JP2010262905A - Nonaqueous electrolytic solution battery - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a nonaqueous electrolytic solution battery of which swelling in the first time discharge can be suppressed and an electric discharge capacity maintenance rate during repeated charge and discharge can be improved. <P>SOLUTION: The nonaqueous electrolytic solution battery is equipped with a nonaqueous electrolytic solution together with a positive electrode and a negative electrode, and the nonaqueous electrolytic solution contains straight chain carbonic ester having a hydrocarbon group of a carbon number of 13 to 20 and a halogenated cyclic carbonic ester of a carbon number of 5 or 6. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a non-aqueous electrolyte composition that maintains excellent charge / discharge efficiency while suppressing battery expansion during high-temperature storage, and a non-aqueous electrolyte battery using the same.

  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 addition, a laminate battery using an aluminum laminate film for the exterior can increase the amount of active material and has a high energy density because the exterior is thin and 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.

However, as the capacity of the battery has increased, the gap between the battery active materials has become smaller, making it difficult to sufficiently impregnate the electrode with the electrolytic solution. If the electrode is not impregnated with the electrolytic solution, the battery performance is greatly deteriorated, and there is a problem that the discharge capacity maintenance rate during repeated charging and discharging is reduced. In particular, when chain carbonate having 5 or 6 carbon atoms is used as an electrolyte solvent for suppressing swelling during high temperature storage, the viscosity of the electrolyte is increased, making it difficult to impregnate the electrode.
On the other hand, it has been reported that by adding a chain carbonate having a hydrocarbon group having 13 to 20 carbon atoms, the discharge capacity retention rate during repeated charging and discharging is improved (Patent Document 1).

JP 2007-207482 A

However, the effect was insufficient only by adding a chain carbonate having a hydrocarbon group having 13 to 20 carbon atoms.
The present invention has been made in view of such problems, and a non-aqueous electrolyte composition capable of suppressing swelling during initial charge and further improving the discharge capacity maintenance rate during repeated charge and discharge and the same are used. The object is to provide a non-aqueous electrolyte battery.

  In the present invention, by combining a halogenated cyclic carbonate together with a chain carbonate having a hydrocarbon group having 13 to 20 carbon atoms, swelling during initial charge can be suppressed, and discharge capacity maintenance rate during repeated charge and discharge I found that I could improve more.

That is, the present invention provides the following non-aqueous electrolyte battery and non-aqueous electrolyte composition.
[1] A nonaqueous electrolyte battery comprising a nonaqueous electrolyte together with a positive electrode and a negative electrode,
The non-aqueous electrolyte battery in which the non-aqueous electrolyte contains a chain carbonate having a hydrocarbon group having 13 to 20 carbon atoms, a chain carbonate having 5 or 6 carbon atoms, and a halogenated cyclic carbonate.
[2] A non-aqueous electrolyte composition containing a chain carbonate having a hydrocarbon group having 13 to 20 carbon atoms, a chain carbonate having 5 or 6 carbon atoms, and a halogenated cyclic carbonate.

  According to the present invention, swelling at the time of initial charge can be suppressed, and the discharge capacity maintenance rate at repeated charge / discharge can be further improved.

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.

  FIG. 1 schematically shows the configuration of a laminated nonaqueous electrolyte secondary 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 each made of a metal material such as aluminum, copper, nickel, and 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, and 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 positive electrode active material layer 23B is preferably applied and dried to 14 to 30 mg / cm ² per side, and the negative electrode active material layer 24B is applied and dried per side. It is preferable to set it as 7-15 mg / cm < ² >.

  The thickness per one side of the positive electrode active material layer 23B and the negative electrode active material layer 24B 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, and 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, and a conductive agent such as a carbon material and polyvinylidene fluoride as necessary. 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), and 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 positive electrode materials 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, for example, a metal material such as copper, nickel, and stainless steel.

  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 and 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.

  As the negative electrode material, in addition to the above-described carbon material, a material containing an element that forms an alloy with lithium, such as silicon, tin, and a compound thereof, magnesium, aluminum, and germanium 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. The separator 25 is impregnated with, for example, a nonaqueous electrolytic solution that is a liquid electrolyte.

(Nonaqueous electrolyte)
The non-aqueous electrolyte composition of the present invention contains a chain carbonate having a hydrocarbon group having 13 to 20 carbon atoms, a chain carbonate having 5 or 6 carbon atoms, and a halogenated cyclic carbonate. This is considered to suppress swelling at the time of first charge and improve the discharge capacity maintenance rate at repeated charge / discharge.

  As the chain carbonate having a hydrocarbon group having 13 to 20 carbon atoms, a compound of the following formula (A) is preferable. It is considered that the chain carbonic acid ester having a hydrocarbon group having 13 to 20 carbon atoms forms a protective film on the electrode and suppresses decomposition of the solvent, thereby suppressing swelling.

_{R1: -C n H 2n + 1} -m F m (13 ≦ n ≦ 20,0 ≦ m ≦ 2n)
_{R2: -C n H 2n + 1} -m F m (1 ≦ n ≦ 20,0 ≦ m ≦ 2n)
In R1, the number of carbon atoms is required to be 13-20, but 13-14 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.

Specific examples of the chain carbonate having a hydrocarbon group having 13 to 20 carbon atoms include ditridecyl carbonate [(C ₁₃ H ₂₇ O) ₂ C═O], ditetradecyl carbonate [(C ₁₄ H ₂₉ O ) ₂ C═O], dieicosyl carbonate [(C ₂₀ H ₄₁ O) ₂ C═O], methyl tetradecyl carbonate [(CH ₃ ) (C ₁₄ H ₂₉ O) C═O], methyl tridecyl carbonate Etc. Of these, ditetradecyl carbonate is preferred from the viewpoint of permeability. In addition, these may be used individually by 1 type and may be used in mixture of multiple types.

  The content of the chain carbonate having a hydrocarbon group having 13 to 20 carbon atoms in the nonaqueous electrolytic solution is preferably 0.1 to 1.0% by mass, and more preferably 0.1 to 0.5% by mass. . It is because a higher effect is acquired by setting it as this range.

  Examples of the chain carbonate having 5 or 6 carbon atoms include diethyl carbonate (DEC), methyl propyl carbonate (MPC), butyl methyl carbonate (BMC), and ethyl propyl carbonate. Of these, diethyl carbonate is preferred from the viewpoints of low reactivity and low viscosity. These may be used alone or in combination.

  10-70 mass% is preferable, and, as for content of a C5-C6 linear carbonate in a non-aqueous electrolyte, 20-60 mass% is more preferable. It is because a higher effect is acquired by setting it as this range.

Preferable examples of the halogenated cyclic carbonate include fluorinated cyclic carbonate and chlorinated cyclic carbonate.
Examples of the fluorinated cyclic carbonate include 4-fluoro-1,3-dioxolan-2-one (fluoroethylene carbonate) (FEC) represented by formula (1) and trans-4,5-difluoro- represented by formula (2). Examples thereof include fluoro-1,3-dioxolan-2-one (difluoroethylene carbonate) (DFEC), trifluoropropylene carbonate represented by the formula (3), and the like. Of these, fluoroethylene carbonate is preferred from the viewpoint of cycle characteristics. In addition, these may be used individually by 1 type and may be used in mixture of multiple types.

  Examples of the chlorinated cyclic carbonate include 4-chloro-1,3-dioxolan-2-one (chloroethylene carbonate) (ClEC) represented by formula (4), trichloropropylene carbonate represented by formula (5), and the like. It is done. Of these, chloroethylene carbonate is preferred from the viewpoint of high reactivity. In addition, these may be used individually by 1 type and may be used in mixture of multiple types.

  0.5-2 mass% is preferable and, as for content of the halogenated cyclic carbonate in a non-aqueous electrolyte, 0.7-1.5 mass% is more preferable. It is because a higher effect is acquired by setting it as this range.

The non-aqueous electrolyte in the present invention preferably further contains a boron-containing lithium salt. This is because the cycle characteristics are improved.
Examples of the boron-containing lithium salt include lithium tetrafluoroborate (LiBF ₄ ), lithium oxalatodifluoroborate (LiFOB), bis [oxolato-O, O ′] lithium borate [LiB (C ₂ O ₄ ) ₂ ]. Etc. Of these, lithium tetrafluoroborate is preferable from the viewpoint of suppressing swelling during high-temperature storage. In addition, these may be used individually by 1 type, and may mix and use multiple types.

  0.05-1.0 mass% is preferable and, as for content of the boron containing lithium salt in a non-aqueous electrolyte, 0.1-0.5 mass% is more preferable. It is because a higher effect is acquired by setting it as this range.

  The nonaqueous electrolytic solution of the present invention further contains a solvent and an electrolyte salt dissolved in the solvent. The solvent used for the non-aqueous electrolyte 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 nonaqueous 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 cyclic carbamic acid esters 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 non-aqueous electrolyte is preferably used by mixing a low-viscosity solvent having a viscosity of 1 mPa · s or less with the above-mentioned 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 and ethyl methyl carbonate, methyl acetate, ethyl acetate, methyl propionate, ethyl propionate, methyl butyrate, methyl isobutyrate, methyl trimethyl acetate, and ethyl trimethyl acetate. Chain carboxylic acid esters, chain amides such as N, N-dimethylacetamide, chain carbamic acid esters such as methyl N, N-diethylcarbamate and ethyl N, N-diethylcarbamate, and 1,2-dimethoxy And ethers such as ethane, tetrahydrofuran, tetrahydropyran and 1,3-dioxolane. These low-viscosity solvents may be used alone or in combination of two or more.

As the electrolyte salt, e.g., lithium hexafluorophosphate (LiPF _6), lithium hexafluoroarsenate (LiAsF _6), lithium hexafluoro antimonate (LiSbF _6), lithium perchlorate (LiClO ₄₎ and four Inorganic lithium salts such as lithium chloroaluminate (LiAlCl ₄ ), as well as lithium trifluoromethanesulfonate (CF ₃ SO ₃ Li), lithium bis (trifluoromethanesulfone) imide [(CF ₃ SO ₂ ) ₂ NLi], lithium bis ( Examples include lithium salts of perfluoroalkanesulfonic acid derivatives such as pentafluoroethanesulfone) imide [(C ₂ F ₅ SO ₂ ) ₂ NLi] and lithium tris (trifluoromethanesulfone) methide [(CF ₃ SO ₂ ) ₃ CLi]. It is done. One electrolyte salt may be used alone, or a plurality of electrolyte salts may be mixed and used. The content of the electrolyte salt in the nonaqueous electrolytic solution is preferably 6 to 25% by mass.

(Polymer compound)
The battery of this invention is good also as a gel form by including the high molecular compound used as the holding body which swells with a non-aqueous electrolyte and hold | maintains a non-aqueous electrolyte. This is because by including a polymer compound that swells with a non-aqueous electrolyte, high ionic conductivity can be obtained, excellent charge / discharge efficiency can be obtained, and battery leakage can be prevented. When the polymer compound is added to the non-aqueous electrolyte and used, the content of the polymer compound in the non-aqueous electrolyte is preferably in the range of 0.1% by mass to 2% by mass. Further, when a polymer compound such as polyvinylidene fluoride is applied on both sides of the separator, the mass ratio of the non-aqueous electrolyte 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 an ether polymer compound such as polyvinyl formal [formula (6)], polyethylene oxide and a crosslinked product containing polyethylene oxide, and an ester polymer compound such as polymethacrylate [formula (7)]. , An acrylate polymer compound, and polyvinylidene fluoride [formula (8)], and a vinylidene fluoride polymer such as 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 (6) to (8), s, t, and u are each an integer of 100 to 10,000, R is C _x H _{2x + 1} O _y (x is an integer of 1 to 8, y is an integer of 0 to 4) , Y is x-1 or less).

(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 a nonaqueous 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 edge portions of the exterior members 30 are in close contact with each other 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 via the separator 25 and wound. 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 except for one side is heat-sealed to form a bag shape, and is stored inside the exterior member 30. Subsequently, an electrolyte composition including a non-aqueous electrolyte, 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. After injection into the interior, 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 released from the positive electrode 23 and inserted in the negative electrode 24 through the nonaqueous electrolytic solution. On the other hand, when discharging is performed, for example, lithium ions are released from the negative electrode 24 and inserted into the positive electrode 24 through the nonaqueous 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 a non-aqueous electrolyte is used as an electrolyte, a case where a gel electrolyte in which a non-aqueous electrolyte is held in a polymer compound is also described is described. An electrolyte may be used. Other electrolytes include, for example, a mixture of an ion conductive inorganic compound such as ion conductive ceramics, ion conductive glass and ionic crystal and a non-aqueous electrolyte, or another inorganic compound and a non-aqueous electrolyte. The thing which mixed and those which mixed these inorganic compounds and gel electrolyte are mentioned.

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

  Furthermore, in the above embodiment, the capacity of the negative electrode is expressed by a capacity component due to insertion and extraction of lithium, or a so-called lithium ion secondary battery, 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, and can be similarly applied to other batteries such as a primary battery.

<Example 1-1>
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 surfaces 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 with a width of 30 mm and a length of 250 mm to produce a positive electrode.
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 with a width of 30 mm and a length of 250 mm to prepare a negative electrode. The electrolyte is ethylene carbonate: ethyl methyl carbonate: diethyl carbonate: lithium hexafluorophosphate: fluoroethylene carbonate: ditetradecyl carbonate = 33: 17: 34: 14.5: 1: 0.5 (weight ratio) Mixed.
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 12 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.

<Evaluation>
Expansion rate at first charge:
Table 1 shows the change in battery thickness when the prepared battery was charged at 800 mA in a 23 ° C. environment and 4.2 V as the upper limit for 3 hours as the expansion rate at the first charge. The expansion coefficient is a value calculated using the battery thickness before charging as the denominator and the thickness increased during charging as the numerator.
Discharge capacity maintenance rate after 300 cycles:
Table 1 shows the change in discharge capacity when the battery was charged for 3 hours at a maximum of 4.2V at 800mA in a 23 ° C environment, then paused for 10 minutes and discharged until reaching 3.0V at 800mA. Show.
Expansion rate when stored at 90 ° C for 4 hours:
Table 1 shows the change in battery thickness when stored at 90 ° C for 4 hours after charging it for 3 hours at 800mA at 23 ° C and 800mA at 23 ° C. Show. 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.

<Examples 1-2 and 1-3>
A laminate type battery was prepared in the same manner as in Example 1-1 except that the concentration of ditetradecyl carbonate in the electrolytic solution was set as Table 1, and diethyl carbonate was increased or decreased accordingly.

<Examples 1-4 to 1-6>
A laminate type battery was prepared in the same manner as in Example 1-1 except that the chain carbonate having a hydrocarbon group having 13 to 20 carbon atoms was used as the compound shown in Table 1.

<Examples 1-7 and 1-8>
A laminated battery was prepared in the same manner as in Example 1-1 except that the halogenated cyclic carbonate was changed to the compound shown in Table 1.

<Example 1-9>
A laminated battery was prepared in the same manner as in Example 1-1 except that the boron-containing lithium salt shown in Table 1 was added and the amount of lithium hexafluorophosphate was reduced by that amount.

<Example 1-10>
A laminate type battery was prepared in the same manner as in Example 1-9 except that the concentration of fluoroethylene carbonate was 0.4 mass% and the amount of ethylene carbonate was increased accordingly.

<Examples 1-11 and 1-12>
A laminate type battery was prepared in the same manner as in Example 1-9 except that fluoroethylene carbonate was adjusted to the concentration shown in Table 1 and the amount of ethylene carbonate was reduced accordingly.

<Example 1-13>
A laminate type battery was prepared in the same manner as in Example 1-9 except that the concentration of fluoroethylene carbonate was 2.5 mass% and the amount of ethylene carbonate was reduced by that amount.

<Examples 1-14 and 1-15>
A laminated battery was prepared in the same manner as in Example 1-1 except that the boron-containing lithium salt shown in Table 1 was added and the amount of lithium hexafluorophosphate was reduced by that amount.

<Examples 1-16 and 1-17>
A laminate type battery was produced in the same manner as in Example 1-9 except that a chain carbonate having 5 or 6 carbon atoms in Table 1 was used as a solvent instead of diethyl carbonate.

<Comparative Example 1-1>
A laminate type battery was prepared in the same manner as in Example 1-1 except that the chain carbonate having a hydrocarbon group having 13 to 20 carbon atoms was not added and diethyl carbonate was increased by that amount.

<Comparative Example 1-2>
Example 1 except that a chain carbonate having a hydrocarbon group having 13 to 20 carbon atoms was not added, and instead didodecyl carbonate was added as a chain carbonate having a hydrocarbon group having 12 carbon atoms. A laminated battery was prepared in the same manner as in -1.

<Comparative Example 1-3>
Example except that a chain carbonate having a hydrocarbon group having 13 to 20 carbon atoms was not added, and dihenicosyl carbonate was added as a chain carbonate having a hydrocarbon group having 21 carbon atoms instead. A laminated battery was prepared in the same manner as in 1-1.

<Comparative Example 1-4>
A laminate type battery was prepared in the same manner as in Example 1-1 except that the halogenated cyclic carbonate was not added and the amount of ethylene carbonate was increased accordingly.

<Comparative Example 1-5>
A laminate type battery was prepared in the same manner as in Example 1-1 except that vinylene carbonate was added instead of the halogenated cyclic carbonate.

<Comparative Example 1-6>
A laminate type battery was prepared in the same manner as in Example 1-9 except that diethyl carbonate was not used and ethyl methyl carbonate was increased instead.

<Comparative Example 1-7>
A laminate type battery was prepared in the same manner as in Example 1-9 except that diethyl carbonate was not used and dipropyl carbonate was increased instead.

  For Examples 1-2 to 1-17 and Comparative Examples 1-1 to 1-7, the expansion rate at the first charge and the discharge capacity retention rate after 300 cycles were measured in the same manner as in Example 1-1. For Examples 1-9 to 1-13, 1-16, 1-17 and Comparative Examples 1-6, 1-7, the expansion coefficient during storage at 90 ° C. for 4 hours was measured in the same manner as in Example 1-1. The results are shown in Table 1.

From the results of Examples 1-1 to 1-8, by using a chain carbonate having a hydrocarbon group having 13 to 20 carbon atoms and a halogenated cyclic carbonate as described above, the expansion rate at the first charge is obtained. And it turns out that the discharge capacity maintenance factor after 300 cycles is improved from Comparative Example 1-1.
From the result of Example 1-9, by using a chain carbonate having a hydrocarbon group having 13 to 20 carbon atoms, a halogenated cyclic carbonate, and a boron-containing lithium salt, the battery thickness at the first charge is obtained. It can be seen that the increase in the discharge capacity, the discharge capacity retention rate after 300 cycles, and the swelling during storage at 90 ° C. are improved from those in Example 1-1 and Comparative Example 1-1. Moreover, it turns out that the swelling at the time of 90 degreeC preservation | save is suppressed from Comparative Example 1-6 by using a C5-C6 linear carbonate ester as a solvent.
From the results of Examples 1-10 to 1-13, 300 cycles were obtained by using a chain carbonate having a hydrocarbon group having 13 to 20 carbon atoms, a halogenated cyclic carbonate, and a boron-containing lithium salt. It turns out that the later discharge capacity maintenance factor is improved from Example 1-1 and Comparative Example 1-1. Moreover, it turns out that the expansion coefficient at the time of first charge or the expansion coefficient at 90 degreeC preservation | save is improved.
From the results of Examples 1-14 and 1-15, the first charge was obtained by using a chain carbonate having a hydrocarbon group having 13 to 20 carbon atoms, a halogenated cyclic carbonate, and a boron-containing lithium salt. It can be seen that the increase in battery thickness at the time and the discharge capacity retention rate after 300 cycles are improved over those of Example 1-1 and Comparative Example 1-1.
From the results of Examples 1-16 and 1-17, a chain carbonate having a hydrocarbon group having 13 to 20 carbon atoms, a halogenated cyclic carbonate, a boron-containing lithium salt, and a carbon number of 5 or 6 By using chain carbonate as a solvent, it turns out that the swelling at the time of 90 degreeC preservation | save is suppressed from Comparative Example 1-6.
From the results of Comparative Examples 1-1 to 1-3, if a chain carbonate having a hydrocarbon group having 13 to 20 carbon atoms is not added, the battery thickness increases during the first charge and the discharge capacity after 300 cycles. It turns out that a maintenance factor is inferior to Examples 1-1 to 1-15.
From the result of Comparative Example 1-4, if the halogenated cyclic carbonate is not added, the increase in battery thickness at the first charge and the discharge capacity retention after 300 cycles are inferior to those of Examples 1-1 to 1-15. I understand that.
From the result of Comparative Example 1-5, when vinylene carbonate is added instead of the halogenated cyclic carbonate, the increase in battery thickness at the first charge and the discharge capacity maintenance rate after 300 cycles are improved as compared with Comparative Example 1-4. However, it turns out that it is inferior to Examples 1-1 to 1-15.
From the result of Comparative Example 1-6, if a chain carbonic acid ester having 5 or 6 carbon atoms is not used as a solvent, the swelling during storage at 90 ° C. is larger than those in Examples 1-9, 1-16, and 1-17. I understand.
From the result of Comparative Example 1-7, when a chain carbonic acid ester having 7 carbon atoms is used as a solvent, the discharge capacity retention rate after 300 cycles is inferior to those of Examples 1-9, 1-16, and 1-17. I understand.

<Example 2-1>
A laminate type battery was prepared in the same manner as in Example 1-1 except that a separator having a thickness of 8 μm and a separator coated with 2 μm of polyvinylidene fluoride on both sides was used.

<Example 2-2, 2-3>
A laminate type battery was prepared in the same manner as in Example 2-1, except that the concentration of ditetradecyl carbonate in the electrolytic solution was set to Table 2 and diethyl carbonate was increased or decreased accordingly.

<Examples 2-4 to 2-6>
A laminate type battery was prepared in the same manner as in Example 2-1, except that a chain carbonate having a hydrocarbon group having 13 to 20 carbon atoms was used as the compound in Table 2.

<Examples 2-7 and 2-8>
A laminate type battery was prepared in the same manner as in Example 2-1, except that the halogenated cyclic carbonate was changed to the compound shown in Table 2.

<Example 2-9>
A laminated battery was prepared in the same manner as in Example 2-1, except that the boron-containing lithium salt shown in Table 2 was added and the amount of lithium hexafluorophosphate was reduced by that amount.

<Example 2-10>
A laminate type battery was prepared in the same manner as in Example 2-9 except that the concentration of fluoroethylene carbonate was 0.4% by mass and the amount of ethylene carbonate was increased by that amount.

<Examples 2-11 and 2-12>
A laminate type battery was prepared in the same manner as in Example 2-9 except that fluoroethylene carbonate was adjusted to the concentration shown in Table 2 and the amount of ethylene carbonate was reduced accordingly.

<Example 2-13>
A laminate type battery was prepared in the same manner as in Example 2-9 except that the concentration of fluoroethylene carbonate was 2.5% by mass and the amount of ethylene carbonate was reduced accordingly.

<Examples 2-14 and 2-15>
A laminated battery was prepared in the same manner as in Example 2-1, except that the boron-containing lithium salt shown in Table 2 was added and the amount of lithium hexafluorophosphate was reduced by that amount.

<Examples 2-16 and 2-17>
A laminate type battery was prepared in the same manner as in Example 2-9, except that a chain carbonate having 5 or 6 carbon atoms in Table 2 was used as a solvent instead of diethyl carbonate.

<Comparative Example 2-1>
A laminate type battery was prepared in the same manner as in Example 2-1, except that the chain carbonate having a hydrocarbon group having 13 to 20 carbon atoms was not added and diethyl carbonate was increased accordingly.

<Comparative Example 2-2>
Example 2 except that a chain carbonate having a hydrocarbon group having 13 to 20 carbon atoms was not added, and instead didodecyl carbonate was added as a chain carbonate having a hydrocarbon group having 12 carbon atoms. A laminated battery was prepared in the same manner as in -1.

<Comparative Example 2-3>
Example except that a chain carbonate having a hydrocarbon group having 13 to 20 carbon atoms was not added, and dihenicosyl carbonate was added as a chain carbonate having a hydrocarbon group having 21 carbon atoms instead. A laminate type battery was prepared in the same manner as in 2-1.

<Comparative Example 2-4>
A laminate type battery was prepared in the same manner as in Example 2-1, except that the halogenated cyclic carbonate was not added and the amount of ethylene carbonate was increased accordingly.

<Comparative Example 2-5>
A laminate type battery was prepared in the same manner as in Example 2-1, except that vinylene carbonate was added instead of the halogenated cyclic carbonate.

<Comparative Example 2-6>
A laminate type battery was prepared in the same manner as in Example 2-9 except that diethyl carbonate was not used and the amount of ethyl methyl carbonate was increased instead.

<Comparative Example 2-7>
A laminate type battery was prepared in the same manner as in Example 2-9, except that diethyl carbonate was not used and dipropyl carbonate was increased instead.

  For Examples 2-1 to 2-17 and Comparative Examples 2-1 to 2-7, the expansion rate at the first charge and the discharge capacity retention rate after 300 cycles were measured in the same manner as in Example 1-1. For Examples 2-1, 2-9 to 2-13, 2-16, 2-17 and Comparative Examples 2-6, 2-7, the coefficient of expansion during storage at 90 ° C. for 4 hours was the same as in Example 1-1. Was measured. The results are shown in Table 2.

From the results of Examples 2-1 to 2-8, by using a chain carbonate having a hydrocarbon group having 13 to 20 carbon atoms and a halogenated cyclic carbonate as described above, the expansion rate at the first charge is obtained. And it turns out that the discharge capacity maintenance factor after 300 cycles is improved from Comparative Example 2-1.
From the result of Example 2-9, by using a chain carbonate having a hydrocarbon group having 13 to 20 carbon atoms, a halogenated cyclic carbonate, and a boron-containing lithium salt, the battery thickness at the time of initial charge is obtained. It can be seen that the increase in the discharge capacity, the discharge capacity retention after 300 cycles, and the swelling during storage at 90 ° C. are improved from those in Example 2-1 and Comparative Example 2-1. Moreover, it turns out that the swelling at the time of 90 degreeC preservation | save is suppressed from Comparative Example 2-6 by using a C5-C6 linear carbonate ester as a solvent.
From the results of Examples 2-10 to 2-13, 300 cycles were obtained by using a chain carbonate having a hydrocarbon group having 13 to 20 carbon atoms, a halogenated cyclic carbonate, and a boron-containing lithium salt. It can be seen that the subsequent discharge capacity retention rate is improved over that of Example 2-1 and Comparative Example 2-1. Moreover, it turns out that the expansion coefficient at the time of first charge or the expansion coefficient at 90 degreeC preservation | save is improved.
From the results of Examples 2-14 and 2-15, the first charge was obtained by using a chain carbonate having a hydrocarbon group having 13 to 20 carbon atoms, a halogenated cyclic carbonate, and a boron-containing lithium salt. It can be seen that the increase in battery thickness at the time and the discharge capacity retention rate after 300 cycles are improved over those of Example 2-1 and Comparative Example 2-1.
From the results of Examples 2-16 and 2-17, a chain carbonate having a hydrocarbon group having 13 to 20 carbon atoms, a halogenated cyclic carbonate, a boron-containing lithium salt, and a carbon number of 5 or 6 By using chain carbonate as a solvent, it turns out that the swelling at the time of 90 degreeC preservation | save is suppressed from Comparative Example 2-6.
From the results of Comparative Examples 2-1 to 2-3, if a chain carbonate having a hydrocarbon group having 13 to 20 carbon atoms is not added, the battery thickness increases during the first charge and the discharge capacity after 300 cycles. It turns out that a maintenance factor is inferior to Examples 2-1 to 2-15.
From the result of Comparative Example 2-4, if the halogenated cyclic carbonate is not added, the increase in battery thickness at the first charge and the discharge capacity retention after 300 cycles are inferior to those in Examples 2-1 to 2-15. I understand that.
From the results of Comparative Example 2-5, when vinylene carbonate is added instead of the halogenated cyclic carbonate, the increase in battery thickness at the first charge and the discharge capacity maintenance rate after 300 cycles are improved as compared with Comparative Example 2-4. However, it turns out that it is inferior to Examples 2-1 to 2-15.
From the results of Comparative Example 2-6, if the chain carbonic acid ester having 5 or 6 carbon atoms is not used as a solvent, the swelling during storage at 90 ° C. is larger than those in Examples 2-9, 2-16 and 2-17. I understand.
From the result of Comparative Example 2-7, when a chain carbonic acid ester having 7 carbon atoms is used as a solvent, the discharge capacity retention after 300 cycles is inferior to that of Examples 2-9, 2-16, and 2-17. I understand.

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 (9)

A non-aqueous electrolyte battery comprising a non-aqueous electrolyte together with a positive electrode and a negative electrode,
The non-aqueous electrolyte battery in which the non-aqueous electrolyte contains a chain carbonate having a hydrocarbon group having 13 to 20 carbon atoms, a chain carbonate having 5 or 6 carbon atoms, and a halogenated cyclic carbonate.   The nonaqueous electrolyte battery according to claim 1, wherein a concentration of the halogenated cyclic carbonate in the nonaqueous electrolyte is 0.5 to 2% by mass.   The non-aqueous electrolyte battery according to claim 1, wherein the non-aqueous electrolyte further contains a boron-containing lithium salt.   The non-aqueous electrolyte battery according to claim 1, comprising a polymer compound that swells with the non-aqueous electrolyte.   The non-aqueous electrolyte battery according to claim 4, wherein the polymer compound is polyvinylidene fluoride.   The non-aqueous electrolyte battery according to claim 1, wherein the positive electrode, the negative electrode, and the non-aqueous electrolyte are accommodated in an exterior member made of a laminate film.   A non-aqueous electrolyte composition containing a chain carbonate having a hydrocarbon group having 13 to 20 carbon atoms, a chain carbonate having 5 or 6 carbon atoms, and a halogenated cyclic carbonate.   The non-aqueous electrolyte composition according to claim 7, wherein a concentration of the halogenated cyclic carbonate in the non-aqueous electrolyte is 0.5 to 2% by mass.   The non-aqueous electrolyte composition according to claim 7, wherein the non-aqueous electrolyte further contains a boron-containing lithium salt.

Images