as an electrolyte is a conventional aqueous electrolyte secondary battery. Since a large energy density can be obtained as compared with a certain lead battery or nickel cadmium battery, it is widely put into practical use.
In particular, a laminated battery using an aluminum laminate film as an exterior member has a high energy density because it is lightweight.
In the laminate type battery, since the deformation of the laminate type battery can be suppressed by swelling the electrolyte in the polymer, the laminate polymer type battery is also widely used.

However, the laminate type battery has a problem that it easily swells in a high temperature environment because the exterior member is soft.
In particular, when lithium nickelate is used as the positive electrode active material for increasing the capacity, there is a problem that it is more likely to swell.

  A non-aqueous electrolyte secondary battery using a positive electrode active material coated with a phosphate has been proposed to solve the problem of easily swelling during high-temperature storage (see Patent Document 1).

JP 2007-335331 A

  However, even the nonaqueous electrolyte secondary battery described in Patent Document 1 has a problem that the effect of suppressing swelling during high-temperature storage is not sufficient.

The present invention has been made in view of such problems of the prior art.
And the place made into the objective is to provide the nonaqueous electrolyte secondary battery which can fully exhibit the swelling suppression effect at the time of high temperature storage, and its manufacturing method.

The inventors of the present invention have made extensive studies to achieve the above object.
As a result, an electrode body formed by winding or laminating a positive electrode and a negative electrode containing a positive electrode active material coated with a phosphate via a separator, a nonaqueous solvent, an electrolyte salt, and a predetermined isocyanate compound It has been found that the above-mentioned object can be achieved by using an electrolyte containing an electrolyte solution, and the present invention has been completed.

  That is, the non-aqueous electrolyte secondary battery of the present invention has an electrode body formed by winding or laminating a positive electrode and a negative electrode with a separator interposed therebetween, an electrolyte, and an exterior member that accommodates the electrode body. And a non-aqueous solvent, an electrolyte salt, and an isocyanate compound represented by any one of the following general formulas (1) to (4): It contains an electrolyte solution containing.

(In the formula (1), N represents nitrogen, C represents carbon, O represents oxygen, R ¹ represents a chain hydrocarbon group having 1 to 22 carbon atoms, or at least a part of carbon and / or hydrogen is halogen, This represents a C1-C22 chain hydrocarbon group substituted with at least one selected from the group consisting of oxygen, sulfur, nitrogen and silicon.)

(In the formula (2), N represents nitrogen, C represents carbon, O represents oxygen, R ² represents a chain hydrocarbon group having 1 to 22 carbon atoms, or at least part of carbon and / or hydrogen is halogen, This represents a C1-C22 chain hydrocarbon group substituted with at least one selected from the group consisting of oxygen, sulfur, nitrogen and silicon.)

(In the formula (3), N represents nitrogen, C represents carbon, O represents oxygen, R ³ represents a cyclic hydrocarbon group having 3 to 20 carbon atoms, or at least part of carbon and / or hydrogen is halogen, oxygen And a C3-C20 cyclic hydrocarbon group substituted with at least one selected from the group consisting of sulfur, nitrogen and silicon.)

(In the formula (4), N represents nitrogen, C represents carbon, O represents oxygen, R ⁴ represents a cyclic hydrocarbon group having 3 to 20 carbon atoms, or at least a part of carbon and / or hydrogen is halogen, oxygen And a C3-C20 cyclic hydrocarbon group substituted with at least one selected from the group consisting of sulfur, nitrogen and silicon.)

  The method for producing a non-aqueous electrolyte secondary battery of the present invention includes an electrode body obtained by winding or laminating a positive electrode and a negative electrode with a separator interposed therebetween, an electrolyte, and an exterior member that accommodates these, The positive electrode contains a positive electrode active material coated with a phosphate, and the electrolyte is represented by any one of a non-aqueous solvent, an electrolyte salt, and the following general formulas (1) to (4). In manufacturing a nonaqueous electrolyte secondary battery containing an electrolyte solution containing an isocyanate compound, an electrode formed by winding or laminating a positive electrode and a negative electrode containing a positive electrode active material coated with a phosphate via a separator A body and an electrolyte containing an electrolyte containing a nonaqueous solvent, an electrolyte salt, and an isocyanate compound represented by any one of the following general formulas (1) to (4) are accommodated in an exterior member. It is a manufacturing method.

(In the formula (1), N represents nitrogen, C represents carbon, O represents oxygen, R ¹ represents a chain hydrocarbon group having 1 to 22 carbon atoms, or at least a part of carbon and / or hydrogen is halogen, This represents a C1-C22 chain hydrocarbon group substituted with at least one selected from the group consisting of oxygen, sulfur, nitrogen and silicon.)

(In the formula (2), N represents nitrogen, C represents carbon, O represents oxygen, R ² represents a chain hydrocarbon group having 1 to 22 carbon atoms, or at least part of carbon and / or hydrogen is halogen, This represents a C1-C22 chain hydrocarbon group substituted with at least one selected from the group consisting of oxygen, sulfur, nitrogen and silicon.)

(In the formula (3), N represents nitrogen, C represents carbon, O represents oxygen, R ³ represents a cyclic hydrocarbon group having 3 to 20 carbon atoms, or at least part of carbon and / or hydrogen is halogen, oxygen And a C3-C20 cyclic hydrocarbon group substituted with at least one selected from the group consisting of sulfur, nitrogen and silicon.)

(In the formula (4), N represents nitrogen, C represents carbon, O represents oxygen, R ⁴ represents a cyclic hydrocarbon group having 3 to 20 carbon atoms, or at least a part of carbon and / or hydrogen is halogen, oxygen And a C3-C20 cyclic hydrocarbon group substituted with at least one selected from the group consisting of sulfur, nitrogen and silicon.)

  According to the present invention, an electrode body formed by winding or laminating a positive electrode and a negative electrode containing a positive electrode active material coated with a phosphate via a separator, a nonaqueous solvent, an electrolyte salt, and a predetermined isocyanate compound Therefore, it is possible to provide a non-aqueous electrolyte secondary battery that can sufficiently exhibit the swelling-suppressing effect during high-temperature storage and a method for manufacturing the same.

1 is an exploded perspective view showing an example of a nonaqueous electrolyte secondary battery according to a first embodiment of the present invention. It is typical sectional drawing along the II-II line of the battery element shown in FIG. It is sectional drawing which shows an example of the nonaqueous electrolyte secondary battery which concerns on the 2nd Embodiment of this invention.

Hereinafter, modes for carrying out the invention (hereinafter referred to as “embodiments”) will be described. The description will be given in the following order.
1. First embodiment (example of first nonaqueous electrolyte secondary battery)
2. Second Embodiment (Example of Manufacturing Method of First Nonaqueous Electrolyte Secondary Battery)
3. Third embodiment (example of second nonaqueous electrolyte secondary battery)
4). Fourth Embodiment (Example of Method for Manufacturing Second Nonaqueous Electrolyte Secondary Battery)

<1. First Embodiment>
[Configuration of non-aqueous electrolyte secondary battery]
FIG. 1 is an exploded perspective view showing an example of the nonaqueous electrolyte secondary battery according to the first embodiment of the present invention. Such a non-aqueous electrolyte secondary battery is called a laminate type battery.

As shown in the figure, this non-aqueous electrolyte secondary battery is configured by enclosing a battery element 20 to which a positive electrode lead 11 and a negative electrode lead 12 are attached inside an exterior member 30.
The positive electrode lead 11 and the negative electrode lead 12 are led out from the inside of the exterior member 30 to the outside, for example, in the same direction.
The positive electrode lead 11 and the negative electrode lead 12 are each made of a metal material such as aluminum (Al), copper (Cu), nickel (Ni), or stainless steel.
In addition, what remove | excluding the electrolyte from the battery element 20 is called an electrode body.

[Exterior material]
The exterior member 30 is configured by a rectangular aluminum laminated film 31 in which, for example, a nylon film, an aluminum foil, and a polyethylene film are bonded together in this order. The exterior member 30 is arrange | positioned so that the polyethylene film side and the battery element 20 may oppose, for example, and each outer edge part is mutually joined by melt | fusion or the adhesive agent.
An adhesion film 32 is inserted between the exterior member 30 and the positive electrode lead 11 and the negative electrode lead 12 to prevent the entry of outside air. The adhesion film 32 is made of a material having adhesion to the positive electrode lead 11 and the negative electrode lead 12. For example, when the positive electrode lead 11 and the negative electrode lead 12 are made of the metal materials described above, polyethylene, polypropylene, modified It is preferably composed of a polyolefin resin such as polyethylene or modified polypropylene.

In addition, the exterior member 30 may be configured by another structure, for example, a laminate film having no metal material, a polymer film such as polypropylene, or a metal film, instead of the above-described laminate film.
Here, the general structure of a laminate film can be represented by the laminated structure of exterior layer / metal foil / sealant layer (however, the exterior layer and sealant layer may be composed of a plurality of layers), and the above. In this example, the nylon film corresponds to the exterior layer, the aluminum foil corresponds to the metal foil, and the polyethylene film corresponds to the sealant layer.
In addition, as metal foil, it is sufficient if it functions as a moisture-permeable barrier film, and not only aluminum foil but also stainless steel foil, nickel foil and plated iron foil can be used, but it is thin and lightweight. Thus, an aluminum foil excellent in workability can be suitably used.

  As the exterior member, usable configurations are listed in the form of (exterior layer / metal foil / sealant layer): Ny (nylon) / Al (aluminum) / CPP (unstretched polypropylene), PET (polyethylene terephthalate) / Al / CPP, PET / Al / PET / CPP, PET / Ny / Al / CPP, PET / Ny / Al / Ny / CPP, PET / Ny / Al / Ny / PE (polyethylene), Ny / PE / Al / LLDPE (direct) Chain low density polyethylene), PET / PE / Al / PET / LDPE (low density polyethylene), and PET / Ny / Al / LDPE / CPP.

[Configuration of battery element]
FIG. 2 is a schematic cross-sectional view taken along the line II-II of the battery element 20 shown in FIG. In the figure, a battery element 20 is wound in such a manner that a positive electrode 21 and a negative electrode 22 face each other with an electrolyte layer 23 containing an electrolytic solution held on a polymer support and a separator 24 interposed therebetween. The outermost periphery is protected by the protective tape 26.
The electrolytic solution is impregnated and held in the positive electrode 21, the negative electrode 22, the electrolyte layer 23, and the separator 24, and as described above, an electrode body obtained by removing the electrolytic solution from the battery element 20 is referred to as an electrode body.

[Positive electrode]
Here, the positive electrode 21 has, for example, a structure in which a positive electrode active material layer 21B is coated on both surfaces or one surface of a positive electrode current collector 21A having a pair of opposed surfaces. The positive electrode current collector 21A has a portion that is exposed without being covered with the positive electrode active material layer 21B at one end portion in the longitudinal direction, and the positive electrode lead 11 is attached to the exposed portion.
The positive electrode current collector 21A is made of a metal foil such as an aluminum foil, a nickel foil, or a stainless steel foil.

The positive electrode active material layer 21B contains a positive electrode active material coated with phosphate.
The positive electrode active material includes one or more positive electrode materials capable of occluding and releasing lithium ions, and if necessary, a conductive agent such as graphite and a binder such as polyvinylidene fluoride. An agent may be included.
Further, a rubber-based binder such as carboxymethyl cellulose (CMC) or styrene-butadiene rubber (SBR) may be used as the binder.

Examples of the positive electrode material capable of inserting and extracting lithium ions include sulfur (S), disulfide such as iron disulfide (FeS ₂ ), titanium disulfide (TiS ₂ ), and molybdenum disulfide (MoS ₂ ). , Chalcogenides not containing lithium such as niobium diselenide (NbSe ₂ ), vanadium oxide (V ₂ O ₅ ), titanium dioxide (TiO ₂ ) and manganese dioxide (MnO ₂ ) (particularly layered compounds and spinel compounds) And lithium-containing compounds containing lithium, and conductive polymer compounds such as polyaniline, polythiophene, polyacetylene, and polypyrrole.

  Among these, lithium-containing compounds are preferable because some compounds can obtain a high voltage and a high energy density. Examples of such a lithium-containing compound include a composite oxide containing lithium and a transition metal element, and a phosphate compound containing lithium and a transition metal element. From the viewpoint of obtaining a higher voltage, cobalt is particularly preferred. (Co), nickel (Ni), manganese (Mn), iron (Fe), copper (Cu), zinc (Zn), chromium (Cr), vanadium (V), titanium (Ti) or any mixture thereof. The inclusion is preferred.

Such lithium-containing compounds are typically represented by the following general formula (6) or (7)
Li _x M ^I O ₂ (6)
Li _y M ^II PO ₄ (7)
[M ^I and M ^{II in} Formulas (6) and (7) represent one or more transition metal elements, and the values of x and y vary depending on the charge / discharge state of the battery, but usually 0.05 ≦ x ≦ 1 .10, 0.05 ≦ y ≦ 1.10. ]. The compound of formula (6) generally has a layered structure, and the compound of formula (7) generally has an olivine structure.

Specific examples of the composite oxide containing lithium and a transition metal element include lithium cobalt composite oxide (Li _x CoO ₂ ), lithium nickel composite oxide (LiNiO ₂ ), and solid solutions thereof (Li (Ni _x Co _y Mn _{z) O} 2), lithium nickel cobalt composite oxide _{(LiNi 1-z Co z O} 2 (z <1)), lithium manganese composite oxide having a spinel structure (LiMn ₂ O ₄₎ and their solid solutions _{(Li (Mn 2-x Ni} y) O 4) , and the like.

Specific examples of the phosphate compound containing lithium and a transition metal element include, for example, a lithium iron phosphate compound having a olivine structure (LiFePO ₄ ) or a lithium iron manganese phosphate compound (LiFe _1-v Mn _v PO ₄ (v < 1)).

Among them, the following general formula (5)
LiNi _x M _1-x O ₂ (5)
(In Formula (5), Li is lithium, Ni is nickel, M is at least one selected from the group consisting of cobalt (Co), manganese (Mn), and aluminum (Al), O is oxygen, and x is The relationship of 0.75 ≦ x ≦ 1 is satisfied.) A nickel-based positive electrode active material represented by the following formula can be given as a suitable example.

  Examples of the phosphate covering the positive electrode active material include lithium phosphate, lithium cobalt phosphate, and iron phosphate.

[Negative electrode]
On the other hand, similarly to the positive electrode 21, the negative electrode 22 has a structure in which a negative electrode active material layer 22B is provided on both surfaces or one surface of a negative electrode current collector 22A having a pair of opposed surfaces, for example. The negative electrode current collector 22A has an exposed portion where the negative electrode active material layer 22B is not provided at one end in the longitudinal direction, and the negative electrode lead 12 is attached to the exposed portion.
The anode current collector 22A is made of a metal foil such as a copper foil, a nickel foil, or a stainless steel foil.

  The negative electrode active material layer 22B contains, as a negative electrode active material, any one or more of negative electrode materials capable of occluding and releasing lithium ions and metallic lithium, and if necessary, polyvinylidene fluoride, etc. The binder may be included. Further, a rubber-based binder such as carboxymethyl cellulose (CMC) or styrene-butadiene rubber (SBR) may be used as the binder.

Examples of the negative electrode material capable of inserting and extracting lithium include a carbon material, a metal oxide, and a polymer compound. Examples of carbon materials include non-graphitizable carbon materials, artificial graphite materials, and graphite-based materials. More specifically, pyrolytic carbons, cokes, graphites, glassy carbons, organic polymer compound firing Body, carbon fiber, activated carbon and carbon black.
Among these, coke includes pitch coke, needle coke and petroleum coke, and the organic polymer compound fired body is carbonized by firing a polymer material such as phenol resin or furan resin at an appropriate temperature. Say things. In addition, examples of the metal oxide include iron oxide, ruthenium oxide, and molybdenum oxide, and examples of the polymer compound include polyacetylene and polypyrrole.

Further, examples of the negative electrode material capable of inserting and extracting lithium include a material containing as a constituent element at least one of a metal element and a metalloid element capable of forming an alloy with lithium. The negative electrode material may be a single element, alloy or compound of a metal element or a metalloid element, or may have at least a part of one or more of these phases.
In the present invention, alloys include those containing one or more metal elements and one or more metalloid elements in addition to those composed of two or more metal elements. Moreover, the nonmetallic element may be included. Some of the structures include a solid solution, a eutectic (eutectic mixture), an intermetallic compound, or a mixture of two or more of these.

Examples of such a metal element or metalloid element include tin (Sn), lead (Pb), magnesium (Mg), aluminum (Al), indium (In), silicon (Si), zinc (Zn), antimony ( Sb), bismuth (Bi), gallium (Ga), germanium (Ge), arsenic (As), silver (Ag), hafnium (Hf), zirconium (Zr) and yttrium (Y).
Among them, a group 14 metal element or metalloid element in the long-period type periodic table is preferable, and silicon or tin is particularly preferable. This is because silicon and tin have a large ability to occlude and release lithium, and a high energy density can be obtained.

Examples of the tin alloy include silicon, magnesium (Mg), nickel, copper, iron, cobalt, manganese, zinc, indium, silver, titanium (Ti), germanium, bismuth, and antimony as second constituent elements other than tin. And at least one selected from the group consisting of chromium (Cr).
As an alloy of silicon, for example, as a second constituent element other than silicon, tin, magnesium, nickel, copper, iron, cobalt, manganese, zinc, indium, silver, titanium, germanium, bismuth, antimony, and chromium can be used. The thing containing at least 1 sort (s) of them is mentioned.

  Examples of the tin compound or the silicon compound include those containing oxygen (O) or carbon (C), and may contain the second constituent element described above in addition to tin or silicon.

  Furthermore, the negative electrode material as described above may be an element that forms a composite oxide with lithium, such as titanium. Of course, metallic lithium may be precipitated and dissolved, and magnesium and aluminum other than lithium may be precipitated and dissolved.

[Separator]
The separator 24 has a high ion permeability and a predetermined mechanical strength, such as a porous film made of a polyolefin-based synthetic resin such as polypropylene or polyethylene, or a porous film made of an inorganic material such as a ceramic nonwoven fabric. It is good also as a structure which laminated | stacked these 2 or more types of porous films. In particular, those containing a polyolefin-based porous membrane are suitable because they have excellent separability between the positive electrode 21 and the negative electrode 22 and can further reduce internal short-circuiting and open circuit voltage reduction.

[Nonaqueous solvent]
As the non-aqueous solvent, various high dielectric constant solvents and low viscosity solvents can be used.
Examples of the high dielectric constant solvent include those containing ethylene carbonate, but are not limited thereto.
Examples of the high dielectric constant solvent include cyclic carbonates such as propylene carbonate, butylene carbonate, and vinylene carbonate.

  In addition, a solvent in which hydrogen of these cyclic carbonates is substituted with halogen can be added and used. Specifically, 4-fluoro-1,3-dioxolane-2-one (fluoroethylene carbonate (FEC)), 4,5-fluoro-1,3-dioxolane-2-one (difluoroethylene carbonate (DFEC)) Mention may also be made of cyclic carbonates such as 4-chloro-1,3-dioxolan-2-one (chloroethylene carbonate) and trifluoromethylethylene carbonate. For DFEC, the trans form is particularly desirable.

  Further, as a high dielectric constant solvent, instead of or in combination with a cyclic carbonate, a lactone such as γ-butyrolactone and γ-valerolactone, a lactam such as N-methylpyrrolidone, and a cyclic carbamic acid such as N-methyloxazolidinone Sulfone compounds such as esters and tetramethylene sulfone can also be used.

  On the other hand, examples of the low-viscosity solvent include those containing diethyl carbonate, but are not limited thereto. For example, chain carbonates such as dimethyl carbonate, ethyl methyl carbonate, and methyl propyl carbonate, chains such as methyl acetate, ethyl acetate, methyl propionate, ethyl propionate, methyl butyrate, methyl isobutyrate, methyl trimethyl acetate, and ethyl trimethyl acetate Carboxylic acid esters, chain amides such as N, N-dimethylacetamide, chain carbamic acid esters such as methyl N, N-diethylcarbamate, ethyl N, N-diethylcarbamate, 1,2-dimethoxyethane, tetrahydrofuran And ethers such as tetrahydropyran and 1,3-dioxolane.

In addition, said high dielectric constant solvent and low-viscosity solvent can be used individually by 1 type or in mixture of these 2 or more types arbitrarily.
Moreover, it is preferable that content of said nonaqueous solvent shall be 70-90 mass%. If it is less than 70% by mass, the viscosity may increase excessively, and if it exceeds 90% by mass, sufficient conductivity may not be obtained.

[Electrolyte salt]
Any electrolyte salt may be used as long as it dissolves or disperses in the non-aqueous solvent to generate ions, and includes an electrolyte containing lithium hexafluorophosphate (LiPF ₆ ) and lithium tetrafluoroborate (LiBF ₄ ). Needless to say, it can be preferably used, but is not limited thereto.
For example, lithium hexafluoroarsenate (LiAsF _6), lithium hexafluoro antimonate (LiSbF _6), lithium perchlorate (LiClO _4), four lithium aluminum chloride acid or an inorganic lithium salt (LiAlCl ₄₎ or the like, trifluoperazine Lithium methanesulfonate (LiCF ₃ SO ₃ ), lithium bis (trifluoromethanesulfone) imide (LiN (CF ₃ SO ₂ ) ₂ ), lithium bis (pentafluoroethanesulfone) methide (LiC (C ₂ F ₅ SO ₂ ) ₂ ), Lithium salts of perfluoroalkanesulfonic acid derivatives such as lithium tris (trifluoromethanesulfone) methide (LiC (CF ₃ SO ₂ ) ₃ ), and the like can be used. It is also possible to use a mixture.

  In addition, it is preferable that content of such electrolyte salt shall be 10-30 mass%. If it is less than 10% by mass, sufficient conductivity may not be obtained, and if it exceeds 30% by mass, the viscosity may increase excessively.

[Isocyanate compound]
As an isocyanate compound, the isocyanate compound represented by any one among the following general formula (1)-(4) can be mentioned.

(In the formula (1), N represents nitrogen, C represents carbon, O represents oxygen, R ¹ represents a chain hydrocarbon group having 1 to 22 carbon atoms, or at least a part of carbon and / or hydrogen is halogen, This represents a C1-C22 chain hydrocarbon group substituted with at least one selected from the group consisting of oxygen, sulfur, nitrogen and silicon.)

(In the formula (2), N represents nitrogen, C represents carbon, O represents oxygen, R ² represents a chain hydrocarbon group having 1 to 22 carbon atoms, or at least part of carbon and / or hydrogen is halogen, This represents a C1-C22 chain hydrocarbon group substituted with at least one selected from the group consisting of oxygen, sulfur, nitrogen and silicon.)

(In the formula (3), N represents nitrogen, C represents carbon, O represents oxygen, R ³ represents a cyclic hydrocarbon group having 3 to 20 carbon atoms, or at least part of carbon and / or hydrogen is halogen, oxygen And a C3-C20 cyclic hydrocarbon group substituted with at least one selected from the group consisting of sulfur, nitrogen and silicon.)

(In the formula (4), N represents nitrogen, C represents carbon, O represents oxygen, R ⁴ represents a cyclic hydrocarbon group having 3 to 20 carbon atoms, or at least a part of carbon and / or hydrogen is halogen, oxygen And a C3-C20 cyclic hydrocarbon group substituted with at least one selected from the group consisting of sulfur, nitrogen and silicon.)

Although the octadecyl isocyanate can be mentioned as a suitable example as an isocyanate compound represented by said General formula (1), It is not limited to this. That is, for example, isocyanatomethane, 1-isocyanatoethane, 1-isocyanatopropane, 2-isocyanatopropane, 2-isocyanato-2methylpropane, 1-isocyanatobutane, 2-isocyanatobutane, 1-isocyanatopentane 1-isocyanatohexane, 1-isocyanatoheptane, 1-isocyanatooctane, 1-isocyanatononane, 1-isocyanatodecane, 1-isocyanatoundecane, 1-isocyanatododecane, 1-isocyanatotridecane, 1-isocyanatotetradecane, 1-isocyanatopentadecane, 1-isocyanatohexadecane, 1-isocyanatoheptadecane, 1-isocyanatononadecane, 1-isocyanatoeicosan, 1-isocyanatohenicosan, 1-isocyanate Natodokosan, 2- Soshianato -2,4,4 carbon and hydrogen, such as trimethylpentane is halogen, oxygen, mention may be made of sulfur, an isocyanate compound having a nitrogen or unsubstituted silicon chain hydrocarbon group.
In the present invention, preferred examples of the halogen include fluorine, chlorine, and bromine.

  Moreover, as an isocyanate compound represented by said general formula (1), carbon and hydrogen, such as 1-isocyanatoethylene and 3-isocyanato-1-propene, are substituted by halogen, oxygen, sulfur, nitrogen, or silicon. There may also be mentioned isocyanate compounds having an unsaturated bond.

Further, the isocyanate compound represented by the above general formula (1) includes trifluoromethane isocyanate, pentafluoroethane isocyanate, 1-isocyanato-2-methoxyethane, 1-isocyanato-3-methoxypropane, 1-isocyanato-3. -Ethoxypropane, 1-isocyanato-4-methoxybutane, 1-isocyanato-4-ethoxybutane, 1-isocyanato-5-methoxypentane, 1-isocyanato-5-ethoxypentane, 1-isocyanato-6-methoxyhexane, 1 -Isocyanato-6-ethoxyhexane, methyl isocyanatoformate, ethyl isocyanatoacetate, ethyl-3-isocyanatopropanoate, butyl isocyanatoacetate, ethyl-4-isocyanatobutanoate, ethyl- An isocyanate compound having a chain hydrocarbon group in which at least a part of carbon and hydrogen such as isocyanatohexanoate and 2-isocyanatoethyl-2-methyl acrylate is substituted with halogen, oxygen, sulfur, nitrogen or silicon It can also be mentioned.
Even if hydrogen in the molecule is substituted with halogen, it is considered that halogen bonded to carbon is inactive and does not affect battery characteristics, and thus has the same effect as that of non-substituted hydrogen.

In the present invention, “substitution” is not limited to what is obtained by a so-called substitution reaction. For example, when chlorobenzene (C ₆ H ₅ Cl) is obtained by replacing one hydrogen (H) of benzene (C ₆ H ₆ ) with (Cl), such chlorobenzene is substituted. Of course, it is included in what was done. Further, in the present invention, for example, methanol (CH ₃ —O—H) is substituted with carbon (ethane) of ethane (CH ₃ —CH ₂ —H) and (CH ₂ ) which is a part of hydrogen with oxygen (O). Should also be construed to include the substitutions.

  As an isocyanate compound having two isocyanate groups represented by the general formula (2), hexamethylene diisocyanate can be cited as a preferred example, but is not limited thereto. That is, for example, 1,3-diisocyanatopropane, 1,4-diisocyanatobutane, 1,5-diisocyanatopentane, 1,5-diisocyanato-2-methylpentane, 1,6-diisocyanatohexane, 1,7-diisocyanatoheptane, 1,8-diisocyanatooctane, 1,9-diisocyanatononane, 1,10-diisocyanatodecane, 1,11-diisocyanatoundecane, 1,12-di Isocyanatododecane, 1,13-diisocyanatotridecane, 1,14-diisocyanatotetradecane, 1,15-diisocyanatopentadecane, 1,16-diisocyanatohexadecane, 2,2-dimethylpentane-1, Chains in which carbon and hydrogen such as 5-diyl diisocyanate are not substituted by halogen, oxygen, sulfur, nitrogen or silicon And an isocyanate compound having a hydrocarbon group.

  Examples of the isocyanate compound having two isocyanate groups represented by the general formula (2) include 1,4-diisocyanato-2-butene, 1,5-diisocyanato-2-pentene, and 1,6-diisocyanato- Mention may also be made of isocyanate compounds in which carbon and hydrogen such as 2-hexene and 1,6-diisocyanato-3-hexene are not substituted with halogen, oxygen, sulfur, nitrogen or silicon and have an unsaturated bond.

  Furthermore, as an isocyanate compound having two isocyanate groups represented by the general formula (2), 1,3-diisocyanato-2-fluoropropane, 1,4-diisocyanato-2-fluorobutane, 1,4- Diisocyanato-2,3-difluorobutane, 1,6-diisocyanato-3-fluorohexane, 1,6-diisocyanato-3,4-difluorohexane, hexafluoropropane-1,3-diyl diisocyanate, octafluorobutane 1,4-diyldiisocyanate, methyl 2,6-diisocyanatohexanoate, dimethyldiisocyanatosilane, 1,6-diisocyanato-2,2,4-trimethylhexane, hexadecafluorooctane-1,8- Diyl diisocyanate, bis (2-isocyanatoethyl) sulfide, (3-isocyanatopropyl) sulfide, dibutyl diisocyanato silane, diethoxy diisocyanato silane, ethyl diisocyanato phosphine oxide, methyl diisocyanato phosphine oxide, isopropyl diisocyanato phosphine oxide, butoxy diisocyanato phosphine oxide An isocyanate compound having a chain hydrocarbon group in which at least a part of carbon and hydrogen such as halogen, oxygen, sulfur, nitrogen or silicon is substituted can also be mentioned.

Examples of the isocyanate compound represented by the general formula (3) include isocyanatocyclopropane, isocyanatocyclopentane, isocyanatocyclohexane, isocyanatomethyl (cyclohexane), isocyanatocyclooctane, and 1-isocyanatoadamantane. Mention may be made of isocyanate compounds having a cyclic hydrocarbon group in which carbon and hydrogen are not substituted by halogen, oxygen, sulfur, nitrogen or silicon.
Moreover, as an isocyanate compound represented by said general formula (3), at least one part of carbon and hydrogen, such as 2- (isocyanatomethyl) furan, was substituted by halogen, oxygen, sulfur, nitrogen, or silicon, for example. Mention may also be made of isocyanate compounds having a cyclic hydrocarbon group.
Examples of the cyclic hydrocarbon group include not only alicyclic cyclic hydrocarbons such as the above compounds but also aromatic cyclic hydrocarbon groups.

  As an isocyanate compound having two isocyanate groups represented by the general formula (4), the chemical formula (8)

As a suitable example, dicyclohexylmethane-4,4'-diisocyanate represented by the following can be given, but the invention is not limited thereto. That is, for example, 1,3-bis (isocyanatomethyl) cyclohexane, methylenebis (cyclohexane-4,1-diyl) diisocyanate, cyclohexane-1,3-diyl diisocyanate, cyclohexane-1,4-diyl diisocyanate , Cyclohexane-1,3-diylbis (methyl isocyanate), 1-methylcyclohexane-2,4-diyl diisocyanate and the like, in which the carbon and hydrogen are not substituted by halogen, oxygen, sulfur, nitrogen or silicon And an isocyanate compound having a cyclic hydrocarbon group.

  In addition, as an isocyanate compound having two isocyanate groups represented by the above general formula (4), at least part of carbon and hydrogen such as isophorone diisocyanate is substituted with halogen, oxygen, sulfur, nitrogen or silicon. Mention may also be made of isocyanate compounds having an alicyclic cyclic hydrocarbon group.

  Furthermore, as the isocyanate compound having two isocyanate groups represented by the general formula (4), 4,4-methylenebis (phenyl isocyanate), 2,6-tolylene diisocyanate, 2,4-tolylene diene Isocyanate, m-phenylenebis (1-methylethane-1,1-diyl) diisocyanate, p-phenylenebis (1-methylethane-1,1-diyl) diisocyanate, m-xylylenediisocyanate, naphthalene -1,5-diyl diisocyanate, naphthalene-2,6-diyl diisocyanate, naphthalene-2,7-diyl diisocyanate, 3,3′-dimethylbiphenyl-4,4′-diisocyanate, 1 , 3-phenylene diisocyanate, 1,4-phenylene diisocyanate, 2-methyl-1 4-phenylene diisocyanate, naphthalene-1,4-diisocyanate, methylenebis (2,1-phenylene) diisocyanate, naphthalene-1,4-diylbis (methylene) diisocyanate, naphthalene-1,5-diylbis (Methylene) diisocyanate, 2,4-dimethyl-1,3-phenylene diisocyanate, 4,6-dimethyl-1,3-phenylene diisocyanate, 2,5-dimethyl-1,3-phenylene diisocyanate Narate, 2-methyl-4,6-diethylbenzene-1,3-diyldiisocyanate, 2,4,6-triethylbenzene-1,3-diyldiisocyanate, 2,6-dimethylbenzene-1,4- Diyl diisocyanate, 2,6-diethylbenzene-1,4-diyl diisocyanate, methylene bi (2,6-dimethyl-4,1-phenylene) diisocyanate, methylene bis (3-methyl-4,1-phenylene) diisocyanate, methylene bis (2,6-diisopropyl-4,1-phenylene) diisocyanate , Isopropylidenebis (4,1-phenylene) diisocyanate, 9H-fluorene-2,7-diyl diisocyanate and the like in which aromatic carbon and hydrogen are not substituted by halogen, oxygen, sulfur, nitrogen or silicon An isocyanate compound having a cyclic hydrocarbon group can be exemplified.

Furthermore, as the isocyanate compound having two isocyanate groups represented by the general formula (4), 4-[(2-isocyanatophenyl) oxy] phenyl isocyanate, 4,4′-oxybis (phenyl isocyanate) ), 2,2′-dimethoxybiphenyl-4,4′-diyl diisocyanate, 1- (trifluoromethyl) -2,2,2-trifluoroethylidenebis (4,1-phenylene) diisocyanate, [ Hexahydrobiphenyl] -4,4-diyl] diisocyanate, 4-chlorobenzene-1,3-diyl diisocyanate, 2,4-dichlorobenzene-1,3-diisocyanate, 4,6-dichlorobenzene- 1,3-diisocyanate, 2,5-dichlorobenzene-1,4-diisocyanate, 4- (trifluoromethyl Benzene-1,3-diyl diisocyanate, 2- (trifluoromethyl) benzene-1,3-diyl diisocyanate, trimethylenedioxybis (4,1-phenylene) diisocyanate, thiobis (4,1 -Phenylene) diisocyanate, 9H-carbazole-3,6-diyl diisocyanate, diphenyldiisocyanatosilane, diphenoxydiisocyanatosilane, phenyldiisocyanatophosphine oxide, phenoxydiisocyanatophosphine oxide, phenyldiisocyanate Mention may also be made of isocyanate compounds having an aromatic cyclic hydrocarbon group in which at least part of carbon and hydrogen such as natophosphine is substituted with halogen, oxygen, sulfur, nitrogen or silicon.
In addition, in an isocyanate compound, what has 1-4 cyclic structures can be used suitably, It does not ask | require whether these cyclic structures are an alicyclic thing or an aromatic thing.

  The said isocyanate compound can be used individually by 1 type or in mixture of 2 or more types as appropriate.

  The content of the isocyanate compound is preferably 0.01 to 5% by mass based on the total amount of the electrolytic solution. When it is within the above range, it is easy to dissolve in the electrolytic solution and to easily exert the swelling effect. These values are particularly effective in the state before the initial charge, and when the solid electrolyte membrane (SEI) is formed on the electrode (mainly the negative electrode) during charging (particularly during initial charging), a part of the isocyanate compound is present. Since it is consumed, the amount and concentration of the isocyanate compound in the electrolytic solution are considered to be somewhat different values after the initial charging.

[Polymer support]
Furthermore, the electrolytic solution can be impregnated or held by the polymer support.
By swelling, gelling or non-fluidizing the polymer support, it is possible to effectively suppress leakage of the electrolyte in the obtained battery.

  In addition, as a polymer which forms such a polymer support, polyvinyl formal (9), polyacrylic acid ester (10) represented by the following chemical formulas (9) to (11), and polyvinylidene fluoride (PVdF) (11) can be exemplified.

  However, N in the formula (9) represents the degree of polymerization, and preferably N = 100 to 10,000. If N is less than 100, gelation is not sufficient, and if it exceeds 10,000, the viscosity may be large and the capacity may be reduced.

However, R in the formula (10) represents C _n H _2n-1 O _m (n represents an integer of 1 to 8, m represents an integer of 0 to 4), N represents a degree of polymerization, and preferably N = 100 to 10,000. If N is less than 100, gelation is difficult, and if it exceeds 10,000, fluidity may decrease.

However, N in the formula (11) indicates the degree of polymerization, and preferably N = 100 to 10,000. If N is less than 100, gelation is not sufficient, and if it exceeds 10,000, the viscosity may be large and the capacity may be reduced.
In addition, it is preferable that content of the above-mentioned polymer compound shall be 0.1-5 mass parts with respect to 100 mass parts of electrolyte solution. If it is less than 0.1 part by mass, gelation is difficult, and if it exceeds 5 parts by mass, the fluidity may decrease.

The polymer support is not limited to these as long as it can impregnate or retain the above non-aqueous solvent, the above electrolyte salt and the above isocyanate compound. That is, for example, a copolymer or multi-component copolymer containing vinylidene fluoride, hexafluoropropylene, polytetrafluoroethylene, or the like as a constituent component can be applied. Specific examples include polyvinylidene fluoride-hexafluoropropylene copolymer (PVdF-HFP) and polyvinylidene fluoride-hexafluoropropylene-chlorotrifluoroethylene copolymer (PVdF-HEP-CTFE).
Some matrix resins are swelled, gelled or non-fluidized by impregnating or holding the non-aqueous solvent or electrolyte salt. Thereby, in the battery obtained, leakage of the nonaqueous electrolyte can be suppressed.

<2. Second Embodiment>
[Production of non-aqueous electrolyte secondary battery]
An example of the manufacturing method of the nonaqueous electrolyte secondary battery according to the first embodiment will be described. In addition, since each component in 2nd Embodiment is the same as each component in 1st Embodiment, the description is abbreviate | omitted.
First, the positive electrode 21 is produced. For example, when using a particulate positive electrode active material, a positive electrode active material coated with a phosphate and, if necessary, a conductive agent and a binder are mixed to prepare a positive electrode mixture, and N-methyl- A positive electrode mixture slurry is prepared by dispersing in a dispersion medium such as 2-pyrrolidone.
Next, the positive electrode mixture slurry is applied to the positive electrode current collector 21A, dried, and compression molded to form the positive electrode active material layer 21B.

  Moreover, the negative electrode 22 is produced. For example, when a particulate negative electrode active material is used, a negative electrode mixture is prepared by mixing the negative electrode active material and, if necessary, a conductive agent and a binder, and a dispersion medium such as N-methyl-2-pyrrolidone. To prepare a negative electrode mixture slurry. Thereafter, the negative electrode mixture slurry is applied to the negative electrode current collector 22A, dried, and compression molded to form the negative electrode active material layer 22B.

  Next, the positive electrode lead 11 is attached to the positive electrode 21, and the negative electrode lead 12 is attached to the negative electrode 22, and then the negative electrode 22, the separator 24 having the polymer support layer formed on both sides, the positive electrode 21 and the polymer support layer on both sides. The formed separators 24 are sequentially stacked and wound, and a protective tape 25 is adhered to the outermost peripheral portion to form a wound electrode body. Furthermore, this wound electrode body is sandwiched between aluminum laminate films 31 which are an example of the exterior member 30, and the outer peripheral edge portion excluding one side is heat-sealed to form a bag shape.

  Thereafter, an electrolytic solution is injected into the wound electrode body from the opening of the aluminum laminate film, and the opening of the aluminum laminate film is heat-sealed and sealed. Thus, the electrolyte solution is held on the polymer support layer to form the electrolyte layer 23, and the nonaqueous electrolyte secondary battery shown in FIGS. 1 and 2 is completed.

[Description of operation]
In the non-aqueous electrolyte secondary battery described above, when charged, lithium ions are released from the positive electrode active material layer 21B and inserted into the negative electrode active material layer 22B through the electrolyte layer 23. When discharge is performed, lithium ions are released from the negative electrode active material layer 22B and inserted into the positive electrode active material layer 21B through the electrolyte layer 23. In particular, during initial charging, a solid electrolyte membrane (SEI) derived from an isocyanate compound is formed on the electrode (mainly the negative electrode).
As described above, the isocyanate compound added to the electrolytic solution acts on the negative electrode to form a film, whereas the positive electrode has a phosphate film, so that the swelling suppression effect in both the negative electrode and the positive electrode does not compete with the negative electrode. A good swelling suppression effect can be obtained with both the positive electrode and the positive electrode.

<3. Third Embodiment>
[Configuration of non-aqueous electrolyte secondary battery]
FIG. 3 is a cross-sectional view showing an example of a nonaqueous electrolyte secondary battery according to the third embodiment of the present invention. Such a nonaqueous electrolyte secondary battery is called a cylindrical battery.
As shown in the figure, this non-aqueous electrolyte secondary battery has a battery element 20 inside a battery can 33 which is a part of an exterior member and has a substantially hollow cylindrical shape. In the battery element 20, a positive electrode 21 and a negative electrode 22 are positioned so as to face each other with a separator 24 interposed therebetween, and are wound. The battery element 20 excluding the electrolyte is referred to as a wound electrode body 25.

The battery can 33 is made of, for example, iron plated with nickel, and has one end closed and the other end open. An insulating plate 13 is disposed inside the battery can 33 so as to sandwich the battery element 20 from above and below.
Further, at the open end of the battery can 33, a battery lid 34 constituting a part of the exterior member, a safety valve mechanism 14 provided inside the battery lid 34, and a thermal resistance element (Positive Temperature Coefficient; PTC element) 15) is attached by caulking through the gasket 16, and the inside of the battery can 33 is sealed.

  The battery lid 34 is made of the same material as the battery can 33, for example. The safety valve mechanism 14 is electrically connected to the battery lid 34 via the heat sensitive resistance element 15, and when the internal pressure of the battery becomes a certain level or more due to internal short circuit or external heating, the disc plate 14A. Is reversed to disconnect the electrical connection between the battery lid 34 and the battery element 20. When the temperature rises, the heat sensitive resistance element 15 limits the current by increasing the resistance value and prevents abnormal heat generation due to a large current, and is made of, for example, barium titanate semiconductor ceramics. The gasket 16 is made of, for example, an insulating material, and the surface is coated with asphalt.

  The battery element 20 is wound around, for example, the center pin 17. A positive electrode lead 11 made of aluminum or the like is connected to the positive electrode 21 of the battery element 20, and a negative electrode lead 12 made of nickel or the like is connected to the negative electrode 22. The positive electrode lead 11 is electrically connected to the battery lid 34 by being welded to the safety valve mechanism 14, and the negative electrode lead 12 is welded and electrically connected to the battery can 33.

  In addition, since each component in 3rd Embodiment is the same as each component in 1st Embodiment, the description is abbreviate | omitted.

<4. Fourth Embodiment>
[Production of non-aqueous electrolyte secondary battery]
An example of the manufacturing method of the nonaqueous electrolyte secondary battery according to the third embodiment will be described. In addition, since each component in 4th Embodiment is the same as each component in 1st Embodiment, the description is abbreviate | omitted.
First, the positive electrode 21 is produced. For example, when using a particulate positive electrode active material, a positive electrode active material coated with a phosphate and, if necessary, a conductive agent and a binder are mixed to prepare a positive electrode mixture, and N-methyl- A positive electrode mixture slurry is prepared by dispersing in a dispersion medium such as 2-pyrrolidone.
Next, the positive electrode mixture slurry is applied to the positive electrode current collector 21A, dried, and compression molded to form the positive electrode active material layer 21B.

  Moreover, the negative electrode 22 is produced. For example, when a particulate negative electrode active material is used, a negative electrode mixture is prepared by mixing the negative electrode active material and, if necessary, a conductive agent and a binder, and a dispersion medium such as N-methyl-2-pyrrolidone. To prepare a negative electrode mixture slurry. Thereafter, the negative electrode mixture slurry is applied to the negative electrode current collector 22A, dried, and compression molded to form the negative electrode active material layer 22B.

  Next, the positive electrode lead 11 is led out from the positive electrode current collector 21A, and the negative electrode lead 12 is led out from the negative electrode current collector 22A. Thereafter, for example, the positive electrode 21 and the negative electrode 22 are wound through a separator 24 to form a wound electrode body 25, and the distal end portion of the positive electrode lead 11 is welded to the safety valve mechanism 14 and the distal end portion of the negative electrode lead 12 is The positive electrode 21 and the negative electrode 22 which are welded to the battery can 33 and wound are sandwiched between a pair of insulating plates 13 and stored in the battery can 33. After the positive electrode 21 and the negative electrode 22 are accommodated in the battery can 33, an electrolyte of the present invention (not shown) is injected into the battery can 33 and impregnated in the separator 24. Thereafter, the battery lid 34, the safety valve mechanism 14, and the heat sensitive resistance element 15 are fixed to the opening end of the battery can 33 by caulking through the gasket 16. Thereby, the secondary battery shown in FIG. 3 is completed.

[Description of operation]
In the nonaqueous electrolyte secondary battery described above, when charged, lithium ions are released from the positive electrode active material layer 21B and inserted into the negative electrode active material layer 22B through the electrolyte. When discharging is performed, lithium ions are released from the negative electrode active material layer 22B and inserted into the positive electrode active material layer 21B through the electrolyte. In particular, during initial charging, a solid electrolyte membrane (SEI) derived from an isocyanate compound is formed on the electrode (mainly the negative electrode).
As described above, the isocyanate compound added to the electrolytic solution acts on the negative electrode to form a film, whereas the positive electrode has a phosphate film, so that the swelling suppression effect in both the negative electrode and the positive electrode does not compete with the negative electrode. A good swelling suppression effect can be obtained with both the positive electrode and the positive electrode.

EXAMPLES Hereinafter, although an Example and a comparative example demonstrate this invention further in detail, this invention is not limited to these Examples.
Specifically, for Examples 1 to 11 and Comparative Examples 1 to 8, a non-aqueous electrolyte secondary battery in which an electrolyte layer in which an electrolytic solution is held by a polymer support is not formed is manufactured. , Evaluated its performance. Specifically, for Examples 12 to 22 and Comparative Examples 9 to 16, non-aqueous electrolyte secondary batteries as shown in FIGS. 1 and 2 were prepared and their performance was evaluated. .

Example 1
(Preparation of positive electrode)
First, 94 parts by mass of lithium / nickel / cobalt / aluminum composite oxide (LiNi _0.77 Co _0.20 Al _0.03 O ₂ ) coated with lithium phosphate as a positive electrode active material and graphite as a conductive agent 3 parts by mass and 3 parts by mass of polyvinylidene fluoride (PVdF) as a binder were homogeneously mixed and dispersed in N-methyl-2-pyrrolidone (NMP) to obtain a positive electrode mixture coating solution.
Next, the obtained positive electrode mixture coating liquid was uniformly applied to both surfaces of a 20 μm-thick aluminum foil serving as a positive electrode current collector and dried to form a positive electrode active material layer of 40 mg / cm ² per side. This was cut into a shape having a width of 30 mm and a length of 250 mm to produce a positive electrode, and a positive electrode lead was further attached.

(Preparation of negative electrode)
Next, 97 parts by mass of graphite as a negative electrode active material and 3 parts by mass of PVdF as a binder were homogeneously mixed and dispersed in NMP to obtain a negative electrode mixture coating liquid.
Next, the obtained negative electrode mixture coating liquid was uniformly applied to both surfaces of a 15 μm thick copper foil serving as a negative electrode current collector and dried to form a negative electrode active material layer having a concentration of 24 mg / cm ² per side. This was cut into a shape with a width of 30 mm and a length of 250 mm to produce a negative electrode, and a negative electrode lead was further attached.

(Preparation of electrolyte)
Moreover, as electrolyte solution, ethylene carbonate: diethyl carbonate: fluoroethylene carbonate: hexamethylene diisocyanate: lithium hexafluorophosphate: lithium tetrafluoroborate = 25: 58: 1: 0.5: 15: 0.5 What was mixed in the ratio of (mass ratio) was used.

(Preparation of non-aqueous electrolyte secondary battery)
The obtained positive electrode and negative electrode are laminated and wound up via a separator made of a microporous polyethylene film having a thickness of 12 μm, and placed in a bag-shaped exterior member made of an aluminum laminate film. After injecting 2 g of the electrolytic solution obtained in this bag, the bag was heat-sealed and sealed to obtain a nonaqueous electrolyte secondary battery of this example. The capacity of this battery is 850 mAh. A part of the specification of the battery is shown in Table 1. In Tables 1 and 2, lithium-nickel-cobalt-aluminum composite oxide (LiNi _0.77 Co _0.20 Al _0.03 O ₂ ) is abbreviated as LNO.

(Example 2)
As an electrolytic solution, ethylene carbonate: diethyl carbonate: fluoroethylene carbonate: hexamethylene diisocyanate: lithium hexafluorophosphate: lithium tetrafluoroborate = 25: 58.4: 1: 0.1: 15: 0.5 ( The non-aqueous electrolyte secondary battery of this example was obtained by repeating the same operation as in Example 1 except that the mixture at a ratio of (mass ratio) was used. The capacity of this battery is 850 mAh. A part of the specification of the battery is shown in Table 1.

(Example 3)
As an electrolytic solution, ethylene carbonate: diethyl carbonate: fluoroethylene carbonate: hexamethylene diisocyanate: lithium hexafluorophosphate: lithium tetrafluoroborate = 25: 57.5: 1: 1: 15: 0.5 (mass ratio) The non-aqueous electrolyte secondary battery of this example was obtained by repeating the same operation as in Example 1 except that the mixture at a ratio of) was used. The capacity of this battery is 850 mAh. A part of the specification of the battery is shown in Table 1.

Example 4
As an electrolytic solution, ethylene carbonate: diethyl carbonate: fluoroethylene carbonate: octadecyl isocyanate: lithium hexafluorophosphate: lithium tetrafluoroborate = 25: 58: 1: 0.5: 15: 0.5 (mass ratio) The non-aqueous electrolyte secondary battery of this example was obtained by repeating the same operation as in Example 1 except that the mixture at a ratio of The capacity of this battery is 850 mAh. A part of the specification of the battery is shown in Table 1.

(Example 5)
As an electrolytic solution, ethylene carbonate: diethyl carbonate: fluoroethylene carbonate: dicyclohexylmethane-4,4′-diisocyanate: lithium hexafluorophosphate: lithium tetrafluoroborate = 25: 58: 1: 0.5: 15: A non-aqueous electrolyte secondary battery of this example was obtained by repeating the same operation as in Example 1 except that a mixture of 0.5 (mass ratio) was used. The capacity of this battery is 850 mAh. A part of the specification of the battery is shown in Table 1.

(Example 6)
As an electrolytic solution, ethylene carbonate: diethyl carbonate: difluoroethylene carbonate: hexamethylene diisocyanate: lithium hexafluorophosphate: lithium tetrafluoroborate = 25: 58: 1: 0.5: 15: 0.5 (mass ratio) The non-aqueous electrolyte secondary battery of this example was obtained by repeating the same operation as in Example 1 except that the mixture at a ratio of) was used. The capacity of this battery is 850 mAh. A part of the specification of the battery is shown in Table 1.

(Example 7)
As an electrolytic solution, ethylene carbonate: diethyl carbonate: hexamethylene diisocyanate: lithium hexafluorophosphate: lithium tetrafluoroborate = 26: 58: 0.5: 15: 0.5 (mass ratio) were mixed. Except having used what was used, the same operation as Example 1 was repeated and the nonaqueous electrolyte secondary battery of this example was obtained. The capacity of this battery is 850 mAh. A part of the specification of the battery is shown in Table 1.

(Example 8)
As an electrolytic solution, ethylene carbonate: diethyl carbonate: hexamethylene diisocyanate: lithium hexafluorophosphate: lithium tetrafluoroborate = 26: 58.4: 0.1: 15: 0.5 (mass ratio) A non-aqueous electrolyte secondary battery of this example was obtained by repeating the same operation as in Example 1 except that the mixed one was used. The capacity of this battery is 850 mAh. A part of the specification of the battery is shown in Table 1.

Example 9
The electrolyte was mixed at a ratio of ethylene carbonate: diethyl carbonate: hexamethylene diisocyanate: lithium hexafluorophosphate: lithium tetrafluoroborate = 26: 57.5: 1: 15: 0.5 (mass ratio). Except having used what was used, the same operation as Example 1 was repeated and the nonaqueous electrolyte secondary battery of this example was obtained. The capacity of this battery is 850 mAh. A part of the specification of the battery is shown in Table 1.

(Example 10)
As the electrolytic solution, a mixture of ethylene carbonate: diethyl carbonate: fluoroethylene carbonate: hexamethylene diisocyanate: lithium hexafluorophosphate = 25: 58: 1: 0.5: 15.5 (mass ratio) is used. Except for the above, the same operation as in Example 1 was repeated to obtain a nonaqueous electrolyte secondary battery of this example. The capacity of this battery is 850 mAh. A part of the specification of the battery is shown in Table 1.

(Example 11)
The non-aqueous electrolyte secondary battery of this example was repeated by repeating the same operation as in Example 1 except that lithium-cobalt-composite oxide (LiCoO ₂ ) coated with lithium phosphate was used as the positive electrode active material. Got. The capacity of this battery is 800 mAh. A part of the specification of the battery is shown in Table 1. In Tables 1 and 2, lithium / cobalt / composite oxide (LiCoO ₂ ) is abbreviated as LCO.

(Comparative Example 1)
As an electrolytic solution, ethylene carbonate: diethyl carbonate: fluoroethylene carbonate: lithium hexafluorophosphate: lithium tetrafluoroborate = 25: 58.5: 1: 15: 0.5 (mass ratio) were mixed. Except having used what was used, the same operation as Example 1 was repeated and the nonaqueous electrolyte secondary battery of this example was obtained. The capacity of this battery is 850 mAh. A part of the specification of the battery is shown in Table 1.

(Comparative Example 2)
Other than using an electrolyte mixed at a ratio of ethylene carbonate: diethyl carbonate: lithium hexafluorophosphate: lithium tetrafluoroborate = 26: 58.5: 15: 0.5 (mass ratio) Repeated the same operation as Example 1, and obtained the nonaqueous electrolyte secondary battery of this example. The capacity of this battery is 850 mAh. A part of the specification of the battery is shown in Table 1.

(Comparative Example 3)
Implementation was performed except that the electrolyte used was a mixture of ethylene carbonate: diethyl carbonate: fluoroethylene carbonate: lithium hexafluorophosphate = 25: 58.5: 1: 15.5 (mass ratio). The same operation as in Example 1 was repeated to obtain a nonaqueous electrolyte secondary battery of this example. The capacity of this battery is 850 mAh. A part of the specification of the battery is shown in Table 1.

(Comparative Example 4)
Example 1 except that lithium-nickel-cobalt-aluminum composite oxide (LiNi _0.77 Co _0.20 Al _0.03 O ₂ ) not coated with lithium phosphate was used as the positive electrode active material. The same operation was repeated to obtain the nonaqueous electrolyte secondary battery of this example. The capacity of this battery is 850 mAh. A part of the specification of the battery is shown in Table 1.

(Comparative Example 5)
Lithium / nickel / cobalt / aluminum composite oxide (LiNi _0.77 Co _0.20 Al _0.03 O ₂ ) not covered with lithium phosphate is used as the positive electrode active material, and ethylene carbonate is used as the electrolyte. : Diethyl carbonate: Hexamethylene diisocyanate: Lithium hexafluorophosphate: Lithium tetrafluoroborate = Other than using a mixture of 26: 58: 0.5: 15: 0.5 (mass ratio) Repeated the same operation as Example 1, and obtained the nonaqueous electrolyte secondary battery of this example. The capacity of this battery is 850 mAh. A part of the specification of the battery is shown in Table 1.

(Comparative Example 6)
Lithium / nickel / cobalt / aluminum composite oxide (LiNi _0.77 Co _0.20 Al _0.03 O ₂ ) not covered with lithium phosphate is used as the positive electrode active material, and ethylene carbonate is used as the electrolyte. : Diethyl carbonate: Fluoroethylene carbonate: Hexamethylene diisocyanate: Lithium hexafluorophosphate = 25: 58: 1: 0.5: 15.5 (mass ratio) The same operation as in Example 1 was repeated to obtain a nonaqueous electrolyte secondary battery of this example. The capacity of this battery is 850 mAh. A part of the specification of the battery is shown in Table 1.

(Comparative Example 7)
Lithium / nickel / cobalt / aluminum composite oxide (LiNi _0.77 Co _0.20 Al _0.03 O ₂ ) not covered with lithium phosphate is used as the positive electrode active material, and ethylene carbonate is used as the electrolyte. : Diethyl carbonate: Fluoroethylene carbonate: Lithium hexafluorophosphate: Lithium tetrafluoroborate = 25: 58.5: 1: 15: 0.5 (except for using a mixture in a mass ratio) Repeated the same operation as Example 1, and obtained the nonaqueous electrolyte secondary battery of this example. The capacity of this battery is 850 mAh. A part of the specification of the battery is shown in Table 1.

(Comparative Example 8)
As the positive electrode active material, lithium / cobalt / composite oxide (LiCoO ₂ ) that is not coated with lithium phosphate is used. Further, as the electrolyte, ethylene carbonate: diethyl carbonate: fluoroethylene carbonate: lithium hexafluorophosphate: This example was repeated by repeating the same operation as in Example 1 except that lithium tetrafluoroborate = 25: 58.5: 1: 15: 0.5 (mass ratio) was used. A non-aqueous electrolyte secondary battery was obtained. The capacity of this battery is 800 mAh. A part of the specification of the battery is shown in Table 1.

[Performance evaluation]
The nonaqueous electrolyte secondary batteries of Examples 1 to 10 and Comparative Examples 1 to 7 were charged for 3 hours at 850 mA and an upper limit of 4.2 V in an environment of 23 ° C., and then stored for 12 hours in an environment of 85 ° C. The thickness increase rate (%) was measured and calculated. The obtained results are also shown in Table 1 as blisters when stored for 12 hours in an environment of 85 ° C.
After charging the non-aqueous electrolyte secondary batteries of Example 11 and Comparative Example 8 at 800 mA in a 23 ° C. environment at 4.2 V and an upper limit of 4.2 V for 3 hours, the percentage of increase in thickness when stored in an 85 ° C. environment for 12 hours (% ) Measured and calculated. The obtained results are also shown in Table 1 as blisters when stored for 12 hours in an environment of 85 ° C.

From Table 1, by using a positive electrode active material coated with a phosphate and using an electrolytic solution containing an isocyanate compound, the environment of the nonaqueous electrolyte secondary battery of Example 1 to Example 10 at 85 ° C. It can be seen that the swelling stored for 12 hours below can be improved more than that of the nonaqueous electrolyte secondary batteries of Comparative Examples 1 to 7.
Further, from Table 1, by using a positive electrode active material coated with a phosphate and using an electrolytic solution containing an isocyanate compound, the nonaqueous electrolyte secondary battery of Example 11 under an environment of 85 ° C. 12 It can be seen that the swelling stored for a time can be improved more than that of the nonaqueous electrolyte secondary battery of Comparative Example 8.
Furthermore, in Examples 1 to 11, the excellent swelling suppression effect can be exhibited because the isocyanate compound added to the electrolytic solution acts on the negative electrode to form a film, while the positive electrode has a phosphate film. Therefore, it is considered that this is because there is no competition between the swelling suppression effects in both the negative electrode and the positive electrode.

  Further, from Table 1, when no halogenated ethylene carbonate is added, a positive electrode active material coated with a phosphate is used, and an electrolytic solution containing an isocyanate compound is used. The swelling of the nonaqueous electrolyte secondary battery stored at 85 ° C. for 12 hours in an environment cannot be improved more than that of the nonaqueous electrolyte secondary battery of Example 1, but it is more than that of the nonaqueous electrolyte secondary battery of Comparative Example 2. Can also be improved.

  Further, from Table 1, when lithium tetrafluoroborate was not added, the non-aqueous solution of Example 10 was obtained by using a positive electrode active material coated with phosphate and using an electrolyte solution containing an isocyanate compound. The swelling of the electrolyte secondary battery stored for 12 hours in an environment of 85 ° C. cannot be improved more than that of the nonaqueous electrolyte secondary battery of Example 1, but is improved more than that of the nonaqueous electrolyte secondary battery of Comparative Example 3. I understand that I can do it.

  Further, from Table 1, when the positive electrode active material coated with phosphate is not used, the swelling of the nonaqueous electrolyte secondary battery of Comparative Example 7 stored for 12 hours in an environment of 85 ° C. is the nonaqueous water of Comparative Example 1. It turns out that it cannot improve more than that of the electrolyte secondary battery.

(Examples 12 to 22, Comparative Examples 9 to 16)
Examples 1 to 5 were carried out except that a separator made of a microporous polyethylene film having a thickness of 12 μm was replaced with a separator made of a microporous polyethylene film having a thickness of 8 μm and each having 2 μm of polyvinylidene fluoride applied thereto. The same operations as in Example 11 and Comparative Examples 1 to 8 were repeated to obtain nonaqueous electrolyte secondary batteries of each example. The batteries of Examples 12 to 21 and Comparative Examples 9 to 15 have a capacity of 850 mAh. Moreover, the capacity | capacitance of the battery of Example 22 and Comparative Example 16 is 800 mAh. Further, some of the specifications of these batteries are shown in Table 1.

[Performance evaluation]
The nonaqueous electrolyte secondary batteries of Examples 12 to 21 and Comparative Examples 9 to 15 were charged at 850 mA and 23 V in an environment of 23 ° C. for 3 hours and then stored at 85 ° C. for 12 hours in an environment of 85 ° C. The thickness increase rate (%) was measured and calculated. The obtained results are also shown in Table 2 as swelling during storage for 12 hours in an environment of 85 ° C.
After charging the nonaqueous electrolyte secondary batteries of Example 22 and Comparative Example 16 at 800 mA in a 23 ° C. environment and 4.2 V as the upper limit for 3 hours and then storing them in an 85 ° C. environment for 12 hours (% ) Measured and calculated. The obtained results are also shown in Table 2 as swelling during storage for 12 hours in an environment of 85 ° C.

From Table 2, by using a positive electrode active material coated with a phosphate and using an electrolytic solution containing an isocyanate compound, the environment of the nonaqueous electrolyte secondary battery of Examples 12 to 21 at 85 ° C. It can be seen that the swelling stored for the last 12 hours can be improved more than that of the nonaqueous electrolyte secondary batteries of Comparative Examples 9 to 15.
Further, from Table 2, by using a positive electrode active material coated with a phosphate and using an electrolytic solution containing an isocyanate compound, the nonaqueous electrolyte secondary battery of Example 22 under an environment of 85 ° C. 12 It can be seen that the swollenness preserved over time can be improved more than that of the nonaqueous electrolyte secondary battery of Comparative Example 16.
Furthermore, in Examples 12 to 22, excellent swelling suppression effects can be exhibited because the isocyanate compound added to the electrolytic solution acts on the negative electrode to form a film, while the positive electrode has a phosphate film. Therefore, it is considered that this is because there is no competition between the swelling suppression effects in both the negative electrode and the positive electrode.

  Further, from Table 2, when no halogenated ethylene carbonate is added, a positive electrode active material coated with phosphate is used, and an electrolyte solution containing an isocyanate compound is used. The swelling of the nonaqueous electrolyte secondary battery stored for 12 hours in an environment of 85 ° C. cannot be improved more than that of the nonaqueous electrolyte secondary battery of Example 12, but it is more than that of the nonaqueous electrolyte secondary battery of Comparative Example 10. Can also be improved.

  Further, from Table 2, when lithium tetrafluoroborate was not added, the non-aqueous solution of Example 21 was obtained by using a positive electrode active material coated with phosphate and using an electrolytic solution containing an isocyanate compound. The swelling of the electrolyte secondary battery stored for 12 hours in an environment of 85 ° C. cannot be improved more than that of the nonaqueous electrolyte secondary battery of Example 12, but it is improved more than that of the nonaqueous electrolyte secondary battery of Comparative Example 11. I understand that I can do it.

  Further, from Table 2, when the positive electrode active material coated with phosphate is not used, the swelling of the nonaqueous electrolyte secondary battery of Comparative Example 15 stored in an environment of 85 ° C. for 12 hours is the nonaqueous of Comparative Example 9. It turns out that it cannot improve more than that of the electrolyte secondary battery.

  As mentioned above, although this invention was demonstrated with some embodiment and an Example, this invention is not limited to these, A various deformation | transformation is possible within the range of the summary of this invention.

  For example, in the above embodiment, the case where the battery element 20 in which the positive electrode 21 and the negative electrode 22 are stacked and wound is described, but a flat battery element in which a pair of positive and negative electrodes are stacked, or a plurality of battery elements 20 The present invention can also be applied to a case where a stacked battery element in which a positive electrode and a negative electrode are stacked is provided.

  For example, in the above-described embodiment, the case of a laminate type battery and a cylindrical battery has been described. However, the present invention can also be applied to a case of a square battery, for example.

  Furthermore, as described above, the present invention relates to a battery using lithium as an electrode reactant, but the technical idea of the present invention is that other alkali metals such as sodium (Na) or potassium (K), magnesium ( The present invention can also be applied to the case of using an alkaline earth metal such as Mg) or calcium (Ca), or another light metal such as aluminum.

DESCRIPTION OF SYMBOLS 11 ... Positive electrode lead, 12 ... Negative electrode lead, 13 ... Insulating plate, 14 ... Safety valve mechanism, 14A ... Disc board, 15 ... Heat sensitive resistance element, 16 ... Gasket, 17 ... Center pin, 20 ... Battery element, 21 ... Positive electrode, 21A ... positive electrode current collector, 21B ... positive electrode active material layer, 22 ... negative electrode, 22A ... negative electrode current collector, 22B ... negative electrode active material layer, 23 ... electrolyte layer, 24 ... separator, 25 ... wound electrode body, 26 ... Protective tape, 30 ... exterior member, 31 ... aluminum laminate film, 32 ... adhesion film, 33 ... battery can, 34 ... battery lid

Claims (10)

An electrode body formed by winding or laminating a positive electrode and a negative electrode with a separator interposed therebetween, an electrolyte, and an exterior member that accommodates them,
The positive electrode contains a positive electrode active material coated with phosphate,
The non-aqueous electrolyte secondary battery in which the electrolyte contains an electrolytic solution containing a non-aqueous solvent, an electrolyte salt, and an isocyanate compound represented by any one of the following general formulas (1) to (4) .

(In the formula (1), N represents nitrogen, C represents carbon, O represents oxygen, R ¹ represents a chain hydrocarbon group having 1 to 22 carbon atoms, or at least a part of carbon and / or hydrogen is halogen, This represents a C1-C22 chain hydrocarbon group substituted with at least one selected from the group consisting of oxygen, sulfur, nitrogen and silicon.)

(In the formula (2), N represents nitrogen, C represents carbon, O represents oxygen, R ² represents a chain hydrocarbon group having 1 to 22 carbon atoms, or at least part of carbon and / or hydrogen is halogen, This represents a C1-C22 chain hydrocarbon group substituted with at least one selected from the group consisting of oxygen, sulfur, nitrogen and silicon.)

(In the formula (3), N represents nitrogen, C represents carbon, O represents oxygen, R ³ represents a cyclic hydrocarbon group having 3 to 20 carbon atoms, or at least part of carbon and / or hydrogen is halogen, oxygen And a C3-C20 cyclic hydrocarbon group substituted with at least one selected from the group consisting of sulfur, nitrogen and silicon.)

(In the formula (4), N represents nitrogen, C represents carbon, O represents oxygen, R ⁴ represents a cyclic hydrocarbon group having 3 to 20 carbon atoms, or at least a part of carbon and / or hydrogen is halogen, oxygen And a C3-C20 cyclic hydrocarbon group substituted with at least one selected from the group consisting of sulfur, nitrogen and silicon.)   The nonaqueous electrolyte secondary battery according to claim 1, wherein the electrolytic solution further contains a halogenated ethylene carbonate.   The nonaqueous electrolyte secondary battery according to claim 1, wherein the electrolyte salt contains lithium tetrafluoroborate.   The non-aqueous electrolyte secondary battery according to claim 1, wherein the phosphate contains lithium phosphate. The nonaqueous electrolyte secondary battery according to claim 1, wherein the positive electrode active material contains a nickel-based positive electrode active material represented by the following general formula (5).
LiNi _x M _1-x O ₂ (5)
(In Formula (5), Li is lithium, Ni is nickel, M is at least one selected from the group consisting of cobalt (Co), manganese (Mn), and aluminum (Al), O is oxygen, and x is The relationship of 0.75 ≦ x ≦ 1 is satisfied.)   The nonaqueous electrolyte secondary battery according to claim 1 or 2, wherein the content of the isocyanate compound is 0.01 to 5% by mass based on the total amount of the electrolytic solution.   The nonaqueous electrolyte secondary battery according to claim 1, wherein the exterior member is an aluminum laminate film.   The nonaqueous electrolyte secondary battery according to claim 1, wherein the electrode body further has a polymer support between at least one of the positive electrode and the negative electrode and the separator.   The nonaqueous electrolyte secondary battery according to claim 8, wherein the polymer support contains polyvinylidene fluoride. An electrode body formed by winding or laminating a positive electrode and a negative electrode with a separator interposed therebetween, an electrolyte, and an exterior member that accommodates them,
The positive electrode contains a positive electrode active material coated with phosphate,
The non-aqueous electrolyte secondary battery in which the electrolyte contains an electrolytic solution containing a non-aqueous solvent, an electrolyte salt, and an isocyanate compound represented by any one of the following general formulas (1) to (4) In manufacturing
An electrode body formed by winding or laminating a positive electrode and a negative electrode containing a positive electrode active material coated with a phosphate via a separator, a nonaqueous solvent, an electrolyte salt, and the following general formulas (1) to (4) ), An electrolyte containing an electrolyte solution containing an isocyanate compound represented by any one of them, and a method for producing a nonaqueous electrolyte secondary battery, which is housed in an exterior member.

(In the formula (1), N represents nitrogen, C represents carbon, O represents oxygen, R ¹ represents a chain hydrocarbon group having 1 to 22 carbon atoms, or at least a part of carbon and / or hydrogen is halogen, This represents a C1-C22 chain hydrocarbon group substituted with at least one selected from the group consisting of oxygen, sulfur, nitrogen and silicon.)

(In the formula (2), N represents nitrogen, C represents carbon, O represents oxygen, R ² represents a chain hydrocarbon group having 1 to 22 carbon atoms, or at least part of carbon and / or hydrogen is halogen, This represents a C1-C22 chain hydrocarbon group substituted with at least one selected from the group consisting of oxygen, sulfur, nitrogen and silicon.)

(In the formula (3), N represents nitrogen, C represents carbon, O represents oxygen, R ³ represents a cyclic hydrocarbon group having 3 to 20 carbon atoms, or at least part of carbon and / or hydrogen is halogen, oxygen And a C3-C20 cyclic hydrocarbon group substituted with at least one selected from the group consisting of sulfur, nitrogen and silicon.)

(In the formula (4), N represents nitrogen, C represents carbon, O represents oxygen, R ⁴ represents a cyclic hydrocarbon group having 3 to 20 carbon atoms, or at least a part of carbon and / or hydrogen is halogen, oxygen And a C3-C20 cyclic hydrocarbon group substituted with at least one selected from the group consisting of sulfur, nitrogen and silicon.)

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