JP4940625B2 - Electrolyte and battery - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a battery capable of enhancing high temperature characteristics. <P>SOLUTION: A separator is impregnated with an electrolyte. The electrolyte contains a solvent and an electrolyte salt. The solvent contains halogenated ethyl carbonate such as 4-fluoro-1,3-dioxolane and a phosphorus-containing compound such as trimethyl phosphate. Thereby, chemical stability at high temperature can be increased. By furthermore containing vineylene carbonate as the solvent, higher effect can be obtained. <P>COPYRIGHT: (C)2007,JPO&amp;INPIT

Description

  The present invention relates to an electrolytic solution containing a phosphorus-containing compound and a battery using the same.

  In recent years, many portable electronic devices such as notebook portable computers, cellular phones, and camera-integrated VTRs (video tape recorders) have appeared, and their weight and size have been reduced. Accordingly, as a power source for these portable electronic devices, development of a secondary battery that is lightweight and capable of obtaining a high energy density is in progress. As a secondary battery capable of obtaining a high energy density, for example, a lithium secondary battery is known.

In such a lithium secondary battery, in order to improve battery characteristics such as charge / discharge efficiency or flame retardancy, for example, an electrolytic solution containing a phosphate ester has been proposed (see, for example, Patent Document 1). .
JP 2002-319431 A

  However, as the use of portable electronic devices increases, recently, the portable electronic devices are often placed under high temperature conditions during transportation or use, resulting in a problem of deterioration in battery characteristics. Accordingly, it has been desired to develop a battery capable of obtaining excellent characteristics not only at room temperature but also at high temperatures.

  The present invention has been made in view of such problems, and an object thereof is to provide an electrolytic solution capable of improving high temperature characteristics and a battery using the same.

The first electrolytic solution according to the present invention comprises 4-fluoro-1,3-dioxolan-2-one as halogenated ethylene carbonate, propyldimethyl phosphate, butyldimethyl phosphate, pentyldimethyl phosphate, octyldimethyl phosphate. is one that contains a solvent and at least one phosphorus-containing compound of the phosphoric acid ester le or Ranaru group shown in triphenyl phosphate and of 1.
Moreover, the 2nd electrolyte solution by this invention contains the solvent containing halogenated ethylene carbonate and the phosphazene compound shown to Chemical formula 2 as a phosphorus containing compound.

（Ｒ４は、炭素数が１から１０のアルキル基，アルケニル基，アルキニル基，アラルキル基，アリール基，またはこれらの少なくとも一部の水素を置換基で置換した基を表す。Ｒ５は、炭素数が２から４のアルキレン基を表す。）

(R4 represents an alkyl group having 1 to 10 carbon atoms, an alkenyl group, an alkynyl group, an aralkyl group, an aryl group, or a group obtained by substituting at least a part of hydrogens with a substituent. R5 represents a carbon number. Represents an alkylene group of 2 to 4.)

（Ｒ６，Ｒ７，Ｒ８，Ｒ９，Ｒ１０，Ｒ１１は、炭素数が１から１０のアルキル基，アルケニル基，アルキニル基，アラルキル基，アリール基，アルコキシ基，フェノキシ基，またはこれらの少なくとも一部の水素をハロゲン基あるいはハロゲン以外の置換基で置換した基、またはハロゲン基を表す。）

(R6, R7, R8, R9, R10, and R11 are each an alkyl group having 1 to 10 carbon atoms, an alkenyl group, an alkynyl group, an aralkyl group, an aryl group, an alkoxy group, a phenoxy group, or at least part of hydrogen atoms thereof. Represents a group substituted with a halogen group or a substituent other than halogen, or a halogen group.)

A first battery of the present invention includes an electrolyte solution together with a positive electrode and a negative electrode, and the electrolyte solution includes 4-fluoro-1,3-dioxolan-2-one as halogenated ethylene carbonate, phosphoric acid solvent containing dimethyl, butyl dimethyl phosphate, phosphoric acid pentyl dimethyl, octyl dimethyl phosphate, and at least one phosphorus-containing compound of the phosphoric acid ester le or Ranaru group shown in triphenyl phosphate and of 3 It contains.
The second battery of the present invention is provided with an electrolytic solution together with a positive electrode and a negative electrode, and the electrolytic solution contains halogenated ethylene carbonate and a phosphazene compound shown in Chemical formula 4 as a phosphorus-containing compound. It contains a solvent.

（Ｒ４は、炭素数が１から１０のアルキル基，アルケニル基，アルキニル基，アラルキル基，アリール基，またはこれらの少なくとも一部の水素を置換基で置換した基を表す。Ｒ５は、炭素数が２から４のアルキレン基を表す。）

(R4 represents an alkyl group having 1 to 10 carbon atoms, an alkenyl group, an alkynyl group, an aralkyl group, an aryl group, or a group obtained by substituting at least a part of hydrogens with a substituent. R5 represents a carbon number. Represents an alkylene group of 2 to 4.)

（Ｒ６，Ｒ７，Ｒ８，Ｒ９，Ｒ１０，Ｒ１１は、炭素数が１から１０のアルキル基，アルケニル基，アルキニル基，アラルキル基，アリール基，アルコキシ基，フェノキシ基，またはこれらの少なくとも一部の水素をハロゲン基あるいはハロゲン以外の置換基で置換した基、またはハロゲン基を表す。）

(R6, R7, R8, R9, R10, and R11 are each an alkyl group having 1 to 10 carbon atoms, an alkenyl group, an alkynyl group, an aralkyl group, an aryl group, an alkoxy group, a phenoxy group, or at least part of hydrogen atoms thereof. Represents a group substituted with a halogen group or a substituent other than halogen, or a halogen group.)

According to the first or second electrolytic solution of the present invention, 4-fluoro-1,3-dioxolan-2-one , propyldimethyl phosphate, butyldimethyl phosphate, pentyldimethyl phosphate, octyldimethyl phosphate, It contains a solvent and at least one phosphorus-containing compound of the phosphoric acid ester le or Ranaru group shown in triphenyl phosphate and of 1, or a halogenated ethylene carbonate, phosphazene compound represented by chemical Formula 2 since so as to contain a solvent containing bets, even at high temperatures, it is possible to improve the chemical stability. Therefore, according to the 1st or 2nd battery of this invention using this electrolyte solution, a high temperature characteristic can be improved.

In particular, if the phosphorus-containing compound content in the solvent is 1% by mass or more and 20% by mass or less, or the halogenated ethylene carbonate content in the solvent is 1% by mass or more and 40% by mass or less. if, Oh Rui be to further include a carbonate-bi two lens, it is possible to obtain a higher effect.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

  The electrolytic solution according to an embodiment of the present invention includes, for example, a solvent and an electrolyte salt dissolved in the solvent.

  The solvent is composed of a halogenated ethylene carbonate obtained by substituting at least a part of hydrogen of ethylene carbonate with a halogen, a phosphate ester shown in Chemical Formula 7, a phosphate ester shown in Chemical Formula 8 and a phosphazene compound shown in Chemical Formula 9. And at least one phosphorus-containing compound. As a result, the stability of the electrolyte can be improved even at high temperatures. A phosphorus containing compound may be used individually by 1 type, and multiple types may be mixed and used for it.

（Ｒ１，Ｒ２，Ｒ３は、炭素数が１から１０のアルキル基，アルケニル基，アルキニル基，アラルキル基，アリール基，またはこれらの少なくとも一部の水素を置換基で置換した基を表す。Ｒ１，Ｒ２，Ｒ３は、同一のものがあってもよいし、全てが異なっていてもよい。）

(R1, R2, and R3 represent an alkyl group having 1 to 10 carbon atoms, an alkenyl group, an alkynyl group, an aralkyl group, an aryl group, or a group obtained by substituting at least a part of hydrogens with a substituent. R2 and R3 may be the same, or all may be different.)

（Ｒ４は、炭素数が１から１０のアルキル基，アルケニル基，アルキニル基，アラルキル基，アリール基，またはこれらの少なくとも一部の水素を置換基で置換した基を表す。Ｒ５は、炭素数が２から４のアルキレン基を表す。）

(R4 represents an alkyl group having 1 to 10 carbon atoms, an alkenyl group, an alkynyl group, an aralkyl group, an aryl group, or a group obtained by substituting at least a part of hydrogens with a substituent. R5 represents a carbon number. Represents an alkylene group of 2 to 4.)

（Ｒ６，Ｒ７，Ｒ８，Ｒ９，Ｒ１０，Ｒ１１は、炭素数が１から１０のアルキル基，アルケニル基，アルキニル基，アラルキル基，アリール基，アルコキシ基，フェノキシ基，またはこれらの少なくとも一部の水素をハロゲン基あるいはハロゲン以外の置換基で置換した基、またはハロゲン基を表す。Ｒ６，Ｒ７，Ｒ８，Ｒ９，Ｒ１０，Ｒ１１は、同一のものがあってもよいし、全てが異なっていてもよい。）

(R6, R7, R8, R9, R10, and R11 are each an alkyl group having 1 to 10 carbon atoms, an alkenyl group, an alkynyl group, an aralkyl group, an aryl group, an alkoxy group, a phenoxy group, or at least part of hydrogen atoms thereof. Represents a group substituted with a halogen group or a substituent other than halogen, or a halogen group, and R6, R7, R8, R9, R10, and R11 may be the same or all different. .)

  Examples of the halogenated ethylene carbonate include 4-fluoro-1,3-dioxolan-2-one shown in Chemical formula 10 (1), and 4-chloro-1,3-dioxolane-2 shown in Chemical formula 10 (2). -One, 4,4-difluoro-1,3-dioxolan-2-one represented by Chemical Formula 10 (3), 4,4-dichloro-1,3-dioxolan-2-one represented by Chemical Formula 10 (4) 4,5-difluoro-1,3-dioxolan-2-one represented by Chemical Formula 10 (5), 4,5-dichloro-1,3-dioxolan-2-one represented by Chemical Formula 10 (6) 4,4,5-trifluoro-1,3-dioxolan-2-one shown in 10 (7), 4,4,5-trichloro-1,3-dioxolane-2-one shown in Chemical formula 10 (8) ON, 4,4,5,5-tetrafluoro-1,3 shown in Chemical Formula 10 (9) Dioxolan-2-one, or of 10 4,4,5,5-tetrachloro-1,3-dioxolan-2-one expressed are mentioned in (10). Of these, 4-fluoro-1,3-dioxolan-2-one is preferable. This is because a higher effect can be obtained. One kind of halogenated ethylene carbonate may be used alone, or a plurality of kinds may be mixed and used.

  The content of the halogenated ethylene carbonate is preferably 1% by mass or more and 40% by mass or less in the solvent. This is because a higher effect can be obtained.

  Specific examples of phosphate esters include trimethyl phosphate, triethyl phosphate, methyl diethyl phosphate, ethyl dimethyl phosphate, propyl dimethyl phosphate, butyl dimethyl phosphate, pentyl dimethyl phosphate, octyl dimethyl phosphate, 2-methoxy-2-oxo-1,3,2-dioxaphosphorane, 2-ethoxy-2-oxo-1,3,2-dioxaphosphorane, 2-methoxy-2-oxo-1,3, There are 2-dioxaphosphorinane, 4,4-dimethyl-2-methoxy-2-oxo-1,3,2-dioxaphosphorinane, or ethylene ethyl phosphate, among which triethyl phosphate or methyl phosphate Diethyl is preferred. This is because a higher effect can be obtained.

  Specific examples of the phosphazene compound include the compound shown in Chemical formula 11 below. Among these, the compound shown in Chemical formula 11 (4) or the compound shown in Chemical formula 11 (8) is preferable. This is because a higher effect can be obtained.

  The content of the phosphorus-containing compound is preferably 1% by mass or more and 20% by mass or less, and more preferably 2% by mass or more and 10% by mass or less in the solvent. This is because a higher effect can be obtained.

  It is preferable that the solvent also contains vinylene carbonate. This is because the stability of the electrolyte at a high temperature can be further improved. The content of vinylene carbonate in the solvent is preferably 10% by mass or less, and more preferably 0.5% by mass to 3% by mass. This is because a higher effect can be obtained.

  As the solvent, in addition to these, other solvents may be mixed and used. The other solvent preferably contains a cyclic carbonate other than halogenated ethylene carbonate such as ethylene carbonate or propylene carbonate. This is because the dielectric constant can be increased. The content of the cyclic carbonate in the solvent is preferably 20% by mass or more, and more preferably 20% by mass or more and 90% by mass or less. This is because a higher effect can be obtained. The other solvent preferably further contains a chain carbonate such as dimethyl carbonate, diethyl carbonate or ethyl methyl carbonate. This is because ion conductivity can be improved. The content of the chain carbonate is preferably 10% by mass or more and more preferably 10% by mass or more and 50% by mass or less in the solvent. A higher effect can be obtained.

  In addition to these, examples of other solvents include 1,2-dimethoxyethane, 1,2-diethoxyethane, γ-butyrolactone, tetrahydrofuran, 2-methyltetrahydrofuran, 1,3-dioxolane, 4-methyl- Nonaqueous solvents such as 1,3-dioxolane, 4-vinyl-1,3-dioxolan-2-one, dimethyl ether, acetonitrile, ptopionitrile, acetate ester, butyrate ester, or propionate ester are listed. Another solvent may be used individually by 1 type, and multiple types may be mixed and used for it.

Examples of the electrolyte salt include LiPF ₆ , LiBF ₄ , LiAsF ₆ , LiClO ₄ , LiB (C ₆ H ₅ ) ₄ , LiCH ₃ SO ₃ , LiCF ₃ SO ₃ , LiN (SO ₂ CF ₃ ) ₂ , LiC (SO ₂ CF ₃ ) ₃ , LiAlCl ₄ , LiSiF ₆ , LiCl, difluoro [oxolato-O, O ′] lithium borate, lithium bisoxalate borate, or LiBr. Among them, LiPF ₆ is preferable because it can obtain high ion conductivity and can improve cycle characteristics. Any one electrolyte salt may be used alone, or two or more electrolyte salts may be mixed and used.

  This electrolytic solution is used for a secondary battery as follows, for example.

(First secondary battery)
FIG. 1 illustrates a cross-sectional configuration of the first secondary battery. This secondary battery is a so-called lithium ion secondary battery in which lithium (Li) is used as an electrode reactant and the capacity of the negative electrode is represented by a capacity component due to insertion and extraction of lithium. This secondary battery is a so-called cylindrical type, and a wound electrode body 20 in which a belt-like positive electrode 21 and a negative electrode 22 are wound through a separator 23 inside a substantially hollow cylindrical battery can 11. have. The battery can 11 is made of, for example, iron (Fe) plated with nickel (Ni), and has one end closed and the other end open. Inside the battery can 11, a pair of insulating plates 12, 13 are arranged perpendicular to the winding peripheral surface so as to sandwich the winding electrode body 20.

  At the open end of the battery can 11, a battery lid 14, a safety valve mechanism 15 provided inside the battery lid 14 and a heat sensitive resistance element (Positive Temperature Coefficient; PTC element) 16 are interposed via a gasket 17. It is attached by caulking, and the inside of the battery can 11 is sealed. The battery lid 14 is made of, for example, the same material as the battery can 11. The safety valve mechanism 15 is electrically connected to the battery lid 14 via the heat sensitive resistance element 16, and the disk plate 15A is reversed when the internal pressure of the battery exceeds a certain level due to an internal short circuit or external heating. Thus, the electrical connection between the battery lid 14 and the wound electrode body 20 is cut off. When the temperature rises, the heat sensitive resistance element 16 limits the current by increasing the resistance value and prevents abnormal heat generation due to a large current. The gasket 17 is made of, for example, an insulating material, and asphalt is applied to the surface.

  For example, a center pin 24 is inserted in the center of the wound electrode body 20. A positive electrode lead 25 made of aluminum (Al) or the like is connected to the positive electrode 21 of the spirally wound electrode body 20, and a negative electrode lead 26 made of nickel or the like is connected to the negative electrode 22. The positive electrode lead 25 is electrically connected to the battery lid 14 by being welded to the safety valve mechanism 15, and the negative electrode lead 26 is welded to and electrically connected to the battery can 11.

  FIG. 2 shows an enlarged part of the spirally wound electrode body 20 shown in FIG. The positive electrode 21 has, for example, a structure in which a positive electrode active material layer 21B is provided on both surfaces of a positive electrode current collector 21A having a pair of opposed surfaces. The positive electrode current collector 21A is made of, for example, a metal foil such as an aluminum foil, a nickel foil, or a stainless steel foil.

The positive electrode active material layer 21B includes, for example, any one or more of positive electrode materials capable of inserting and extracting lithium, and a conductive material such as a carbon material and a binder such as polyvinylidene fluoride as necessary. It may contain material. The positive electrode material capable of inserting and extracting lithium does not contain lithium such as titanium sulfide (TiS ₂ ), molybdenum sulfide (MoS ₂ ), niobium selenide (NbSe ₂ ), or vanadium oxide (V ₂ O ₅ ). Examples include chalcogenides and lithium-containing compounds containing lithium.

Among these, lithium-containing compounds are preferable because some compounds can obtain a high voltage and a high energy density. Examples of such a lithium-containing compound include a composite oxide containing lithium and a transition metal element, or a phosphate compound containing lithium and a transition metal element. In particular, cobalt (Co), nickel and manganese (Mn Among these, those containing at least one of them are preferred. This is because a higher voltage can be obtained. The chemical formula is represented by, for example, Li _x MIO ₂ or Li _y MIIPO ₄ . In the formula, MI and MII represent one or more transition metal elements. The values of x and y vary depending on the charge / discharge state of the battery, and are generally 0.05 ≦ x ≦ 1.10.

Specific examples of the composite oxide containing lithium and a transition metal element include lithium cobalt composite oxide (Li _x CoO ₂ ), lithium nickel composite oxide (Li _x NiO ₂ ), and lithium nickel cobalt composite oxide (Li _x Ni _1-z Co _z O ₂ (z <1)), lithium nickel cobalt manganese composite oxide (Li _x Ni _1-vw Co _v Mn _w O ₂ (v + w <1)), or lithium manganese having a spinel structure Examples include composite oxide (LiMn ₂ O ₄ ). Among these, a composite oxide containing nickel is preferable. This is because a high capacity can be obtained and excellent cycle characteristics can also be obtained. Specific examples of the phosphate compound containing lithium and a transition metal element include, for example, a lithium iron phosphate compound (LiFePO ₄ ) or a lithium iron manganese phosphate compound (LiFe _1-u Mn _u PO ₄ (u <1)). Can be mentioned.

  The negative electrode 22 has, for example, a structure in which a negative electrode active material layer 22B is provided on both surfaces of a negative electrode current collector 22A having a pair of opposed surfaces. The negative electrode current collector 22A is made of, for example, a metal foil such as a copper foil, a nickel foil, or a stainless steel foil.

  The negative electrode active material layer 22B includes, for example, any one or more of negative electrode materials capable of inserting and extracting lithium as a negative electrode active material. Examples of the negative electrode material capable of inserting and extracting lithium include a material containing tin (Sn) or silicon (Si) as a constituent element. This is because tin and silicon have a large ability to occlude and release lithium, and a high energy density can be obtained.

  As such a negative electrode material, specifically, a simple substance, an alloy, or a compound of tin, a simple substance, an alloy, or a compound of silicon, or a material having one or more phases thereof at least in part. Is mentioned. In the present invention, alloys include those containing one or more metal elements and one or more metalloid elements in addition to those composed of two or more metal elements. Moreover, the nonmetallic element may be included. There are structures in which a solid solution, a eutectic (eutectic mixture), an intermetallic compound, or two or more of them coexist.

  As an alloy of tin, for example, as a second constituent element other than tin, silicon, nickel, copper (Cu), iron, cobalt, manganese, zinc (Zn), indium (In), silver (Ag), titanium ( Examples include those containing at least one member selected from the group consisting of Ti), germanium (Ge), bismuth (Bi), antimony (Sb), and chromium (Cr). As an alloy of silicon, for example, as a second constituent element other than silicon, among the group consisting of tin, nickel, copper, iron, cobalt, manganese, zinc, indium, silver, titanium, germanium, bismuth, antimony and chromium The thing containing at least 1 sort (s) of these is mentioned.

  Examples of the tin compound or silicon compound include those containing oxygen (O) or carbon (C), and may contain the second constituent element described above in addition to tin or silicon.

  Among these, as this negative electrode material, tin, cobalt, and carbon are included as constituent elements, the carbon content is 9.9 mass% or more and 29.7 mass% or less, and the total of tin and cobalt is A CoSnC-containing material having a cobalt ratio Co / (Sn + Co) of 30% by mass to 70% by mass is preferable. This is because a high energy density can be obtained in such a composition range, and excellent cycle characteristics can be obtained.

  This CoSnC-containing material may further contain other constituent elements as necessary. As other constituent elements, for example, silicon, iron, nickel, chromium, indium, niobium (Nb), germanium, titanium, molybdenum (Mo), aluminum, phosphorus (P), gallium (Ga) or bismuth is preferable. It may contain more than seeds. This is because the capacity or cycle characteristics can be further improved.

  This CoSnC-containing material has a phase containing tin, cobalt, and carbon, and this phase preferably has a low crystallinity or an amorphous structure. In this CoSnC-containing material, it is preferable that at least a part of carbon as a constituent element is bonded to a metal element or a semimetal element as another constituent element. The decrease in cycle characteristics is thought to be due to the aggregation or crystallization of tin or the like, but this is because such aggregation or crystallization can be suppressed by combining carbon with other elements. .

  As a measuring method for examining the bonding state of elements, for example, X-ray photoelectron spectroscopy (XPS) can be cited. In XPS, the peak of the carbon 1s orbital (C1s) appears at 284.5 eV in an energy calibrated apparatus so that the peak of the gold atom 4f orbital (Au4f) is obtained at 84.0 eV if it is graphite. . Moreover, if it is surface contamination carbon, it will appear at 284.8 eV. On the other hand, when the charge density of the carbon element increases, for example, when carbon is bonded to a metal element or a metalloid element, the C1s peak appears in a region lower than 284.5 eV. That is, when the peak of the synthetic wave of C1s obtained for the CoSnC-containing material appears in a region lower than 284.5 eV, at least a part of the carbon contained in the CoSnC-containing material is a metal element or a half of other constituent elements. Combined with metal elements.

  In XPS measurement, for example, the C1s peak is used to correct the energy axis of the spectrum. Usually, since surface-contaminated carbon exists on the surface, the C1s peak of the surface-contaminated carbon is set to 284.8 eV, which is used as an energy standard. In the XPS measurement, the waveform of the C1s peak is obtained as a shape including the surface contamination carbon peak and the carbon peak in the CoSnC-containing material. For example, by analyzing using a commercially available software, the surface contamination The carbon peak and the carbon peak in the CoSnC-containing material are separated. In the waveform analysis, the position of the main peak existing on the lowest bound energy side is used as the energy reference (284.8 eV).

  As a negative electrode material capable of inserting and extracting lithium, for example, a material containing another metal element or other metalloid element capable of forming an alloy with lithium as a constituent element can also be used. Such metal elements or metalloid elements include magnesium (Mg), boron (B), aluminum, gallium, indium, germanium, lead (Pb), bismuth, cadmium (Cd), silver, zinc, hafnium (Hf). , Zirconium (Zr), yttrium (Y), palladium (Pd), or platinum (Pt).

  As a negative electrode material capable of inserting and extracting lithium, for example, a carbon material such as graphite, non-graphitizable carbon, or graphitizable carbon may be used. The negative electrode material may be used together. The carbon material has very little change in crystal structure due to insertion and extraction of lithium. For example, when used together with the negative electrode material described above, a high energy density and excellent cycle characteristics can be obtained. It is also preferable because it functions as a conductive material.

  The negative electrode active material layer 22B may also include a conductive material or a binder. Examples of the conductive material include graphite fiber, metal fiber, and metal powder. Examples of the binder include fluorine-based polymer compounds such as polyvinylidene fluoride.

  Note that in this embodiment, by adjusting the amount of the positive electrode active material and the negative electrode material capable of inserting and extracting lithium, lithium can be stored and released rather than the charge capacity of the positive electrode active material. The charge capacity of the possible negative electrode material is increased so that lithium metal does not deposit on the negative electrode 22 even during full charge.

  The separator 23 separates the positive electrode 21 and the negative electrode 22 and allows lithium ions to pass through while preventing a short circuit of current due to contact between the two electrodes. The separator 23 is made of, for example, a porous film made of synthetic resin made of polytetrafluoroethylene, polypropylene, polyethylene or the like, or a multi-hard film made of ceramic, and these two or more kinds of porous films are laminated. It may be made the structure.

  The separator 23 is impregnated with the above-described electrolytic solution. As a result, the high temperature characteristics can be improved.

  For example, the secondary battery can be manufactured as follows.

  First, for example, the positive electrode active material layer 21B is formed on the positive electrode current collector 21A to produce the positive electrode 21. The positive electrode active material layer 21B is prepared, for example, by mixing a positive electrode active material powder, a conductive material, and a binder to prepare a positive electrode mixture, and then using the positive electrode mixture in a solvent such as N-methyl-2-pyrrolidone. The positive electrode mixture slurry is dispersed to form a positive electrode mixture slurry, and the positive electrode mixture slurry is applied to the positive electrode current collector 21A, dried, and compression molded. Further, for example, in the same manner as the positive electrode 21, the negative electrode active material layer 22 </ b> B is formed on the negative electrode current collector 22 </ b> A to produce the negative electrode 22.

  Next, the positive electrode lead 25 is attached to the positive electrode current collector 21A by welding or the like, and the negative electrode lead 26 is attached to the negative electrode current collector 22A by welding or the like. Subsequently, the positive electrode 21 and the negative electrode 22 are wound through the separator 23, and the tip of the positive electrode lead 25 is welded to the safety valve mechanism 15, and the tip of the negative electrode lead 26 is welded to the battery can 11. The positive electrode 21 and the negative electrode 22 are sandwiched between a pair of insulating plates 12 and 13 and stored in the battery can 11. After the positive electrode 21 and the negative electrode 22 are accommodated in the battery can 11, the electrolytic solution is injected into the battery can 11 and impregnated in the separator 23. After that, the battery lid 14, the safety valve mechanism 15, and the heat sensitive resistance element 16 are fixed to the opening end of the battery can 11 by caulking through a gasket 17. Thereby, the secondary battery shown in FIGS. 1 and 2 is completed.

  In the secondary battery, when charged, for example, lithium ions are extracted from the positive electrode 21 and inserted in the negative electrode 22 through the electrolytic solution. On the other hand, when discharging is performed, for example, lithium ions are extracted from the negative electrode 22 and inserted in the positive electrode 21 through the electrolytic solution. At that time, since the electrolytic solution contains the halogenated ethylene carbonate and the phosphorus-containing compound described above, high chemical stability can be obtained even at high temperatures.

  As described above, according to the electrolytic solution of the present embodiment, among the group consisting of halogenated ethylene carbonate, the phosphoric acid ester shown in chemical formula 7, the phosphoric acid ester shown in chemical formula 8 and the phosphazene compound shown in chemical formula 9. Since the solvent containing at least one phosphorus-containing compound is contained, chemical stability can be improved even at high temperatures. Therefore, according to the first secondary battery using this electrolytic solution, the high temperature characteristics can be improved.

  In particular, if the phosphorus-containing compound content in the solvent is 1% by mass or more and 20% by mass or less, or the halogenated ethylene carbonate content in the solvent is 1% by mass or more and 40% by mass or less. For example, if 4-fluoro-1,3-dioxolan-2-one is contained as the halogenated ethylene carbonate, or if it further contains binylene carbonate, a higher effect can be obtained.

(Secondary secondary battery)
The second secondary battery has the same configuration, operation, and effects as the first secondary battery except that the configuration of the negative electrode is different, and can be manufactured in the same manner. Therefore, with reference to FIG. 1 and FIG. 2, the same code | symbol is attached | subjected to a corresponding component and description of the same part is abbreviate | omitted.

  Similar to the first secondary battery, the negative electrode 22 has a structure in which a negative electrode active material layer 22B is provided on both surfaces of a negative electrode current collector 22A. The negative electrode active material layer 22B contains a negative electrode material containing, for example, tin or silicon as a constituent element. Specifically, for example, it contains a simple substance, an alloy, or a compound of tin, or a simple substance, an alloy, or a compound of silicon, and may contain two or more of them.

  The negative electrode active material layer 22B is formed using, for example, a vapor phase method, a liquid phase method, a firing method, or two or more of these methods. The negative electrode active material layer 22B and the negative electrode current collector 22A are formed. Are preferably alloyed in at least part of the interface. Specifically, the constituent elements of the negative electrode current collector 22A are preferably diffused into the negative electrode active material layer 22B, the constituent elements of the negative electrode material are diffused into the negative electrode current collector 22A, or they are mutually diffused at the interface. This is because breakage due to expansion / contraction of the negative electrode active material layer 22B due to charging / discharging can be suppressed, and electronic conductivity between the negative electrode active material layer 22B and the negative electrode current collector 22A can be improved. .

  As the vapor phase method, for example, a physical deposition method or a chemical deposition method can be used. Specifically, a vacuum deposition method, a sputtering method, an ion plating method, a laser ablation method, a thermal chemical vapor deposition ( Examples include CVD (Chemical Vapor Deposition), plasma chemical vapor deposition, and thermal spraying. As the liquid phase method, a known method such as electroplating or electroless plating can be used. The firing method is, for example, a method in which a particulate negative electrode active material is mixed with a binder, dispersed in a solvent, applied, and then heat-treated at a temperature higher than the melting point of the binder. A known method can also be used for the firing method, for example, an atmospheric firing method, a reactive firing method, or a hot press firing method.

(Third secondary battery)
The third secondary battery is a so-called lithium metal secondary battery in which the capacity of the negative electrode 22 is represented by a capacity component due to precipitation and dissolution of lithium. This secondary battery has the same configuration and effects as those of the first embodiment except that the negative electrode active material layer 22B is made of lithium metal, and can be manufactured in the same manner. Therefore, with reference to FIG. 1 and FIG. 2, the same code | symbol is attached | subjected to a corresponding component and description of the same part is abbreviate | omitted.

  That is, this secondary battery uses lithium metal as a negative electrode active material, and thereby can obtain a high energy density. The negative electrode active material layer 22B may be configured to be already provided from the time of assembly, but may be configured by lithium metal which is not present at the time of assembly and is deposited during charging. Alternatively, the negative electrode active material layer 22B may be used as a current collector, and the negative electrode current collector 22A may be deleted.

  In the secondary battery, when charged, for example, lithium ions are extracted from the positive electrode 21 and deposited as lithium metal on the surface of the negative electrode current collector 22A through the electrolytic solution. When the discharge is performed, for example, lithium metal is eluted as lithium ions from the negative electrode active material layer 22B, and is occluded in the positive electrode 21 through the electrolytic solution. Also in this secondary battery, since the electrolytic solution contains the halogenated ethylene carbonate and the phosphorus-containing compound described above, high chemical stability can be obtained at high temperatures.

(Fourth secondary battery)
In the fourth secondary battery, the capacity of the negative electrode includes a capacity component due to insertion and extraction of lithium and a capacity component due to precipitation and dissolution of lithium, and is represented by the sum thereof. This secondary battery has the same configuration as that of the first embodiment except that the configuration of the negative electrode active material layer 22B is different, and can be manufactured in the same manner. Therefore, with reference to FIG. 1 and FIG. 2, the same code | symbol is attached | subjected to a corresponding component and description of the same part is abbreviate | omitted.

  The negative electrode active material layer 22B includes one or more negative electrode materials capable of inserting and extracting lithium as a negative electrode active material, and may include a binder as necessary. As such a negative electrode material, for example, a carbon material described in the first secondary battery, or a material containing a metal element or a metalloid element capable of forming an alloy with lithium as a constituent element can be given. Among these, it is preferable to use a carbon material because excellent cycle characteristics can be obtained.

  The amount of the negative electrode material capable of inserting and extracting lithium is adjusted so that the charge capacity of the negative electrode material is smaller than the charge capacity of the positive electrode 21. As a result, in the secondary battery, lithium metal starts to deposit on the negative electrode 22 at the time when the open circuit voltage (that is, the battery voltage) is lower than the overcharge voltage in the charging process. Therefore, in this secondary battery, both the negative electrode material capable of occluding and releasing lithium and lithium metal function as the negative electrode active material, and the negative electrode material capable of occluding and releasing lithium is a base material on which the lithium metal is deposited. It has become. Thereby, in this secondary battery, the characteristics of both a so-called lithium ion secondary battery and a so-called lithium metal secondary battery can be obtained. That is, a high energy density can be obtained and the cycle characteristics can be improved.

  The overcharge voltage refers to the open circuit voltage when the battery is overcharged. For example, the “lithium secondary battery” is one of the guidelines established by the Japan Storage Battery Industry Association (Battery Industry Association). Refers to a voltage that is higher than the open circuit voltage of a “fully charged” battery as defined and defined in the “Safety Evaluation Criteria Guidelines” (SBA G1101). In other words, it refers to a voltage higher than the open circuit voltage after charging using the charging method, standard charging method, or recommended charging method used when determining the nominal capacity of each battery.

  In the secondary battery, when charged, lithium ions are released from the positive electrode 21 and are first inserted into the negative electrode material capable of inserting and extracting lithium contained in the negative electrode 22 through the electrolytic solution. When charging is further continued, lithium metal begins to deposit on the surface of the negative electrode material capable of inserting and extracting lithium in a state where the open circuit voltage is lower than the overcharge voltage. After that, lithium metal continues to deposit on the negative electrode 22 until charging is completed. Next, when discharging is performed, first, lithium metal deposited on the negative electrode 22 is eluted as ions, and is occluded in the positive electrode 21 through the electrolytic solution. When the discharge is further continued, lithium ions are released from the negative electrode material capable of inserting and extracting lithium in the negative electrode 22 and inserted into the positive electrode 21 through the electrolytic solution. Also in this secondary battery, since the electrolytic solution contains the halogenated ethylene carbonate and the phosphorus-containing compound described above, high chemical stability can be obtained at high temperatures.

(Fifth secondary battery)
FIG. 3 shows the configuration of the fifth secondary battery. This secondary battery is a so-called laminate film type, and has a wound electrode body 30 to which a positive electrode lead 31 and a negative electrode lead 32 are attached accommodated in a film-shaped exterior member 40.

  The positive electrode lead 31 and the negative electrode lead 32 are led out from the inside of the exterior member 40 to the outside, for example, in the same direction. The positive electrode lead 31 and the negative electrode lead 32 are each made of a metal material such as aluminum, copper, nickel, or stainless steel, and each have a thin plate shape or a mesh shape.

  The exterior member 40 is made of, for example, a rectangular aluminum laminated film in which a nylon film, an aluminum foil, and a polyethylene film are bonded together in this order. For example, the exterior member 40 is disposed so that the polyethylene film side and the wound electrode body 30 face each other, and the outer edge portions are in close contact with each other by fusion bonding or an adhesive. An adhesive film 41 is inserted between the exterior member 40 and the positive electrode lead 31 and the negative electrode lead 32 to prevent intrusion of outside air. The adhesion film 41 is made of a material having adhesion to the positive electrode lead 31 and the negative electrode lead 32, for example, a polyolefin resin such as polyethylene, polypropylene, modified polyethylene, or modified polypropylene.

  The exterior member 40 may be made of a laminated film having another structure, a polymer film such as polypropylene, or a metal film instead of the above-described aluminum laminated film.

  FIG. 4 shows a cross-sectional structure taken along line II of the spirally wound electrode body 30 shown in FIG. The electrode winding body 30 is obtained by laminating a positive electrode 33 and a negative electrode 34 via a separator 35 and an electrolyte layer 36 and winding them, and the outermost periphery is protected by a protective tape 37.

  The positive electrode 33 has a structure in which a positive electrode active material layer 33B is provided on both surfaces of a positive electrode current collector 33A. The negative electrode 34 has a structure in which a negative electrode active material layer 34B is provided on both surfaces of a negative electrode current collector 34A, and the negative electrode active material layer 34B and the positive electrode active material layer 33B are arranged to face each other. The configuration of the positive electrode current collector 33A, the positive electrode active material layer 33B, the negative electrode current collector 34A, the negative electrode active material layer 34B, and the separator 35 is the same as that of the positive electrode current collector 21A, the positive electrode active material in the first to fourth secondary batteries described above. This is the same as the material layer 21B, the negative electrode current collector 22A, the negative electrode active material layer 22B, and the separator 23.

  The electrolyte layer 36 includes the above-described electrolytic solution and a polymer compound serving as a holding body that holds the electrolytic solution, and has a so-called gel shape. As a result, the high temperature characteristics can be improved. In addition, a gel electrolyte is preferable because high ion conductivity can be obtained and battery leakage can be prevented. Examples of the polymer compound include, for example, an ether polymer compound such as polyethylene oxide or a crosslinked product containing polyethylene oxide, an ester polymer compound such as polymethacrylate, or an acrylate polymer compound, or polyvinylidene fluoride or vinylidene fluoride. Examples thereof include polymers of vinylidene fluoride such as a copolymer with hexafluoropropylene, and any one of these or a mixture of two or more thereof is used. In particular, from the viewpoint of redox stability, it is desirable to use a fluorine-based polymer compound such as a vinylidene fluoride polymer.

  For example, the secondary battery can be manufactured as follows.

  First, a precursor solution containing the above-described electrolytic solution, a polymer compound, and a mixed solvent is applied to each of the positive electrode 33 and the negative electrode 34, and the mixed solvent is volatilized to form the electrolyte layer 36. Next, the positive electrode lead 31 is attached to the positive electrode current collector 33A, and the negative electrode lead 32 is attached to the negative electrode current collector 34A. Subsequently, the positive electrode 33 and the negative electrode 34 on which the electrolyte layer 36 is formed are laminated via a separator 35 to form a laminated body, and then the laminated body is wound in the longitudinal direction, and the protective tape 37 is attached to the outermost peripheral portion. The wound electrode body 30 is formed by bonding. After that, for example, the wound electrode body 30 is sandwiched between the exterior members 40, and the outer edge portions of the exterior members 40 are sealed and sealed by thermal fusion or the like. At that time, the adhesion film 41 is inserted between the positive electrode lead 31 and the negative electrode lead 32 and the exterior member 40. Thereby, the secondary battery shown in FIGS. 3 and 4 is completed.

  Further, this secondary battery may be manufactured as follows. First, the positive electrode 33 and the negative electrode 34 are prepared as described above, and after the positive electrode lead 31 and the negative electrode lead 32 are attached to the positive electrode 33 and the negative electrode 34, the positive electrode 33 and the negative electrode 34 are stacked via the separator 35 and wound. Rotate and adhere the protective tape 37 to the outermost periphery to form a wound body that is a precursor of the wound electrode body 30. Next, the wound body is sandwiched between the exterior members 40, and the outer peripheral edge portion excluding one side is heat-sealed to form a bag shape, and is stored inside the exterior member 40. Subsequently, an electrolyte composition containing the above-described electrolytic solution, a monomer that is a raw material of the polymer compound, and other materials such as a polymerization initiator or a polymerization inhibitor as necessary is prepared, and the exterior member 40 After injection into the interior, the opening of the exterior member 40 is heat-sealed and sealed. After that, if necessary, heat is applied to polymerize the monomer to form a polymer compound, thereby forming the gel electrolyte layer 36 and assembling the secondary battery shown in FIGS.

  The operation and effect of this secondary battery are the same as those of the first to fourth secondary batteries described above.

  Further, specific embodiments of the present invention will be described in detail.

( Experimental Examples 1-1 to 1-16)
The cylindrical secondary battery shown in FIGS. First, lithium carbonate (Li ₂ CO ₃ ) and cobalt carbonate (CoCO ₃ ) are mixed at a molar ratio of 0.5: 1 and calcined in the air for 5 hours to obtain lithium cobalt oxide (LiCoO ₂ ). This was prepared and used as a positive electrode active material. Next, 90 parts by mass of this lithium cobaltate, 5 parts by mass of graphite as a conductive material, and 3 parts by mass of polyvinylidene fluoride as a binder are mixed and dispersed in N-methyl-2-pyrrolidone as a solvent to form a positive electrode. A mixture slurry was obtained. Subsequently, the positive electrode mixture slurry was uniformly applied to both surfaces of a positive electrode current collector 21A made of an aluminum foil having a thickness of 20 μm, dried, and compression-molded to form a positive electrode active material layer 21B, thereby producing the positive electrode 21. After that, an aluminum positive electrode lead 25 was attached to one end of the positive electrode current collector 21A.

  Moreover, the negative electrode 22 was produced by forming the negative electrode active material layer 22B which consists of silicon by the electron beam vapor deposition method in 22 A of negative electrode collectors which consist of copper foil. After that, a nickel negative electrode lead 26 was attached to one end of the negative electrode current collector 22A. The filling amount of the positive electrode active material and silicon was adjusted so that lithium metal was not deposited on the negative electrode 22 during charging.

  Next, a separator 23 made of a microporous polypropylene film having a thickness of 25 μm was prepared, and the negative electrode 22, the separator 23, the positive electrode 21, and the separator 23 were laminated in this order and wound many times in a spiral shape to produce a wound electrode body 20. . Subsequently, the wound electrode body 20 is sandwiched between the pair of insulating plates 12 and 13, the negative electrode lead 26 is welded to the battery can 11, and the positive electrode lead 25 is welded to the safety valve mechanism 15. The can 11 was stored inside. After that, an electrolytic solution was injected into the battery can 11 by a reduced pressure method.

At that time, in Experimental Examples 1-1 to 1-14, ethylene carbonate (EC), dimethyl carbonate (DMC) as the solvent, and 4-fluoro-1,3-dioxolan-2-one (FEC) as the halogenated ethylene carbonate were used. ) And a phosphorus-containing compound in a solvent obtained by mixing ethylene carbonate: dimethyl carbonate: 4-fluoro-1,3-dioxolan-2-one: phosphorus-containing compound = 45: 40: 10: 5 in an electrolyte. An electrolytic solution in which lithium hexafluorophosphate was dissolved as a salt at a concentration of 1 mol / l was used. Phosphorus-containing compounds include trimethyl phosphate, triethyl phosphate, methyl diethyl phosphate, triphenyl phosphate, hexachloro-cyclo-tri-phosphazene shown in Chemical formula 11 (1), and monomethoxy-shown in Chemical formula 11 (2). Pentachloro-cyclo-tri-phosphazene, hexafluoro-cyclo-tri-phosphazene shown in Chemical formula 11 (4), monomethoxy-pentafluoro-cyclo-tri-phosphazene shown in Chemical formula 11 (5), Chemical formula 11 (6) 1,3-dimethoxy-tetrafluoro-cyclo-tri-phosphazene shown in FIG. 1, 1,3,5-trimethoxy-trifluoro-cyclo-tri-phosphazene shown in Chemical formula 11 (7), shown in Chemical formula 11 (8) Monoethoxy-pentafluoro-cyclo-tri-phosphazene, 1,3 shown in Chemical Formula 11 (9) -Diethoxy-tetrafluoro-cyclo-tri-phosphazene, monophenoxy-pentachloro-cyclo-tri-phosphazene represented by formula 11 (11), monotrifluoroethoxy-pentafluoro-cyclo-tri represented by formula 11 (14) -Phosphazene.

In Experimental Example 1-15, ethylene carbonate and dimethyl carbonate as solvents, 4-fluoro-1,3-dioxolan-2-one as halogenated ethylene carbonate, vinylene carbonate (VC), and phosphorus-containing compounds In a solvent in which trimethyl phosphate was mixed at a mass ratio of ethylene carbonate: dimethyl carbonate: 4-fluoro-1,3-dioxolan-2-one: vinylene carbonate: trimethyl phosphate = 38: 40: 10: 2: 10 An electrolytic solution in which lithium hexafluorophosphate was dissolved at a concentration of 1 mol / l was used as an electrolyte salt.

Furthermore, in Experimental Example 1-16, ethylene carbonate and dimethyl carbonate as solvents, 4-chloro-1,3-dioxolan-2-one (ClEC) as halogenated ethylene carbonate, and trimethyl phosphate as the phosphorus-containing compound Is mixed with ethylene carbonate: dimethyl carbonate: 4-chloro-1,3-dioxolan-2-one: trimethyl phosphate = 40: 40: 10: 10 in a mass ratio of phosphorus hexafluoride as an electrolyte salt. An electrolytic solution in which lithium acid was dissolved at a concentration of 1 mol / l was used.

After injecting the electrolytic solution, the battery can 11 was caulked to fix the battery lid 14 and hermetically sealed to obtain secondary batteries of Experimental Examples 1-1 to 1-16.

As Comparative Example 1-1 for Experimental Examples 1-1 to 1-16, a solvent in which ethylene carbonate and dimethyl carbonate were mixed at a mass ratio of 50:50 was used without using a halogenated ethylene carbonate and a phosphorus-containing compound. Other than the above, secondary batteries were fabricated in the same manner as in Experimental Examples 1-1 to 1-16.

Further, as Comparative Examples 1-2 and 1-3, secondary batteries were fabricated in the same manner as in Experimental Examples 1-1 to 1-16, except that no phosphorus-containing compound was used. At that time, the halogenated ethylene carbonate was 4-chloro-1,3-dioxolan-2-one in Comparative Example 1-2, and 4-fluoro-1,3-dioxolan-2-one in Comparative Example 1-3. did. The solvent used was a mixture of ethylene carbonate, dimethyl carbonate, and halogenated ethylene carbonate at a mass ratio of ethylene carbonate: dimethyl carbonate: halogenated ethylene carbonate = 40: 50: 10.

Furthermore, in Comparative Example 1-4, 4-monofluoromethyl-1,3-dioxolan-2-one (FPC) shown in Chemical Formula 12 which is a halogenated propylene carbonate was used instead of the halogenated ethylene carbonate. Except for this, secondary batteries were fabricated in the same manner as in Experimental Examples 1-1 to 1-16. At that time, trimethyl phosphate was used as the phosphorus-containing compound, and ethylene carbonate, dimethyl carbonate, 4-monofluoromethyl-1,3-dioxolan-2-one, and trimethyl phosphate were mixed with ethylene carbonate: dimethyl carbonate. : A solvent mixed at a mass ratio of 4-monofluoromethyl-1,3-dioxolan-2-one: trimethyl phosphate = 40: 45: 10: 5 was used.

For the fabricated secondary batteries of Experimental Examples 1-1 to 1-16 and Comparative Examples 1-1 to 1-4, the discharge capacity retention ratio after high-temperature continuous charging was examined. Specifically, first, constant current charging was performed at 23 ° C. with a current of 600 mA until the battery voltage reached 4.2 V, and then constant voltage charging was performed with a voltage of 4.2 V until the current reached 20 mA. Next, constant current discharge was performed at a current of 300 mA until the battery voltage reached 3.0 V, and the discharge capacity before continuous charge was determined. Subsequently, after charging in a constant temperature bath at 80 ° C. until the battery voltage reaches 4.2 V at a current of 600 mA, continuous charging is performed at a constant voltage of 4.2 V until the total charging time reaches 300 hours. Subsequently, constant current discharge was performed until the battery voltage reached 3.0 V at a current of 300 mA. Next, constant current charging was performed until the battery voltage reached 4.2 V at a current of 600 mA at 23 ° C., and then constant voltage charging was performed until the current reached 20 mA at a voltage of 4.2 V, followed by a current of 300 mA. Then, constant current discharge was performed until the battery voltage reached 3.0 V, and the discharge capacity after continuous charge was determined. The discharge capacity retention rate was determined from the ratio of the discharge capacity after continuous charge to the discharge capacity before continuous charge, that is, (discharge capacity after continuous charge / discharge capacity before continuous charge) × 100 (%). The results are shown in Table 1.

As shown in Table 1, according to Experimental Examples 1-1 to 1-14 using 4-fluoro-1,3-dioxolan-2-one and a phosphorus-containing compound, Comparative Example 1 in which these were not used -1, or the discharge capacity maintenance rate after high temperature continuous charge improved rather than Comparative Example 1-3 which did not use a phosphorus containing compound. Further, in Comparative Example 1-4 using 4-monofluoromethyl-1,3-dioxolan-2-one which is a halogenated propylene carbonate, the effect of improving the discharge capacity retention rate after high-temperature continuous charging was not observed. It was. Furthermore, according to Experimental Example 1-16 using 4-chloro-1,3-dioxolan-2-one and a phosphorus-containing compound, Comparative Example 1-1 where these were not used, or a phosphorus-containing compound was not used Further, the discharge capacity retention rate after high-temperature continuous charging was improved as compared with Comparative Example 1-2. In addition, according to Experimental Example 1-15 using vinylene carbonate, the discharge capacity retention rate after high-temperature continuous charging was improved as compared with Experimental Example 1-1 in which this was not used.

  That is, it has been found that if the electrolytic solution contains a halogenated ethylene carbonate and a phosphorus-containing compound, the high temperature characteristics can be improved, and if it further contains binylene carbonate, it is preferable.

( Experimental examples 2-1 to 2-10)
In Experimental Examples 2-1 to 2-5, except that the content of trimethyl phosphate in the solvent was changed in the range of 1% by mass to 30% by mass, the other secondary conditions were performed in the same manner as in Experimental Example 1-1. A battery was produced. The mixing ratio of each solvent was as shown in Table 2.

Further, in Experimental Examples 2-6 to 2-10, except that the content of 4-fluoro-1,3-dioxolan-2-one in the solvent was changed in the range of 1% by mass to 40% by mass, Produced a secondary battery in the same manner as in Experimental Example 1-1. The mixing ratio of each solvent was as shown in Table 2.

For the secondary batteries of Experimental Examples 2-1 to 2-10 were prepared to examine the discharge capacity maintenance rate after high-temperature continuous charging in the same manner as in Experimental Example 1-1 to 1-16. The results are shown in Table 2.

  As shown in Table 2, the discharge capacity retention rate after high-temperature continuous charging increases with an increase in the content of trimethyl phosphate, and shows a tendency to decrease after showing a maximum value. There was a tendency that the content increased with an increase in the content of fluoro-1,3-dioxolan-2-one, and then decreased after showing a maximum value.

  That is, if the content of the phosphorus-containing compound in the solvent is 1% by mass to 20% by mass, or the content of the halogenated ethylene carbonate in the solvent is 1% by mass to 40% by mass. It turned out to be preferable.

( Experimental examples 3-1 to 3-17)
A secondary battery was fabricated in the same manner as in Experimental Examples 1-1 to 1-16, except that the configuration of the negative electrode 22 was changed. Specifically, 90% by mass of silicon powder having an average particle diameter of 1 μm as a negative electrode material and 10% by mass of polyvinylidene fluoride as a binder are dispersed in N-methyl-2-pyrrolidone, which is a solvent, from a copper foil. The negative electrode current collector 22A was coated, dried, compression-molded, and then heat-treated to produce the negative electrode 22.

At that time, in Experimental Examples 3-1 to 3-14, the composition of the electrolytic solution was the same as that of Experimental Examples 1-1 to 1-14. In Experimental Examples 3-16 and 3-17, except that hexafluoro-cyclo-tri-phosphazene shown in Chemical Formula 11 (4) was used in place of trimethyl phosphate, the others were Experimental Examples 1-15, The composition was the same as that of the electrolyte solution 1-16. Further, in Experimental Example 3-15, ethylene carbonate, dimethyl carbonate, 4-fluoro-1,3-dioxolan-2-one as the halogenated ethylene carbonate, trimethyl phosphate as the phosphorus-containing compound, and the compound 11 (5) And monomethoxy-pentafluoro-cyclo-tri-phosphazene represented by the following formula: ethylene carbonate: dimethyl carbonate: 4-fluoro-1,3-dioxolan-2-one: trimethyl phosphate: monomethoxy-pentafluoro-cyclo-tri -Phosphazene = An electrolytic solution in which lithium hexafluorophosphate as an electrolyte salt was dissolved at a concentration of 1 mol / l in a solvent mixed at a mass ratio of 40: 40: 10: 5: 5 was used.

As Comparative Examples 3-1 to 3-4 with respect to Experimental Examples 3-1 to 3-17, except that the same electrolytic solution as Comparative Examples 1-1 to 1-4 was used, the rest was Experimental Example 3-1 A secondary battery was made in the same manner as 3-17.

For the secondary batteries of Experimental Examples 3-1～3-17 and Comparative Examples 3-1 to 3-4 were produced, the discharge capacity retention after high-temperature continuous charging in the same manner as in Experimental Example 1-1 to 1-16 Examined. The results are shown in Table 3.

As shown in Table 3, the same results as in Experimental Examples 1-1 to 1-16 were obtained. Also in Experimental Example 3-15 in which trimethyl phosphate and monomethoxy-pentafluoro-cyclo-tri-phosphazene were used, the discharge capacity retention rate after high-temperature continuous charging was improved.

  That is, even if the negative electrode 22 having another configuration is used, the high temperature characteristics can be improved if the halogenated ethylene carbonate and the phosphorus-containing compound are included, and further if the binylene carbonate is included, It turned out to be preferable.

( Experimental examples 4-1 to 4-10)
In Experimental Examples 4-1 to 4-5, except that the content of hexafluoro-cyclo-tri-phosphazene shown in Chemical Formula 11 (4) in the solvent was changed in the range of 1% by mass to 30% by mass, Otherwise, a secondary battery was fabricated in the same manner as in Experimental Example 3-7. The mixing ratio of each solvent was as shown in Table 4.

In Experimental Examples 4-6 to 4-10, except that the content of 4-fluoro-1,3-dioxolan-2-one in the solvent was changed in the range of 1% by mass to 40% by mass, Produced a secondary battery in the same manner as in Experimental Example 3-7. The mixing ratio of each solvent was as shown in Table 4.

For the secondary batteries of Experimental Examples 4-1 to 4-10 were prepared to examine the discharge capacity maintenance rate after high-temperature continuous charging in the same manner as in Experimental Example 1-1 to 1-16. The results are shown in Table 4.

As shown in Table 4, the same results as in Experimental Examples 2-1 to 2-10 were obtained. That is, even if the negative electrode 22 having another configuration is used, if the content of the phosphorus-containing compound in the solvent is 1% by mass or more and 20% by mass or less, the content of the halogenated ethylene carbonate in the solvent is 1 It has been found that it is preferable to adjust the content to not less than 40% by mass and not more than 40% by mass.

( Experimental examples 5-1 to 5-16)
A secondary battery was fabricated in the same manner as in Experimental Examples 1-1 to 1-16, except that a SnCoC-containing material was used as the negative electrode material. Specifically, 80 parts by mass of CoSnC-containing material powder, 11 parts by mass as a conductive material and 1 part by mass of acetylene black, and 8 parts by mass of polyvinylidene fluoride as a binder, N-methyl-2-2, which is a solvent, are used. The negative electrode 22 was produced by dispersing in pyrrolidone, applying to a negative electrode current collector 22A made of copper foil, drying, and compression molding. Further, in Experimental Examples 5-15 and 5-16, except that monoethoxy-pentafluoro-cyclo-tri-phosphazene shown in Chemical Formula 11 (8) was used instead of trimethyl phosphate, Experimental Example 1- The composition was the same as that of the electrolyte solutions 15 and 1-16. Furthermore, the CoSnC-containing material was synthesized using a mechanochemical reaction by mixing tin / cobalt / indium / titanium alloy powder and carbon powder.

  When the composition of the produced CoSnC-containing material was analyzed, the tin content was 48% by mass, the cobalt content was 23% by mass, the indium content was 5% by mass, and the titanium content was 2%. The content of carbon was 20% by mass, and the ratio Co / (Sn + Co) of cobalt to the total of tin and cobalt was 32% by mass. The carbon content was measured by a carbon / sulfur analyzer, and the contents of tin, cobalt, indium and titanium were measured by ICP (Inductively Coupled Plasma) emission analysis. Further, when X-ray diffraction was performed on the obtained CoSnC-containing material, a diffraction peak having a wide half-width with a diffraction angle 2θ of 1.0 ° or more was observed between diffraction angles 2θ = 20 ° to 50 °. It was. Further, when XPS was performed on the CoSnC-containing material, a peak P1 was obtained as shown in FIG. When the peak P1 was analyzed, a peak P2 of surface contamination carbon and a peak P3 of C1s in the CoSnC-containing material on the lower energy side than the peak P2 were obtained. This peak P3 was obtained in a region lower than 284.5 eV. That is, it was confirmed that carbon in the CoSnC-containing material was bonded to other elements.

As Comparative Examples 5-1 to 5-3 with respect to Experimental Examples 5-1 to 5-16, except that the same electrolytic solution as Comparative Examples 1-1 to 1-3 was used, the rest was Experimental Examples 5-1 A secondary battery was fabricated in the same manner as in 5-16.

For the secondary batteries of Experimental Examples 5-1～5-16 and Comparative Examples 5-1 to 5-3 were produced, the discharge capacity retention after high-temperature continuous charging in the same manner as in Experimental Example 1-1 to 1-16 Examined. The results are shown in Table 5.

As shown in Table 5, the same results as in Experimental Examples 1-1 to 1-16 were obtained. That is, it has been found that even when the negative electrode 22 having another configuration is used, high temperature characteristics can be improved by including halogenated ethylene carbonate and a phosphorus-containing compound.

( Experimental examples 6-1 to 6-10)
In Experimental Examples 6-1 to 6-5, the content of monoethoxy-pentafluoro-cyclo-tri-phosphazene represented by Chemical Formula 11 (8) in the solvent was changed in the range of 1% by mass to 30% by mass. Other than that, a secondary battery was fabricated in the same manner as in Experimental Example 5-11. The mixing ratio of each solvent was as shown in Table 6.

Further, in Experimental Examples 6-6 to 6-10, except that the content of 4-fluoro-1,3-dioxolan-2-one in the solvent was changed in the range of 1% by mass to 40% by mass, Produced a secondary battery in the same manner as in Experimental Example 5-11. The mixing ratio of each solvent was as shown in Table 6.

For the secondary batteries of Experimental Examples 6-1 to 6-10 were prepared to examine the discharge capacity maintenance rate after high-temperature continuous charging in the same manner as in Experimental Example 1-1 to 1-16. The results are shown in Table 6.

As shown in Table 6, the same results as in Experimental Examples 2-1 to 2-10 were obtained. That is, even if the negative electrode 22 having another configuration is used, if the content of the phosphorus-containing compound in the solvent is 1% by mass or more and 20% by mass or less, the content of the halogenated ethylene carbonate in the solvent is 1 It has been found that it is preferable to set the content to not less than 40% by mass.

( Experimental examples 7-1 to 7-4)
A secondary battery was fabricated in the same manner as in Experimental Examples 1-1, 1-2, 1-5, and 1-7, except that graphite was used as the negative electrode material. Specifically, 92 parts by mass of artificial graphite powder and 8 parts by mass of polyvinylidene fluoride as a binder are dispersed in N-methyl-2-pyrrolidone as a solvent, and the negative electrode current collector 22A made of copper foil is dispersed in the negative electrode current collector 22A. The negative electrode 22 was produced by applying, drying, and compression molding.

As Comparative Examples 7-1 and 7-2 with respect to Experimental Examples 7-1 to 7-4, except that the same electrolytic solution as Comparative Examples 1-1 and 1-3 was used, the others were Experimental Examples 7-1 to 7-1. A secondary battery was fabricated in the same manner as 7-4.

For the secondary batteries of Experimental Examples 7-1 to 7-4 and Comparative Examples 7-1 and 7-2 were produced, the discharge capacity retention after high-temperature continuous charging in the same manner as in Experimental Example 1-1 to 1-16 Examined. The results are shown in Table 7.

As shown in Table 7, the same results as in Experimental Examples 1-1, 1-2, 1-5, and 1-7 were obtained. That is, it has been found that even when the negative electrode 22 having another configuration is used, high temperature characteristics can be improved by including halogenated ethylene carbonate and a phosphorus-containing compound.

( Experimental examples 8-1 to 8-7)
A secondary battery was fabricated in the same manner as in Experimental Examples 1-1 to 1-3 and 1-7 to 1-10 except that the negative electrode 22 was fabricated by attaching a lithium metal foil to a copper foil.

As Comparative Examples 8-1 and 8-2 with respect to Experimental Examples 8-1 to 8-7, except that the same electrolytic solution as Comparative Examples 1-1 and 1-3 was used, the other experimental examples 8-1 to 8-1 were used. A secondary battery was fabricated in the same manner as in 8-7.

For the secondary batteries of Experimental Examples 8-1～8-7 and Comparative Examples 8-1 and 8-2 were produced, the discharge capacity retention after high-temperature continuous charging in the same manner as in Experimental Example 1-1 to 1-16 Examined. The results are shown in Table 8.

As shown in Table 8, results similar to those of Experimental Examples 1-1 to 1-3 and 1-7 to 1-10 were obtained. That is, in the case of a lithium metal secondary battery, it was found that high temperature characteristics can be improved by including a halogenated ethylene carbonate and a phosphorus-containing compound.

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

  In the above embodiment or example, a cylindrical or laminated film type secondary battery has been specifically described, but the present invention has other shapes such as a coin type, a button type, or a square type. The present invention can be similarly applied to a secondary battery or a secondary battery having another structure such as a laminated structure. Further, the present invention is not limited to the secondary battery, and can be similarly applied to other batteries such as a primary battery. Further, in the above embodiments and examples, a battery using lithium as an electrode reactant has been described. However, another alkali metal such as sodium (Na) or potassium (K), or an alkali such as magnesium or calcium (Ca) is used. The present invention can also be applied to the case of using an earth metal or another light metal such as aluminum. At that time, a positive electrode active material or a solvent that can occlude and release the electrode reactant is selected according to the electrode reactant.

It is sectional drawing showing the structure of the 1st secondary battery using the electrolyte solution which concerns on one embodiment of this invention. It is sectional drawing which expands and represents a part of winding electrode body in the secondary battery shown in FIG. It is a disassembled perspective view showing the structure of the 5th secondary battery using the electrolyte solution which concerns on one embodiment of this invention. It is sectional drawing showing the structure along the II line of the winding electrode body shown in FIG. 1 shows an example of a peak obtained by X-ray photoelectron spectroscopy relating to a CoSnC-containing material produced in an example.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 11 ... Battery can, 12, 13 ... Insulation board, 14 ... Battery cover, 15 ... Safety valve mechanism, 15A ... Disc board, 16 ... Heat sensitive resistance element, 17 ... Gasket, 20, 30 ... Winding electrode body, 21, 33 ... Positive electrode, 21A, 33A ... Positive electrode current collector, 21B, 33B ... Positive electrode active material layer, 22, 34 ... Negative electrode, 22A, 34A ... Negative electrode current collector, 22B, 34B ... Negative electrode active material layer, 23, 35 ... Separator , 24 ... Center pin, 25, 31 ... Positive electrode lead, 26, 32 ... Negative electrode lead, 36 ... Electrolyte layer, 37 ... Protective tape, 40 ... Exterior member, 41 ... Adhesion film.

Claims (18)

And 4-fluoro-1,3-dioxolan-2-one as a halogenated ethylene carbonate, shown propyl dimethyl phosphate, butyl phosphate, dimethyl phosphate pentyl dimethyl, octyl dimethyl phosphate, a phosphoric acid triphenyl and of 1 and containing a solvent and at least one phosphorus-containing compound of the phosphoric acid ester le or Ranaru group electrolyte.

(R4 represents an alkyl group having 1 to 10 carbon atoms, an alkenyl group, an alkynyl group, an aralkyl group, an aryl group, or a group obtained by substituting at least a part of hydrogens with a substituent. R5 represents a carbon number. Represents an alkylene group of 2 to 4.) 2. The electrolytic solution according to claim 1 , wherein the content of the phosphorus-containing compound in the solvent is 1% by mass or more and 20% by mass or less. 2. The electrolytic solution according to claim 1 , wherein a content of the 4-fluoro-1,3-dioxolan-2-one in the solvent is 1% by mass or more and 40% by mass or less. It said solvent further comprises a carbonate bi two lens, according to claim 1 electrolytic solution according. An electrolytic solution containing a solvent containing a halogenated ethylene carbonate and a phosphazene compound shown in Chemical Formula 2 as a phosphorus-containing compound.

(R6, R7, R8, R9, R10, and R11 are each an alkyl group having 1 to 10 carbon atoms, an alkenyl group, an alkynyl group, an aralkyl group, an aryl group, an alkoxy group, a phenoxy group, or at least part of hydrogen atoms thereof. Represents a group substituted with a halogen group or a substituent other than halogen, or a halogen group.) The electrolytic solution according to claim 5, wherein a content of the phosphazene compound in the solvent is 1% by mass or more and 20% by mass or less. The electrolytic solution according to claim 5, wherein the content of the halogenated ethylene carbonate in the solvent is 1% by mass or more and 40% by mass or less. The electrolytic solution according to claim 5, wherein the halogenated ethylene carbonate contains 4-fluoro-1,3-dioxolan-2-one. The electrolytic solution according to claim 5, wherein the solvent further contains vinylene carbonate. Bei example a cathode, an anode,
The electrolyte includes 4-fluoro-1,3-dioxolan-2-one as a halogenated ethylene carbonate, propyldimethyl phosphate, butyldimethyl phosphate, pentyldimethyl phosphate, octyldimethyl phosphate, and triphenyl phosphate. at least one containing a solvent containing a phosphorus-containing compound, a battery of the phosphoric acid ester le or Ranaru group shown in and of 3.

(R4 represents an alkyl group having 1 to 10 carbon atoms, an alkenyl group, an alkynyl group, an aralkyl group, an aryl group, or a group obtained by substituting at least a part of hydrogens with a substituent. R5 represents a carbon number. Represents an alkylene group of 2 to 4.) The battery according to claim 10 , wherein a content of the phosphorus-containing compound in the solvent is 1% by mass or more and 20% by mass or less. The battery according to claim 10 , wherein a content of the 4-fluoro-1,3-dioxolan-2-one in the solvent is 1% by mass or more and 40% by mass or less. It said solvent further comprises a carbonate bi two lens, battery according to claim 10, wherein. An electrolyte is provided together with the positive electrode and the negative electrode,
The said electrolyte solution contains the solvent containing halogenated ethylene carbonate and the phosphazene compound shown to Chemical formula 4 as a phosphorus containing compound.

(R6, R7, R8, R9, R10, and R11 are each an alkyl group having 1 to 10 carbon atoms, an alkenyl group, an alkynyl group, an aralkyl group, an aryl group, an alkoxy group, a phenoxy group, or at least part of hydrogen atoms thereof. Represents a group substituted with a halogen group or a substituent other than halogen, or a halogen group.) The battery according to claim 14, wherein the content of the phosphazene compound in the solvent is 1% by mass or more and 20% by mass or less. The battery according to claim 14, wherein the content of the halogenated ethylene carbonate in the solvent is 1% by mass or more and 40% by mass or less. The battery of claim 14, wherein the halogenated ethylene carbonate comprises 4-fluoro-1,3-dioxolan-2-one. The battery according to claim 14, wherein the solvent further contains vinylene carbonate.

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