JP2007141760A - Nonaqueous electrolyte battery - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To easily provide a nonaqueous electrolyte battery having superior flame-resistance of a nonaqueous electrolyte, and having a superior high rate discharge characteristics. <P>SOLUTION: As the nonaqueous electrolyte, a phosphate compound is used in which the end of a molecule chain has a CF<SB>2</SB>H- structure. Since the phosphate compound having a structural feature like this is superior in solubility against electrolyte salts and nonaqueous solvents, a large amount of addition is possible, and the high rate discharge characteristics of the nonaqueous electrolyte cell using this is not damaged even if a large amount is added. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a nonaqueous electrolyte battery, and more particularly to a nonaqueous electrolyte battery in which the nonaqueous electrolyte contains a phosphate ester compound.

In recent years, nonaqueous electrolyte batteries, particularly lithium secondary batteries, have attracted attention as power supplies for portable devices such as mobile phones, PHS (simple mobile phones), small computers, power storage power supplies, and electric vehicle power supplies. A lithium secondary battery is generally composed of a positive electrode having a positive electrode active material as a main constituent, a negative electrode having a negative electrode active material as a main constituent, and a non-aqueous electrolyte containing a lithium salt. The positive electrode active material constituting the lithium secondary battery is a lithium-containing transition metal oxide, the negative electrode active material is a carbonaceous material typified by graphite, and the nonaqueous electrolyte is lithium hexafluorophosphate ( It is widely known that an electrolyte such as LiPF ₆ ) is dissolved in a non-aqueous solvent containing ethylene carbonate as a main constituent. These nonaqueous solvents are generally classified as flammable substances because they are easily volatile and have flammability.

  In recent years, there has been a demand for a technique using a non-aqueous electrolyte having flame retardancy or self-extinguishing properties, particularly in applications of relatively large lithium secondary batteries such as power storage power sources and electric vehicle power sources.

  In order to realize a non-aqueous electrolyte with flame retardancy or self-extinguishing properties, a technique for adding a phosphoric acid ester compound, which is a high flash point solvent known as a flame retardant for resin materials, has been studied and proposed. (For example, Patent Documents 1 to 4).

However, in order for these already proposed nonaqueous electrolytes to exhibit sufficient flame retardancy, it is necessary to add a large amount of a phosphoric ester compound (for example, 20 to 40% by volume according to Patent Document 4). Therefore, there is a problem that battery characteristics such as high rate discharge characteristics are impaired. Also, depending on the type of phosphoric acid ester compound, the solubility in lithium salts and other organic solvents constituting the non-aqueous electrolyte is low and it cannot be added in a large amount, so that the non-aqueous electrolyte cannot exhibit sufficient flame retardancy. There was a problem.
Japanese Patent Laid-Open No. 7-114940 JP-A-8-88023 Japanese Patent Laid-Open No. 11-40193 JP 2001-307768 A

  The present invention has been made in view of the above problems, and an object thereof is to easily provide a non-aqueous electrolyte battery in which the electrolyte has excellent flame retardancy and good high rate discharge characteristics. That is.

  In order to solve the above problems, as a result of intensive studies, the present inventors surprisingly have excellent solubility in lithium salts and other organic solvents by using a phosphate ester compound having a specific structure. A non-aqueous electrolyte battery that can be added in a large amount to the non-aqueous electrolyte and thus has a non-aqueous electrolyte with excellent flame retardancy and high energy density and good high-rate discharge characteristics can be provided. And found the present invention. That is, the technical configuration and operational effects of the present invention are as follows. However, the action mechanism includes estimation, and its correctness does not limit the present invention.

（２）前記リン酸エステル化合物は、リン酸トリ（２，２−ジフルオロエチル）及びリン酸トリ（２，２，３，３−テトラフルオロプロピル）からなる群から選択される１種又は２種であることを特徴とする（１）項記載の非水電解質電池。
（３）前記非水電解質は、前記リン酸エステル化合物を５重量％以上含有している（１）項又は（２）項記載の非水電解質電池。
（４）炭素−炭素π結合を有する環状カーボネート、及び、Ｓ＝Ｏ結合を有する環状有機化合物を添加した非水電解質を用いて製造された（１）項〜（３）項のいずれかに記載の非水電解質電池。 (1) In a nonaqueous electrolyte battery comprising a positive electrode, a negative electrode, and a nonaqueous electrolyte containing a lithium salt, the nonaqueous electrolyte contains a phosphate ester compound represented by the following (Chemical Formula 1). Non-aqueous electrolyte battery.

(2) The phosphate compound is one or two selected from the group consisting of tri (2,2-difluoroethyl) phosphate and tri (2,2,3,3-tetrafluoropropyl) phosphate The nonaqueous electrolyte battery according to item (1), wherein
(3) The nonaqueous electrolyte battery according to (1) or (2), wherein the nonaqueous electrolyte contains 5% by weight or more of the phosphate ester compound.
(4) Any one of (1) to (3) manufactured using a non-aqueous electrolyte to which a cyclic carbonate having a carbon-carbon π bond and a cyclic organic compound having an S═O bond are added. Non-aqueous electrolyte battery.

In the invention described in (1), the non-aqueous electrolyte contains a phosphoric ester compound so that the flash point of the non-aqueous electrolyte rises or disappears, and the non-aqueous electrolyte exhibits flame retardancy or self-extinguishing properties. Thus, a non-aqueous electrolyte battery excellent in safety can be obtained. Here, surprisingly, by selecting a phosphate ester compound having the structural characteristics shown in Chemical Formula 1, It is possible to maintain a high solubility in the lithium salt constituting the electrolyte and other organic solvents, and to add a large amount of a phosphate ester compound in order to obtain a non-aqueous electrolyte battery excellent in safety, and Even when added in a large amount, good battery characteristics can be maintained. Although the reason for this is not necessarily clear, the present inventors speculate that the structure of the molecular chain terminal group of the phosphate ester represented by Chemical Formula 1 is related to CF ₂ H—.

  According to the invention described in item (2), the phosphoric acid ester compound contained in the non-aqueous electrolyte is obtained by using tri (2,2-difluoroethyl) phosphate or tri (2,2,3,3-tetraphosphate). Non-aqueous electrolytes that reliably combine excellent electrolyte flame retardancy and excellent high rate discharge characteristics due to the fact that these compounds have a relatively low viscosity by selecting from fluoropropyl) A battery can be provided reliably.

  According to the invention described in item (3), the content of the phosphate ester compound is 5% by weight or more based on the total weight of the nonaqueous electrolyte, so that the flame retardancy of the electrolyte can be reliably exhibited. it can.

  According to the invention described in item (4), the nonaqueous electrolyte battery according to the present invention uses a nonaqueous electrolyte to which a cyclic carbonate having a carbon-carbon π bond and a cyclic organic compound having an S═O bond are added. In the initial charge performed during the manufacturing process of the nonaqueous electrolyte battery, at least a part of the cyclic carbonate having a carbon-carbon π bond and the cyclic organic compound having an S═O bond is decomposed on the negative electrode. In addition, since a lithium ion permeable protective coating is formed on the negative electrode surface, the decomposition of other organic solvents including the phosphoric acid ester compound constituting the non-aqueous electrolyte can be reliably suppressed, so that charge and discharge in the second and subsequent cycles Can be sufficiently performed, and charge / discharge efficiency can be improved. At this time, the non-aqueous electrolyte used for the production of the non-aqueous electrolyte battery contains a carbonate having a carbon-carbon π bond and one or more cyclic organic compounds having an S═O bond. Since the lithium ion permeable protective coating formed on the negative electrode surface is particularly dense and excellent in lithium ion permeability even when added, the decomposition of other organic solvents constituting the non-aqueous electrolyte is further improved. It can be effectively suppressed. Therefore, a nonaqueous electrolyte battery having high charge / discharge efficiency, high energy density, and excellent high rate discharge characteristics can be obtained.

  According to the present invention, it is possible to easily provide a nonaqueous electrolyte battery having excellent electrolyte flame retardancy and good high rate discharge characteristics.

  Embodiments of the present invention are illustrated below, but the present invention is not limited to these descriptions.

  Examples of the phosphate ester compound represented by (Chemical Formula 1) include tri (2,2-difluoroethyl phosphate), tri (2,2,3,3-tetrafluoropropyl) phosphate, and tri (2 phosphate). , 2,3,3,4,4-hexafluorobutyl), triphosphate (1H, 1H, 5H-octafluoropentyl), triphosphate (1H, 1H, 7H-dodecafluoroheptyl), triphosphate (1H, 1H, 3H, 7H-perfluoroheptyl), phosphoric acid tri (1H, 1H, 9H-hexadecafluorononyl) and the like alone or a mixture of two or more thereof can be mentioned. It is not limited. Of these, tri (1,1-difluoroethyl) phosphate and tri (1,1,2,2-tetrafluoropropyl) phosphate are particularly preferred in the present invention.

  The content of the phosphoric acid ester compound represented by Chemical Formula 1 is preferably 5% by weight or more with respect to the total weight of the nonaqueous electrolyte, and in order to obtain particularly excellent flame retardancy of the electrolyte, it is 10% by weight. More preferably. The phosphoric acid ester compound represented by the chemical formula 1 can maintain a high solubility in lithium salts and other organic solvents constituting the nonaqueous electrolyte, so that a phosphoric acid ester can be obtained in order to obtain a nonaqueous electrolyte battery having excellent safety. A large amount of the compound can be added, and good battery characteristics can be maintained even when a large amount is added. In order to obtain a nonaqueous electrolyte battery having excellent high rate discharge characteristics, the content is preferably 50% by weight or less.

  As the organic solvent constituting the non-aqueous electrolyte, organic solvents generally used for non-aqueous electrolytes for non-aqueous electrolyte batteries can be used. For example, cyclic carbonates such as propylene carbonate, ethylene carbonate, butylene carbonate, chloroethylene carbonate; cyclic esters such as γ-butyrolactone, γ-valerolactone, propiolactone; dimethyl carbonate, diethyl carbonate, ethyl methyl carbonate, diphenyl carbonate, etc. Chain carbonates; chain esters such as methyl acetate and methyl butyrate; ethers such as tetrahydrofuran or derivatives thereof, 1,3-dioxane, dimethoxyethane, diethoxyethane, methoxyethoxyethane, methyldiglyme; acetonitrile, benzonitrile, etc. Nitriles of dioxalane or derivatives thereof alone or a mixture of two or more thereof, but not limited thereto.

As the lithium salt constituting the non-aqueous electrolyte, a lithium salt that is stable in a wide potential region generally used for a non-aqueous electrolyte battery can be used. For example, LiBF ₄ , LiPF ₆ , LiClO ₄ , LiCF ₃ SO ₃ , LiN (CF ₃ SO ₂ ) ₂ , LiN (C ₂ F ₅ SO ₂ ) ₂ , LiN (CF ₃ SO ₂ ) (C ₄ F ₉ SO ₂ ), LiC (CF ₃ SO ₂ ) ₃ , LiC (C ₂ F ₅ SO ₂ ) _{3 and the} like, but are not limited thereto. These may be used alone or in combination of two or more.

The concentration of the electrolyte salt in the non-aqueous electrolyte is preferably 0.1 mol / l to 5 mol / l, more preferably 1 mol / l to obtain a non-aqueous electrolyte battery having excellent high rate discharge characteristics. 2.5 mol / l.
When manufacturing a battery to which the present invention is applied, it is strongly recommended to use a cyclic carbonate having a carbon-carbon π bond and a cyclic organic compound having an S═O bond. A cyclic carbonate having a carbon-carbon π bond and a cyclic organic compound having an S═O bond can be used by being added to the non-aqueous electrolyte. It is preferable to use both a cyclic carbonate having a carbon-carbon π bond and a cyclic organic compound having an S═O bond at the same time. When used by adding to a non-aqueous electrolyte, the addition amount is 0 with respect to the weight of the non-aqueous electrolyte. It is preferably 1% by weight or more and 20% by weight or less.

  The cyclic carbonate having a carbon-carbon π bond is one or two selected from the group consisting of vinylene carbonate, styrene carbonate, catechol carbonate, vinyl ethylene carbonate, 1-phenyl vinylene carbonate and 1,2-diphenyl vinylene carbonate. The above is preferable. By selecting the cyclic carbonate having the carbon-carbon π bond in this way, the lithium ion-permeable protective film formed on the negative electrode surface at the time of initial charge is more dense and excellent in lithium ion permeability. Therefore, decomposition of other organic solvents constituting the non-aqueous electrolyte can be more effectively suppressed, charging and discharging after the second cycle can be sufficiently performed, charging and discharging efficiency is improved, and high energy density is achieved. And a non-aqueous electrolyte battery having excellent high rate discharge characteristics.

  The cyclic organic compound having an S═O bond is one or two selected from the group consisting of ethylene sulfite, propylene sulfite, sulfolane, sulfolene, 1,3-propane sultone, 1,4-butane sultone, and derivatives thereof. It is preferable to use more than seeds. By selecting the cyclic organic compound having the S═O bond in this way, the lithium ion-permeable protective coating formed on the negative electrode surface during the initial charge is more dense and excellent in lithium ion permeability. Therefore, the decomposition of other organic solvents constituting the non-aqueous electrolyte can be further effectively suppressed, the second and subsequent cycles can be fully charged and discharged, the charge and discharge efficiency is improved, and the high energy density is achieved. And a non-aqueous electrolyte battery having excellent high rate discharge characteristics.

  Further, the total content of the cyclic carbonate having a carbon-carbon π bond and the cyclic organic compound having an S═O bond is 0.1% by weight or more based on the total weight of the nonaqueous electrolyte. Decomposition of other organic solvents constituting the nonaqueous electrolyte during charging can be suppressed almost completely, and charging in the second and subsequent cycles can be performed more reliably. Further, when the content is 20% by weight or less, deterioration of battery performance due to decomposition of an excessively contained cyclic carbonate having a carbon-carbon π bond or a cyclic organic compound having an S═O bond occurs on the positive electrode. Without, it can be set as the nonaqueous electrolyte battery which has a high energy density and the outstanding high rate discharge characteristic. The content ratio of the cyclic carbonate having a carbon-carbon π bond and the cyclic organic compound having an S═O bond can be arbitrarily selected, but is preferably about 1: 1 by weight.

  The cyclic carbonate having a carbon-carbon π bond and the cyclic organic compound having an S═O bond are those of initial charge / discharge (initialization) performed after assembly during the manufacturing process of the nonaqueous electrolyte battery, unless excessively added. Since a considerable amount is consumed in the process, it may not be detected in the non-aqueous electrolyte battery completed through the initial charge / discharge process.

  Hereinafter, although the further detail of this invention is demonstrated by an Example, this invention is not limited to these description.

(Invention battery)
A cross-sectional view of a nonaqueous electrolyte battery in the battery of the present invention is shown in FIG.

  The lithium battery in the present invention includes a pole group 4 including a positive electrode 1, a negative electrode 2, and a separator 3, a nonaqueous electrolyte, and a metal resin composite film 5. The positive electrode 1 is formed by applying a positive electrode mixture 11 on a positive electrode current collector 12. The negative electrode 2 is formed by applying a negative electrode mixture 21 on a negative electrode current collector 22. The nonaqueous electrolyte is impregnated in the pole group 4. The metal resin composite film 5 covers the pole group 4 and is sealed on all four sides by heat welding.

  Next, a method for manufacturing the battery having the above configuration will be described.

The positive electrode 1 was obtained as follows. First, LiCoO ₂ and acetylene black, which is a conductive agent, are mixed, and further, a N-methyl-2-pyrrolidone solution of polyvinylidene fluoride is mixed as a binder, and this mixture is used as a positive electrode current collector 12 made of aluminum foil. After coating on one side, it was dried and pressed so that the thickness of the positive electrode mixture 11 was 0.1 mm. The positive electrode 1 was obtained by the above process.

  Moreover, the negative electrode 2 was obtained as follows. First, graphite as a negative electrode active material and an N-methyl-2-pyrrolidone solution of polyvinylidene fluoride as a binder were mixed, and this mixture was applied to one side of a negative electrode current collector 22 made of copper foil. It dried and pressed so that the negative mix 21 thickness might be set to 0.1 mm. The negative electrode 2 was obtained by the above process.

  On the other hand, a polyethylene microporous film (thickness: 25 μm, porosity: 50%) was used for the separator 3.

  The pole group 4 was configured by facing the positive electrode mixture 11 and the negative electrode mixture 21, placing the separator 3 therebetween, and laminating the positive electrode 1, the separator 3, and the negative electrode 2 in this order.

    The nonaqueous electrolyte is composed of 1 liter of a mixed solvent in which ethylene carbonate and diethyl carbonate are mixed at a volume ratio of 1: 1, 3% by weight of tri (2,2,3,3-tetrafluoropropyl) phosphate, vinylene carbonate. Was obtained by mixing 2% by weight of 1 and 2% by weight of 1,3-propane sultone, and further dissolving 1 mol of LiPF6. This is designated as electrolyte a1.

    Next, the electrode group 4 was impregnated with the non-aqueous electrolyte by immersing the electrode group 4 in the non-aqueous electrolyte. Furthermore, the pole group 4 was covered with the metal resin composite film 5, and the four sides were sealed by heat welding.

  The nonaqueous electrolyte battery obtained by the above production method is referred to as the present invention battery A1. The design capacity of the battery A1 of the present invention is 10 mAh.

As a non-aqueous electrolyte, 5% by weight of tri (2,2,3,3-tetrafluoropropyl) phosphate, vinylene carbonate in 1 liter of a mixed solvent obtained by mixing ethylene carbonate and diethyl carbonate in a volume ratio of 1: 1. 2% by weight and 1,3-propane sultone 2% by weight, and 1 mol of LiPF ₆ dissolved therein (electrolyte a2) was used. A non-aqueous electrolyte battery with a capacity of 10 mAh was produced and designated as a battery of the present invention A2.

As a non-aqueous electrolyte, 10% by weight of tri (2,2,3,3-tetrafluoropropyl) phosphate, vinylene carbonate in 1 liter of a mixed solvent obtained by mixing ethylene carbonate and diethyl carbonate in a volume ratio of 1: 1. the 2 wt% and 1,3-propane sultone was mixed 2 wt%, except for using those obtained by further dissolving 1 mol of LiPF ₆ (electrolyte a3), the present invention cell a same material as and preparation A non-aqueous electrolyte battery with a capacity of 10 mAh was produced and designated as a battery A3 of the present invention.

As a non-aqueous electrolyte, 25% by weight of tri (2,2,3,3-tetrafluoropropyl) phosphate, vinylene carbonate in 1 liter of a mixed solvent obtained by mixing ethylene carbonate and diethyl carbonate in a volume ratio of 1: 1. 2% by weight and 1,3-propane sultone 2% by weight, and 1 mol of LiPF ₆ dissolved therein (electrolyte a4) was used. A non-aqueous electrolyte battery having a capacity of 10 mAh was produced and designated as a battery A4 of the present invention.

As a non-aqueous electrolyte, 1 liter of a mixed solvent in which ethylene carbonate and diethyl carbonate are mixed at a volume ratio of 1: 1, 50% by weight of tri (2,2,3,3-tetrafluoropropyl) phosphate, vinylene carbonate 2% by weight and 1,3-propane sultone 2% by weight, and 1 mol of LiPF ₆ dissolved therein (electrolyte a5) was used. A non-aqueous electrolyte battery having a capacity of 10 mAh was produced and designated as a battery A5 of the present invention.

As a non-aqueous electrolyte, 75% by weight of tri (2,2,3,3-tetrafluoropropyl) phosphate, vinylene carbonate in 1 liter of a mixed solvent in which ethylene carbonate and diethyl carbonate were mixed at a volume ratio of 1: 1. 2% by weight and 1,3-propane sultone 2% by weight, and 1 mol of LiPF ₆ dissolved therein (electrolyte a6) was used. A non-aqueous electrolyte battery with a capacity of 10 mAh was produced and designated as the present invention battery A6.

As a non-aqueous electrolyte, 25% by weight of tri (2,2,3,3-tetrafluoropropyl) phosphate, vinylene carbonate in 1 liter of a mixed solvent obtained by mixing ethylene carbonate and diethyl carbonate in a volume ratio of 1: 1. The battery A was the same as the battery A of the present invention except that 0.05 wt% of 1,3-propane sultone was mixed and 0.05 mol% of 1PF LiPF ₆ was dissolved (electrolyte a7). A non-aqueous electrolyte battery having a capacity of 10 mAh was produced from the raw materials and the production method, and was designated as a battery of the present invention A7.

As a non-aqueous electrolyte, 25% by weight of tri (2,2,3,3-tetrafluoropropyl) phosphate, vinylene carbonate in 1 liter of a mixed solvent obtained by mixing ethylene carbonate and diethyl carbonate in a volume ratio of 1: 1. 10% by weight and 1,3-propane sultone mixed with 10% by weight, and 1 mol of LiPF ₆ dissolved (electrolyte a8) was used. A non-aqueous electrolyte battery having a capacity of 10 mAh was produced and designated as a battery A8 of the present invention.

As a non-aqueous electrolyte, 1 liter of a mixed solvent in which ethylene carbonate and diethyl carbonate were mixed at a volume ratio of 1: 1, 25% by weight of tri (2,2-difluoroethyl phosphate), 2% by weight of vinylene carbonate and Except for using 2 wt% of 1,3-propane sultone and further dissolving 1 mol of LiPF ₆ (electrolyte b), the same raw material and manufacturing method as those of the battery A of the present invention were used. A water electrolyte battery was produced and designated as the present invention battery B.

As a non-aqueous electrolyte, 1 liter of a mixed solvent in which ethylene carbonate and diethyl carbonate were mixed at a volume ratio of 1: 1, 25% by weight of tri (2,2-difluoroethyl phosphate), 2% by weight of styrene carbonate, and A non-aqueous electrolyte battery having a capacity of 10 mAh was produced by the same raw material and production method as the battery A of the present invention except that 2% by weight of sulfolane was mixed and 1 mol of LiPF ₆ was dissolved (electrolyte c). Thus, the present invention battery C was obtained.

As a non-aqueous electrolyte, 1 liter of a mixed solvent in which ethylene carbonate and diethyl carbonate were mixed at a volume ratio of 1: 1, 25% by weight of tri (1H, 1H, 5H-octafluoropentyl) phosphate, and vinyl ethylene carbonate Except for using 2 wt% and 2 wt% ethylene sulfite mixed and further dissolving 1 mol of LiPF ₆ (electrolyte d), the same raw material and manufacturing method as in the present invention battery A had a capacity of 10 mAh. A nonaqueous electrolyte battery was produced and designated as the battery D of the present invention.

(Comparison battery)
As a non-aqueous electrolyte, 25% by weight of tri (2,2,3,3-tetrafluoropropyl) phosphate was mixed with 1 liter of a mixed solvent in which ethylene carbonate and diethyl carbonate were mixed at a volume ratio of 1: 1. Further, a non-aqueous electrolyte battery having a capacity of 10 mAh was produced by using the same raw materials and manufacturing method as in the battery A of the present invention except that 1 mol of LiPF ₆ was dissolved (electrolyte e), and used as a comparative battery e.

As a non-aqueous electrolyte, 25% by weight of tri (2,2,3,3-tetrafluoropropyl) phosphate and vinylene carbonate are mixed in 1 liter of a mixed solvent in which ethylene carbonate and diethyl carbonate are mixed at a volume ratio of 1: 1. A non-aqueous electrolyte battery having a capacity of 10 mAh was produced by the same raw material and manufacturing method as in the battery A of the present invention, except that 2 wt% was mixed and 1 mol of LiPF ₆ was dissolved (electrolyte f). Comparative battery F was obtained.

As a nonaqueous electrolyte, 1 liter of a mixed solvent obtained by mixing ethylene carbonate and diethyl carbonate in a volume ratio of 1: 1 was mixed with 25% by weight of tri (2,2,3,3-tetrafluoropropyl) phosphate, A non-aqueous electrolyte having a capacity of 10 mAh is obtained by the same raw material and production method as in the battery A of the present invention, except that 2% by weight of 3-propane sultone is mixed and 1 mol of LiPF ₆ is dissolved (electrolyte g). A battery was produced and used as a comparative battery G.

As a non-aqueous electrolyte, 1 liter of a mixed solvent in which ethylene carbonate and diethyl carbonate were mixed at a volume ratio of 1: 1, 25% by weight of triethyl phosphate, 2% by weight of vinylene carbonate, and 2 of 1,3-propane sultone A non-aqueous electrolyte battery having a capacity of 10 mAh was prepared by the same raw material and manufacturing method as in the present invention battery A except that 1% by weight of LiPF ₆ was dissolved (electrolyte h). Battery H was designated.

As a non-aqueous electrolyte, 1 liter of a mixed solvent obtained by mixing ethylene carbonate and diethyl carbonate in a volume ratio of 1: 1, 25% by weight of tri (2,2,2-trifluoroethyl) phosphate, and 2 of vinylene carbonate. According to the same raw material and manufacturing method as the battery A of the present invention, except that 1 wt% and 1 wt% of 1,3-propane sultone were mixed and 1 mol of LiPF ₆ was dissolved (electrolyte i) was used. A 10 mAh non-aqueous electrolyte battery was produced and used as comparative battery I.

The battery of the present invention except that 1 mol of LiPF ₆ was dissolved (electrolyte j) in 1 liter of a mixed solvent in which ethylene carbonate and diethyl carbonate were mixed at a volume ratio of 1: 1 as the nonaqueous electrolyte. A non-aqueous electrolyte battery having a capacity of 10 mAh was produced using the same raw material and production method as A, and was designated as comparative battery J.

(Electrolyte flammability test)
An electrolyte flammability test was performed on the nonaqueous electrolytes (electrolytes a1 to a8 and b to j) described above. 5 ml of each electrolyte was taken on a watch glass, and the presence of ignition / combustion was confirmed by bringing the fire of an alcohol lamp closer to 10 seconds.

(Battery performance test)
For these inventive batteries A1 to A8, B, C, D and comparative batteries E, F, G, H, I, J, the initial discharge capacity and the high rate discharge capacity were measured. The initial discharge capacity was a constant current constant voltage charge with a current of 10 mA and a final voltage of 4.2 V at 20 ° C., and then a constant current discharge with a current of 2 mA and a final voltage of 2.7 V was performed at 20 ° C. to obtain an initial discharge capacity. . Further, the high rate discharge capacity is a constant rate constant voltage charge with a current of 10 mA and a final voltage of 4.2 V at 20 ° C., followed by a constant current discharge with a current of 30 mA and a final voltage of 2.7 V at 20 ° C. It was set as the discharge capacity. The above test results are summarized in Table 1. In Table 1, the following abbreviations are used.
TFPP: Tri (2,2,3,3-tetrafluoropropyl) phosphate
DFEP: Tri (2,2-difluoroethyl phosphate)
OFPP: Triphosphate (1H, 1H, 5H-octafluoropentyl)
TEP: Triethyl phosphate TFEP: Tri (2,2,2-trifluoroethyl) phosphate
VC: vinylene carbonate SC: styrene carbonate VEC: vinyl ethylene carbonate PS: 1,3-propane sultone SF: sulfolane ES: ethylene sulfite

As shown in Table 1, the comparative battery J using the electrolyte j to which no phosphate ester was added had good initial discharge capacity and high rate discharge capacity, but the non-aqueous electrolyte used for this was a combustion Had sex. The electrolyte h containing a phosphate ester whose molecular chain end group structure is CH ₃ — and the electrolyte i containing a phosphate ester whose molecular chain end group structure is CF ₃ — are self-extinguishing. However, it was found that the comparative batteries H and I using the same had an initial discharge capacity slightly lower than the design capacity and inferior to a high rate discharge capacity. In addition, in the comparative batteries E, F, and G using a non-aqueous electrolyte to which either or both of a cyclic carbonate having a carbon-carbon π bond and a cyclic organic compound having an S═O bond are not added, initial discharge is performed. It was found that the capacity was slightly lower than the design capacity and was inferior to the high rate discharge capacity.

  In contrast, the present invention batteries A1 to A8, B, C, and D are excellent in both initial discharge capacity and high rate discharge capacity as compared with comparative batteries E, F, G, H, I, and J. In addition, the non-aqueous electrolyte used in this test also has good flammability test results, and it was confirmed that the non-aqueous electrolyte battery has both excellent flame retardancy and high-rate discharge characteristics.

  In addition, in order to obtain a nonaqueous electrolyte battery having both excellent flame retardance and high rate discharge characteristics of the electrolyte, the content of the phosphate ester compound is 5% by weight or more by comparison between the batteries A1 to A6 of the present invention. It was confirmed that it is preferably 10% by weight or more and 50% by weight or less.

  For each of the batteries A1 to A8, B, C, D of the present invention and a plurality of comparative batteries E, F, G, H, I, J, the initial discharge capacity and the high rate discharge capacity were measured. The composition was subjected to composition analysis. A part of the metal resin composite film as the outer package was cut out, the nonaqueous electrolyte in the battery was collected using a centrifuge, and the nonaqueous solvent component was analyzed. As a result, for almost all non-aqueous electrolytes, the detected amounts of cyclic carbonate and cyclic organic compound having an S═O bond were both lower than the added amount at the time of production, and some were not detected. In particular, cyclic carbonates were not detected for most nonaqueous electrolytes. This is considered to be because a considerable amount was consumed in the initial charge / discharge (initialization) step performed after assembly during the manufacturing process of the nonaqueous electrolyte battery.

  As described above, according to the present invention, it is possible to easily provide a nonaqueous electrolyte battery having both excellent flame retardance and high rate discharge characteristics of an electrolyte, and its industrial value is great. .

It is sectional drawing of the nonaqueous electrolyte battery of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Positive electrode 11 Positive electrode mixture 12 Positive electrode collector 2 Negative electrode mixture 21 Negative electrode mixture 22 Negative electrode collector 3 Separator 4 Electrode group 5 Metal resin composite film

Claims (4)

In a non-aqueous electrolyte battery including a positive electrode, a negative electrode, and a non-aqueous electrolyte containing a lithium salt, the non-aqueous electrolyte contains a phosphoric ester compound represented by the following (Chemical Formula 1). Electrolyte battery.

The phosphate compound is one or two selected from the group consisting of tri (2,2-difluoroethyl) phosphate and tri (2,2,3,3-tetrafluoropropyl) phosphate. The nonaqueous electrolyte battery according to claim 1. The nonaqueous electrolyte battery according to claim 1, wherein the nonaqueous electrolyte contains 5 wt% or more of the phosphate ester compound. The nonaqueous electrolyte battery according to any one of claims 1 to 3, produced using a nonaqueous electrolyte to which a cyclic carbonate having a carbon-carbon π bond and a cyclic organic compound having an S═O bond are added.

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