JP2005190873A - Nonaqueous electrolyte for battery, and nonaqueous electrolyte battery equipped with it - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a nonaqueous electrolyte for a battery, capable of reducing the risk of firing and flashing of an aprotic organic solvent remaining in the battery and an aprotic organic solvent leaking to the outside of the battery, by evaporating or the like when the temperature of the battery abnormally rises. <P>SOLUTION: This nonaqueous electrolyte for a battery contains one or more kinds of aprotic organic solvents and a support electrolyte. The electrolyte is characterized by containing, in each aprotic organic solvent, a compound for which a difference of a boiling point from that of the aprotic organic solvent is below 25°C and which has phosphorus and/or nitrogen in molecules. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a battery non-aqueous electrolyte and a non-aqueous electrolyte battery including the same, and more particularly to a battery non-aqueous electrolyte in which the risk of ignition in an emergency is greatly reduced.

  In recent years, there has been a demand for a light, 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 battery non-aqueous electrolyte to which the phosphazene compound is added has greatly reduced the risk of ignition and ignition, but the phosphazene compound is aprotic when the temperature of the battery rises during an emergency such as a short circuit. When vaporized before the organic solvent, the remaining aprotic organic solvent was vaporized and decomposed alone to generate gas, or the battery was ruptured and ignited by the generated gas and heat. The risk of sparks igniting aprotic organic solvents cannot be eliminated. Further, when the aprotic organic solvent is vaporized prior to the phosphazene compound, the vaporized aprotic organic solvent may leak out of the battery and ignite.

  Therefore, the object of the present invention is to ignite and ignite the aprotic organic solvent remaining in the battery and the aprotic organic solvent leaking out of the battery due to vaporization when the temperature of the battery rises abnormally. An object of the present invention is to provide a non-aqueous electrolyte for batteries with reduced risk. Another object of the present invention is to provide a non-aqueous electrolyte battery comprising such a non-aqueous electrolyte and having reduced risk of ignition and the like inside and outside the battery even if the temperature rises abnormally. There is.

  As a result of intensive studies to achieve the above object, the inventors of the present invention, in a battery non-aqueous electrolyte containing at least one aprotic organic solvent, further corresponding to each aprotic organic solvent, Risk of ignition or ignition of aprotic organic solvent remaining in the battery and aprotic organic solvent leaking out of the battery due to vaporization, etc. by adding phosphorus and / or nitrogen-containing compounds having close boiling points Has been found to be significantly reduced, and the present invention has been completed.

  That is, the battery non-aqueous electrolyte of the present invention is a battery non-aqueous electrolyte containing at least one aprotic organic solvent and a supporting salt. A difference in boiling point from the protic organic solvent is 25 ° C. or less, and each compound contains phosphorus and / or nitrogen in the molecule.

  In a preferred example of the battery non-aqueous electrolyte of the present invention, the compound having phosphorus and / or nitrogen in the molecule has a phosphorus-nitrogen double bond. Here, as the compound having phosphorus and / or nitrogen in the molecule and having a phosphorus-nitrogen double bond, a phosphazene compound is particularly preferable.

  In another preferred embodiment of the battery non-aqueous electrolyte of the present invention, the aprotic organic solvent is selected from the group consisting of ethylene carbonate, propylene carbonate, diethyl carbonate, dimethyl carbonate, ethyl methyl carbonate, and methyl formate. Is at least one kind. The non-aqueous electrolyte is particularly suitable as an electrolyte for a non-aqueous electrolyte secondary battery.

  In another preferred embodiment of the battery non-aqueous electrolyte of the present invention, the aprotic organic solvent is at least one selected from the group consisting of propylene carbonate, 1,2-dimethoxyethane and γ-butyrolactone. The non-aqueous electrolyte is particularly suitable as an electrolyte for a non-aqueous electrolyte primary battery.

  Moreover, the non-aqueous electrolyte battery of the present invention includes the above-described non-aqueous electrolyte, a positive electrode, and a negative electrode.

  According to the present invention, the battery-containing non-aqueous electrolyte containing at least one aprotic organic solvent is further provided with phosphorus and / or nitrogen-containing compounds having close boiling points corresponding to the respective aprotic organic solvents, respectively. By adding, it is possible to provide a non-aqueous electrolyte for a battery that greatly reduces the risk of ignition and ignition of an aprotic organic solvent remaining in the battery or leaking out of the battery. In addition, it is possible to provide a non-aqueous electrolyte battery that includes such a non-aqueous electrolyte and that greatly reduces the risk of ignition and the like inside and outside the battery even if the temperature rises abnormally.

<Non-aqueous electrolyte for batteries>
Below, the nonaqueous electrolyte for batteries of the present invention will be described in detail. The non-aqueous electrolyte for a battery of the present invention contains at least one aprotic organic solvent and a supporting salt, and further has a difference in boiling point between each of the aprotic organic solvents of 25 ° C. or less and phosphorus in the molecule. And / or a compound having nitrogen.

  In the nonaqueous electrolyte for battery of the present invention, the compound having phosphorus and / or nitrogen in the molecule generates nitrogen gas and / or phosphate ester, etc., and the nonaqueous electrolyte is made nonflammable, flame retardant or self Fire extinguishing has the effect of reducing the risk of battery ignition and the like. However, when the non-aqueous electrolyte containing the aprotic organic solvent does not contain phosphorus and / or nitrogen-containing compounds having a boiling point close to that of the aprotic organic solvent, the aprotic organic solvent is in either the gas phase or the liquid phase. Because of the wide temperature range where phosphorus and / or nitrogen-containing compounds do not coexist, when the battery temperature rises abnormally, ignition of the aprotic organic solvent vaporized or the aprotic organic solvent remaining in the battery The risk of ignition cannot be reduced. In contrast, the battery non-aqueous electrolyte of the present invention contains an aprotic organic solvent and a phosphorus and / or nitrogen-containing compound having a boiling point close to that of the aprotic organic solvent, and the battery temperature rises abnormally. In addition, since the aprotic organic solvent and the phosphorus and / or nitrogen-containing compound are vaporized at a temperature close to the aprotic organic solvent, the aprotic organic solvent is present in both a liquid state and a gas state. And phosphorus and / or nitrogen-containing compounds coexist, and as a result, the risk of non-aqueous electrolyte ignition and ignition is greatly reduced.

  Further, for example, when the non-aqueous electrolyte for a battery of the present invention contains a low-boiling aprotic organic solvent and a high-boiling aprotic organic solvent, the temperature at which the low-boiling aprotic organic solvent vaporizes is reduced. Since the corresponding phosphorus and / or nitrogen-containing compound is vaporized in the vicinity, the risk of ignition and ignition of the vaporized aprotic organic solvent can be reduced. In addition, after the low boiling point aprotic organic solvent and the phosphorus and / or nitrogen-containing compound having a boiling point close to that of the low boiling point aprotic organic solvent are vaporized, together with the high boiling point aprotic organic solvent, the high boiling point Since phosphorus and / or nitrogen-containing compounds having a boiling point close to that of the aprotic organic solvent are present in the electrolytic solution, the risk of ignition and ignition of the remaining nonaqueous electrolytic solution can also be reduced.

  The battery non-aqueous electrolyte of the present invention contains at least one aprotic organic solvent. The aprotic organic solvent can keep the viscosity of the non-aqueous electrolyte low 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 battery non-aqueous electrolyte of the present invention contains a supporting salt. The supporting salt is preferably a supporting salt that serves as an ion source for lithium ions. 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 battery non-aqueous electrolyte of the present invention is preferably 0.2 to 1.5 mol / L (M), more preferably 0.5 to 1 mol / L (M). When the concentration of the supporting salt is less than 0.2 mol / L (M), the conductivity of the electrolytic solution cannot be sufficiently ensured, and the discharge characteristics and charging characteristics of the battery may be hindered, and 1.5 mol / L ( (M) exceeds the viscosity of the electrolyte and the mobility of lithium ions cannot be sufficiently secured, so that the conductivity of the electrolyte cannot be sufficiently secured as described above. May cause trouble.

  The nonaqueous electrolytic solution for a battery of the present invention contains a compound having a boiling point difference of 25 ° C. or less and phosphorus and / or nitrogen in the molecule, with an aprotic organic solvent contained in the electrolytic solution. When the difference in boiling point between the aprotic organic solvent and the phosphorus and / or nitrogen-containing compound contained in the non-aqueous electrolyte exceeds 25 ° C, the aprotic organic solvent is vaporized first, and the gaseous aprotic organic solvent Is ignited, and phosphorus and / or nitrogen-containing compounds are vaporized first, and the remaining liquid aprotic organic solvent is ignited. Here, from the viewpoint of further reducing the risk of ignition of the aprotic organic solvent, the difference in boiling point between the aprotic organic solvent and the compound having phosphorus and / or nitrogen in the molecule is 20 ° C. or less. preferable. The non-aqueous electrolyte for a battery of the present invention may contain at least a phosphorus and / or nitrogen-containing compound having a boiling point of 25 ° C. or less from each of the aprotic organic solvents, and the difference in boiling point is 25. Phosphorus and / or nitrogen-containing compounds that exceed ° C. may further be included.

  Examples of the compound having phosphorus and / or nitrogen in the molecule include compounds having phosphorus in the molecule such as phosphate ester compounds, polyphosphate ester compounds, and condensed phosphate ester compounds; triazine compounds, guanidine compounds, pyrrolidine compounds, etc. Compound having nitrogen in molecule; and composite of phosphazene compound, isomer of phosphazene compound, phosphazane compound, compound exemplified as compound having phosphorus in molecule and compound exemplified as compound having nitrogen in molecule Examples thereof include compounds having phosphorus and nitrogen in the molecule such as compounds. Note that the compound having phosphorus and nitrogen in the molecule is also an example of a compound having phosphorus in the molecule and a compound having nitrogen in the molecule. The phosphorus and / or nitrogen-containing compound is appropriately selected according to the aprotic organic solvent used in the electrolytic solution.

  Among the compounds containing phosphorus and / or nitrogen in the molecule, compounds having phosphorus and nitrogen in the molecule are preferable from the viewpoint of the cycle characteristics of the secondary battery. Among the compounds having phosphorus and nitrogen in the molecule, compounds having a phosphorus-nitrogen double bond such as a phosphazene compound are particularly preferable from the viewpoint of improving the thermal stability of the battery and improving the high-temperature storage characteristics.

（式中、Ｒ¹、Ｒ²及びＲ³は、夫々独立して一価の置換基又はハロゲン元素を表し；Ｘ¹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し；Ｙ¹、Ｙ²及びＹ³は、夫々独立して２価の連結基、２価の元素又は単結合を表す。）

(ＮＰＲ⁴ ₂)_n ・・・ (II)
（式中、Ｒ⁴は夫々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。） Specific examples of the phosphazene compound include a chain phosphazene compound represented by the following formula (I) and a cyclic phosphazene compound represented by the following formula (II).

(Wherein R ¹ , R ² and R ³ each independently represents a monovalent substituent or a halogen element; X ¹ represents carbon, silicon, germanium, tin, nitrogen, phosphorus, arsenic, antimony, bismuth) And represents a substituent containing at least one element selected from the group consisting of oxygen, sulfur, selenium, tellurium and polonium; Y ¹ , Y ² and Y ³ are each independently a divalent linking group, divalent Represents an element or a single bond.)

(NPR ⁴ ₂ ) _n ... (II)
(In the formula, each R ⁴ independently represents a monovalent substituent or a halogen element; n represents 3 to 15)

  Among the phosphazene compounds represented by formula (I) or formula (II), 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 viscometer [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 low temperature conditions such as below the freezing point. Further, since these phosphazene compounds are in a liquid state, they have the same conductivity as that of a normal liquid electrolyte, and exhibit excellent cycle characteristics when used in an electrolyte solution for a secondary battery.

In the formula (I), R ¹ , R ² and R ³ are not particularly limited as long as they are monovalent substituents or halogen elements. 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 because the viscosity of the electrolytic solution can be reduced. On the other hand, preferred examples of the halogen element include fluorine, chlorine, bromine and the like. R ^{1 to} R ³ may all be the same type of substituent, and some of them may be different types of substituents. Here, examples of the alkoxy group include a methoxy group, an ethoxy group, a propoxy group, a butoxy group, and an alkoxy-substituted alkoxy group such as a methoxyethoxy group and a methoxyethoxyethoxy group. Among these, a methoxy group, An ethoxy group, a methoxyethoxy group, and a methoxyethoxyethoxy group are preferable, and a methoxy group or an ethoxy group is particularly 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.

In the formula (I), examples of the divalent linking group represented by Y ¹ , Y ² and Y ³ include CH ₂ group, oxygen, sulfur, selenium, nitrogen, 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, iron, cobalt, And divalent linking groups containing at least one element selected from the group consisting of nickel. Among these, at least one element selected from the group consisting of CH ₂ groups and oxygen, sulfur, selenium, and nitrogen is included. A divalent linking group containing a seed is preferred, and a divalent linking group containing a sulfur and / or selenium element is particularly preferred. Y ¹ , Y ² and Y ³ may be a divalent element such as oxygen, sulfur or selenium, or a single bond. Y ^{1 to} Y ³ may all be the same type, or some of them may be different types.

［式(III)、式(IV)及び式(V)において、Ｒ⁵〜Ｒ⁹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；Ｙ⁵〜Ｙ⁹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。］ In the formula (I), X ¹ is a substituent containing at least one element selected from the group consisting of carbon, silicon, nitrogen, phosphorus, oxygen, and sulfur from the viewpoint of toxicity, environment, and the like. preferable. Of these substituents, substituents having a structure represented by the following formula (III), formula (IV) or formula (V) are more preferred.

[In Formula (III), Formula (IV) and Formula (V), R ^{5 to} R ⁹ each independently represents a monovalent substituent or a halogen element; Y ^{5 to} Y ⁹ each independently represents a divalent group. A linking group, a divalent element or a single bond; Z represents a divalent group or a divalent element. ]

In formula (III), formula (IV) and formula (V), R ^{5 to} R ⁹ are the same monovalent substituents or halogen elements as those described for R ^{1 to} R ³ in formula (I). Any of these is preferably mentioned. In addition, these may be the same type within the same substituent, or some of them may be different from each other. R ⁵ and R ^{6 in} formula (III) and R ⁸ and R ^{9 in} formula (V) may be bonded to each other to form a ring.

In the formula (III), formula (IV) and formula (V), the group represented by Y ^{5 to} Y ⁹ is a divalent linkage similar to that described for Y ^{1 to} Y ³ in the formula (I). In the same manner, a group containing a sulfur and / or selenium element is particularly preferable because the risk of ignition and ignition of the electrolyte is reduced. These may be the same type within the same substituent, or some of them may be different from each other.

In the formula (III), as Z, for example, CH ₂ group, CHR (R represents an alkyl group, an alkoxyl group, a phenyl group, etc .; the same shall apply hereinafter) group, 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, Examples include divalent groups containing at least one element selected from the group consisting of polonium, tungsten, iron, cobalt and nickel. Among these, in addition to CH ₂ groups, CHR groups, NR groups, oxygen, sulfur A divalent group containing at least one element selected from the group consisting of selenium is preferred. 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 reduced. Z may be a divalent element such as oxygen, sulfur, or selenium.

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

In the formula (II), R ⁴ is not particularly limited as long as it is a monovalent substituent or a halogen element. 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 because the viscosity of the electrolytic solution can be reduced. On the other hand, preferred examples of the halogen element include fluorine, chlorine, bromine and the like. Here, examples of the alkoxy group include a methoxy group, an ethoxy group, a methoxyethoxy group, a propoxy group, a phenoxy group, and the like. Among these, when used for a non-aqueous electrolyte primary battery, a methoxy group and an ethoxy group. N-propoxy group and phenoxy group are particularly preferable, and when used in a non-aqueous electrolyte secondary battery, a methoxy group, an ethoxy group, a methoxyethoxy group, and a phenoxy group are particularly preferable. 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. Examples of the substituent substituted with a fluorine atom include Examples thereof include a trifluoroethoxy group.

By appropriately selecting R ^{1 to} R ⁹ , Y ^{1 to} Y ³ , Y ^{5 to} Y ⁹ , and Z in the formulas (I) to (V), it has more suitable viscosity, solubility suitable for addition / mixing, and the like. The electrolytic solution can be prepared. These phosphazene compounds may be used alone or in combination of two or more.

Among the phosphazene compounds of the above formula (II), from the viewpoint of reducing the electrolyte solution viscosity to improve the low temperature characteristics of the battery, and further improving the deterioration resistance and safety of the electrolyte solution, it is represented by the following formula (VI). Preferred are phosphazene compounds.

(NPF ₂ ) _n ... (VI)
(In the formula, n represents 3 to 13.)

  The phosphazene compound represented by the formula (VI) is a low-viscosity liquid at room temperature (25 ° C.) and has a freezing point lowering action. For this reason, by adding the phosphazene compound of the formula (VI) to the electrolytic solution, it is possible to impart excellent low-temperature characteristics to the electrolytic solution. It is possible to provide a nonaqueous electrolyte battery having high conductivity. For this reason, it is possible to provide a nonaqueous electrolyte battery that exhibits excellent discharge characteristics over a long period of time even when used under low temperature conditions, particularly in regions and times when the temperature is low.

  In the formula (VI), n is preferably 3 to 5, more preferably 3 to 4, and particularly preferably 3 in that it can impart excellent low-temperature characteristics to the electrolyte and can reduce the viscosity of the electrolyte. preferable. When the value of n is small, the boiling point is low, and the ignition prevention property at the time of flame contact can be improved. On the other hand, since the boiling point increases as the value of n increases, it can be used stably even at high temperatures. A plurality of phosphazenes can be selected and used in a timely manner in order to obtain the desired performance using the above properties.

  By appropriately selecting the n value in the formula (VI), it is possible to prepare an electrolytic solution having a more suitable viscosity, solubility suitable for mixing, low temperature characteristics, and the like. These phosphazene compounds may be used alone or in combination of two or more.

  The viscosity of the phosphazene compound represented by the formula (VI) is not particularly limited as long as it is 20 mPa · s or less, but is preferably 10 mPa · s or less from the viewpoint of improving conductivity and improving low-temperature characteristics, and 5 mPa · s. -S or less is more preferable.

Among the phosphazene compounds of the above formula (II), the phosphazene compounds represented by the following formula (VII) are preferable from the viewpoint of improving the deterioration resistance and safety of the electrolytic solution.

(NPR ¹⁰ ₂ ) _n ... (VII)
(In the formula, each R ¹⁰ independently represents a monovalent substituent or fluorine, at least one of all R ¹⁰ is a monovalent substituent or fluorine containing fluorine, and n represents 3 to 8) (However, not all R ¹⁰ are fluorine.)

If the phosphazene compound of the above formula (II) is contained, the electrolyte solution can be given excellent self-extinguishing properties or flame retardancy, and the safety of the electrolyte solution can be improved, but is represented by the formula (VII), If at least one of all R ¹⁰ contains a phosphazene compound which is a monovalent substituent containing fluorine, it is possible to impart superior safety to the electrolytic solution. Furthermore, if a phosphazene compound represented by the formula (VII) and at least one of all R ¹⁰ is fluorine is contained, further excellent safety can be imparted. That is, as compared with a phosphazene compound not containing fluorine, a phosphazene compound represented by the formula (VII), in which at least one of all R ¹⁰ is a monovalent substituent containing fluorine or fluorine, makes the electrolyte more difficult to burn. There is an effect, and it is possible to give further excellent safety to the electrolytic solution.

  Examples of the monovalent substituent in the formula (VII) include an alkoxy group, an alkyl group, an acyl group, an aryl group, and a carboxyl group, and an alkoxy group is preferable because it is particularly excellent in improving the safety of the electrolytic solution. is there. Here, examples of the alkoxy group include a methoxy group, an ethoxy group, an n-propoxy group, an i-propoxy group, a butoxy group, an alkoxy group-substituted alkoxy group such as a methoxyethoxy group, and the like. A methoxy group, an ethoxy group, and an n-propoxy group are particularly preferable in terms of excellent improvement in the above. Moreover, a methoxy group is preferable in terms of reducing the viscosity of the electrolytic solution.

  In the formula (VII), n is preferably 3 to 5 and more preferably 3 to 4 in that it can impart excellent safety to the electrolytic solution.

The monovalent substituent is preferably substituted with fluorine, and when at least one R ^{10 in} formula (VII) is not fluorine, at least one monovalent substituent contains fluorine.

  The fluorine content in the phosphazene compound of the formula (VII) is preferably 3 to 70% by mass, more preferably 7 to 45% by mass. If the fluorine content is 3 to 70% by mass, “excellent safety” can be particularly suitably imparted to the electrolytic solution.

  The phosphazene compound of the formula (VII) may contain a halogen element such as chlorine and bromine in addition to the above-mentioned fluorine. However, fluorine is most preferred, followed by chlorine. Those containing fluorine tend to have a greater effect of improving the cycle characteristics of the secondary battery than those containing chlorine.

By appropriately selecting R ¹⁰ and n value in the formula (VII), it is possible to prepare an electrolytic solution having more suitable safety, viscosity, solubility suitable for mixing, and the like. These phosphazene compounds may be used alone or in combination of two or more.

  The viscosity of the phosphazene compound of the formula (VII) is not particularly limited as long as it is 20 mPa · s or less, but is preferably 10 mPa · s or less, and 5 mPa · s or less from the viewpoint of improving conductivity and improving low-temperature characteristics. Is more preferable.

Among the phosphazene compounds of the above formula (II), from the viewpoint of improving the deterioration resistance and safety of the electrolytic solution while suppressing the increase in the viscosity of the electrolytic solution, it is solid at 25 ° C. (room temperature) and has the following formula: A phosphazene compound represented by (VIII) is also preferred.

(NPR ¹¹ ₂ ) _n ... (VIII)
(In the formula, each R ¹¹ independently represents a monovalent substituent or a halogen element; n represents 3 to 6)

  Since the phosphazene compound represented by the formula (VIII) is solid at room temperature, when added to the electrolyte, it dissolves in the electrolyte and increases the viscosity of the electrolyte. However, if the addition amount is a predetermined amount, the rate of increase in the viscosity of the electrolyte is low, and a nonaqueous electrolyte battery having low internal resistance and high conductivity is obtained. Further, since the phosphazene compound of the formula (VIII) is dissolved in the electrolytic solution, the long-term stability of the electrolytic solution is excellent.

In the formula (VIII), R ¹¹ is not particularly limited as long as it is a monovalent substituent or a halogen element. Here, preferred examples of the monovalent substituent include an alkoxy group, an alkyl group, a carboxyl group, an acyl group, and an aryl group, and preferred examples of the halogen element include fluorine, chlorine, bromine, and iodine. . Among these, an alkoxy group is preferable in that an increase in the viscosity of the electrolytic solution can be suppressed. The alkoxy group is preferably a methoxy group, an ethoxy group, a methoxyethoxy group, a propoxy group (i-propoxy group, n-propoxy group), a phenoxy group, a trifluoroethoxy group, or the like, and can suppress an increase in the viscosity of the electrolytic solution. In this respect, a methoxy group, an ethoxy group, a propoxy group (i-propoxy group, n-propoxy group), a phenoxy group, a trifluoroethoxy group, and the like are more preferable. The monovalent substituent preferably contains the aforementioned halogen element.

  In the formula (VIII), n is particularly preferably 3 or 4 from the viewpoint of suppressing an increase in the viscosity of the electrolytic solution.

The phosphazene compounds of the formula (VIII), the structure R ¹¹ in formula (VIII) is an n-a methoxy group 3, be at least one R ¹¹ is a methoxy group and phenoxy group in formula (VIII) a structure in which n is 4, a structure in which R ¹¹ is an ethoxy group and n is 4 in formula (VIII), and a structure in which R ¹¹ is an i-propoxy group and n is 3 or 4 in formula (VIII) A structure in which R ¹¹ is an n-propoxy group and n is 4 in formula (VIII), a structure in which R ¹¹ is a trifluoroethoxy group and n is 3 or 4 in formula (VIII), ), A structure in which R ¹¹ is a phenoxy group and n is 3 or 4 is particularly preferable in that an increase in the viscosity of the electrolytic solution can be suppressed.

  By appropriately selecting each substituent and n value in the formula (VIII), it is possible to prepare an electrolytic solution having a more suitable viscosity, solubility suitable for mixing, and the like. These phosphazene compounds may be used alone or in combination of two or more.

［式(IX)及び(X)において、Ｒ¹²、Ｒ¹³及びＲ¹⁴は、夫々独立して一価の置換基又はハロゲン元素を表し；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より選ばれる元素の少なくとも１種を含む置換基を表し；Ｙ¹²及びＹ¹³は、夫々独立して２価の連結基、２価の元素又は単結合を表す。］ Specific examples of the isomers of the phosphazene compound include compounds represented by the following formula (IX). The compound of formula (IX) is an isomer of a phosphazene compound represented by the following formula (X).

[In the formulas (IX) and (X), R ¹² , R ¹³ and R ¹⁴ each independently represents a monovalent substituent or a halogen element; X ² represents carbon, silicon, germanium, tin, nitrogen, Represents a substituent containing at least one element selected from the group consisting of phosphorus, arsenic, antimony, bismuth, oxygen, sulfur, selenium, tellurium and polonium; Y ¹² and Y ¹³ each independently represent a divalent linkage Represents a divalent element or a single bond. ]

R ¹² , R ¹³ and R ¹⁴ in formula (IX) are not particularly limited as long as they are monovalent substituents or halogen elements, and are the same as those described for R ^{1 to} R ³ in formula (I) above. Suitable examples include monovalent substituents and halogen elements. In the formula (IX), the divalent linking group or divalent element represented by Y ¹² and Y ¹³ may be the same divalent as described for Y ^{1 to} Y ³ in the formula (I). Suitable examples include a linking group or a divalent element. Further, in the formula (IX), as the substituent represented by X ² , any of the same substituents as those described for X ¹ in the formula (I) can be preferably exemplified.

  The isomer of the phosphazene compound represented by the formula (IX) and represented by the formula (X) can exhibit extremely low temperature characteristics in the electrolyte when added to the electrolyte. Deterioration resistance and safety can be improved.

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

  Specific examples of the phosphate ester include alkyl phosphates such as triphenyl phosphate, tricresyl phosphate, tris (fluoroethyl) phosphate, tris (trifluoroneopentyl) phosphate, alkoxy phosphate, and derivatives thereof.

  In the nonaqueous electrolytic solution for a battery of the present invention, the content of the compound containing phosphorus and / or nitrogen in the molecule is preferably 3% by volume or more, and 5% by volume or more from the viewpoint of improving the safety of the electrolytic solution. Is more preferable.

<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 in the same mixing ratio as in the past. Specifically, in the case of a positive electrode of a primary battery, the mass ratio of positive electrode active material: binder: conductive agent is 8: 1: 0.2. ~ 8: 1: 1 is preferable, and in the case of a positive electrode and a negative electrode of a secondary battery, the mass ratio of active material: binder: conductive agent is preferably 94: 3: 3.

  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.

  As another member used in the nonaqueous electrolyte battery of the present invention, a separator interposed in the nonaqueous electrolyte battery between the positive and negative electrodes to prevent a short circuit of current due to contact of both electrodes can be mentioned. 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 non-woven 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 up 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)
Ethylene carbonate (EC, boiling point 238 ° C.) 50% by volume, diethyl carbonate (DEC, boiling point 127 ° C.) 40% by volume, additive A [in formula (II), n is 3 and 3 of 6 R ⁴ A cyclic phosphazene compound having one methoxy group (CH ₃ O—) and three fluorines, viscosity at 25 ° C .: 3.9 mPa · s, boiling point 230 ° C., 5% by volume and additive B [in the formula (II), n is 3 A cyclic phosphazene compound in which one of the six R ⁴ groups is an ethoxy group (CH ₃ CH ₂ O—) and five are fluorine, viscosity at 25 ° C .: 1.2 mPa · s, boiling point 125 ° C.] from 5% by volume A non-aqueous electrolyte was prepared by dissolving LiPF ₆ (supporting salt) at a concentration of 1 mol / L (M) in the mixed solution. Moreover, the safety | security of the obtained non-aqueous electrolyte was evaluated by the following method. The results are shown in Table 1.

(1) Safety of electrolyte solution The safety of the non-aqueous electrolyte solution was evaluated from the combustion behavior of flames ignited in an atmospheric environment by the method of arranging the UL94HB method of UL (Underwriting Laboratory) standard. At that time, ignitability, combustibility, formation of carbides, and secondary ignition phenomena were also observed. Specifically, based on the UL test standard, a non-combustible quartz fiber was impregnated with 1.0 mL of the electrolytic solution, and a test piece of 127 mm × 12.7 mm was produced. Here, when the test flame does not ignite the test piece (combustion length: 0 mm), it is “non-flammable”, and when the ignited flame does not reach the 25 mm line and the fallen object is not ignited, “flame retardant” The case where the ignited flame was extinguished on the 25 to 100 mm line and the fallen object was not ignited was evaluated as “self-extinguishing”, and the case where the ignited flame exceeded the 100 mm line was evaluated as “combustible”.

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), kneaded product was coated on aluminum foil (current collector) with a thickness of 25μm with a doctor blade, and dried with hot air (100 ~ 120 ℃) Thus, a positive electrode sheet having a thickness of 80 μm was produced.

  A 150 μm-thick lithium metal foil was overlapped and wound on the positive electrode sheet via a 25 μm-thick separator (microporous film: made of polypropylene) to produce a cylindrical electrode. The positive electrode length of the cylindrical electrode was about 260 mm. The electrolyte was poured into the cylindrical electrode and sealed to prepare an AA lithium battery (non-aqueous electrolyte secondary battery). The obtained battery was subjected to a nail penetration test and an overcharge test by the following methods. The results are shown in Table 1.

(2) Nail penetration test After fully charging the test battery, a nail with a diameter of 5 mm penetrates in the middle of the battery in the direction perpendicular to the electrode surface and is allowed to stand for 24 hours. Observed whether or not.

(3) Overcharge test
The test battery was overcharged to 250% of the rated capacity with a current value of 1C (current value that reached full charge in 1 hour), and whether or not the battery ignited was observed. However, a safety circuit is not included with the test battery.

(Examples 2-9 and Comparative Examples 1-6)
A mixed solution having the composition shown in Table 1 or 2 was prepared, and LiPF ₆ (supporting salt) was dissolved in the mixed solution at a concentration of 1 mol / L (M) to prepare a non-aqueous electrolyte. The safety of the obtained nonaqueous electrolytic solution was evaluated in the same manner as in Example 1. Further, a non-aqueous electrolyte secondary battery was produced using the non-aqueous electrolyte in the same manner as in Example 1, and a nail penetration test and an overcharge test were performed on the battery. The results are shown in Tables 1 and 2.

  In Tables 1 and 2, PC is propylene carbonate (boiling point 242 ° C.), DMC is dimethyl carbonate (boiling point 90 ° C.), EMC is ethyl methyl carbonate (boiling point 108 ° C.), and MF is methyl formate (boiling point). 32 ° C).

Additive C is a cyclic phosphazene compound (viscosity at 25 ° C .: 0.8 mPa · s, boiling point 86 ° C.) in which n is 4 and all 8 R ⁴ are fluorine in formula (II). Yes; additive D is a cyclic phosphazene compound (viscosity at 25 ° C .: 0.8 mPa · s, boiling point 51 ° C.) in which n is 3 and all six R ⁴ are fluorine in formula (II) Yes; Additive E is a cyclic phosphazene compound (viscosity at 25 ° C.) in which n is 3 and one of six R ⁴ is methoxy group (CH ₃ O—) and five are fluorine in formula (II) The additive F is represented by formula (II) in which n is 3, and three of the six R ⁴ groups are ethoxy groups (CH ₃ CH ₂ O—), Three are cyclic phosphazene compounds (viscosity at 25 ° C .: 4.0 mPa · s, boiling point> 300 ° C.); additive G is represented by formula (II) Te, n is a 3, one isopropoxy group of the six _{^{R 4 [(CH 3) 2}} CHO -], 5 one the viscosity of the cyclic phosphazene compound (25 ° C. is fluorine: 1.1 mPa · s, a boiling point 137 ° C).

  The non-aqueous electrolyte solution of the example in which the phosphazene compound having a near boiling point is added to each of the aprotic organic solvents is highly safe, and the non-aqueous electrolyte solution 2 of the example using the non-aqueous electrolyte solution 2 The secondary battery did not ignite in both the nail penetration test and the overcharge test, and it was confirmed that the safety was high even in an emergency.

  On the other hand, the batteries of Comparative Examples 1 and 2 using the non-aqueous electrolyte containing no phosphorus and / or nitrogen-containing compound ignited in the nail penetration test and the overcharge test. In addition, the battery of Comparative Example 3 using a nonaqueous electrolytic solution containing a phosphazene compound having a boiling point close to that of DEC but not including phosphorus and / or a nitrogen-containing compound having a boiling point close to EC, phosphorus having a boiling point close to EC and / or The battery of Comparative Example 4 using a non-aqueous electrolyte containing no nitrogen-containing compound, phosphorus having a boiling point close to that of DEC, and / or a phosphazene compound not containing a nitrogen-containing compound and having a boiling point not close to either EC or DEC, Comparison using a non-aqueous electrolyte containing a phosphazene compound having a boiling point close to that of EC and not containing a phosphorus and / or nitrogen-containing compound having a boiling point close to that of MF, and further containing a phosphazene compound having a boiling point close to that of EC and MF The battery of Example 6 ignited in the nail penetration test and the overcharge test. Furthermore, the battery of Comparative Example 5 using a non-aqueous electrolyte containing a phosphazene compound having a boiling point close to that of DEC but not containing a phosphorus and / or nitrogen-containing compound having a boiling point close to that of EC did not ignite in the nail penetration test. However, it ignited in the overcharge test.

  From the above results, by adding a compound having a close boiling point and having phosphorus and / or nitrogen in the molecule to each of the aprotic organic solvents constituting the non-aqueous electrolyte, It can be seen that safety can be improved, and that the safety of the nonaqueous electrolyte secondary battery in an emergency can be remarkably improved by using the nonaqueous electrolyte in a nonaqueous electrolyte secondary battery.

(Example 10)
Propylene carbonate (PC, boiling point 242 ° C.) 60% by volume, 1,2-dimethoxyethane (DME, boiling point 84 ° C.) 30% by volume, additive A [in the formula (II), n is 3 and 6 R Cyclic phosphazene compound in which 3 out of ⁴ are methoxy groups (CH ₃ O—) and 3 are fluorine, viscosity at 25 ° C .: 3.9 mPa · s, boiling point 230 ° C. 5% by volume and additive C [in the formula (II) , N is 4 and cyclic phosphazene compound in which all 8 R ⁴ are fluorine, viscosity at 25 ° C .: 0.8 mPa · s, boiling point 86 ° C.] 5% by volume is prepared and mixed. LiBF ₄ (supporting salt) was dissolved in the solution at a concentration of 0.75 mol / L (M) to prepare a non-aqueous electrolyte. The safety of the obtained nonaqueous electrolytic solution was evaluated in the same manner as in Example 1. The results are shown in Table 3.

Next, after mixing and kneading MnO ₂ (positive electrode active material), acetylene black (conductive agent), and polyvinylidene fluoride (binder) in a ratio (mass ratio) of 8: 1: 1, The kneaded product was pressure-bonded and pelletized on a nickel foil (current collector) having a thickness of 25 μm, and further heated and dried (100 to 120 ° C.) to produce a positive electrode pellet having a thickness of 500 μm.

  The positive electrode pellet punched out to φ16mm is used as the positive electrode, the lithium foil (thickness 0.5mm) punched out to φ16mm is used as the negative electrode, and the positive and negative electrodes are opposed to each other through a cellulose separator [TF4030 manufactured by Nippon Kogyo Paper Industries Co., Ltd.]. The electrolyte solution was injected and sealed to produce a CR2016 type non-aqueous electrolyte primary battery (lithium primary battery). A heating test was performed on the obtained battery by the following method. The results are shown in Table 3.

(4) Heat test The battery was placed in an oven, heated to 160 ° C. at a rate of 5 ± 2 ° C./min, held at 160 ° C. for 60 minutes, and observed whether the battery ignited.

(Examples 11-15 and Comparative Examples 7-12)
A mixed solution having the composition shown in Table 3 was prepared, and LiBF ₄ (supporting salt) was dissolved in the mixed solution at a concentration of 0.75 mol / L (M) to prepare a nonaqueous electrolytic solution. The safety of the obtained nonaqueous electrolytic solution was evaluated in the same manner as in Example 1. Moreover, the nonaqueous electrolyte primary battery was produced using this nonaqueous electrolyte like Example 10, and the heating test was implemented with respect to this battery. The results are shown in Table 3.

In Table 3, GBL represents γ-butyrolactone (boiling point 204 ° C.). The additive B is a cyclic phosphazene compound (25 ° C.) in which n is 3 and one of the six R ⁴ groups is an ethoxy group (CH ₃ CH ₂ O—) and five are fluorine atoms in the formula (II). In the formula (II), n is 3 and 3 out of 6 R ⁴ are ethoxy groups (CH ₃ CH ₂ O— ) A cyclic phosphazene compound in which three are fluorine (viscosity at 25 ° C .: 4.0 mPa · s, boiling point> 300 ° C.); additive H is a compound of formula (II) where n is 3 and 6 R ⁴ is a cyclic phosphazene compound (viscosity at 25 ° C .: 1.2 mPa · s, boiling point 195 ° C.) in which 2 of ⁴ are ethoxy groups (CH ₃ CH ₂ O—) and 4 are fluorine; in), n is a 3, 6 one of a phenoxy group of R ⁴ (PhO -), 5 one is a fluorine-containing cyclic Sufazen compound: is (viscosity at 25 ℃ 1.7mPa · s, boiling point 195 ° C.).

  The nonaqueous electrolytic solution of the example in which the phosphazene compound having a near boiling point is added to each of the aprotic organic solvents has high safety, and the nonaqueous electrolytic solution 1 of the example using the nonaqueous electrolytic solution 1 The secondary battery did not ignite in the heating test and was confirmed to be highly safe even in an emergency.

  On the other hand, the batteries of Comparative Examples 7 and 8 using the non-aqueous electrolyte containing no phosphorus and / or nitrogen-containing compound ignited in the heating test. Further, the battery of Comparative Example 9 using a non-aqueous electrolyte containing a phosphazene compound having a boiling point close to PC but not containing phosphorus and / or a nitrogen-containing compound having a boiling point close to DME, phosphorus having a boiling point close to PC and / or The battery of Comparative Example 10 using a non-aqueous electrolyte containing no nitrogen-containing compound, phosphorus having a boiling point close to that of DME, and / or a phosphazene compound not containing a nitrogen-containing compound and having a boiling point not close to either PC or DME, In addition, the batteries of Comparative Examples 11 and 12 using a non-aqueous electrolyte containing a phosphazene compound not containing phosphorus and / or nitrogen having a boiling point close to that of GBL and not having a boiling point close to GBL ignited in the heating test.

  From the above results, by adding a compound having a close boiling point and having phosphorus and / or nitrogen in the molecule to each of the aprotic organic solvents constituting the non-aqueous electrolyte, It can be seen that safety can be improved, and that the safety of the non-aqueous electrolyte primary battery in an emergency can be remarkably improved by using the non-aqueous electrolyte in a non-aqueous electrolyte primary battery.

Claims (6)

In a non-aqueous electrolyte for a battery comprising at least one aprotic organic solvent and a supporting salt,
Furthermore, each of the aprotic organic solvents contains a compound having a difference in boiling point from the aprotic organic solvent of 25 ° C. or less and having phosphorus and / or nitrogen in the molecule. Non-aqueous electrolyte for batteries.   The nonaqueous electrolytic solution for a battery according to claim 1, wherein the compound having phosphorus and / or nitrogen in the molecule has a phosphorus-nitrogen double bond.   The nonaqueous electrolytic solution for a battery according to claim 2, wherein the compound having phosphorus and / or nitrogen in the molecule is a phosphazene compound.   The battery according to claim 1, wherein the aprotic organic solvent is at least one selected from the group consisting of ethylene carbonate, propylene carbonate, diethyl carbonate, dimethyl carbonate, ethyl methyl carbonate, and methyl formate. Non-aqueous electrolyte for use.   2. The nonaqueous electrolytic solution for a battery according to claim 1, wherein the aprotic organic solvent is at least one selected from the group consisting of propylene carbonate, 1,2-dimethoxyethane, and γ-butyrolactone.   A nonaqueous electrolyte battery comprising the nonaqueous electrolyte solution according to claim 1, a positive electrode, and a negative electrode.