JP2005340161A - Additive for nonaqueous electrolyte for battery, nonaqueous electrolyte for battery, and nonaqueous electrolyte battery - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an additive for a nonaqueous electrolyte for a battery containing a combustion-suppressing-material-releasing compound capable of releasing a combustion suppressing material that exhibits a high combustion suppressing effect during combustion, in particular. <P>SOLUTION: In the additive for a nonaqueous electrolyte for a battery containing the combustion-suppressing-material-releasing compound that releases a combustion suppressing material during combustion, the combustion suppressing material is a phosphine oxide compound having a P-F bond and/or a P-NH<SB>2</SB>bond in molecules. The phosphine oxide compound is preferably a compound represented by formula (I): O=PR<SP>1</SP><SB>3</SB>, where R<SP>1</SP>each independently represent a monovalent substituent group or a halogen, and at least one R<SP>1</SP>is fluorine or an amino group. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a battery non-aqueous electrolyte additive, a battery non-aqueous electrolyte containing the additive, and a non-aqueous electrolyte battery including the non-aqueous electrolyte. The present invention relates to an additive for non-aqueous electrolyte.

  In recent years, there has been a demand for a lightweight, long-life, high-energy-density battery as a main power source or auxiliary power source for electric vehicles and fuel cell vehicles, or as a power source for small electronic devices. In contrast, a non-aqueous electrolyte battery using lithium as a negative electrode active material is known as one of batteries having a high energy density because the electrode potential of lithium is the lowest among metals and the electric capacity per unit volume is large. Many types of batteries, whether primary batteries or secondary batteries, have been actively researched, and some have been put into practical use and supplied to the market. For example, non-aqueous electrolyte primary batteries are used as power sources for cameras, electronic watches, and various memory backups. In addition, non-aqueous electrolyte secondary batteries are used as drive power sources for notebook computers and mobile phones, and are also being considered for use as main power sources or auxiliary power sources for electric vehicles and fuel cell vehicles. .

  In these non-aqueous electrolyte batteries, lithium as the negative electrode active material reacts violently with compounds having active protons such as water and alcohol, so that the electrolyte used in the batteries is non-ester compounds and ether compounds. Limited to protic organic solvents.

  However, although the aprotic organic solvent has low reactivity with the lithium of the negative electrode active material, for example, when a battery is short-circuited, a large current flows suddenly, and when the battery abnormally generates heat, it is vaporized and decomposed. Therefore, there is a high risk of generating gas, causing the battery to rupture or ignite due to the generated gas and heat, and sparks generated during a short circuit.

  In contrast, a phosphazene compound is added to the battery non-aqueous electrolyte to impart non-flammability, flame retardancy or self-extinguishing properties to the non-aqueous electrolyte, and the battery ignites and ignites in the event of an emergency such as a short circuit. A non-aqueous electrolyte battery with a greatly reduced risk has been developed (see Patent Document 1).

JP-A-6-13108

  The phosphazene compound releases a substance that is thermally decomposed and suppresses burning of the aprotic organic solvent in the electrolyte when the non-aqueous electrolyte battery becomes extremely hot due to a short circuit or the like, and the safety of the battery However, depending on the molecular structure of the phosphazene compound used, there is a portion that does not contribute to combustion suppression, so there is room for further improvement.

  Accordingly, an object of the present invention is to provide a non-aqueous electrolyte additive for a battery containing a combustion-suppressing substance-releasing compound capable of releasing a combustion-suppressing substance having a particularly excellent combustion-suppressing effect during combustion. is there. In addition, another object of the present invention is to provide a non-aqueous electrolyte solution for a battery having such an excellent safety, including the non-aqueous electrolyte additive, and a highly safe non-aqueous electrolyte battery comprising the non-aqueous electrolyte solution. Is to provide.

  As a result of intensive studies to achieve the above-mentioned object, the present inventors have found that a combustion-inhibiting substance-releasing compound capable of releasing such a combustion-inhibiting substance has a superior combustion-inhibiting effect. By adding to the non-aqueous electrolyte, it was found that the safety of the non-aqueous electrolyte and the non-aqueous electrolyte battery provided with the non-aqueous electrolyte can be greatly improved, and the present invention has been completed.

That is, the non-aqueous electrolyte additive for a battery of the present invention contains a combustion-suppressing substance-releasing compound that releases a combustion-suppressing substance upon combustion, and the combustion-suppressing substance contains PF bonds and / or P- in the molecule. It is a phosphine oxide compound having an NH ₂ bond.

  In a preferred example of the non-aqueous electrolyte additive for a battery according to the present invention, the combustion-inhibiting substance is at least one of a self-extinguishing substance, a flame retardant substance, and a non-flammable substance.

In another preferred embodiment of the additive for a non-aqueous electrolyte solution of the battery of the present invention, the phosphine oxide compound is represented by the following formula (I):
O = PR ¹ ₃ ... (I)
(Wherein R ¹ is each independently a monovalent substituent or a halogen element, and at least one R ¹ is fluorine or an amino group). Wherein R ¹ in formula (I) is independently selected from the group consisting of fluorine, amino group, alkyl group and alkoxy group, and at least one R ¹ is fluorine or amino group. preferable. And a phosphine oxide compound in which at least one R ¹ in the formula (I) is fluorine and at least one R ^{1 in} the formula (I) is an amino group, and the total of R ¹ in the formula (I) In particular, phosphine oxide compounds which are fluorine or amino groups are particularly preferred.

  In another preferred embodiment of the additive for a non-aqueous electrolyte of a battery according to the present invention, the combustion-suppressing substance-releasing compound contains phosphorus and fluorine and / or nitrogen in the molecule. Here, it is more preferable that the combustion-suppressing substance-releasing compound has a phosphorus-nitrogen bond in the molecule, and even more preferable that it has a phosphorus-nitrogen double bond in the molecule. It is also preferred that the combustion-suppressing substance-releasing compound has a phosphorus-fluorine bond in the molecule. Preferred examples of the combustion-suppressing substance-releasing compound include phosphazene compounds and isomers of phosphazene compounds.

  The battery non-aqueous electrolyte of the present invention comprises the above battery non-aqueous electrolyte additive and a supporting salt.

  It is preferable that the nonaqueous electrolytic solution for a battery of the present invention further contains an aprotic organic solvent. Here, as the aprotic organic solvent, cyclic and chain ester compounds and chain ether compounds are preferable.

  In addition, the battery non-aqueous electrolyte of the present invention is preferably capable of releasing 0.03 mol or more of a combustion inhibiting substance per liter of the battery non-aqueous electrolyte during combustion.

  The non-aqueous electrolyte for a battery of the present invention preferably contains 3% by volume or more of the combustion-suppressing substance releasing compound, and more preferably contains 5% by volume or more.

  Furthermore, the non-aqueous electrolyte battery of the present invention comprises the above-described non-aqueous electrolyte for a battery, a positive electrode, and a negative electrode.

According to the present invention, a combustion-suppressing substance-releasing compound that releases a phosphine oxide compound having a PF bond and / or a P-NH ₂ bond in a molecule as a combustion-suppressing substance at the time of combustion is contained. Therefore, it is possible to provide an additive for a non-aqueous electrolyte for a battery that can greatly reduce the property. In addition, it is possible to provide a non-aqueous electrolyte for a battery containing such an additive and having a greatly reduced risk of ignition and ignition. Furthermore, it is possible to provide a non-aqueous electrolyte battery including the non-aqueous electrolyte and having significantly improved safety.

<Additive for non-aqueous electrolyte of battery>
Below, the additive for non-aqueous electrolyte of the battery of the present invention will be described in detail. The additive for a non-aqueous electrolyte of a battery according to the present invention contains a combustion-suppressing substance-releasing compound that releases a combustion-suppressing substance upon combustion, and the combustion-suppressing substance contains PF bonds and / or P-NH _{2 in the} molecule. It is a phosphine oxide compound having a bond, and may contain other components as required. The phosphine oxide compound having a P—F bond and / or a P—NH ₂ bond in the molecule has a function of greatly suppressing the combustibility of the aprotic organic solvent usually contained in the electrolyte. Therefore, non-aqueous electrolysis is achieved by adding a combustion-suppressing substance releasing compound that releases a phosphine oxide compound having a PF bond and / or a P-NH ₂ bond in the molecule as a combustion-suppressing substance during combustion to the non-aqueous electrolyte. The flammability of the liquid can be greatly suppressed.

  The combustion-suppressing substance is not particularly limited as long as it can suppress the combustion of the flame ignited in the non-aqueous electrolyte during combustion, but can make the non-aqueous electrolyte self-extinguishing, flame retardant or non-flammable, i.e., self A fire extinguishing substance, a flame retardant substance or an incombustible substance is preferable. Here, self-extinguishing property, flame retardancy and non-flammability are defined by a method based on UL94HB method of UL (Underlighting Laboratory) standard. Specifically, 1.0 mL is applied to nonflammable quartz fiber. When a test piece of 127 mm x 12.7 mm was soaked with the electrolyte solution and the test piece was ignited in an atmospheric environment, the ignited flame was extinguished between 25 and 100 mm line, and the fallen object from the net If there is no ignition, it is assumed that there is “self-extinguishing”, and if the ignited flame does not reach the 25mm line of the device, and the fallen object from the net is not ignited, "If there is no ignition (combustion length 0mm), it is" non-combustible ".

The combustion-suppressing substance is not particularly limited as long as it is a phosphine oxide compound having a PF bond and / or a P-NH ₂ bond in the molecule. Among such phosphine oxide compounds, phosphine oxide compounds represented by the above formula (I) are preferable. In the formula (I), each R ¹ is independently a monovalent substituent or a halogen element, and at least one R ¹ is fluorine or an amino group. Here, preferred examples of the halogen element include fluorine, chlorine, bromine, etc. Among these, fluorine is particularly preferred. On the other hand, examples of the monovalent substituent include an amino group, an alkoxy group, an alkyl group, a carboxyl group, an acyl group, and an aryl group. Among these, the effect of reducing the risk of ignition and ignition of the electrolyte An amino group is preferable in terms of superiority. Examples of the alkoxy group include a methoxy group, an ethoxy group, a methoxyethoxy group, a propoxy group, and a phenoxy group. Examples of the alkyl group include a methyl group, an ethyl group, a propyl group, a butyl group, and a pentyl group. Examples of the acyl group include a formyl group, an acetyl group, a propionyl group, a butyryl group, an isobutyryl group, and a valeryl group. Examples of the aryl group include a phenyl group, a tolyl group, and a naphthyl group. The hydrogen element in these monovalent substituents is preferably substituted with a halogen element, and preferred examples of the halogen element include fluorine, chlorine, bromine, etc., with fluorine being most preferred, and then chlorine being preferred. .

  In the phosphine oxide compound, 10% by mass or more in the molecule is preferably a halogen element, and more preferably 15% by mass or more in the molecule is a halogen element. Further, in the phosphine oxide compound, 7% by mass or more in the molecule is preferably fluorine, and more preferably 10% by mass or more in the molecule is fluorine. A phosphine oxide compound in which 10% by mass or more in the molecule is a halogen element is excellent in suppressing the combustion of the non-aqueous electrolyte, and a phosphine oxide compound in which 7% by mass or more in the molecule is fluorine is a non-aqueous electrolyte. It is particularly excellent in the effect of suppressing the combustion.

Examples of the phosphine oxide compound, at least one of fluorine and phosphine oxide compound is at least one amino group of R ¹ in formula (I) R ¹ in formula (I), as well as the formula (I) Particularly preferred are phosphine oxide compounds in which all of R ¹ are fluorine or amino groups. Since these phosphine oxide compounds have a high proportion of fluorine and amino groups in the molecule that contribute to the suppression of combustion of the electrolyte, they have an excellent combustion suppression effect.

Specific examples of the phosphine oxide compound of the above formula (I) include trifluorophosphine oxide [O = PF ₃ ], triaminophosphine oxide [O═P (NH ₂ ) ₃ ], aminodifluorophosphine oxide [O═PF. ₂ NH ₂ ], diaminofluorophosphine oxide [O═PF (NH ₂ ) ₂ ], dimethoxyfluorophosphine oxide [O═PF (OCH ₃ ) ₂ ], ethoxydifluorophosphine oxide [O═PF ₂ (OC ₂ H ₅ ) ], methoxy difluoro phosphine oxide _{[O = PF 2 (OCH 3} )], diethoxy-fluoro phosphine oxide _{[O = PF (OC 2 H} 5) 2] , and the like.

The combustion-suppressing substance-releasing compound used for the non-aqueous electrolyte additive of the battery of the present invention is not particularly limited as long as the combustion-suppressing substance can be released at the time of combustion, and other combustion-suppressing substances such as CO ₂ and phosphate esters May be released. Here, “at the time of combustion” means when a flame is ignited in the non-aqueous electrolyte. The combustion-suppressing substance releasing compound is preferably a compound containing phosphorus and fluorine and / or nitrogen in the molecule from the viewpoint that the combustion-suppressing substance can be suitably released.

  Here, when the combustion-suppressing substance-releasing compound contains phosphorus and fluorine in the molecule, it suppresses the flammability of the electrolyte more effectively by the action of fluorine gas generated during combustion in addition to the above-mentioned combustion-suppressing substance. Can do. In compounds containing fluorine, generation of fluorine radicals may be a problem. However, in the above-mentioned combustion-inhibiting substance releasing compound, phosphorus in the molecule captures fluorine radicals to form stable phosphorus fluoride. Therefore, such a problem does not occur. The fluorine content in the combustion-suppressing substance-releasing compound is preferably in the range of 2 to 80% by mass, more preferably in the range of 2 to 60% by mass, and still more preferably in the range of 2 to 50% by mass. When the fluorine content of the combustion-suppressing substance-releasing compound is less than 2% by mass, the effect of suppressing the flammability of the electrolyte is small, and when it exceeds 80% by mass, the viscosity increases and the conductivity of the electrolyte decreases. There is.

In addition, as the combustion suppressing substance releasing compound, a compound having a phosphorus-nitrogen bond in the molecule is preferable in that a phosphine oxide compound having a P—NH ₂ bond in the molecule can be suitably released as the combustion suppressing substance. A compound having a phosphorus-nitrogen double bond therein is more preferred. Here, examples of the compound having a phosphorus-nitrogen bond in the molecule include phosphazene compounds and isomers of phosphazene compounds, and examples of the compound having a phosphorus-nitrogen double bond in the molecule include phosphazene compounds. be able to.

  Furthermore, as the combustion-suppressing substance releasing compound, a compound having a phosphorus-fluorine bond in the molecule is preferable in that a phosphine oxide compound having a PF bond in the molecule can be suitably released as the combustion-suppressing substance. Compounds having a phosphorus-fluorine bond in the molecule include phosphine compounds, cyclophosphine compounds, phosphine oxide compounds, cyclophosphine oxide compounds, phosphine borane compounds, silaphosphane compounds, phosphoarsenic cyclosilazane compounds, phosphooxide borane compounds, and Phosphorus-containing compounds such as chain and cyclic phosphazene compounds, in which fluorine is directly bonded to phosphorus in the molecule, can be used.

［式中、Ｒ²は、それぞれ独立して一価の置換基又はハロゲン元素を表し；Ｙ²は、それぞれ独立して２価の連結基、２価の元素又は単結合を表し；Ｘ²は、炭素、ケイ素、ゲルマニウム、スズ、窒素、リン、ヒ素、アンチモン、ビスマス、酸素、硫黄、セレン、テルル及びポロニウムからなる群から選ばれる元素の少なくとも１種を含む置換基を表す］で表される鎖状ホスファゼン化合物、及び下記式(III)：
(ＮＰＲ³ ₂)_n ・・・ (III)
［式中、Ｒ³はそれぞれ独立して一価の置換基又はハロゲン元素を表し；ｎは３〜１５を表す］で表される環状ホスファゼン化合物が好適に挙げられる。 Examples of the phosphazene compound include the following formula (II):

Wherein, R ² each independently represents a monovalent substituent or a halogen element; Y ² are each independently a divalent linking group, a divalent element or a single bond; X ² is Represents a substituent containing at least one element selected from the group consisting of carbon, silicon, germanium, tin, nitrogen, phosphorus, arsenic, antimony, bismuth, oxygen, sulfur, selenium, tellurium and polonium] A chain phosphazene compound and the following formula (III):
(NPR ³ ₂ ) _n ... (III)
Preferable examples include cyclic phosphazene compounds represented by the formula: wherein R ³ independently represents a monovalent substituent or a halogen element; n represents 3 to 15.

  Among the phosphazene compounds represented by the above formula (II) or formula (III), those which are liquid at 25 ° C. (room temperature) are preferable. The viscosity at 25 ° C. of the liquid phosphazene compound is preferably 300 mPa · s (300 cP) or less, more preferably 20 mPa · s (20 cP) or less, and particularly preferably 5 mPa · s (5 cP) or less. In the present invention, the viscosity is measured at 1 rpm, 2 rpm, 3 rpm, 5 rpm, 7 rpm, 10 rpm, 20 rpm, and 50 rpm using a viscosity meter [R-type viscometer Model RE500-SL, manufactured by Toki Sangyo Co., Ltd.] The measurement was performed at a speed of 120 seconds, and the rotation speed when the indicated value reached 50 to 60% was set as an analysis condition, and the viscosity was measured at that time. When the viscosity of the phosphazene compound at 25 ° C exceeds 300 mPa · s (300 cP), the supporting salt becomes difficult to dissolve, the wettability to the positive electrode material, negative electrode material, separator, etc. decreases, and the viscosity resistance of the electrolyte increases. The ionic conductivity is remarkably lowered, and the performance becomes insufficient particularly when used under a low temperature condition such as below the freezing point. In addition, since these phosphazene compounds are in a liquid state, they have conductivity equivalent to that of a normal liquid electrolyte, and exhibit excellent cycle characteristics when used in an electrolyte solution for a secondary battery.

R ^{2 in} formula (II) is not particularly limited as long as it is a monovalent substituent or a halogen element, and each R ² may be the same or different. Here, examples of the monovalent substituent include an alkoxy group, an alkyl group, a carboxyl group, an acyl group, and an aryl group. Among these, an alkoxy group is preferable in that the phosphazene compound has low viscosity. On the other hand, preferred examples of the halogen element include fluorine, chlorine, bromine and the like. Examples of the alkoxy group include methoxy group, ethoxy group, propoxy group, butoxy group, and alkoxy-substituted alkoxy groups such as methoxyethoxy group and methoxyethoxyethoxy group. Among these, methoxy group, ethoxy group, methoxy group, etc. An ethoxy group and a methoxyethoxyethoxy group are preferable, and a methoxy group and an ethoxy group are more preferable from the viewpoint of low viscosity and high dielectric constant. Examples of the alkyl group include a methyl group, an ethyl group, a propyl group, a butyl group, and a pentyl group. Examples of the acyl group include a formyl group, an acetyl group, a propionyl group, a butyryl group, an isobutyryl group, and a valeryl group. Examples of the aryl group include a phenyl group, a tolyl group, and a naphthyl group. The hydrogen element in these monovalent substituents is preferably substituted with a halogen element. As the halogen element, fluorine, chlorine and bromine are preferred, fluorine is most preferred, and chlorine is then preferred. Those in which the hydrogen element in the monovalent substituent is substituted with fluorine tend to have a greater effect of improving the cycle characteristics of the secondary battery than those in which chlorine is substituted. Among the monovalent substituents and halogen elements, fluorine is particularly preferable as R ^{2 in the} formula (II).

Y ^{2 in} formula (II) is not particularly limited as long as it is a divalent linking group, a divalent element, or a single bond, and each Y ² may be the same or different. Here, as the divalent linking group, in addition to CH ₂ group, oxygen, sulfur, selenium, nitrogen, boron, aluminum, scandium, gallium, yttrium, indium, lanthanum, thallium, carbon, silicon, titanium, tin, germanium Divalent containing at least one element selected from the group consisting of zirconium, lead, phosphorus, vanadium, arsenic, niobium, antimony, tantalum, bismuth, chromium, molybdenum, tellurium, polonium, tungsten, iron, cobalt, nickel From the viewpoint of effectively reducing the risk of ignition / ignition of the electrolyte, a divalent linking group containing sulfur and / or selenium elements is preferable. Examples of the divalent element include oxygen, sulfur, and selenium. Among these, Y ^{2 in} the formula (II) is preferably a single bond. The phosphazene compound in which at least one Y ² R ^{2 of the} formula (II) is fluorine has a PF bond in the molecule, and a phosphine oxide compound having a PF bond in the molecule as a combustion suppressing substance at the time of combustion. It can be suitably released.

［式(IV)、式(V)及び式(VI)中、Ｒ⁴、Ｒ⁵及びＲ⁶は、それぞれ独立に一価の置換基又はハロゲン元素を表し；Ｙ⁴、Ｙ⁵及びＹ⁶は、それぞれ独立に２価の連結基、２価の元素又は単結合を表し；Ｚは２価の基又は２価の元素を表す］で表される置換基が更に好ましい。 X ^{2 in} formula (II) is a substitution containing at least one element selected from the group consisting of carbon, silicon, germanium, tin, nitrogen, phosphorus, arsenic, antimony, bismuth, oxygen, sulfur, selenium, tellurium and polonium. There is no particular limitation as long as it is a group. From the viewpoint of consideration for toxicity, environment, etc., X ^{2 in} the formula (II) is preferably a substituent containing at least one element selected from the group consisting of carbon, silicon, nitrogen, phosphorus, oxygen and sulfur. The following formula (IV), formula (V) or formula (VI):

[In formula (IV), formula (V) and formula (VI), R ⁴ , R ⁵ and R ⁶ each independently represents a monovalent substituent or a halogen element; Y ⁴ , Y ⁵ and Y ⁶ are And each independently represents a divalent linking group, a divalent element or a single bond; and Z represents a divalent group or a divalent element].

R ⁴ in Formula (IV), as the R ⁶ in R ⁵ of the formula (V) (VI), the substituent or a halogen element similar monovalent to that described by R ² of formula (II) is either Are also preferred. Further, two R ^{4 s} of the formula (IV) and two R ^{6 s} of the formula (VI) may be the same or different, and may be bonded to each other to form a ring.

Y ⁴ of Formula (IV), as the Y ⁶ of Y ⁵ of the formula (V) (VI), 2 divalent linking group or a bivalent element similar to that described in Y ² of the formula (II) Are preferably mentioned. Similarly, in the case of a divalent linking group containing sulfur and / or selenium elements, the risk of ignition and ignition of the electrolyte is greatly reduced, which is particularly preferable. Y ⁴ , Y ⁵ and Y ⁶ are also preferably single bonds. Two Y ^{4 in} the formula (IV) and two Y ^{6 in} the formula (VI) may be the same or different.

Z in the formula (IV) is not particularly limited as long as it is a divalent group or a divalent element. Here, as the divalent group, CH ₂ group, CHR group (where R represents an alkyl group, alkoxy group, phenyl group, etc.), NR group, oxygen, sulfur, selenium, boron, aluminum , Scandium, gallium, yttrium, indium, lanthanum, thallium, carbon, silicon, titanium, tin, germanium, zirconium, lead, phosphorus, vanadium, arsenic, niobium, antimony, tantalum, bismuth, chromium, molybdenum, tellurium, polonium, tungsten , A divalent group containing at least one element selected from the group consisting of iron, cobalt, and nickel; and examples of the divalent element include oxygen, sulfur, and selenium. Among these, Z in the formula (IV) is preferably a divalent group containing at least one element selected from the group consisting of oxygen, sulfur and selenium in addition to the CH ₂ group, CHR group and NR group. In particular, a divalent group containing an element of sulfur and / or selenium is preferable because the risk of ignition and ignition of the electrolyte is greatly reduced.

  As these substituents, a substituent containing phosphorus as represented by the formula (IV) is particularly preferable in that the risk of ignition / flammability can be particularly effectively reduced. In addition, when the substituent is a substituent containing sulfur as represented by the formula (V), it is particularly preferable in terms of reducing the interface resistance of the electrolytic solution.

R ^{3 in the} formula (III) is not particularly limited as long as it is a monovalent substituent or a halogen element. Here, examples of the monovalent substituent include an alkoxy group, an alkyl group, a carboxyl group, an acyl group, and an aryl group. Among these, an alkoxy group is preferable in that the phosphazene compound has low viscosity. On the other hand, preferred examples of the halogen element include fluorine, chlorine, bromine and the like, and among these, fluorine is particularly preferred. Examples of the alkoxy group include a methoxy group, an ethoxy group, a methoxyethoxy group, a propoxy group, and a phenoxy group. Among these, a methoxy group, an ethoxy group, a methoxyethoxy group, and a phenoxy group are particularly preferable. Examples of the alkyl group include a methyl group, an ethyl group, a propyl group, a butyl group, and a pentyl group; examples of the acyl group include a formyl group, an acetyl group, a propionyl group, a butyryl group, an isobutyryl group, and a valeryl group. Examples of the aryl group include a phenyl group, a tolyl group, and a naphthyl group. The hydrogen element in these monovalent substituents is preferably substituted with a halogen element. Preferred examples of the halogen element include fluorine, chlorine, bromine, and the like. And a trifluoroethoxy group. Among the monovalent substituents and halogen elements, fluorine is particularly preferable as R ^{3 in the} formula (III). The phosphazene compound in which at least one R ³ is fluorine has a PF bond in the molecule, and can suitably release a phosphine oxide compound having a PF bond in the molecule as a combustion inhibitor during combustion.

A phosphazene compound having more suitable viscosity, solubility suitable for addition and mixing, etc., by appropriately selecting R ^{2 to} R ⁶ , Y ² , Y ^{4 to} Y ⁶ , and Z in formulas (II) to (VI) Is obtained. These phosphazene compounds may be used alone or in combination of two or more.

［式中、Ｒ⁷は、それぞれ独立して一価の置換基又はハロゲン元素を表し；Ｙ⁷は、それぞれ独立して２価の連結基、２価の元素又は単結合を表し；Ｘ⁷は、炭素、ケイ素、ゲルマニウム、スズ、窒素、リン、ヒ素、アンチモン、ビスマス、酸素、硫黄、セレン、テルル及びポロニウムからなる群より選ばれる元素の少なくとも１種を含む置換基を表す］で表される化合物が挙げられる。なお、上記式(VII)の化合物は、下記式(VIII)：

［式中、Ｒ⁷、Ｙ⁷、及びＸ⁷は、上記と同義である］で表されるホスファゼン化合物の異性体である。 Further, as an isomer of the phosphazene compound, specifically, the following formula (VII):

Wherein, R ⁷ each independently represents a monovalent substituent or a halogen element; Y ⁷ are each independently a divalent linking group, a divalent element or a single bond; X ⁷ is Represents a substituent containing at least one element selected from the group consisting of carbon, silicon, germanium, tin, nitrogen, phosphorus, arsenic, antimony, bismuth, oxygen, sulfur, selenium, tellurium and polonium] Compounds. The compound of the above formula (VII) is represented by the following formula (VIII):

[Wherein, R ⁷ , Y ⁷ , and X ⁷ are as defined above].

R ⁷ in formula (VII) is not particularly limited as long as it is a monovalent substituent or a halogen element, and the same monovalent substituent and halogen element as those described for R ² in formula (II) above. Are preferably mentioned. In the formula (VII), the divalent linking group or divalent element represented by Y ⁷ is the same as the divalent linking group or divalent group described for Y ⁷ in the formula (II). Any of the elements is preferably exemplified. Further, in the formula (VII), as the substituent represented by X ⁷ , any of the same substituents as those described for X ² in the formula (II) can be preferably exemplified. Here, the isomer of the phosphazene compound in which at least one Y ⁷ R ⁷ is fluorine has a PF bond in the molecule, and has a PF bond in the molecule as a combustion inhibitor during combustion. Can be suitably released.

  The compound represented by the formula (VII) is an isomer of the phosphazene compound represented by the formula (VIII). For example, the degree of vacuum and / or the temperature at the time of producing the phosphazene compound represented by the formula (VIII) It can be manufactured by adjusting. The content (volume%) of the isomer of the phosphazene compound can be measured by gel permeation chromatography (GPC) or high performance liquid chromatography (HPLC).

  The additive for non-aqueous electrolyte of the present invention can contain any additive other than the above-described combustion-suppressing substance-releasing compound as long as the effect of suppressing the combustion of the electrolyte is not inhibited. Note that the content of the combustion-suppressing substance releasing compound in the non-aqueous electrolyte additive is appropriately selected according to the content of the combustion-suppressing substance releasing compound in the non-aqueous electrolyte described later.

<Non-aqueous electrolyte for batteries>
Next, the nonaqueous electrolytic solution for batteries of the present invention will be described in detail. The non-aqueous electrolyte for a battery of the present invention includes the above-described additive for a non-aqueous electrolyte for a battery and a supporting salt, and may include an aprotic organic solvent and the like as necessary.

As the supporting salt used in the nonaqueous electrolytic solution for a battery of the present invention, a supporting salt serving as an ion source of lithium ions is preferable. The supporting salt is not particularly limited, and for example, LiClO ₄ , LiBF ₄ , LiPF ₆ , LiCF ₃ SO ₃ , LiAsF ₆ , LiC ₄ F ₉ SO ₃ , Li (CF ₃ SO ₂ ) ₂ N and Li ( Preferable examples include lithium salts such as C ₂ F ₅ SO ₂ ) ₂ N. These supporting salts may be used alone or in combination of two or more.

  The concentration of the supporting salt in the non-aqueous electrolyte is preferably 0.2 to 1.5 mol / L (M), more preferably 0.5 to 1 mol / L (M). If the concentration of the supporting salt is less than 0.2 mol / L, the conductivity of the electrolyte cannot be sufficiently ensured, and the discharge characteristics and charging characteristics of the battery may be hindered. Since the viscosity of the electrolytic solution increases and the mobility of lithium ions cannot be ensured sufficiently, the conductivity of the electrolytic solution cannot be sufficiently ensured in the same manner as described above, which may hinder battery discharge characteristics and charge characteristics. .

  The aprotic organic solvent that can be used in the non-aqueous electrolyte of the present invention can further suppress the viscosity of the non-aqueous electrolyte without reacting with the negative electrode. Specific examples of the aprotic organic solvent include dimethyl carbonate (DMC), diethyl carbonate (DEC), diphenyl carbonate, ethyl methyl carbonate (EMC), ethylene carbonate (EC), propylene carbonate (PC), γ-butyrolactone ( Preferred examples include esters such as GBL), γ-valerolactone, and methyl formate (MF), and ethers such as 1,2-dimethoxyethane (DME) and tetrahydrofuran (THF). Among these, propylene carbonate, 1,2-dimethoxyethane, and γ-butyrolactone are preferable as the aprotic organic solvent for the non-aqueous electrolyte of the primary battery, while for the non-aqueous electrolyte of the secondary battery. As the aprotic organic solvent, ethylene carbonate, propylene carbonate, diethyl carbonate, dimethyl carbonate, ethyl methyl carbonate and methyl formate are preferable. Cyclic esters are preferred in that they have a high relative dielectric constant and excellent solubility of the supporting salt, while chain esters and chain ethers have low viscosity, so It is suitable in terms of lowering the viscosity. These aprotic organic solvents may be used alone or in combination of two or more.

  The non-aqueous electrolyte for a battery of the present invention preferably releases 0.03 mol or more, more preferably 0.05 to 0.5 mol, of the above-mentioned combustion-inhibiting substance per liter of the non-aqueous electrolyte during combustion. If the amount of the combustion-suppressing substance released during combustion is less than 0.03 mol per liter of the non-aqueous electrolyte, the flammability of the non-aqueous electrolyte may not be sufficiently suppressed.

  The content of the combustion-inhibiting substance-releasing compound in the non-aqueous electrolyte for batteries of the present invention is preferably 3% by volume or more, and more preferably 5% by volume or more. If the content rate of the combustion-inhibiting substance releasing compound in the non-aqueous electrolyte is 3% by volume or more, the risk of ignition / flammability of the non-aqueous electrolyte can be sufficiently suppressed. In addition, the non-aqueous electrolyte for a battery of the present invention may contain only one kind of the above-mentioned combustion suppressing substance releasing compound, or may contain two or more kinds.

<Nonaqueous electrolyte battery>
Next, the nonaqueous electrolyte battery of the present invention will be described in detail. The non-aqueous electrolyte battery of the present invention includes the above-described non-aqueous electrolyte for a battery, a positive electrode, and a negative electrode, and is usually used in the technical field of non-aqueous electrolyte batteries such as a separator as necessary. Other members are provided.

The positive electrode active material of the non-aqueous electrolyte battery of the present invention is partially different between the primary battery and the secondary battery. For example, as the positive electrode active material of the non-aqueous electrolyte primary battery, fluorinated graphite [(CF _x ) _n ], MnO ₂ (which may be electrochemical synthesis or chemical synthesis), V ₂ O ₅ , MoO ₃ , Ag ₂ CrO ₄ , CuO, CuS, FeS ₂ , SO ₂ , SOCl ₂ , TiS _2, etc. Among these, MnO ₂ and fluorinated graphite are preferable from the viewpoints of high capacity and high safety, and high discharge potential and excellent wettability of the electrolytic solution. These positive electrode active materials may be used individually by 1 type, and may use 2 or more types together.

On the other hand, as the positive electrode active material of the non-aqueous electrolyte secondary battery, metal oxides such as V ₂ O ₅ , V ₆ O ₁₃ , MnO ₂ , MnO ₃ , LiCoO ₂ , LiNiO ₂ , LiMn ₂ O ₄ , LiFeO _{2 are used.} Preferable examples include lithium-containing composite oxides such as LiFePO ₄ , metal sulfides such as TiS ₂ and MoS ₂ , and conductive polymers such as polyaniline. The lithium-containing composite oxide may be a composite oxide containing two or three transition metals selected from the group consisting of Fe, Mn, Co, and Ni. In this case, the composite oxide includes: LiFe _x Co _y Ni (wherein, 0 ≦ x <1,0 ≦ y <1,0 <x + y ≦ 1) (1-xy) O 2, or represented by LiMn _x Fe _y O _2-xy like. Among these, LiCoO ₂ , LiNiO ₂ , and LiMn ₂ O ₄ are particularly preferable in terms of high capacity, high safety, and excellent electrolyte wettability. These positive electrode active materials may be used individually by 1 type, and may use 2 or more types together.

  The negative electrode active material of the nonaqueous electrolyte battery of the present invention is partially different between the primary battery and the secondary battery. For example, as the negative electrode active material of the nonaqueous electrolyte primary battery, lithium metal itself, lithium alloy, etc. Is mentioned. Examples of the metal that forms an alloy with lithium include Sn, Pb, Al, Au, Pt, In, Zn, Cd, Ag, and Mg. Among these, Al, Zn, and Mg are preferable from the viewpoints of rich reserves and toxicity. These negative electrode active materials may be used individually by 1 type, and may use 2 or more types together.

  On the other hand, preferred examples of the negative electrode active material of the non-aqueous electrolyte secondary battery include lithium metal itself, an alloy of lithium and Al, In, Pb or Zn, a carbon material such as graphite doped with lithium, and the like. Among these, a carbon material such as graphite is preferable, and graphite is particularly preferable in view of higher safety and excellent wettability of the electrolytic solution. Here, examples of graphite include natural graphite, artificial graphite, mesophase carbon microbeads (MCMB), and the like, and widely include graphitizable carbon and non-graphitizable carbon. These negative electrode active materials may be used individually by 1 type, and may use 2 or more types together.

  The positive electrode and the negative electrode can be mixed with a conductive agent and a binder as necessary. Examples of the conductive agent include acetylene black, and the binder includes polyvinylidene fluoride (PVDF) and polytetrafluoro. Examples thereof include ethylene (PTFE), styrene / butadiene rubber (SBR), carboxymethyl cellulose (CMC), and the like. These additives can be used at a blending ratio similar to the conventional one.

  Moreover, there is no restriction | limiting in particular as a shape of the said positive electrode and a negative electrode, It can select suitably from well-known shapes as an electrode. For example, a sheet shape, a columnar shape, a plate shape, a spiral shape, and the like can be given.

  Other members that can be used in the non-aqueous electrolyte battery of the present invention include a separator that is interposed between positive and negative electrodes in a role of preventing current short-circuiting due to contact between both electrodes in the non-aqueous electrolyte battery. As the material of the separator, it is possible to reliably prevent contact between the two electrodes and to allow the electrolyte to pass through or to contain, for example, synthesis of polytetrafluoroethylene, polypropylene, polyethylene, cellulose, polybutylene terephthalate, polyethylene terephthalate, etc. Preferred examples include resin nonwoven fabrics and thin layer films. Of these, polypropylene or polyethylene microporous films having a thickness of about 20 to 50 μm, cellulose-based films, polybutylene terephthalate, polyethylene terephthalate, and the like are particularly suitable. In the present invention, in addition to the separators described above, known members that are normally used in batteries can be suitably used.

  The form of the non-aqueous electrolyte battery of the present invention described above is not particularly limited, and various known forms such as a coin-type, button-type, paper-type, square-type or spiral-type cylindrical battery are suitable. Can be mentioned. In the case of the button type, a non-aqueous electrolyte battery can be produced by preparing a sheet-like positive electrode and negative electrode and sandwiching a separator between the positive electrode and the negative electrode. In the case of a spiral structure, for example, a non-aqueous electrolyte battery can be manufactured by preparing a sheet-like positive electrode, sandwiching a current collector, and stacking and winding a sheet-like negative electrode on the current collector. it can.

  Hereinafter, the present invention will be described in more detail with reference to examples. However, the present invention is not limited to the following examples.

(Example 1)
Cyclic phosphazene compound in which ethylene carbonate (EC) 27% by volume, ethyl methyl carbonate (EMC) 63% by volume, and in the above formula (III), n is 3, 1 of 6 R ³ , 1 is an ethoxy group and 5 is fluorine LiPF ₆ (supporting salt) was dissolved in a mixed solution consisting of 10% by volume of A [viscosity at 25 ° C .: 1.2 mPa · s] to 1 mol / L (M) to prepare a nonaqueous electrolytic solution. The safety of the obtained nonaqueous electrolytic solution was evaluated by a method based on the UL94HB method of the above-mentioned UL (Underwriting Laboratory) standard. When the flame ignited in the test exceeded the 100 mm line, it was regarded as “combustible”. Further, the critical oxygen index of the non-aqueous electrolyte and the amount of phosphine oxide compound generated during combustion were measured by the following methods. The results are shown in Table 1.

(1) Limiting oxygen index of electrolyte solution The limiting oxygen index of the electrolyte solution was measured according to JIS K7201. The larger the limiting oxygen index, the more difficult the electrolyte is to burn. Specifically, a SiO ₂ sheet (quartz filter paper, non-combustible) 127 mm × 12.7 mm can be reinforced with a U-shaped aluminum foil so that it can be self-supporting, and the SiO ₂ sheet is impregnated with 1.0 mL of the electrolyte solution, and a test piece Was made. The test piece was perpendicular to the test piece support, and a combustion cylinder (with an inner diameter of 75 mm, a height of 450 mm, and a diameter of 4 mm was uniformly filled with a thickness of 100 ± 5 mm from the bottom, and a metal net was placed thereon. It is attached so that it is located at a distance of 100 mm or more from the upper end of the object), and then oxygen (JIS K 1101 or equivalent) or nitrogen (JIS K 1107 grade 2 or equivalent or more) is attached to the combustion cylinder. The test piece was ignited under predetermined conditions (the heat source was JIS K 2240 Type 1 No. 1), and the combustion state was examined. However, the total flow rate in the combustion cylinder is 11.4 L / min. This test was performed three times, and the average value is shown in Table 2. The oxygen index refers to the value of the minimum oxygen concentration expressed by the volume percent necessary for the material to continue burning. In this application, the test piece burns continuously for 3 minutes or longer, From the minimum oxygen flow rate required for burning 50 mm or more and the nitrogen flow rate at that time, the following formula:
Critical oxygen index = (oxygen flow rate) / [(oxygen flow rate) + (nitrogen flow rate)] × 100 (volume%)
The limiting oxygen index was calculated according to

(2) Amount of phosphine oxide compound generated during combustion In the combustion chamber (30 x 30 x 30 cm), the electrolyte soaked in the non-combustible quartz sheet is ignited at a flame temperature of 800 ° C, and the generated gas is trapped. It was made to adsorb | suck to a collection tube (TenaxTA filling), and analyzed by TDS-GC-MS. The GC uses a DB-5 column (column length 30 m, inner diameter 0.25 mm, film thickness 0.25 μm), column temperature 40 to 300 ° C. (heating rate 25 ° C./min), and MS measurement mass range 5 to 500.

<Preparation of non-aqueous electrolyte secondary battery>
Next, 3 parts by mass of acetylene black (conductive agent) and 3 parts by mass of polyvinylidene fluoride (binder) are added to 94 parts by mass of LiMn ₂ O ₄ (positive electrode active material), and an organic solvent (acetic acid (50/50 mass% mixed solvent of ethyl and ethanol), and then the kneaded product is applied to a 25 μm thick aluminum foil (current collector) with a doctor blade and further dried with hot air (100 to 120 ° C.) Thus, a positive electrode sheet having a thickness of 80 μm was produced. A lithium electrode foil having a thickness of 150 μm was overlapped and wound on the obtained positive electrode sheet via a separator having a thickness of 25 μm (microporous film: made of polypropylene) to produce a cylindrical electrode. The positive electrode length of the cylindrical electrode was about 260 mm. The above electrolytic solution was injected into the cylindrical electrode and sealed to prepare an AA lithium battery (non-aqueous electrolyte secondary battery). After the initial battery characteristics (voltage, internal resistance) of the obtained battery were measured at 20 ° C., the cycle characteristics and low temperature characteristics of the battery were evaluated by the following methods. The results are shown in Table 1.

(3) Battery cycle characteristics
Under an environment of 20 ° C, charge and discharge were repeated up to 50 cycles under the conditions of an upper limit voltage of 4.5 V, a lower limit voltage of 3.0 V, a discharge current of 100 mA, and a charge current of 50 mA. The following formula:
Capacity remaining rate S = discharge capacity after 50 cycles / initial discharge capacity × 100 (%)
The capacity remaining rate S was calculated according to the above, and used as an index of the battery cycle characteristics.

(4) Low temperature characteristics of the battery
Repeated charging and discharging up to 50 cycles under conditions of upper limit voltage 4.5V, lower limit voltage 3.0V, discharge current 100mA, charge current 50mA in each environment of 20 ℃ and -10 ℃, and measured discharge capacity after 50 cycles did. From the discharge capacity after 50 cycles at 20 ° C and the discharge capacity after 50 cycles at -10 ° C, the following formula:
Capacity remaining rate L = discharge capacity (−10 ° C.) / Discharge capacity (20 ° C.) × 100 (%)
The capacity remaining rate L was calculated according to the above and used as an index of the low temperature characteristics of the battery.

(Example 2)
Instead of the cyclic phosphazene compound A, the cyclic phosphazene compound B [in the formula (III), the viscosity at 25 ° C. of the cyclic phosphazene compound in which n is 3, 2 out of 6 R ³ are ethoxy groups and 4 are fluorines : 1.2 mPa · s], a non-aqueous electrolyte was prepared in the same manner as in Example 1, and the safety of the non-aqueous electrolyte and the amount of phosphine oxide compound generated were evaluated and measured. Further, using the non-aqueous electrolyte, a non-aqueous electrolyte secondary battery was produced in the same manner as in Example 1, and the performance of the battery was evaluated. The results are shown in Table 1.

(Example 3)
In place of the cyclic phosphazene compound A, a cyclic phosphazene compound C [in the formula (III), n is 3, 1 of 6 R ³ is a phenoxy group (PhO-) and 5 is fluorine] A non-aqueous electrolyte and a non-aqueous electrolyte secondary battery were prepared and evaluated in the same manner as in Example 1 except that the viscosity at 25 ° C .: 1.7 mPa · s (1.7 cP)] was used. The results are shown in Table 1.

(Comparative Example 1)
LiPF ₆ (supporting salt) is dissolved in a mixed solution composed of 30% by volume of ethylene carbonate (EC) and 70% by volume of ethyl methyl carbonate (EMC) so as to be 1 mol / L (M), and a non-aqueous electrolyte is obtained. Prepared and evaluated as in Example 1. Further, a non-aqueous electrolyte secondary battery was produced and evaluated in the same manner as in Example 1 using the non-aqueous electrolyte. The results are shown in Table 1.

In Examples 1 to 3, a phosphine oxide compound having a P—F bond and / or a P—NH ₂ bond is generated in the molecule during combustion of the non-aqueous electrolyte, and the combustibility of the non-aqueous electrolyte is suppressed. I understand that. Moreover, the non-aqueous electrolyte batteries of Examples 1 to 3 had sufficient characteristics as batteries.

Claims (18)

A non-aqueous electrolyte additive for a battery containing a combustion-suppressing substance releasing compound that releases a combustion-suppressing substance upon combustion, wherein the combustion-suppressing substance has a PF bond and / or a P-NH ₂ bond in the molecule. A non-aqueous electrolyte additive for a battery, which is an oxide compound.   The additive for a non-aqueous electrolyte for a battery according to claim 1, wherein the combustion-suppressing substance is at least one of a self-extinguishing substance, a flame-retardant substance, and a non-flammable substance. The phosphine oxide compound is represented by the following formula (I):
O = PR ¹ ₃ ... (I)
2. wherein R ¹ is independently a monovalent substituent or a halogen element, and at least one R ¹ is fluorine or an amino group. Additive for non-aqueous electrolyte of batteries. R ¹ in the formula (I) is independently selected from the group consisting of fluorine, amino group, alkyl group and alkoxy group, and at least one R ¹ is fluorine or amino group. The additive for non-aqueous electrolyte of a battery according to claim 3. 5. The non-aqueous electrolyte for a battery according to claim 4, wherein at least one of R ¹ in the formula (I) is fluorine and at least one of R ^{1 in} the formula (I) is an amino group. Additives. The additive for a non-aqueous electrolyte for a battery according to claim 4, wherein R ¹ in the formula (I) is independently a fluorine or an amino group.   The additive for a non-aqueous electrolyte for a battery according to claim 1, wherein the combustion-inhibiting substance releasing compound contains phosphorus and fluorine and / or nitrogen in the molecule.   The additive for a non-aqueous electrolyte for a battery according to claim 7, wherein the combustion-inhibiting substance-releasing compound has a phosphorus-nitrogen bond in the molecule.   The additive for a non-aqueous electrolyte for a battery according to claim 8, wherein the combustion-suppressing substance-releasing compound has a phosphorus-nitrogen double bond in the molecule.   The additive for a non-aqueous electrolyte for a battery according to claim 7, wherein the combustion-inhibiting substance-releasing compound has a phosphorus-fluorine bond in the molecule.   The additive for a non-aqueous electrolyte for a battery according to claim 8, wherein the combustion-inhibiting substance releasing compound is a phosphazene compound or an isomer of a phosphazene compound.   A battery non-aqueous electrolyte comprising the battery non-aqueous electrolyte additive according to claim 1 and a supporting salt.   The nonaqueous electrolytic solution for a battery according to claim 12, further comprising an aprotic organic solvent.   The non-aqueous electrolyte for a battery according to claim 13, wherein the aprotic organic solvent contains a cyclic or chain ester compound or a chain ether compound.   The nonaqueous electrolytic solution for a battery according to claim 12, wherein 0.03 mol or more of a combustion inhibiting substance is released per liter of the nonaqueous electrolytic solution for a battery during combustion.   The nonaqueous electrolytic solution for a battery according to claim 12, comprising 3% by volume or more of the combustion suppressing substance releasing compound.   The non-aqueous electrolyte for a battery according to claim 16, comprising 5% by volume or more of the combustion-suppressing substance releasing compound.   The nonaqueous electrolyte battery provided with the nonaqueous electrolyte for batteries according to any one of claims 12 to 17, a positive electrode, and a negative electrode.