JP5007506B2 - Nonaqueous electrolyte composition for secondary battery and nonaqueous electrolyte secondary battery using the same - Google Patents

Description

The present invention relates to a non-aqueous electrolyte composition for a secondary battery and a non-aqueous electrolyte secondary battery, and more specifically, a non-aqueous electrolyte composition for a secondary battery containing a predetermined carbonate ester, and the same. The present invention relates to a lithium ion non-aqueous electrolyte secondary battery.

  In recent years, many portable electronic devices such as a camera-integrated VTR (video tape recorder), a digital camera, a mobile phone, a personal digital assistant, and a notebook computer have appeared, and their size and weight have been reduced. As a portable power source for these 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 carbon as a negative electrode active material, a lithium-transition metal composite oxide as a positive electrode active material, and a carbonate ester mixture as an electrolyte is a lead battery or a conventional non-aqueous electrolyte secondary battery. Since a large energy density can be obtained as compared with a nickel cadmium battery, it has been widely put into practical use (for example, see Patent Document 1).

In particular, a laminated battery using an aluminum laminated film for an exterior has a high energy density because it is lightweight (see, for example, Patent Document 2). In such a laminated battery, when a polymer swollen with an electrolytic solution is used, deformation of the battery can be suppressed. Therefore, a laminated polymer battery is also widely used (for example, see Patent Document 3).
JP-A-4-332479 Japanese Patent No. 3482591 JP 2005-166448 A

  However, with the recent increase in capacity of batteries, the density of the electrode active material disposed on the electrode has increased and the gap has become smaller, making it difficult to sufficiently impregnate the electrode with the electrolyte. It has become to. As described above, when the electrode is not impregnated with the electrolytic solution, the battery performance is greatly deteriorated, and there is a problem in that the discharge capacity maintenance ratio at the time of repeated charge and discharge is reduced.

The present invention has been made in view of such problems of the prior art, and an object of the present invention is to provide a non-aqueous electrolyte composition for a secondary battery that can improve the discharge capacity retention rate during repeated charge and discharge. And a nonaqueous electrolyte secondary battery using the same.

  As a result of intensive studies to achieve the above object, the present inventors have found that the above object can be achieved by using a predetermined chain ester carbonate, and have completed the present invention.

That is, the secondary battery for non-aqueous electrolyte composition of the present invention, an electrolyte salt, a nonaqueous solvent, carbon atoms containing a chain carbonate having a hydrocarbon group of 13 to 20, the chain carbonic ester Content is 0.1 mass% or more and 2 mass% or less with respect to the total mass of the nonaqueous electrolyte composition for secondary batteries, It is characterized by the above-mentioned.

Moreover, the nonaqueous electrolyte secondary battery of the present invention contains a positive electrode and a negative electrode using a material capable of inserting and extracting lithium ions as a positive electrode active material or a negative electrode active material, a nonaqueous electrolyte composition, a separator, and these. A non-aqueous electrolyte secondary battery comprising an exterior member,
The non-aqueous electrolyte composition, an electrolyte salt, a nonaqueous solvent, carbon atoms containing a chain carbonate having a hydrocarbon group of 13 to 20, the content of the chain carbonate is a non-aqueous electrolyte It is 0.1 mass% or more and 2 mass% or less with respect to the total mass of a composition .

According to the present invention, since a predetermined chain ester carbonate is used , a non-aqueous electrolyte composition for a secondary battery capable of improving the discharge capacity maintenance rate during repeated charging and discharging, and a non-aqueous electrolyte using the same A secondary battery can be provided.

Hereinafter, the nonaqueous electrolyte composition of the present invention will be described in detail. In the present specification, “%” represents mass percentage unless otherwise specified.
As described above, the nonaqueous electrolyte composition of the present invention contains an electrolyte salt, a nonaqueous solvent, and a chain carbonate ester having a hydrocarbon group or halogenated hydrocarbon group having 13 to 20 carbon atoms. Yes, it is suitably used for lithium ion non-aqueous electrolyte secondary batteries.
Such a chain ester carbonate is excellent in impregnation or permeability to a positive electrode active material layer and a negative electrode active material layer, which will be described later, can suppress deterioration of battery performance, and improve the discharge capacity maintenance rate during repeated charge and discharge. Can do.

  Here, as the chain carbonic acid ester having a hydrocarbon group or a halogenated hydrocarbon group having 13 to 20 carbon atoms, the following chemical formula (1)

[R1 in the formula _{C n H 2n + 1-m} X m (X is fluorine (F), chlorine (Cl), bromine (Br) or iodine (I), n represents an integer of 13 to 20, m is 0 ≦ m ≦ 2n is satisfied.), R2 is C _n H _{2n + 1−m} X _m (X is F, Cl, Br or I, n is an integer of 1 to 20, and m is 0 ≦ m ≦ 2n) ). The compound represented by this can be mentioned.

In R1 of the formula (1), as described above, the number of carbons is required to be 13 to 20, but 13 to 14 is preferable. If R1 is less than 13, the permeability is insufficient, and if it exceeds 20, the solubility in a non-aqueous solvent decreases.
Similarly, the number of carbon atoms in R2 is required to be 1-20, but is preferably 1-14, more preferably 5-14. When R2 exceeds 20, the solubility in a nonaqueous solvent decreases.
In addition, it is preferable from a viewpoint of manufacture that the carbon number of R1 and R2 is mutually the same.
Further, the halogen element is preferably fluorine, and the number of halogen elements is preferably 1 (2n-1: n is a natural number), more preferably 1-6. When the number of halogen elements exceeds 6, the solubility in a non-aqueous solvent may be reduced.

Specifically, as the chain carbonate represented by the formula (1), ditridecyl carbonate [C ₁₃ H ₂₇ O) ₂ CO (2)] represented by the following chemical formulas 2 to 4, respectively, Tetradecyl carbonate [(C ₁₄ H ₂₉ O) ₂ CO (3)] and dieicosyl carbonate [(C ₂₀ H ₄₁ O) ₂ CO) (4)] can be preferably used. Needless to say, it is not limited to compounds.
That is, in the present invention, any chain carbonate ester having the structure of the formula (1) can be applied, including structural isomers in which the hydrocarbon group of the above compound is branched from a straight chain.

  In the nonaqueous electrolyte composition of the present invention, the content of the chain carbonate is preferably 0.1 to 2%. If it is less than 0.1%, the desired effect may not be realized, and if it exceeds 2%, the capacity during large current discharge may be reduced.

The non-aqueous electrolyte composition of the present invention contains the chain carbonate ester as an essential component, but it is possible to add other compounds besides this.
Specifically, it is possible to combine with other carbonic acid ester having a hydrocarbon group having a double bond, such as vinylene carbonate or vinyl ethylene carbonate. Further improvement can be achieved.
The content of the other carbonate ester having a hydrocarbon group having such a double bond is preferably 0.1 to 5%. If it is less than 0.1%, the desired effect may not be obtained, and if it exceeds 5%, the capacity during large current discharge may be reduced.

In addition, in the nonaqueous electrolyte composition of the present invention, it is possible to add cyclic sulfonate esters such as 1,3-propane sultone and 1,3-prop-1-ene sultone. Swelling of the battery using the composition during high temperature storage can be effectively suppressed.
The content of the cyclic sulfonic acid ester is preferably 0.1 to 2%. If it is less than 0.1%, the desired effect may not be obtained, and if it exceeds 2%, the capacity during large current discharge may be reduced.

Furthermore, a predetermined polymer compound is added, and the polymer compound is swollen with the non-aqueous electrolyte composition of the present invention so that the polymer compound is impregnated or held in the polymer compound. Can do.
The swelling, gelation or non-fluidization of the polymer compound can effectively suppress the occurrence of leakage of the nonaqueous electrolyte composition in the obtained battery. In addition, the chain carbonic acid ester represented by the above formula (1) is presumed to have good impregnation properties with respect to such a polymer compound, and the discharge capacity maintenance rate at the time of repeated charge / discharge of the obtained battery is also improved. It seems to do.

  Examples of such a polymer compound include polyvinyl formal (5), polyacrylate (6), and polyvinylidene fluoride (7) represented by the following chemical formulas 5 to 7. Can do.

In the formula (6), R 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, preferably N = 100 to 10,000. If N is less than 100, gelation is difficult, and if it exceeds 10,000, fluidity may decrease.

  In addition, it is preferable that content of the above-mentioned polymer compound shall be 0.1 to 5%. If it is less than 0.1%, gelation is difficult, and if it exceeds 5%, fluidity may decrease.

Examples of the non-aqueous solvent used in the non-aqueous electrolyte composition of the present invention include various high dielectric constant solvents and low viscosity solvents.
As the high dielectric constant solvent, ethylene carbonate, propylene carbonate, and the like can be suitably used, but are not limited thereto, butylene carbonate, vinylene carbonate, 4-fluoro-1,3-dioxolan-2-one Cyclic carbonates such as (fluoroethylene carbonate), 4-chloro-1,3-dioxolan-2-one (chloroethylene carbonate), and trifluoromethylethylene carbonate can be used.

  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, diethyl carbonate can be preferably used as the low-viscosity solvent, but besides this, chain carbonates such as dimethyl carbonate, ethyl methyl carbonate and methyl propyl carbonate, methyl acetate, ethyl acetate, propionic acid Chain carboxylic acid esters such as methyl, ethyl propionate, methyl butyrate, methyl isobutyrate, methyl trimethylacetate and ethyl trimethylacetate, chain amides such as N, N-dimethylacetamide, methyl N, N-diethylcarbamate and N , N-diethylcarbamate ethyl ester and the like, and 1,2-dimethoxyethane, tetrahydrofuran, tetrahydropyran, and ether such as 1,3-dioxolane can be used.

In the non-aqueous electrolyte composition of the present invention, the high dielectric constant solvent and the low viscosity solvent described above can be used alone or in combination of two or more.
Moreover, it is preferable that content of the above-mentioned non-aqueous solvent shall be 70 to 90%. If it is less than 70%, the viscosity may increase excessively, and if it exceeds 90%, sufficient conductivity may not be obtained.

The electrolyte salt used in the non-aqueous electrolyte composition of the present invention may be any salt that dissolves or disperses in the above-described non-aqueous solvent to generate ions, and lithium hexafluorophosphate (LiPF ₆ ) is preferably used. Needless to say, the present invention is not limited to this.
That is, lithium tetrafluoroborate (LiBF _4), lithium hexafluoroarsenate (LiAsF _6), lithium hexafluoro antimonate (LiSbF _6), lithium perchlorate (LiClO _4), four lithium aluminum chloride acid ( Inorganic lithium salts such as LiAlCl ₄ ), lithium trifluoromethanesulfonate (LiCF ₃ SO ₃ ), lithium bis (trifluoromethanesulfone) imide (LiN (CF ₃ SO ₂ ) ₂ ), lithium bis (pentafluoromethanesulfone) methide (LiN (C ₂ F ₅ SO ₂ ) ₂ ) and lithium salts of perfluoroalkanesulfonic acid derivatives such as lithium tris (trifluoromethanesulfone) methide (LiC (CF ₃ SO ₂ ) ₃ ) can also be used. These can be used alone or in combination of two or more. It is also possible to use it.

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

Next, the nonaqueous electrolyte secondary battery of the present invention will be described in detail.
FIG. 1 is an exploded perspective view showing an example of a laminated battery as an embodiment of the nonaqueous electrolyte secondary battery of the present invention.
In the figure, the secondary battery is configured by enclosing a battery element 20 to which a positive electrode terminal 11 and a negative electrode terminal 12 are attached in a film-like exterior member 30. The positive electrode terminal 11 and the negative electrode terminal 12 are led out, for example, in the same direction from the inside of the exterior member 30 to the outside. The positive electrode terminal 11 and the negative electrode terminal 12 are each made of a metal material such as aluminum (Al), copper (Cu), nickel (Ni), or stainless steel.

The exterior member 30 is configured by a rectangular laminate film 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 31 is inserted between the exterior member 30 and the positive electrode terminal 11 and the negative electrode terminal 12 to prevent intrusion of outside air. The adhesion film 31 is made of a material having adhesion to the positive electrode terminal 11 and the negative electrode terminal 12. For example, when the positive electrode terminal 11 and the negative electrode terminal 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 a laminated film having another structure, a polymer film such as polypropylene, a metal film, or the like instead of the above-described laminated film.
Here, the general structure of an exterior member can be represented by the laminated structure of an exterior layer / metal foil / sealant layer (however, the exterior layer and the 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.

  The structures that can be used as the exterior member 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.

  FIG. 2 is a cross-sectional view taken along the line II of the battery element 20 shown in FIG. In the figure, a battery element 20 is wound with a positive electrode 21 and a negative electrode 22 facing each other with a non-aqueous electrolyte composition layer 23 made of the non-aqueous electrolyte composition of the present invention and a separator 24 therebetween. The outermost peripheral part is protected by the protective tape 25.

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 21 </ b> A has a portion exposed without being covered with the positive electrode active material layer 21 </ b> B at one end portion in the longitudinal direction, and the positive electrode terminal 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 includes one or more positive electrode materials capable of occluding and releasing lithium ions as a positive electrode active material, and a conductive material and a binder as necessary. May be included.
Examples of the positive electrode material capable of inserting and extracting lithium include sulfur (S), iron disulfide (FeS ₂ ), titanium disulfide (TiS ₂ ), molybdenum disulfide (MoS ₂ ), and niobium diselenide. lithium (NbSe _2), vanadium oxide _{(V 2 O} 5), chalcogenides containing no lithium, such as titanium dioxide (TiO ₂₎ and manganese dioxide (MnO ₂₎ (especially layered compound and the spinel-type compound), containing lithium Examples thereof include conductive 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 (8) or (9):
LiM ^I O ₂ (8)
Li _y M ^II PO ₄ (9)
(In the formula, M ^I and M ^II 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), and the compound of the formula (8) generally has a layered structure, and the compound of the formula (9) 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 complex 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 (LiFePO ₄ ) or a lithium iron manganese phosphate compound (LiFe _1-v MnPO ₄ (v <1) having an olivine structure. ).

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 without being provided with the negative electrode active material layer 22B at one end in the longitudinal direction, and the negative electrode terminal 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 includes one or more of a negative electrode material capable of inserting and extracting lithium ions and metallic lithium as a negative electrode active material, and a conductive material and a binder as necessary. An adhesive may be included.
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 the carbon material 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 metal elements or metalloid elements include tin (Sn), lead (Pb), aluminum, indium (In), silicon (Si), zinc (Zn), antimony (Sb), bismuth (Bi), Examples include 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.

  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.

Next, an example of a method for manufacturing the secondary battery described above will be described.
The laminate type secondary battery can be manufactured as follows.
First, the positive electrode 21 is produced. For example, when a particulate positive electrode active material is used, a positive electrode mixture is prepared by mixing a positive electrode active material and, if necessary, a conductive material and a binder, and a dispersion medium such as N-methyl-2-pyrrolidone. To produce a positive electrode mixture slurry.
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 a negative electrode active material and, if necessary, a conductive material 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, after attaching the positive electrode terminal 11 to the positive electrode 21 and attaching the negative electrode terminal 12 to the negative electrode 22, the separator 24, the positive electrode 21, the separator 24, and the negative electrode 22 are sequentially stacked and wound, and the protective tape 25 is attached to the outermost peripheral portion. A wound electrode body is formed by bonding. Further, the wound electrode body is sandwiched between the exterior members 30, and the outer peripheral edge except one side is heat-sealed to form a bag shape.

  Thereafter, a non-aqueous electrolyte composition containing the above-described chain carbonate, an electrolyte salt such as lithium hexafluorophosphate, and a non-aqueous solvent such as ethylene carbonate is prepared and wound from the opening of the exterior member 30. It inject | pours into the inside of an electrode body, the opening part of the exterior member 30 is heat-sealed and sealed. Thereby, the nonaqueous electrolyte composition layer 23 is formed, and the secondary battery shown in FIGS. 1 and 2 is completed.

In addition, you may manufacture this secondary battery as follows.
For example, instead of injecting the nonaqueous electrolyte composition after producing the wound electrode body, the nonaqueous electrolyte composition is applied on the positive electrode 21 and the negative electrode 22 or the separator 24 and then wound, and the exterior member 30 is wound. You may make it enclose inside.

In the secondary battery described above, when charged, lithium ions are released from the positive electrode active material layer 21 </ b> B and inserted into the negative electrode active material layer 22 </ b> B through the nonaqueous electrolyte composition layer 23. When discharge is performed, lithium ions are released from the negative electrode active material layer 22 </ b> B and inserted into the positive electrode active material layer 21 </ b> B through the nonaqueous electrolyte composition layer 23.
Here, the non-aqueous electrolyte composition contained in the non-aqueous electrolyte composition layer 23 is excellent in impregnation and permeability into the positive electrode active material layer 21B and the negative electrode active material 22B. Accordingly, since the electrolyte is sufficiently in contact with many active materials, the battery performance of the secondary battery is not greatly deteriorated during charging and discharging, and the discharge capacity maintenance rate during repeated charging and discharging is improved. .

EXAMPLES Hereinafter, although an Example and a comparative example demonstrate this invention further in detail, this invention is not limited to these Examples.
Specifically, the operations described in the following examples were performed to produce a laminate type battery as shown in FIGS. 1 and 2, and its performance was evaluated.

Example 1
First, 94 parts by weight of lithium-cobalt composite oxide (LiCoO ₂ ) as a positive electrode active material, 3 parts by weight of graphite as a conductive material, and 3 parts by weight of polyvinylidene fluoride (PVdF) as a binder are homogeneous. After mixing, N-methylpyrrolidone was added to obtain a positive electrode mixture coating solution.
Next, the obtained positive electrode mixture coating solution was uniformly applied on both sides of an aluminum foil having a thickness of 20 μm and dried to form a positive electrode mixture layer of 40 mg / cm ² per side. This was cut into a shape having a width of 50 mm and a length of 300 mm to produce a positive electrode, and a positive electrode terminal was further attached.
Next, 97 parts by weight of graphite as a negative electrode active material and 3 parts by weight of PVdF as a binder were homogeneously mixed, and N-methylpyrrolidone was added to obtain a negative electrode mixture coating solution. Next, the obtained negative electrode mixture coating liquid was uniformly applied on both sides of a 15 μm-thick copper foil serving as a negative electrode current collector and dried to form a negative electrode mixture layer of 20 mg / cm ² per side. This was cut into a shape having a width of 50 mm and a length of 300 mm to prepare a negative electrode, and a negative electrode terminal was further attached.
The nonaqueous electrolyte composition is a mixture of ethylene carbonate: propylene carbonate: diethyl carbonate: lithium hexafluorophosphate: ditetradecyl carbonate = 17: 8: 60: 14: 1 (weight ratio). Was used.

  The positive electrode and the negative electrode were laminated and wound up via a separator made of a microporous polyethylene film having a thickness of 20 μm, and placed in a bag as an example of an exterior member made of an aluminum laminate film. After injecting 2 g of the non-aqueous electrolyte composition into the bag, the bag was heat-sealed to produce a laminate type battery. The capacity of this battery is 700 mAh.

Table 1 shows the change in discharge capacity after charging the battery for 12 hours at 700 mA in an environment of 23 ° C. with 4.2 V as the upper limit, then resting for 10 minutes and discharging until reaching 700 V at 700 mA. Shown in
Thus, it turns out that the charging / discharging capacity maintenance factor after 100 cycles is improved rather than the comparative example 1 by using the chain carbonate which has a C13-C20 hydrocarbon group.

(Example 2)
The same procedure as in Example 1 was repeated except that the concentration of ditetradecyl carbonate in the non-aqueous electrolyte composition was 0.1% and diethyl carbonate was increased by that amount to obtain a laminate type battery of this example. The change in discharge capacity was measured in the same manner as described above, and the results obtained are shown in Table 1.
From Table 1, when the concentration of the chain carbonate having a hydrocarbon group having 13 to 20 carbon atoms is 0.1%, the discharge capacity retention after 100 cycles is lower than that in Example 1, but the comparative example It turns out that it is improving rather than 1.

(Example 3)
The same procedure as in Example 1 was repeated except that the concentration of ditetradecyl carbonate in the non-aqueous electrolyte composition was 0.2% and diethyl carbonate was reduced by that amount, to obtain a laminate type battery of this example. The change in discharge capacity was measured in the same manner as described above, and the results obtained are shown in Table 1.
From Table 1, when the concentration of the chain carbonate having a hydrocarbon group having 13 to 20 carbon atoms is 0.2%, the discharge capacity retention rate after 100 cycles is lower than that of Example 1, but the comparative example It turns out that it is improving rather than 1.

(Examples 4 and 5)
As the predetermined chain carbonate ester, as shown in Table 1, the same operation as in Example 1 was repeated except that ditridecyl carbonate was used in Example 4 and dieicosyl carbonate was used in Example 5. Laminated batteries 4 and 5 were obtained. The change in discharge capacity was measured in the same manner as described above, and the results obtained are shown in Table 1.
From Table 1, it can be seen that the discharge capacity retention rate after 100 cycles is improved as compared with Comparative Example 1 by using a chain carbonate having a hydrocarbon group having 13 to 20 carbon atoms.

(Example 6)
The same procedure as in Example 1 was repeated except that methyl tetradecyl carbonate having an asymmetric molecular structure was used as the predetermined chain carbonate, to obtain a laminate type battery of this example. The change in discharge capacity was measured in the same manner as described above, and the results obtained are shown in Table 1.
From Table 1, it can be seen that the discharge capacity retention rate after 100 cycles is improved as compared with Comparative Example 1 by using a chain carbonate having a hydrocarbon group having 13 to 20 carbon atoms.

(Example 7)
The same procedure as in Example 1 was repeated except that 1% of vinylene carbonate was added to the nonaqueous electrolyte composition and diethyl carbonate was reduced by that amount to obtain a laminate type battery of this example. The change in discharge capacity was measured in the same manner as described above, and the results obtained are shown in Table 1.
From Table 1, when a carbonate ester having a double bond is used in combination with a chain ester carbonate having a hydrocarbon group having 13 to 20 carbon atoms, the discharge capacity retention rate after 100 cycles is improved from that in Example 1. I understand that.

(Comparative Example 1)
The same procedure as in Example 1 was repeated except that the predetermined chain carbonate was not added and diethyl carbonate was increased by that amount to obtain a laminate type battery of this example. The change in discharge capacity was measured in the same manner as described above, and the results obtained are shown in Table 1.
From Table 1, it can be seen that the discharge capacity retention rate after 100 cycles deteriorates more than in Examples 1 to 5 unless a chain carbonate having a hydrocarbon group having 13 to 20 carbon atoms is added.

(Comparative Example 2)
The same procedure as in Example 1 was repeated except that didodecyl carbonate, which is a chain carbonate having a hydrocarbon group having 12 carbon atoms, was used instead of the predetermined chain carbonate, and the laminate type of this example A battery was obtained. The change in discharge capacity was measured in the same manner as described above, and the results obtained are shown in Table 1.
From Table 1, it can be seen that the discharge capacity retention rate after 100 cycles deteriorates more than in Examples 1 to 7 unless a chain carbonate having a hydrocarbon group having 13 to 20 carbon atoms is added.

(Comparative Example 3)
The same procedure as in Example 1 was repeated except that dihenicosyl carbonate, which is a chain carbonate having a hydrocarbon group having 21 carbon atoms, was used instead of the predetermined chain carbonate, and the laminate of this example A type battery was obtained. The change in discharge capacity was measured in the same manner as described above, and the results obtained are shown in Table 1.
From Table 1, it can be seen that the discharge capacity retention rate after 100 cycles deteriorates more than in Examples 1 to 7 unless a chain carbonate having a hydrocarbon group having 13 to 20 carbon atoms is added.

(Example 8)
The same procedure as in Example 1 was repeated except that 1% polyvinyl formal was added to the nonaqueous electrolyte composition to swell it, and diethyl carbonate was reduced accordingly, to obtain a laminate type battery of this example. The change in discharge capacity was measured in the same manner as described above, and the results obtained are shown in Table 2.
From Table 2, it can be seen that the discharge capacity retention rate after 100 cycles is improved from Comparative Example 4 by using a chain carbonate having a hydrocarbon group having 13 to 20 carbon atoms.

Example 9
The same procedure as in Example 8 was repeated except that the concentration of ditetradecyl carbonate in the non-aqueous electrolyte composition was 0.1% and diethyl carbonate was increased by that amount to obtain a laminate type battery of this example. The change in discharge capacity was measured in the same manner as described above, and the results obtained are shown in Table 2.
From Table 2, when the concentration of the chain carbonate having a hydrocarbon group having 13 to 20 carbon atoms is set to 0.1%, the discharge capacity retention rate after 100 cycles deteriorates more than that in Example 8, but the comparative example It can be seen that it is improved from 4.

(Example 10)
The same procedure as in Example 8 was repeated except that the concentration of the predetermined chain carbonate in the non-aqueous electrolyte composition was 2% and diethyl carbonate was reduced by that amount to obtain a laminate type battery of this example. The change in discharge capacity was measured in the same manner as described above, and the results obtained are shown in Table 2.
From Table 2, when the concentration of the chain carbonate having a hydrocarbon group having 13 to 20 carbon atoms is 2%, the discharge capacity retention rate after 100 cycles is lower than that in Example 8, but from Comparative Example 4 Can be seen to be improved.

(Examples 11 and 12)
As the predetermined chain carbonate ester, as shown in Table 2, the same operation as in Example 8 was repeated except that ditridecyl carbonate was used in Example 11 and dieicosyl carbonate was used in Example 12, and each Example was repeated. 11 and 12 laminated batteries were obtained. The change in discharge capacity was measured in the same manner as described above, and the results obtained are shown in Table 2.
From Table 2, it can be seen that the discharge capacity retention rate after 100 cycles is improved as compared with Comparative Example 4 by using a chain carbonate having a hydrocarbon group having 13 to 20 carbon atoms.

(Example 13)
The same procedure as in Example 8 was repeated except that methyl tetradecyl carbonate having an asymmetric molecular structure was used as the predetermined chain carbonate, to obtain a laminate type battery of this example. The change in discharge capacity was measured in the same manner as described above, and the results obtained are shown in Table 2.
From Table 2, it can be seen that the discharge capacity retention rate after 100 cycles is improved as compared with Comparative Example 4 by using a chain carbonate having a hydrocarbon group having 13 to 20 carbon atoms.

(Example 14)
The same procedure as in Example 8 was repeated except that 1% vinylene carbonate was added to the nonaqueous electrolyte composition and diethyl carbonate was reduced by that amount to obtain a laminate type battery of this example. The change in discharge capacity was measured in the same manner as described above, and the results obtained are shown in Table 2.
From Table 2, when a carbonate ester having a double bond is used in combination with a chain ester carbonate having a hydrocarbon group having 13 to 20 carbon atoms, the discharge capacity retention rate after 100 cycles is improved from that in Example 8. I understand that.

(Comparative Example 4)
The same procedure as in Example 8 was repeated except that the predetermined chain carbonate was not added to obtain a laminate type battery of this example. The change in discharge capacity was measured in the same manner as described above, and the results obtained are shown in Table 2.
From Table 2, it can be seen that the discharge capacity retention rate after 100 cycles deteriorates more than in Examples 8 to 14 unless a chain carbonate having a hydrocarbon group having 13 to 20 carbon atoms is added.

(Comparative Example 5)
The same procedure as in Example 8 was repeated except that didodecyl carbonate, which is a chain carbonate having a hydrocarbon group having 12 carbon atoms, was used instead of the predetermined chain carbonate, and the laminate type of this example A battery was obtained. The change in discharge capacity was measured in the same manner as described above, and the results obtained are shown in Table 2.
From Table 2, it can be seen that the discharge capacity retention rate after 100 cycles deteriorates more than in Examples 8 to 14 unless a chain carbonate having a hydrocarbon group having 13 to 20 carbon atoms is added.

(Comparative Example 6)
The same procedure as in Example 8 was repeated except that dihenicosyl carbonate, which is a chain carbonate having a hydrocarbon group having 21 carbon atoms, was used instead of the predetermined chain carbonate, and the laminate of this example A type battery was obtained. The change in discharge capacity was measured in the same manner as described above, and the results obtained are shown in Table 2.
From Table 2, it can be seen that the discharge capacity retention rate after 100 cycles deteriorates more than in Examples 8 to 14 unless a chain carbonate having a hydrocarbon group having 13 to 20 carbon atoms is added.

(Example 15)
The same procedure as in Example 1 was repeated except that 1% polyacrylic acid ester was added to the nonaqueous electrolyte composition to swell it, and the amount of diethyl carbonate was reduced accordingly, to obtain a laminate type battery of this example. The change in discharge capacity was measured in the same manner as described above, and the results obtained are shown in Table 3.
From Table 3, it can be seen that the discharge capacity retention rate after 100 cycles is improved as compared with Comparative Example 7 by using a chain carbonic acid ester derivative having a hydrocarbon group having 13 to 20 carbon atoms.

(Example 16)
The same procedure as in Example 15 was repeated, except that the concentration of ditetradecyl carbonate in the nonaqueous electrolyte composition was 0.1%, and diethyl carbonate was increased by that amount to obtain a laminate type battery of this example. The change in discharge capacity was measured in the same manner as described above, and the results obtained are shown in Table 3.
From Table 3, when the concentration of the chain carbonate having a hydrocarbon group having 13 to 20 carbon atoms is 0.1%, the discharge capacity retention rate after 100 cycles deteriorates from that in Example 15, but Comparative Example 7 shows. It turns out that it is improved.

(Example 17)
The same procedure as in Example 15 was repeated except that the concentration of the predetermined chain carbonate in the nonaqueous electrolyte composition was 2%, and diethyl carbonate was reduced by that amount to obtain a laminate type battery of this example. The change in discharge capacity was measured in the same manner as described above, and the results obtained are shown in Table 3.
From Table 3, when the concentration of the chain carbonate having a hydrocarbon group having 13 to 20 carbon atoms is set to 2%, the discharge capacity retention rate after 100 cycles is deteriorated from that in Example 15, but more than that in Comparative Example 7. It can be seen that it is improved.

(Examples 18 and 19)
As shown in Table 3, as the predetermined chain ester carbonate, the same operation as in Example 15 was repeated except that ditridecyl carbonate was used in Example 18 and ditridecyl carbonate was used in Example 19, and Example 18 was repeated. And 19 laminated batteries were obtained. The change in discharge capacity was measured in the same manner as described above, and the results obtained are shown in Table 3.
From Table 3, it can be seen that the discharge capacity retention rate after 100 cycles is improved as compared with Comparative Example 7 by using a chain carbonate having a hydrocarbon group having 13 to 20 carbon atoms.

(Example 20)
The same procedure as in Example 15 was repeated except that methyl tetradecyl carbonate having an asymmetric molecular structure was used as the predetermined chain carbonate to obtain a laminate type battery of this example. The change in discharge capacity was measured in the same manner as described above, and the results obtained are shown in Table 3.
From Table 3, it can be seen that the discharge capacity retention rate after 100 cycles is improved as compared with Comparative Example 7 by using a chain carbonate having a hydrocarbon group having 13 to 20 carbon atoms.

(Example 21)
The same procedure as in Example 15 was repeated except that 1% of vinylene carbonate was added to the nonaqueous electrolyte composition and the amount of ethylene carbonate was reduced by that amount to obtain a laminate type battery of this example. The change in discharge capacity was measured in the same manner as described above, and the results obtained are shown in Table 3.
From Table 3, when a carbonate ester having a double bond is used in combination with a chain ester carbonate having a hydrocarbon group having 13 to 20 carbon atoms, the discharge capacity retention rate after 100 cycles is improved from that in Example 15. I understand that.

(Comparative Example 7)
Except that the predetermined chain carbonate was not added, the same operation as in Example 15 was repeated to obtain a laminate type battery of this example. The change in discharge capacity was measured in the same manner as described above, and the results obtained are shown in Table 3.
From Table 3, it can be seen that the discharge capacity retention rate after 100 cycles deteriorates more than in Examples 15 to 21 unless a chain carbonate having a hydrocarbon group having 13 to 20 carbon atoms is added.

(Comparative Example 8)
The same procedure as in Example 15 was repeated except that didodecyl carbonate, which is a chain carbonate having a hydrocarbon group having 12 carbon atoms, was used instead of the predetermined chain carbonate, and the laminate type of this example A battery was obtained. The change in discharge capacity was measured in the same manner as described above, and the results obtained are shown in Table 3.
From Table 3, it can be seen that the discharge capacity retention rate after 100 cycles deteriorates more than in Examples 15 to 21 unless a chain carbonate having a hydrocarbon group having 13 to 20 carbon atoms is added.

(Comparative Example 9)
The same procedure as in Example 15 was repeated except that dihenicosyl carbonate, which is a chain carbonate having a hydrocarbon group having 21 carbon atoms, was used instead of the predetermined chain carbonate, and the laminate of this example A type battery was obtained. The change in discharge capacity was measured in the same manner as described above, and the results obtained are shown in Table 3.
From Table 3, it can be seen that the discharge capacity retention rate after 100 cycles deteriorates more than in Examples 15 to 21 unless a chain carbonate having a hydrocarbon group having 13 to 20 carbon atoms is added.

(Example 22)
A laminated battery of this example was obtained by repeating the same operation as in Example 1 except that the thickness of the separator was 10 μm, and 2 μm of polyvinylidene fluoride was applied to both sides thereof. The change in discharge capacity was measured in the same manner as described above, and the results obtained are shown in Table 4.
From Table 4, it can be seen that the discharge capacity retention rate after 100 cycles is improved as compared with Comparative Example 10 by using a chain carbonate having a hydrocarbon group having 13 to 20 carbon atoms.

(Example 23)
The same procedure as in Example 22 was repeated, except that the concentration of ditetradecyl carbonate in the nonaqueous electrolyte composition was 0.1%, and diethyl carbonate was increased by that amount, to obtain a laminate type battery of this example. The change in discharge capacity was measured in the same manner as described above, and the results obtained are shown in Table 4.
From Table 4, when the concentration of the chain carbonate having a hydrocarbon group having 13 to 20 carbon atoms is 0.1%, the discharge capacity retention rate after 100 cycles deteriorates from that in Example 22, but Comparative Example 10 shows. It turns out that it is improved.

(Example 24)
A laminated battery of this example was obtained by repeating the same operation as in Example 22 except that the concentration of the predetermined chain carbonate in the nonaqueous electrolyte composition was 2% and diethyl carbonate was reduced by that amount. The change in discharge capacity was measured in the same manner as described above, and the results obtained are shown in Table 4.
From Table 4, when the concentration of the chain carbonate having a hydrocarbon group having 13 to 20 carbon atoms is set to 2%, the discharge capacity retention rate after 100 cycles is deteriorated from that in Example 22, but more than that in Comparative Example 10. It can be seen that it is improved.

(Examples 25 and 26)
As shown in Table 4, as the predetermined chain ester carbonate, the same operation as in Example 22 was repeated except that ditridecyl carbonate was used in Example 25 and dieicosyl carbonate was used in Example 26. 25 and 26 laminated batteries were obtained. The change in discharge capacity was measured in the same manner as described above, and the results obtained are shown in Table 4.
From Table 4, it can be seen that the discharge capacity retention rate after 100 cycles is improved as compared with Comparative Example 10 by using a chain carbonate having a hydrocarbon group having 13 to 20 carbon atoms.

(Example 27)
The same procedure as in Example 22 was repeated except that methyl tetradecyl carbonate having an asymmetric molecular structure was used as the predetermined chain carbonate, to obtain a laminate type battery of this example. The change in discharge capacity was measured in the same manner as described above, and the results obtained are shown in Table 4.
From Table 4, it can be seen that the discharge capacity retention rate after 100 cycles is improved as compared with Comparative Example 10 by using a chain carbonate having a hydrocarbon group having 13 to 20 carbon atoms.

(Example 24)
The same procedure as in Example 22 was repeated, except that 1% vinylene carbonate was added to the nonaqueous electrolyte composition and the amount of ethylene carbonate was reduced by that amount, whereby a laminate type battery of this example was obtained. The change in discharge capacity was measured in the same manner as described above, and the results obtained are shown in Table 4.
From Table 4, when a carbonate ester having a double bond is used in combination with a chain ester carbonate having a hydrocarbon group having 13 to 20 carbon atoms, the discharge capacity retention rate after 100 cycles is improved from that in Example 22. I understand that.

(Comparative Example 10)
Except that the predetermined chain carbonate was not added, the same operation as in Example 22 was repeated to obtain a laminate type battery of this example. The change in discharge capacity was measured in the same manner as described above, and the results obtained are shown in Table 4.
From Table 4, it can be seen that the discharge capacity retention rate after 100 cycles deteriorates more than that in Examples 22 to 28 unless a chain carbonate having a hydrocarbon group having 13 to 20 carbon atoms is added.

(Comparative Example 11)
The laminate type of this example was repeated by repeating the same operation as in Example 22 except that didodecyl carbonate, which is a chain carbonate having a hydrocarbon group having 12 carbon atoms, was used instead of the predetermined chain carbonate. A battery was obtained. The change in discharge capacity was measured in the same manner as described above, and the results obtained are shown in Table 4.
From Table 4, it can be seen that the discharge capacity retention rate after 100 cycles deteriorates more than that in Examples 22 to 28 unless a chain carbonate having a hydrocarbon group having 13 to 20 carbon atoms is added.

(Comparative Example 12)
The same procedure as in Example 22 was repeated except that dihenicosyl carbonate, which is a chain carbonate having a hydrocarbon group having 21 carbon atoms, was used instead of the predetermined chain carbonate, and the laminate of this example A type battery was obtained. The change in discharge capacity was measured in the same manner as described above, and the results obtained are shown in Table 4.
From Table 4, it can be seen that the discharge capacity retention rate after 100 cycles deteriorates more than that in Examples 22 to 28 unless a chain carbonate having a hydrocarbon group having 13 to 20 carbon atoms is added.

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-described 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 electrodes and negative electrodes are stacked, or a plurality of positive electrodes The present invention can also be applied to a case where a laminated battery element in which a negative electrode and a negative electrode are laminated.
In the above embodiment, the case where the film-shaped exterior member 30 is used has been described. However, the battery having other shapes such as a so-called cylindrical shape, square shape, coin shape, and button shape using a can as the exterior member. Similarly, the present invention can be applied. Furthermore, it is applicable not only to a secondary battery but also to a primary battery.

  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.

It is one Embodiment of the nonaqueous electrolyte secondary battery of this invention, Comprising: It is a disassembled perspective view which shows an example of a laminate type battery. It is sectional drawing along the II line of the battery element shown in FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 11 ... Positive electrode terminal, 12 ... Negative electrode terminal, 20 ... Battery element, 21 ... Positive electrode, 21A ... Positive electrode collector, 21B ... Positive electrode active material layer, 22 ... Negative electrode, 22A ... Negative electrode collector, 22B ... Negative electrode active material layer , 23 ... non-aqueous electrolyte composition layer, 24 ... separator, 25 ... protective tape, 30 ... exterior member, 31 ... adhesion film.

Claims (6)

Electrolyte salt,
A non-aqueous solvent;
A chain carbonate having a C hydrocarbon group 13-20,
Contain,
The content of the chain carbonate ester is 0.1% by mass or more and 2% by mass or less with respect to the total mass of the nonaqueous electrolyte composition for secondary batteries. Composition. Further containing other carbonate ester having a hydrocarbon group having a double bond ,
The content of the other ester carbonate, second according to claim 1, relative to the total weight of the non-aqueous electrolyte composition for a secondary battery, characterized in that 5 wt% or less than 0.1 wt% Nonaqueous electrolyte composition for secondary battery . The nonaqueous electrolyte composition for a secondary battery according to claim 1 or 2, further comprising a polymer compound. The non-aqueous electrolyte composition for a secondary battery according to claim 3, wherein the polymer compound is at least one selected from the group consisting of polyvinyl formal, polyacrylic acid ester and polyvinylidene fluoride. object. A positive electrode and a negative electrode using a material capable of inserting and extracting lithium ions as a positive electrode active material or a negative electrode active material;
A non-aqueous electrolyte composition;
A separator;
An exterior member for housing these;
A non-aqueous electrolyte secondary battery comprising:
The non-aqueous electrolyte composition comprises an electrolyte salt,
A non-aqueous solvent;
A chain carbonate having a C hydrocarbon group 13-20,
Contain,
Content of the said chain carbonate is 0.1 to 2 mass% with respect to the total mass of the said non-aqueous electrolyte composition, The non-aqueous electrolyte secondary battery characterized by the above-mentioned .   6. The nonaqueous electrolyte secondary battery according to claim 5, wherein the exterior member is made of a metal laminate film.

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