JP2008243786A - Nonaqueous electrolyte secondary battery and nonaqueous electrolyte - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a battery capable of restraining its expansion at the time of storage at high temperature, while maintaining its charge and discharge efficiency. <P>SOLUTION: In the nonaqueous electrolyte secondary battery having an electrode body laminating a current collector, and positive and negative electrodes with an active material supported by the current collector via a separator and an electrolyte, the electrolyte includes a compound expressed in an formula (1), and the thickness of the active material per side is 40 μm or larger. Here, R1 to R4 in the formula (1) denote, each independently, a substituent selected from among a hydrogen group, a halogen group, and an alkyl group, and may be the same or different, and where at least one from among R1 to R4 is to be a chlorine group. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a non-aqueous electrolyte secondary battery having reduced expansion under a high temperature environment while maintaining good cycle characteristics.

  In recent years, many portable electronic devices such as a camera-integrated VTR, 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. As portable power sources 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 that uses 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 that is a conventional non-aqueous electrolyte secondary battery, Since a large energy density can be obtained compared to a nickel cadmium battery, it is widely put into practical use. In particular, a laminated battery using an aluminum laminated film for the exterior has a high energy density because it is lightweight. In the laminate battery, since the deformation of the laminate battery can be suppressed by swelling the electrolyte in the polymer, the laminate polymer battery is also widely used.

  On the other hand, the laminate battery has a problem that it easily expands in a high temperature environment. This is presumably because the carbonic acid ester in the electrolyte solution decomposes by reacting with the electrode in a high-temperature environment to generate gas. Such a phenomenon becomes a problem particularly in a thin battery such as a laminated battery. Accordingly, dimethyl carbonate or diethyl carbonate, which has a viscosity higher than that of ethyl methyl carbonate but hardly swells, has been used as an electrolyte solution as a main component. In recent years, the battery active material has been thickly coated to increase the capacity of the battery. However, since the electrolytic solution mainly composed of diethyl carbonate having a high viscosity is difficult to impregnate the electrode, charging and discharging are repeated. There is a problem that the lithium metal is deposited on the negative electrode and the discharge capacity is lowered.

  In view of this, it has been proposed to add a fluoroethylene carbonate to the electrolytic solution to suppress a decrease in the discharge capacity retention rate during the charge / discharge cycle (Patent Document 1).

JP 2005-38722 A

  However, when fluoroethylene carbonate is used, there is a problem that the battery tends to expand under a high temperature environment. Therefore, the present invention has been made in view of such problems, and an object thereof is to provide a battery capable of suppressing expansion during high-temperature storage while maintaining charge / discharge efficiency.

In the present invention, it has been found that by containing chloroethylene carbonates in the electrolytic solution, expansion under a high temperature environment is reduced while maintaining good charge / discharge cycle characteristics.
That is, the present invention provides the following non-aqueous electrolyte secondary battery and non-aqueous electrolyte.
[1] A non-aqueous electrolyte secondary comprising an electrode body in which a positive electrode and a negative electrode having a current collector and an active material layer carried on the current collector are stacked via a separator, and an electrolyte In the battery, the electrolytic solution contains a compound represented by the following formula (1):
A non-aqueous electrolyte secondary battery, wherein the active material layer has a thickness of 40 μm or more per side.

[In the above formula (1), R1 to R4 each independently represent a substituent selected from the group consisting of a hydrogen group, a halogen group and an alkyl group, and they may be the same or different. However, at least one of R1 to R4 is a chlorine group. ]
[2] A nonaqueous electrolytic solution comprising a compound represented by the following formula (1).

[In the above formula (1), R1 to R4 each independently represent a substituent selected from the group consisting of a hydrogen group, a halogen group and an alkyl group, and they may be the same or different. However, at least one of R1 to R4 is a chlorine group. ]

  According to the battery of the present invention, a good film can be formed on the negative electrode surface by adding the compound represented by the formula (1), that is, chloroethylene carbonates, to the electrolytic solution. Thereby, even when the active material is thickly coated, expansion during high temperature storage can be suppressed and excellent charge / discharge efficiency can be maintained.

  Hereinafter, the best mode for carrying out the present invention will be described with reference to the drawings, but the present invention is not limited to the following mode.

  FIG. 1 schematically shows a configuration of a laminated battery according to an embodiment of the present invention. This secondary battery is a so-called laminate film type, and has a wound electrode body 20 to which a positive electrode lead 21 and a negative electrode lead 22 are attached accommodated in a film-shaped exterior member 30.

  The positive electrode lead 21 and the negative electrode lead 22 are led out from the inside of the exterior member 30 to the outside, for example, in the same direction. The positive electrode lead 21 and the negative electrode lead 22 are made of, for example, a metal material such as aluminum, copper, nickel, or stainless steel, and each have a thin plate shape or a mesh shape.

  The exterior member 30 is made of, for example, a rectangular aluminum laminated film in which a nylon film, an aluminum foil, and a polyethylene film are bonded together in this order. The exterior member 30 is disposed, for example, so that the polyethylene film side and the wound electrode body 20 face each other, and the outer edge portions are in close contact with each other by fusion or an adhesive. An adhesion film 31 is inserted between the exterior member 30 and the positive electrode lead 21 and the negative electrode lead 22 to prevent intrusion of outside air. The adhesion film 31 is made of a material having adhesion to the positive electrode lead 21 and the negative electrode lead 22, for example, a polyolefin resin such as polyethylene, polypropylene, modified polyethylene, or modified polypropylene.

  The exterior member 30 may be made of a laminated film having another structure, a polymer film such as polypropylene, or a metal film instead of the above-described aluminum laminated film.

  FIG. 2 shows a cross-sectional structure taken along line II of the spirally wound electrode body 20 shown in FIG. The wound electrode body 20 is obtained by laminating a positive electrode 23 and a negative electrode 24 via a separator 25 and an electrolyte layer 26 and winding them, and the outermost periphery is protected by a protective tape 27.

(Active material layer)
The positive electrode 23 has a structure in which a positive electrode active material layer 23B is provided on both surfaces of a positive electrode current collector 23A. The negative electrode 24 has a structure in which a negative electrode active material layer 24B is provided on both surfaces of a negative electrode current collector 24A, and the negative electrode active material layer 24B and the positive electrode active material layer 23B are arranged to face each other. In the non-aqueous electrolyte secondary battery of the present invention, the thickness of each of the positive electrode active material layer 23B and the negative electrode active material layer 24B per side is 40 μm or more, preferably 80 μm or less. More preferably, it is the range of 40 micrometers or more and 60 micrometers or less. By setting the thickness of the active material layer to 40 μm or more, it is possible to increase the capacity of the battery. Moreover, the discharge capacity maintenance factor when charging / discharging is repeated can be enlarged by setting it as 80 micrometers or less.

(Positive electrode)
The positive electrode current collector 23A is made of, for example, a metal material such as aluminum, nickel, or stainless steel. The positive electrode active material layer 24B includes, for example, any one or more of positive electrode materials capable of occluding and releasing lithium as a positive electrode active material. It may contain a binder.

Examples of the positive electrode material capable of inserting and extracting lithium include lithium cobaltate, lithium nickelate, and solid solutions thereof (Li (NiCo _y Mn _z ) O ₂ )) (x, y, and z have values of 0 <x <1, 0 <y <1, 0 ≦ z <1, x + y + z = 1.), Manganese spinel (LiMn ₂ O ₄ ) and its solid solution (Li (Mn _2−v Ni _v ) O ₄ ) (The value of v is v <2.) Lithium composite oxides and the like, and phosphate compounds having an olivine structure such as lithium iron phosphate (LiFePO ₄ ) are preferable. This is because a high energy density can be obtained. Examples of the positive electrode material capable of inserting and extracting lithium include oxides such as titanium oxide, vanadium oxide and manganese dioxide, disulfides such as iron disulfide, titanium disulfide and molybdenum sulfide, sulfur, And conductive polymers such as polyaniline and polythiophene.

(Negative electrode)
The negative electrode 24 has, for example, a structure in which a negative electrode active material layer 24B is provided on both surfaces of a negative electrode current collector 24A having a pair of opposed surfaces. The negative electrode current collector 24A is made of a metal material such as copper, nickel, and stainless steel, for example.

  The negative electrode active material layer 24B includes one or more negative electrode materials capable of occluding and releasing lithium as a negative electrode active material. In this secondary battery, the charge capacity of the negative electrode material capable of inserting and extracting lithium is larger than the charge capacity of the positive electrode 23 so that lithium metal does not deposit on the negative electrode 24 during the charge. It has become.

  Examples of the negative electrode material capable of inserting and extracting lithium include non-graphitizable carbon, graphitizable carbon, graphite, pyrolytic carbons, cokes, glassy carbons, and fired organic polymer compounds And carbon materials such as carbon fiber or activated carbon. Among these, examples of coke include pitch coke, needle coke, and petroleum coke. An organic polymer compound fired body refers to a carbonized material obtained by firing a polymer material such as phenol resin or furan resin at an appropriate temperature, and in part, it is made of non-graphitizable carbon or graphitizable carbon. Some are classified. Examples of the polymer material include polyacetylene and polypyrrole. These carbon materials are preferable because the change in crystal structure that occurs during charge and discharge is very small, a high charge and discharge capacity can be obtained, and good cycle characteristics can be obtained. In particular, graphite is preferable because it has a high electrochemical equivalent and can provide a high energy density. Further, non-graphitizable carbon is preferable because excellent characteristics can be obtained. Furthermore, those having a low charge / discharge potential, specifically, those having a charge / discharge potential close to that of lithium metal are preferable because a high energy density of the battery can be easily realized.

  Further, as the negative electrode material, in addition to the carbon material shown above, a material containing an element that forms an alloy with lithium, such as silicon, tin, and a compound thereof, magnesium, aluminum, germanium, or the like may be used. Further, a material containing an element that forms a composite oxide with lithium, such as titanium, can be considered.

(Separator)
The separator 25 separates the positive electrode 23 and the negative electrode 24 and allows lithium ions to pass through while preventing a short circuit of current due to contact between the two electrodes. The separator 25 is made of, for example, a porous film made of a synthetic resin made of polytetrafluoroethylene, polypropylene, polyethylene, or the like, or a multi-hard film made of ceramic, and a plurality of these porous films are laminated. It may be a structure. For example, the separator 25 is impregnated with an electrolytic solution that is a liquid electrolyte.

(Electrolyte)
The electrolytic solution contains, for example, a solvent and an electrolyte salt dissolved in the solvent.

(solvent)
The solvent used for the electrolytic solution is preferably a high dielectric constant solvent having a relative dielectric constant of 30 or more. This is because the number of lithium ions can be increased. The content of the high dielectric constant solvent in the electrolytic solution is preferably in the range of 15 to 50% by mass. It is because higher charging / discharging efficiency is obtained by setting it within this range.

  Examples of the high dielectric constant solvent include cyclic carbonates such as vinylene carbonate, ethylene carbonate, propylene carbonate, butylene carbonate and vinyl ethylene carbonate, lactones such as γ-butyrolactone and γ-valerolactone, and N-methyl-2-pyrrolidone. And lactams such as N-methyl-2-oxazolidinone, and sulfone compounds such as tetramethylene sulfone. Cyclic carbonates are particularly preferable, and ethylene carbonate and vinylene carbonate having a carbon-carbon double bond are more preferable. Moreover, the said high dielectric constant solvent may be used individually by 1 type, and may mix and use multiple types.

  The solvent used for the electrolytic solution is preferably used by mixing a low-viscosity solvent having a viscosity of 1 mPa · s or less with the high dielectric constant solvent. This is because high ion conductivity can be obtained. The ratio (mass ratio) of the low-viscosity solvent to the high-dielectric-constant solvent is preferably in the range of high-dielectric-constant solvent: low-viscosity solvent = 2: 8 to 5: 5. It is because a higher effect can be obtained by setting it within this range.

  Examples of the low viscosity solvent include chain carbonates such as dimethyl carbonate, diethyl carbonate, ethyl methyl carbonate, and methyl propyl carbonate, methyl acetate, ethyl acetate, methyl propionate, ethyl propionate, methyl butyrate, methyl isobutyrate, and trimethyl. Chain carboxylic acid esters such as methyl acetate and ethyl trimethylacetate, chain amides such as N, N-dimethylacetamide, chain carbamic acid esters such as methyl N, N-diethylcarbamate and ethyl N, N-diethylcarbamate And ethers such as 1,2-dimethoxyethane, tetrahydrofuran, tetrahydropyran and 1,3-dioxolane. These low-viscosity solvents may be used alone or in combination of two or more.

(Electrolyte salt)
As the electrolyte salt, e.g., lithium hexafluorophosphate (LiPF _6), lithium tetrafluoroborate (LiBF _4), lithium hexafluoroarsenate (LiAsF _6), lithium hexafluoro antimonate (LiSbF ₆₎ , Inorganic lithium salts such as lithium perchlorate (LiClO ₄ ) and lithium tetrachloroaluminate (LiAlCl ₄ ), and lithium trifluoromethanesulfonate (CF ₃ SO ₃ Li), lithium bis (trifluoromethanesulfone) imide [(CF ₃ SO ₂ ) ₂ NLi], lithium bis (pentafluoroethanesulfone) imide [(C ₂ F ₅ SO ₂ ) ₂ NLi] and lithium tris (trifluoromethanesulfone) methide [(CF ₃ SO ₂ ) ₃ CLi] Of perfluoroalkanesulfonic acid derivatives Lithium salts. One electrolyte salt may be used alone, or a plurality of electrolyte salts may be mixed and used.

  Furthermore, the non-aqueous electrolyte secondary battery of the present invention contains a compound represented by the following formula (1) in the electrolyte.

  In the above formula (1), R1 to R4 each independently represent a substituent selected from the group consisting of a hydrogen group, a halogen group and an alkyl group, and they may be the same or different. However, at least one of R1 to R4 is a chlorine group. That is, the compound represented by the above formula (1) (hereinafter also referred to as compound (1)) means chloroethylene carbonates. By including the chloroethylene carbonates in the electrolytic solution, it is possible to reduce expansion under a high temperature environment while maintaining good charge / discharge cycle characteristics. Chloroethylene carbonate is decomposed by charging and reacts with lithium ions in the electrolytic solution to form a lithium chloride film on the negative electrode surface. Since this film suppresses decomposition of the solvent in the electrolytic solution, generation of gas is suppressed. As a result, it is considered that the expansion of the battery is reduced.

  Fluoroethylene carbonate also decomposes to form a lithium fluoride film, but chloroethylene carbonates are more likely to decompose (easily liberate chloride ions), so it is considered that the film is formed better. That is, chloroethylene carbonate suppresses decomposition of the electrolytic solution more efficiently than fluoroethylene carbonate. In addition, the lithium chloride film produced as a result of decomposition has higher lithium ion conductivity than lithium fluoride film produced by the decomposition of fluoroethylene carbonate, making it easier to insert and desorb lithium from the negative electrode, and good cycle characteristics Can be obtained.

  As compound (1), when R1-R4 is a halogen group, a chlorine group or a fluorine group is preferable, and when it is an alkyl group, the number of carbon atoms is 1-2. Specifically, a series of compounds shown in the following formulas (1-1) to (1-5) can be mentioned.

That is, 4-chloro-1,3-dioxolan-2-one (chloroethylene carbonate) of the following formula (1-1),
4-fluoro-5-chloro-1,3-dioxolan-2-one of (1-2),
4,5-dichloro-1,3-dioxolan-2-one (dichloroethylene carbonate) of (1-3),
(1-4) tetrachloro-1,3-dioxolan-2-one,
(1-5) 4,5-dichloro-4,5-dimethyl-1,3-dioxolan-2-one, and the like.

  These may be used alone or in combination of two or more. Among these, 4-chloro-1,3-dioxolan-2-one (chloroethylene carbonate) of the formula (2-1) is preferable. This is because they are easily available and higher effects can be obtained.

  Content of the said compound (1) in electrolyte solution becomes like this. Preferably it is 0.1 to 5 mass% on a solvent basis, More preferably, it is 0.2 to 3.0 mass%. The amount of 0.2% by mass or more is preferable because a sufficient film can be formed. Moreover, when 5 mass% or more is added, it becomes difficult to reduce expansion particularly in a laminate type battery. This is presumably because the decomposition of the compound (1) itself is likely to affect a laminated battery having a film material as an exterior.

(Polymer compound)
The battery of the present invention may be in the form of a gel by containing a polymer compound that swells with the electrolyte and serves as a holding body that holds the electrolyte. It is because high ion conductivity can be obtained by including a polymer compound that swells with the electrolytic solution, excellent charge / discharge efficiency can be obtained, and battery leakage can be prevented. When a polymer compound is added to the electrolytic solution and used, the content of the polymer compound in the electrolytic solution is preferably in the range of 0.1% by mass to 2.0% by mass. When a polymer compound such as polyfucavinylidene is applied on both sides of the separator, the mass ratio of the electrolytic solution to the polymer compound is preferably in the range of 50: 1 to 10: 1. It is because higher charging / discharging efficiency is obtained by setting it within this range.

  Examples of the polymer compound include ether-based polymer compounds such as polyvinyl formal represented by the following formula (2), polyethylene oxide and a crosslinked product containing polyethylene oxide, and ester-based polymers such as polymethacrylate represented by the following formula (3). Examples thereof include a polymer of vinylidene fluoride such as a molecular compound, an acrylate polymer compound, polyvinylidene fluoride represented by the following formula (4), and a copolymer of vinylidene fluoride and hexafluoropropylene. A high molecular compound may be used individually by 1 type, and multiple types may be mixed and used for it. In particular, from the viewpoint of the effect of preventing swelling during high temperature storage, it is desirable to use a fluorine-based polymer compound such as polyvinylidene fluoride.

In the formulas (2) to (4), s, t and u are each an integer of 100 to 10000, R is C _x H _2x-1 O _y (x is 1 to 8, y is 0 to 4) Indicated.

(Production method)
For example, the secondary battery can be manufactured as follows.

  The positive electrode can be produced, for example, by the following method. First, a positive electrode active material, a conductive agent, and a binder are mixed to prepare a positive electrode mixture, and the positive electrode mixture is dispersed in a solvent such as N-methyl-2-pyrrolidone to obtain a paste-like positive electrode mixture. A slurry is obtained. Subsequently, the positive electrode mixture slurry is applied to the positive electrode current collector 23A and the solvent is dried. Then, the positive electrode active material layer 23B is formed by compression molding using a roll press or the like, and the positive electrode 23 is manufactured. At this time, the thickness of the positive electrode active material layer 23B is set to 40 μm or more.

  Moreover, a negative electrode can be produced by the following method, for example. First, after preparing a negative electrode mixture by mixing a negative electrode active material containing at least one of silicon and tin as constituent elements, a conductive agent, and a binder, the negative electrode mixture was mixed with N-methyl-2. -Disperse in a solvent such as pyrrolidone to obtain a paste-like negative electrode mixture slurry. Next, the negative electrode mixture slurry is applied to the negative electrode current collector 24A, dried, and compression-molded to form a negative electrode active material layer 24B containing negative electrode active material particles made of the negative electrode active material described above. Get. At this time, the thickness of the negative electrode active material layer 24B is set to 40 μm or more.

  Next, a precursor solution containing an electrolytic solution, a polymer compound, and a mixed solvent is applied to each of the positive electrode 23 and the negative electrode 24, and the mixed solvent is volatilized to form the electrolyte layer 26. Next, the positive electrode lead 21 is attached to the positive electrode current collector 23A, and the negative electrode lead 22 is attached to the negative electrode current collector 24A. Subsequently, the positive electrode 23 and the negative electrode 24 on which the electrolyte layer 26 is formed are laminated through a separator 25 to form a laminated body, and then the laminated body is wound in the longitudinal direction, and the protective tape 27 is attached to the outermost peripheral portion. The wound electrode body 20 is formed by bonding. After that, for example, the wound electrode body 20 is sandwiched between the exterior members 30, and the outer edges of the exterior members 30 are brought into close contact by thermal fusion or the like and sealed. At that time, an adhesion film 31 is inserted between the positive electrode lead 21 and the negative electrode lead 22 and the exterior member 30. Thereby, the secondary battery shown in FIGS. 1 and 2 is completed.

  Further, this secondary battery may be manufactured as follows. First, the positive electrode 23 and the negative electrode 24 are prepared as described above, and after the positive electrode lead 21 and the negative electrode lead 22 are attached to the positive electrode 23 and the negative electrode 24, the positive electrode 23 and the negative electrode 24 are stacked and wound via the separator 25. Rotate and adhere the protective tape 27 to the outermost periphery to form a wound body that is a precursor of the wound electrode body 20. Next, the wound body is sandwiched between the exterior members 30, and the outer peripheral edge portion excluding one side is heat-sealed to form a bag shape, and is stored inside the exterior member 30. Subsequently, an electrolyte composition containing an electrolytic solution, a monomer that is a raw material of the polymer compound, and other materials such as a polymerization initiator or a polymerization inhibitor as necessary is prepared, and the interior of the exterior member 30 is prepared. After the injection, the opening of the exterior member 30 is heat-sealed and sealed. After that, if necessary, heat is applied to polymerize the monomer to form a polymer compound, thereby forming the gel electrolyte layer 26 and assembling the secondary battery shown in FIGS.

  In the secondary battery, when charged, for example, lithium ions are extracted from the positive electrode 23 and inserted in the negative electrode 24 through the electrolytic solution. On the other hand, when discharging is performed, for example, lithium ions are extracted from the negative electrode 24 and inserted into the positive electrode 24 through the electrolytic solution.

  Although the present invention has been described with reference to the embodiment, the present invention is not limited to the embodiment, and various modifications can be made. For example, in the above embodiment and the case where an electrolytic solution is used as the electrolyte, and the case where a gel electrolyte in which the electrolytic solution is held in a polymer compound is also described, other electrolytes are used. It may be. Other electrolytes include, for example, a mixture of an ion conductive ceramic such as ion conductive ceramics, ion conductive glass or ionic crystal and an electrolyte, or a mixture of another inorganic compound and an electrolyte. Or a mixture of these inorganic compounds and a gel electrolyte.

  In the above embodiment, a battery using lithium as an electrode reactant has been described. However, another alkali metal such as sodium (Na) or potassium (K), or an alkaline earth metal such as magnesium or calcium (Ca). The present invention can also be applied to the case of using other light metals such as aluminum.

  Further, in the above embodiment, the capacity of the negative electrode is a so-called lithium ion secondary battery represented by a capacity component due to insertion and extraction of lithium, or lithium metal is used for the negative electrode active material, and the capacity of the negative electrode is Although a so-called lithium metal secondary battery represented by a capacity component due to precipitation and dissolution has been described, the present invention makes the charge capacity of the negative electrode material capable of occluding and releasing lithium smaller than the charge capacity of the positive electrode. Thus, the present invention can be similarly applied to a secondary battery in which the capacity of the negative electrode includes a capacity component due to insertion and extraction of lithium and a capacity component due to precipitation and dissolution of lithium, and is expressed by the sum thereof. .

  Furthermore, in the above embodiment, the laminate type secondary battery has been specifically described, but it goes without saying that the present invention is not limited to the above shape. That is, the present invention can be applied to a cylindrical battery, a square battery, and the like. Further, the present invention is not limited to the secondary battery but can be similarly applied to other batteries such as a primary battery.

<Examples 1-1 to 1-10>
(Example 1-1)
First, 94 parts by mass of lithium-cobalt composite oxide (LiCoO ₂ ) as a positive electrode active material, 3 parts by mass of graphite as a conductive agent, and 3 parts by mass 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 liquid was uniformly applied on both surfaces of an aluminum foil having a thickness of 20 μm and dried to form a positive electrode active material layer having a thickness of 40 μm 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.

  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 N-methylpyrrolidone was added to obtain a negative electrode mixture coating solution. Next, the obtained negative electrode mixture coating solution 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 active material layer having a thickness of 40 μm 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.

  The electrolyte was ethylene carbonate (EC) / diethyl carbonate (DEC) / chloroethylene carbonate (CEC) = 39.5 / 60 / 0.5 in a ratio (mass ratio) of 86 g of a solvent and 14 g of lithium hexafluorophosphate. It was prepared by dissolving at a ratio of

  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 9 μm, and placed in a bag made of an aluminum laminate film. After 2 g of electrolyte solution was poured into this bag, the bag was heat-sealed to produce a laminate type battery. The capacity of this battery was 800 mAh.

  Table 1 shows the change in battery thickness as a coefficient of expansion (%) when the battery was charged at 800 mA in a 23 ° C. environment with 4.2 V as the upper limit for 3 hours and then stored at 90 ° C. for 4 hours. The expansion coefficient is a value calculated using the battery thickness before storage as the denominator and the thickness increased during storage as the numerator. In addition, Table 1 shows discharge capacity retention rates when charging at 800 mA at 23 ° C. with 4.2 V as the upper limit for 3 hours and then discharging at 800 mA with 3.0 V as the lower limit was repeated 300 times.

(Example 1-2)
A laminated battery was prepared in the same manner as in Example 1-1 except that the thickness of the active material layer was 45 μm. Since the electrode thickness was 45 μm, the battery capacity was 850 mAh. Table 1 shows the change in battery thickness as an expansion coefficient when the battery was charged at 850 mA at 23 ° C. and 4.2 V as the upper limit for 3 hours and then stored at 90 ° C. for 4 hours. In addition, Table 1 shows the discharge capacity retention ratio when charging at 850 mA for 3 hours with an upper limit of 4.2 V at 23 ° C. and repeating 300 times of discharge with 850 mA and a lower limit of 3.0 V for 300 times.

(Examples 1-3 to 1-5)
As shown in Table 1, a laminate type battery was prepared in the same manner as in Example 1-1 except that the amount of ethylene carbonate and the amount of diethyl carbonate were changed, and the physical properties of the battery were evaluated.

(Example 1-6)
A laminate type battery was prepared in the same manner as in Example 1-1 except that ethyl methyl carbonate (EMC) was added and the amount of diethyl carbonate (DEC) was reduced by that amount, and the physical properties of the battery were evaluated.

(Example 1-7)
A laminated battery was prepared in the same manner as in Example 1-1 except that vinylene carbonate (VC) was added and the amount of ethylene carbonate was reduced by that amount, and the physical properties of the battery were evaluated.

(Examples 1-8 to 1-10)
A laminated battery was prepared in the same manner as in Example 1-1 except that the amount of chloroethylene carbonate added was changed as shown in Table 1, and the amount of ethylene carbonate was increased or decreased accordingly, and the physical properties of the battery were evaluated.

(Comparative Example 1-1)
A laminated battery was prepared in the same manner as in Example 1-1 except that chloroethylene carbonate was not mixed and ethylene carbonate was increased by that amount, and the physical properties of the battery were evaluated.

(Comparative Example 1-2)
A laminate type battery was prepared in the same manner as in Example 1-1 except that fluoroethylene carbonate was used instead of chloroethylene carbonate, and the physical properties of the battery were evaluated.

(Comparative Example 1-3)
A laminate type battery was prepared in the same manner as in Example 1-1 except that vinylene carbonate was used instead of chloroethylene carbonate, and the physical properties of the battery were evaluated.

(Comparative Example 1-4)
A laminate type battery was prepared in the same manner as Comparative Example 1-3 except that the thickness of the active material layer was 35 μm. Since the thickness of the active material layer was 35 μm, the capacity of the battery was 700 mAh. Table 1 shows changes in battery thickness when the battery was charged at 700 mA at 23 ° C. and 4.2 V as the upper limit for 3 hours and then stored at 90 ° C. for 4 hours. In addition, Table 1 shows discharge capacity retention rates when charging at 700 mA and upper limit of 4.2 V for 3 hours in a 23 ° C. environment and then repeating discharge at 700 mA and lower limit of 3.0 V for 300 times.

(Comparative Example 1-5)
A laminate type battery was prepared in the same manner as in Example 1-1 except that the amount of chloroethylene carbonate added was 5%, and the amount of ethylene carbonate was reduced accordingly, and the physical properties of the battery were evaluated.

(Comparative Example 1-6)
A laminate type battery was prepared in the same manner as in Comparative Example 1-1 except that the thickness of the active material layer was set to 35 μm, and the physical properties of the battery were evaluated.

(Reference example)
A laminate type battery was prepared in the same manner as in Example 1-2 except that the thickness of the active material layer was set to 35 μm, and the physical properties of the battery were evaluated.

  Table 1 shows the results of evaluating the physical properties of the laminate type batteries produced in Examples 1-1 to 1-10, Comparative Examples 1-1 to 1-6, and Reference Example.

  As shown in Table 1, in Example 1-1 containing chloroethylene carbonate in the electrolytic solution, the expansion rate of the battery was lower than that of Comparative Example 1-1 not containing, and the discharge capacity was maintained after 300 cycles. The rate has improved. In addition, Example 1-2 containing chloroethylene carbonate in the electrolytic solution and increasing the thickness of the active material layer also decreased the expansion coefficient while maintaining good cycle characteristics as in Example 1-1. Furthermore, the battery capacity increased. On the other hand, even if fluoroethylene carbonate was contained in the electrolyte, Comparative Example 1-2 that did not contain chloroethylene carbonate had a high expansion coefficient.

  In Comparative Example 1-1, in which the thickness of the active material layer was larger than that of Comparative Example 1-6, the battery capacity increased, but the discharge capacity retention rate after 300 cycles decreased. In addition, in both Comparative Example 1-6 and Comparative Example 1-1, the expansion coefficient of the battery remained high. On the other hand, the reference example containing chloroethylene carbonate in the electrolyte solution has the same active material layer thickness and the battery while maintaining good cycle characteristics as compared with Comparative Example 1-6 that does not contain chloroethylene carbonate in the electrolyte solution. The expansion coefficient of was decreased. However, since the reference example had a thickness of the active material layer of 40 μm or less, the battery capacity was low. That is, by containing chloroethylene carbonate in the electrolytic solution, the expansion of the battery was suppressed, and at the same time, a good discharge capacity retention rate after 300 cycles could be obtained even when the active material layer was thickened.

  Further, as can be seen from the comparison of Examples 1-1 and 1-3 to 1-5, the expansion coefficient of the battery tended to decrease as the amount of diethyl carbonate relative to the amount of ethylene carbonate increased.

  In Example 1-6 in which the amount of diethyl carbonate was reduced and the amount of ethyl methyl carbonate was increased accordingly, the expansion rate was slightly increased as compared with Example 1-1 which did not contain ethyl methyl carbonate, but the cycle characteristics were improved.

  In Example 1-7 further containing vinylene carbonate in addition to chloroethylene carbonate, the expansion coefficient was lower than that in Example 1-1, and the cycle characteristics were also improved. On the other hand, even if vinylene carbonate was contained, Comparative Examples 1-3 and 1-4 that did not contain chloroethylene carbonate had a high expansion coefficient, and the cycle characteristics were not improved.

  From the results of Examples 1-8, 1-1, 1-9, 1-10, and Comparative Example 1-5, in Comparative Example 1-5 in which the content of chloroethylene carbonate is 5.0 mass%, the expansion The rate increased. From this, it can be said that in a laminate type battery, the content of chloroethylene carbonate is preferably less than 5.0% by mass.

<Examples 2-1 to 2-10>
(Example 2-1)
A laminate type battery was prepared in the same manner as in Example 1-1 except that 1.0% by mass of polyvinyl formal was swollen in the electrolyte solution to obtain a gel electrolyte solution, and diethyl carbonate was reduced accordingly, and the physical properties of the battery were evaluated. did.

(Example 2-2)
A laminate type battery was prepared in the same manner as in Example 2-1, except that the thickness of the active material layer was 45 μm. Since the electrode thickness was 45 μm, the battery capacity was 850 mAh. Table 2 shows the change in battery thickness as an expansion coefficient when the battery was charged at 850 mA at 23 ° C. and 4.2 V as the upper limit for 3 hours and then stored at 90 ° C. for 4 hours. In addition, Table 2 shows discharge capacity retention ratios when charging was repeated for 3 hours at 700 mA at 23 ° C. with 4.2 V as the upper limit and then repeated 300 times at 850 mA with 3.0 V as the lower limit.

(Examples 2-3 to 2-5)
As shown in Table 2, a laminate type battery was prepared in the same manner as in Example 2-1 except that the amount of ethylene carbonate and the amount of diethyl carbonate were changed, and the physical properties of the battery were evaluated.

(Example 2-6)
A laminate type battery was prepared in the same manner as in Example 2-1, except that ethyl methyl carbonate (EMC) was added and the amount of diethyl carbonate (DEC) was reduced by that amount, and the physical properties of the battery were evaluated.

(Example 2-7)
A laminate type battery was prepared in the same manner as in Example 2-1, except that vinylene carbonate (VC) was added and the amount of ethylene carbonate was reduced by that amount, and the physical properties of the battery were evaluated.

(Examples 2-8 to 2-10)
A laminated battery was prepared in the same manner as in Example 1-2, except that the amount of chloroethylene carbonate added was changed as shown in Table 2, and the amount of ethylene carbonate was increased or decreased accordingly, and the physical properties of the battery were evaluated.

(Comparative Example 2-1)
A laminate type battery was prepared in the same manner as in Example 2-1, except that chloroethylene carbonate was not mixed and ethylene carbonate was increased by that amount, and the physical properties of the battery were evaluated.

(Comparative Example 2-2)
A laminate type battery was prepared in the same manner as in Example 2-1, except that fluoroethylene carbonate was used instead of chloroethylene carbonate, and the physical properties of the battery were evaluated.

(Comparative Example 2-3)
A laminated battery was prepared in the same manner as in Example 2-1, except that vinylene carbonate was used instead of chloroethylene carbonate, and the physical properties of the battery were evaluated.

(Comparative Example 2-4)
A laminate type battery was prepared in the same manner as Comparative Example 2-3 except that the thickness of the active material layer was 35 μm. Since the thickness of the active material layer was 35 μm, the capacity of the battery was 700 mAh. Table 2 shows changes in battery thickness when this battery was charged at 700 mA at 23 ° C. and 4.2 V as the upper limit for 3 hours and then stored at 90 ° C. for 4 hours. In addition, Table 2 shows discharge capacity retention rates when charging at 700 mA and the upper limit of 4.2 V for 3 hours under a 23 ° C. environment and then repeating discharge at 700 mA and the lower limit of 3.0 V for 300 times.

(Comparative Example 2-5)
A laminate type battery was prepared in the same manner as in Example 1-1 except that the amount of chloroethylene carbonate added was 5.0% by mass and ethylene carbonate was reduced by that amount, and the physical properties of the battery were evaluated.

  Table 2 shows the results of evaluating the physical properties of the laminate type batteries produced in Examples 2-1 to 2-10 and Comparative Examples 2-1 to 2-5.

  As shown in Table 2, Example 2-1 containing chloroethylene carbonate in the electrolytic solution had a lower battery expansion rate than that of Comparative Example 2-1 not containing, and maintained the discharge capacity after 300 cycles. The rate has improved. In addition, although the effect which suppresses the expansion | swelling at the time of high-temperature storage was reduced a little in Example 2-1 compared with Example 1-1 which does not contain polyvinyl formal in electrolyte solution, the influence was small.

  In Example 2-2, which contained chloroethylene carbonate in the electrolytic solution and increased the thickness of the active material layer, the expansion coefficient decreased and the cycle characteristics improved as in Example 2-1. On the other hand, even if fluoroethylene carbonate was contained in the electrolyte, Comparative Example 2-2 that did not contain chloroethylene carbonate had a high expansion rate.

  Moreover, as can be seen from the comparison between Examples 2-1 and 2-3 to 2-5, the expansion coefficient of the battery tended to decrease as the amount of diethyl carbonate with respect to the amount of ethylene carbonate increased.

  In Example 2-6 in which the amount of diethyl carbonate was reduced and the amount of ethyl methyl carbonate was increased accordingly, the expansion rate was slightly increased as compared with Example 2-1 not containing ethyl methyl carbonate, but the cycle characteristics were improved.

  In Example 2-7, which further contained vinylene carbonate in addition to chloroethylene carbonate, the expansion coefficient was lower than that in Example 2-1, and the cycle characteristics were also improved. On the other hand, even if it contained vinylene carbonate, Comparative Examples 2-3 and 2-4 which did not contain chloroethylene carbonate had a high expansion coefficient, and the cycle characteristics were not improved.

  From the results of Examples 2-8, 2-1, 2-9, 2-10, and Comparative Example 2-5, in Comparative Example 2-5 in which the content of chloroethylene carbonate is 5.0% by mass, The rate increased. From this, it can be said that in a laminate type battery, the content of chloroethylene carbonate is preferably less than 5.0% by mass.

<Examples 3-1 to 3-10>
(Example 3-1)
A laminate type battery was prepared in the same manner as in Example 1-1 except that 1.0% by mass of polyacrylic acid ester was swollen in the electrolyte solution to obtain a gel electrolyte solution, and diethyl carbonate was reduced by that amount. Evaluated.

(Example 3-2)
A laminated battery was prepared in the same manner as in Example 3-1, except that the thickness of the active material layer was 45 μm. Since the electrode thickness was 45 μm, the battery capacity was 850 mAh. Table 3 shows the change in battery thickness as an expansion coefficient when the battery was charged at 850 mA at 23 ° C. and 4.2 V as the upper limit for 3 hours and then stored at 90 ° C. for 4 hours. In addition, Table 3 shows discharge capacity retention rates when charging was repeated for 3 hours at 700 mA at 23 ° C. with 4.2 V as the upper limit and then repeated 300 times at 850 mA with 3.0 V as the lower limit.

(Examples 3-3 to 3-5)
As shown in Table 3, a laminate type battery was prepared in the same manner as in Example 3-1, except that the amount of ethylene carbonate and the amount of diethyl carbonate were changed, and the physical properties of the battery were evaluated.

(Example 3-6)
A laminate type battery was prepared in the same manner as in Example 3-1, except that ethyl methyl carbonate (EMC) was added and the amount of diethyl carbonate (DEC) was reduced by that amount, and the physical properties of the battery were evaluated.

(Example 3-7)
A laminate type battery was prepared in the same manner as in Example 3-1, except that vinylene carbonate (VC) was added and the amount of ethylene carbonate was reduced by that amount, and the physical properties of the battery were evaluated.

(Examples 3-8 to 3-10)
A laminated battery was prepared in the same manner as in Example 3-1, except that the amount of chloroethylene carbonate added was changed as shown in Table 3, and the amount of ethylene carbonate was increased or decreased accordingly, and the physical properties of the battery were evaluated.

(Comparative Example 3-1)
A laminate type battery was prepared in the same manner as in Example 3-1 except that chloroethylene carbonate was not mixed and ethylene carbonate was increased by that amount, and the physical properties of the battery were evaluated.

(Comparative Example 3-2)
A laminate type battery was prepared in the same manner as in Example 3-1, except that fluoroethylene carbonate was used instead of chloroethylene carbonate, and the physical properties of the battery were evaluated.

(Comparative Example 3-3)
A laminate type battery was prepared in the same manner as in Example 3-1, except that vinylene carbonate was used instead of chloroethylene carbonate, and the physical properties of the battery were evaluated.

(Comparative Example 3-4)
A laminate type battery was prepared in the same manner as Comparative Example 3-3 except that the thickness of the active material layer was set to 35 μm. Since the thickness of the active material layer was 35 μm, the capacity of the battery was 700 mAh. Table 3 shows changes in battery thickness when the battery was charged at 700 mA at 23 ° C. and 4.2 V as the upper limit for 3 hours and then stored at 90 ° C. for 4 hours. In addition, Table 3 shows discharge capacity retention rates when charging at 700 mA and upper limit of 4.2 V for 3 hours in a 23 ° C. environment and then repeating discharge at 700 mA and lower limit of 3.0 V for 300 times.

(Comparative Example 3-5)
A laminate type battery was prepared in the same manner as in Example 3-1, except that the amount of chloroethylene carbonate added was 5.0% by mass and the amount of ethylene carbonate was reduced by that amount, and the physical properties of the battery were evaluated.

  Table 3 shows the results of evaluating the physical properties of the laminate type batteries prepared in Examples 3-1 to 3-10 and Comparative Examples 3-1 to 3-5.

  As shown in Table 3, Example 3-1 containing chloroethylene carbonate in the electrolytic solution had a lower battery expansion rate than that of Comparative Example 3-1, which did not contain, and maintained discharge capacity after 300 cycles. The rate has improved. In Example 3-1, the effect of suppressing expansion during high-temperature storage was slightly reduced compared with Example 1-1 in which the polyacrylic acid ester was not included in the electrolytic solution, but the effect was small.

  In Example 3-2 which contained chloroethylene carbonate in the electrolytic solution and increased the thickness of the active material layer, the expansion coefficient was lowered and the cycle characteristics were improved as in Example 3-1. On the other hand, even if fluoroethylene carbonate was contained in the electrolytic solution, Comparative Example 3-2 not containing chloroethylene carbonate had a high expansion rate.

  Moreover, as can be seen from the comparison between Examples 3-1 and 3-3 to 3-5, the expansion coefficient of the battery tended to decrease as the amount of diethyl carbonate relative to the amount of ethylene carbonate increased.

  In Example 3-6 in which the amount of diethyl carbonate was reduced and the amount of ethyl methyl carbonate was increased accordingly, the expansion rate was slightly increased as compared with Example 3-1, which did not contain ethyl methyl carbonate, but the cycle characteristics were improved.

  In Example 3-7, which further contained vinylene carbonate in addition to chloroethylene carbonate, the expansion coefficient was lower than that in Example 3-1, and the cycle characteristics were also improved. On the other hand, Comparative Examples 3-3 and 3-4, which contain vinylene carbonate but do not contain chloroethylene carbonate, have a high expansion coefficient and do not improve cycle characteristics.

  From the results of Examples 3-8, 3-1, 3-9, 3-10, and Comparative Example 3-5, in Comparative Example 3-5 in which the content of chloroethylene carbonate is 5.0% by mass, The rate increased. From this, it can be said that in a laminate type battery, the content of chloroethylene carbonate is preferably less than 5.0% by mass.

<Examples 4-1 to 4-10>
(Example 4-1)
A laminate type battery was prepared in the same manner as in Example 1-1 except that a separator having a thickness of 7 μm and a separator coated with 2 μm of polyvinylidene fluoride on both sides was used, and the physical properties of the battery were evaluated. At this time, the mass ratio of the electrolytic solution to polyvinylidene fluoride was 20: 1.

(Example 4-2)
A laminate type battery was prepared in the same manner as in Example 4-1, except that the thickness of the active material layer was 45 μm. Since the electrode thickness was 45 μm, the battery capacity was 850 mAh. Table 4 shows the change in battery thickness when the battery was charged at 850 mA in a 23 ° C. environment and 4.2 V as an upper limit for 3 hours and then stored at 90 ° C. for 4 hours as an expansion coefficient. Table 4 shows the discharge capacity retention rate when the discharge was repeated for 300 hours at 700 mA at 23 ° C. with 4.2 V as the upper limit and then repeated 300 times at 850 mA with 3.0 V as the lower limit.

(Examples 4-3 to 4-5)
As shown in Table 4, a laminate type battery was prepared in the same manner as in Example 4-1, except that the amount of ethylene carbonate and the amount of diethyl carbonate were changed, and the physical properties of the battery were evaluated.

(Example 4-6)
A laminate type battery was prepared in the same manner as in Example 4-1, except that ethyl methyl carbonate (EMC) was added and the amount of diethyl carbonate (DEC) was reduced by that amount, and the physical properties of the battery were evaluated.

(Example 4-7)
A laminate type battery was prepared in the same manner as in Example 4-1, except that vinylene carbonate (VC) was added and the amount of ethylene carbonate was reduced by that amount, and the physical properties of the battery were evaluated.

(Examples 4-8 to 4-10)
A laminate type battery was prepared in the same manner as in Example 4-1, except that the amount of chloroethylene carbonate added was changed as shown in Table 4 and the amount of ethylene carbonate was increased or decreased accordingly, and the physical properties of the battery were evaluated.

(Comparative Example 4-1)
A laminate type battery was prepared in the same manner as in Example 4-1, except that chloroethylene carbonate was not mixed and ethylene carbonate was increased by that amount, and the physical properties of the battery were evaluated.

(Comparative Example 4-2)
A laminate type battery was prepared in the same manner as in Example 4-1, except that fluoroethylene carbonate was used instead of chloroethylene carbonate, and the physical properties of the battery were evaluated.

(Comparative Example 4-3)
A laminate type battery was prepared in the same manner as in Example 4-1, except that vinylene carbonate was used instead of chloroethylene carbonate, and the physical properties of the battery were evaluated.

(Comparative Example 4-4)
A laminate type battery was prepared in the same manner as Comparative Example 4-3 except that the thickness of the active material layer was 35 μm. Since the thickness of the active material layer was 35 μm, the capacity of the battery was 700 mAh. Table 4 shows changes in battery thickness when the battery was charged at 700 mA at 23 ° C. and 4.2 V as the upper limit for 3 hours and then stored at 90 ° C. for 4 hours. Table 4 shows the discharge capacity retention rate when charging at 700 mA and the upper limit of 4.2 V for 3 hours under a 23 ° C. environment and then repeating the discharge at 700 mA and the lower limit of 3.0 V for 300 times.

(Comparative Example 4-5)
A laminate type battery was prepared in the same manner as in Example 4-1, except that the amount of chloroethylene carbonate added was 5.0% by mass and the amount of ethylene carbonate was reduced by that amount, and the physical properties of the battery were evaluated.

  Table 4 shows the results of evaluating the physical properties of the laminate type batteries produced in Examples 4-1 to 4-10 and Comparative Examples 4-1 to 4-5.

  As shown in Table 4, in Example 4-1, which contains chloroethylene carbonate in the electrolytic solution, the expansion coefficient of the battery is lower than that of Comparative Example 4-1, which does not contain, and the discharge capacity is maintained after 300 cycles. The rate has improved. In addition, Example 4-1 improved the effect which suppresses the expansion | swelling at the time of high temperature storage compared with Example 1-1 which does not contain polyvinylidene fluoride. From this, in addition to containing chloroethylene carbonate in electrolyte solution, it turned out that the expansion suppression effect of a battery can further be improved by using a polyvinylidene fluoride as a high molecular compound.

  In Example 4-2, which contained chloroethylene carbonate in the electrolytic solution and increased the thickness of the active material layer, the expansion coefficient decreased and the cycle characteristics improved as in Example 4-1. On the other hand, even if fluoroethylene carbonate was contained in the electrolyte, Comparative Example 4-2 that did not contain chloroethylene carbonate had a high expansion rate.

  Moreover, as can be seen from the comparison between Examples 4-1 and 4-3 to 4-5, the expansion coefficient of the battery tended to decrease as the amount of diethyl carbonate relative to the amount of ethylene carbonate increased.

  In Example 4-6 in which the amount of diethyl carbonate was reduced and the amount of ethyl methyl carbonate was increased correspondingly, the expansion rate was slightly increased, but the cycle characteristics were improved as compared with Example 4-1 not containing ethyl methyl carbonate.

  In Example 4-7, which further contained vinylene carbonate in addition to chloroethylene carbonate, the expansion coefficient was reduced and the cycle characteristics were similar to those in Example 4-1. On the other hand, even if it contained vinylene carbonate, Comparative Examples 4-3 and 4-4 which did not contain chloroethylene carbonate had a high expansion coefficient, and the cycle characteristics were not improved.

  From the results of Examples 4-8, 4-1, 4-9, 4-10, and Comparative Example 4-5, in Comparative Example 4-5 in which the content of chloroethylene carbonate was 5.0% by mass, expansion was observed. The rate increased. From this, it can be said that in a laminate type battery, the content of chloroethylene carbonate is preferably less than 5.0% by mass.

  While the present invention has been described with reference to the embodiments, it is needless to say that the present invention is not limited to the above embodiments and can be variously modified.

It is a disassembled perspective view showing the structure of the nonaqueous electrolyte secondary battery which concerns on one embodiment of this invention. It is sectional drawing showing the structure along the II line of the winding electrode body shown in FIG.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 20 ... Winding electrode body, 23 ... Positive electrode, 23A ... Positive electrode collector, 23B ... Positive electrode active material layer, 24 ... Negative electrode, 24A ... Negative electrode collector, 24B ... Negative electrode active material layer, 25 ... Separator, 21 ... Positive electrode Lead, 22 ... negative electrode lead, 26 ... electrolyte layer, 27 ... protective tape, 30 ... exterior member, 31 ... adhesion film.

Claims (10)

A non-aqueous electrolyte secondary battery comprising an electrode body in which a positive electrode and a negative electrode having a current collector and an active material layer carried on the current collector are stacked via a separator, and an electrolyte. And
The electrolytic solution contains a compound represented by the following formula (1),
A non-aqueous electrolyte secondary battery, wherein the active material layer has a thickness of 40 μm or more per side.

[In the above formula (1), R1 to R4 each independently represent a substituent selected from the group consisting of a hydrogen group, a halogen group and an alkyl group, and they may be the same or different. However, at least one of R1 to R4 is a chlorine group. ] The electrode body and the electrolytic solution are accommodated in an exterior member made of a laminate film,
2. The nonaqueous electrolyte secondary battery according to claim 1, wherein the content of the compound represented by the formula (1) in the electrolytic solution is less than 5 mass% based on the solvent.   The non-aqueous electrolyte secondary battery according to claim 1, wherein the electrolyte contains a high dielectric constant solvent having a relative dielectric constant of 30 or more and a low viscosity solvent having a viscosity of 1 mPa · s or less.   The non-aqueous electrolyte secondary battery according to claim 1, wherein the electrolyte contains a carbonic acid ester having a carbon-carbon multiple bond.   The nonaqueous electrolyte secondary battery according to claim 1, comprising a polymer compound that swells with the electrolyte.   The non-aqueous electrolyte secondary battery according to claim 5, wherein the polymer compound is polyvinylidene fluoride. A non-aqueous electrolyte characterized by containing a compound represented by the following formula (1).

[In the above formula (1), R1 to R4 each independently represent a substituent selected from the group consisting of a hydrogen group, a halogen group and an alkyl group, and they may be the same or different. However, at least one of R1 to R4 is a chlorine group. ]   The nonaqueous electrolytic solution according to claim 7, wherein the content of the compound represented by the formula (1) in the electrolytic solution is less than 5% by mass based on the solvent.   The non-aqueous electrolyte according to claim 7, wherein the electrolyte contains a high dielectric constant solvent having a relative dielectric constant of 30 or more and a low viscosity solvent having a viscosity of 1 mPa · s or less.   The non-aqueous electrolyte according to claim 7, wherein the electrolyte contains a carbonic acid ester having a carbon-carbon multiple bond.

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