JP4951923B2 - Electrolyte for lithium ion secondary battery and lithium ion secondary battery - Google Patents

Description

The present invention relates to a lithium ion secondary battery using the lithium ion secondary cell electrolyte and it containing a solvent.

  In recent years, mobile electronic devices such as mobile phones, PDAs (personal digital assistants) or notebook computers have been energetically reduced in size and weight, and as part of these efforts, Improvement of the energy density of a battery as a driving power source, particularly a secondary battery is strongly desired.

  As a secondary battery capable of obtaining a high energy density, for example, a secondary battery using lithium (Li) as an electrode reactant is known. Among these, lithium ion secondary batteries using a material capable of inserting and extracting lithium such as a carbon material in the negative electrode are widely put into practical use. In order to further increase the capacity, it has been studied to use a material capable of forming an alloy with lithium for the negative electrode.

By the way, in these secondary batteries, in order to improve battery characteristics, adding various additives to electrolyte solution is examined. For example, Patent Document 1 describes 3 ′-(trifluoromethoxy) acetophene.
Japanese Patent Application No. 2005-033444

  However, these additives cannot sufficiently suppress the decomposition reaction of the electrolytic solution at a high temperature, and further improvement has been demanded.

The present invention has been made in view of such problems, and an object thereof is to provide an electrolyte for a lithium ion secondary battery capable of improving characteristics at high temperatures and a lithium ion secondary battery using the same. .

The electrolyte for a lithium ion secondary battery according to the present invention contains a solvent containing at least one member selected from the group consisting of chalcone and a halide thereof.

The lithium ion secondary battery by this invention is equipped with an electrolyte with a positive electrode and a negative electrode, and electrolyte contains the solvent containing at least 1 sort (s) of the group which consists of chalcone and its halide.

According to the electrolyte for a lithium ion secondary battery of the present invention, since it includes at least one member selected from the group consisting of chalcone and its halide, the surface of the electrode is used in the lithium ion secondary battery using the electrolyte. In addition, it is possible to form a film by addition polymerization at a portion that is locally overcharged. Therefore, side reactions at high temperatures where local overcharge is likely to occur can be effectively suppressed, and charge / discharge efficiency can be improved.

  In particular, if the content of chalcone and its halide with respect to the solvent is within the range of 0.1% by mass or more and 9% by mass or less, higher effects can be obtained.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. In the following embodiments, a so-called lithium ion secondary battery using lithium as an electrode reactant will be described.

[First Embodiment]
FIG. 1 shows a cross-sectional structure of a secondary battery according to the first embodiment of the present invention. 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 and 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. Although not shown, the positive electrode active material layer 21B may be provided only on one surface of the positive electrode current collector 21A. 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 a positive electrode material capable of inserting and extracting lithium, which is an electrode reactant, for example, as a positive electrode active material. As the positive electrode material capable of inserting and extracting lithium, for example, lithium-containing compounds such as lithium oxide, lithium phosphorus oxide, lithium sulfide, or an intercalation compound containing lithium are suitable, and two or more kinds are mixed. May be used. In particular, in order to increase the energy density, a lithium composite oxide or lithium phosphorus oxide represented by the general formula Li _x MIO ₂ or Li _y MIIPO ₄ is preferable. In the formula, MI and MII represent one or more transition metals, for example, at least one of cobalt (Co), nickel, manganese (Mn), iron, aluminum, vanadium (V), and titanium (Ti). Species are preferred. The values of x and y vary depending on the charge / discharge state of the battery, and are usually values in the range of 0.05 ≦ x ≦ 1.10 and 0.05 ≦ y ≦ 1.10.

Specific examples of the lithium composite oxide include lithium cobalt composite oxide (LiCoO ₂ ), lithium nickel composite oxide (LiNiO ₂ ), lithium nickel cobalt composite oxide (LiNi _v Co _1-v O ₂ ; 0.7 < v <1.0), or lithium manganese composite oxide (LiMn ₂ O ₄ ) having a spinel crystal structure. Specific examples of the lithium phosphorus oxide include LiFePO ₄ or LiFe _0.5 Mn _0.5 PO ₄ .

  The positive electrode active material layer 21B also contains, for example, a conductive agent, and may further contain a binder as necessary. Examples of the conductive agent include carbon materials such as graphite, carbon black, and ketjen black, and one kind or a mixture of two or more kinds is used. In addition to the carbon material, a metal material or a conductive polymer material may be used as long as it is a conductive material. Examples of the binder include synthetic rubber such as styrene butadiene rubber, fluorine rubber or ethylene propylene diene rubber, or a polymer material such as polyvinylidene fluoride, and one or two or more kinds are used in combination. It is done.

  The negative electrode 22 has, for example, a configuration 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, one or more negative electrode materials capable of inserting and extracting lithium, which is an electrode reactant, as a negative electrode active material. For example, the binder similar to the positive electrode active material layer 13B may be included.

  Examples of the negative electrode material capable of inserting and extracting lithium include carbon materials such as graphite, non-graphitizable carbon, and graphitizable carbon. These carbon materials are preferable because the change in crystal structure that occurs during charge / discharge is very small, a high charge / discharge capacity can be obtained, and good charge / discharge cycle characteristics can be obtained. In particular, graphite is preferable because it has a high electrochemical equivalent and can provide a high energy density. The graphite may be artificial graphite or natural graphite.

  Examples of the negative electrode material capable of inserting and extracting lithium include those containing at least one of a metal element and a metalloid element capable of forming an alloy with lithium as a constituent element. This negative electrode material may be a single element or an alloy or a compound of a metal element or a metalloid element, or may have at least a part of one or more of these phases. These are preferable because a high energy density can be obtained. In particular, when used together with a carbon material, a high energy density can be obtained and excellent charge / discharge cycle characteristics can be obtained. 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.

  Examples of metal elements or metalloid elements capable of forming an alloy with lithium include tin (Sn), lead (Pb), aluminum, indium (In), silicon (Si), zinc (Zn), antimony (Sb), bismuth ( Bi), cadmium (Cd), magnesium (Mg), boron (B), gallium (Ga), germanium (Ge), arsenic (As), silver (Ag), zirconium (Zr), yttrium (Y) or hafnium ( Hf). Among them, a group 14 metal element or metalloid element in the long-period type periodic table is preferable, and silicon or tin is particularly preferable.

Examples of the negative electrode material capable of inserting and extracting lithium further include other metal compounds or polymer materials. Examples of the other metal compounds include oxides such as iron oxide, ruthenium oxide, and molybdenum oxide, and LiN _3. Examples of the polymer material include polyacetylene.

  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 composed of, for example, a porous film made of a synthetic resin made of polytetrafluoroethylene, polypropylene, polyethylene, or the like, or a porous film made of an inorganic material such as a ceramic nonwoven fabric. The porous film may be laminated.

  The separator 23 is impregnated with an electrolytic solution that is a liquid electrolyte. The electrolytic solution includes an electrolyte salt and a solvent that dissolves the electrolyte salt.

Examples of the electrolyte salt include LiPF ₆ , LiBF ₄ , LiClO ₄ , LiAsF ₆ , LiN (CF ₃ SO ₂ ) ₂ , LiN (C ₂ F ₅ SO ₂ ) ₂ , LiB (C ₆ H ₅ ) ₄ , CH _3. Examples thereof include lithium salts such as SO ₃ Li, CF ₃ SO ₃ Li, LiCl, and LiBr. As the electrolyte salt, one kind may be used alone, or two or more kinds may be mixed and used.

  Solvents include ethylene carbonate, propylene carbonate, vinylene carbonate, dimethyl carbonate, ethyl methyl carbonate, diethyl carbonate, 1,2-dimethoxyethane, 1,2-diethoxyethane, γ-butyrolactone, γ-valerolactone, tetrahydrofuran, 2 -Methyltetrahydrofuran, 1,3-dioxolane, 4-methyl-1,3-dioxolane, diethyl ether, sulfolane, methyl sulfolane, acetonitrile, propionitrile, anisole, acetate ester, butyrate ester, propionate ester or fluorobenzene Non-aqueous solvents are mentioned. As the solvent, one kind may be used alone, or two or more kinds may be mixed and used.

  In the present embodiment, the solvent contains at least one member selected from the group consisting of chalcone and a halide thereof. Chalcone is 1,3-diphenyl-2-propylene-1-one (1,3-diphenylprop-2-en-1-one) represented by Chemical Formula 1 and is also called benzalacetophenone. . Further, the halide is one in which at least a part of hydrogen contained in chalcone is substituted with halogen, and hydrogen in the benzene ring may be substituted or hydrogen in the vinyl group may be substituted. .

  Chalcone and its halides have a low addition reactivity of vinyl groups compared to isolated double bonds such as ethylene or propylene because phenyl, vinyl and carbonyl groups form conjugated multiple bonds. have. Therefore, in this secondary battery, since this compound is locally added and polymerized to form a film in the overcharged portion of the electrode surface, the increase in internal resistance is suppressed and the electrolyte is decomposed. It is possible to effectively suppress side reactions such as such as side reactions at high temperatures.

  Further, a halide is preferable to chalcone, and the number of substitution of halogen groups is preferably 2 or more. Among them, a halogen group is bonded to both a benzene ring bonded to the carbonyl group (benzene ring bonded to the 1st position) and a benzene ring bonded to the vinyl group (benzene ring bonded to the 3rd position). It is preferable to do. This is because a higher effect can be obtained.

  The content of the chalcone and its halide with respect to the solvent, when two or more types are included, is 0.1 to 9% by mass, and further 0.1 to 7% by mass in total. It is preferable. This is because a higher effect can be obtained within this range.

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

  First, the positive electrode active material layer 21B is formed on the positive electrode current collector 21A to produce the positive electrode 21, and the negative electrode active material layer 22B is formed on the negative electrode current collector 22A to produce the negative electrode 22. The positive electrode 21 and the negative electrode 22 may be formed by coating, for example, or may be formed by a gas phase method or a liquid phase method. 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 released from the positive electrode active material layer 21B and inserted into the negative electrode active material layer 22B through the electrolytic solution. In addition, when discharging is performed, for example, lithium ions are released from the negative electrode active material layer 22B and inserted into the positive electrode active material layer 21B through the electrolytic solution. At that time, since chalcone or a halide thereof is contained in the electrolytic solution, if overcharge occurs locally in the electrode, addition polymerization is performed at that portion to form a film on the electrode. Therefore, side reactions such as decomposition of the electrolytic solution are suppressed while suppressing an increase in internal resistance.

  As described above, according to the present embodiment, chalcone or a halide thereof is included, so that a film can be formed on a portion that is locally overcharged on the surface of the electrode. Therefore, side reactions at high temperatures where local overcharge is likely to occur can be effectively suppressed, and charge / discharge efficiency can be improved.

  In particular, if a halide in which a halogen group is bonded to both a benzene ring bonded to a carbonyl group and a benzene ring bonded to a vinyl group is included, a higher effect can be obtained.

  Further, if the content of chalcone and its halide in the solvent is 0.1% by mass or more and 9% by mass or less, more preferably 0.1% by mass or more and 7% by mass or less, a higher effect can be obtained. Obtainable.

[Second Embodiment]
FIG. 3 shows the configuration of the secondary battery according to the second embodiment of the present invention. 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, for example, in the same direction from the inside of the exterior member 40 to the outside, and are each made of a metal material such as aluminum, copper, nickel, or stainless steel.

  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 an enlarged part of the spirally wound electrode body 30 shown in FIG. The wound electrode body 30 is obtained by stacking and winding a positive electrode 33 and a negative electrode 34 with a separator 35 and an electrolyte layer 36 interposed therebetween.

  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, and the negative electrode 34 also has a structure in which a negative electrode active material layer 34B is provided on both surfaces of the negative electrode current collector 34A. have. The positive electrode 33 and the negative electrode 34 are disposed so that the positive electrode active material layer 33B and the negative electrode active material layer 34B face each other. The specific configurations 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 are the same as those of the positive electrode current collector 21A, the positive electrode active material layer in the first embodiment. This is the same as 21B, the negative electrode current collector 22A, the negative electrode active material layer 22B, and the separator 23.

  The electrolyte layer 36 includes an electrolytic solution and a polymer compound that holds the electrolytic solution, and has a so-called gel shape. A gel electrolyte is preferable because high ion conductivity can be obtained and battery leakage can be prevented. The configuration of the electrolytic solution (that is, the solvent, the electrolyte salt, and the like) is the same as that in the first embodiment described above. Examples of the polymer material include, for example, an ether-based polymer compound such as polyethylene oxide or a crosslinked product containing polyethylene oxide, a polymer of vinylidene fluoride such as polyvinylidene fluoride or a copolymer of vinylidene fluoride and hexafluoropropylene, Or a polyacrylonitrile is mentioned, Among these, 1 type (s) or 2 or more types are mixed and 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, after forming the positive electrode 33 and the negative electrode 34 in the same manner as in the first embodiment, the electrolyte layer 36 in which the electrolytic solution is held in the polymer compound is formed on each of the positive electrode 33 and the negative electrode 34. Next, the positive electrode lead 31 is attached to the end portion of the positive electrode current collector 33A, and the negative electrode lead 32 is attached to the end portion of 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 stacked via the separator 35, and then wound in the longitudinal direction to form the wound electrode body 30. 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, in this secondary battery, the positive electrode 33 and the negative electrode 34 are laminated and wound via the separator 35 and sandwiched between the exterior members 40, and then the electrolytic solution and the polymer compound are opened from the opening of the exterior member 40. The electrolyte layer 36 may be formed by injecting an electrolyte composition containing a monomer as a raw material and polymerizing the monomer.

  This secondary battery operates in the same manner as in the first embodiment, and has the same effect as in the first embodiment.

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

(Examples 1-1 to 1-19)
The laminate film type secondary battery shown in FIGS. First, lithium-cobalt composite oxide (LiCoO ₂ ) is used as a positive electrode active material, and this lithium-cobalt composite oxide, graphite as a conductive agent, and polyvinylidene fluoride as a binder are mixed to form a positive electrode composite. An agent was prepared. Next, this positive electrode mixture was dispersed in N-methyl-2-pyrrolidone as a solvent to form a positive electrode mixture slurry, and then uniformly applied to the positive electrode current collector 33A made of aluminum foil and dried, and a roll press machine The positive electrode active material layer 33B was formed by compression molding to produce the positive electrode 33.

  Further, artificial graphite was prepared as a negative electrode active material, and this negative graphite was mixed with polyvinylidene fluoride as a binder to prepare a negative electrode mixture. Next, this negative electrode mixture was dispersed in N-methyl-2-pyrrolidone as a solvent to form a negative electrode mixture slurry, and then uniformly applied to the negative electrode current collector 34A made of copper foil and dried, and a roll press machine The negative electrode active material layer 34B was formed by compression molding, and the negative electrode 34 was produced.

Subsequently, the positive electrode lead 31 was attached to the positive electrode current collector 33A, the negative electrode lead 32 was attached to the negative electrode current collector 34A, and the electrolyte layer 36 was formed on the positive electrode active material layer 33B and the negative electrode active material layer 34B. The electrolyte layer 36 is prepared by mixing ethylene carbonate and propylene carbonate at a mass ratio of 1: 1, adding chalcone or a fluorinated product thereof, and LiPF ₆ as an electrolyte salt to hexafluoropropylene. And a gelled electrolyte held in a copolymer of vinylidene fluoride. At that time, the content of chalcone and its fluoride in the solvent is 1% by mass, the content of LiPF ₆ in the electrolyte is 0.6 mol / kg, and the ratio of hexafluoropropylene in the copolymer is 6.9% by mass. %. Further, as the fluorinated chalcone, one obtained by substituting a part of hydrogen bonded to the benzene ring with a fluorine group, and the substitution position of the fluorine group is as shown in Table 1 in Examples 1-2 to 1-19. Was changed. The 2nd to 6th positions represent the carbon position of the benzene ring bonded to the carbonyl group, and the 2 ′ to 6 ′ positions represent the carbon position of the benzene ring bonded to the vinyl group.

  Next, the separator 35, the positive electrode 33, the separator 35, and the negative electrode 34 were stacked and wound in this order to form the wound electrode body 30, and then the wound electrode body 30 was sealed between the exterior members 40. Thus, secondary batteries of Examples 1-1 to 1-19 were obtained.

  As Comparative Example 1-1 with respect to Examples 1-1 to 1-19, a secondary battery was obtained in the same manner as in Examples 1-1 to 1-19 except that chalcone and its halide were not added to the electrolytic solution. Was made. In addition, as Comparative Examples 1-2 and 1-3, 3 ′-(trifluoromethoxy) acetophenone shown in Chemical Formula 2 (1) or tri-n-butylvinyltin shown in Chemical Formula 2 (2) was used as the electrolytic solution. A secondary battery was fabricated in the same manner as in Examples 1-1 to 1-19 except that was added. In Comparative Examples 1-2 and 1-3, the content of 3 '-(trifluoromethoxy) acetophenone or tri-n-butylvinyltin in the solvent was 1% by mass.

  The fabricated secondary batteries of Examples 1-1 to 1-19 and Comparative Examples 1-1 to 1-3 were charged and discharged at 45 ° C., and the initial efficiency and high-temperature cycle characteristics were examined. Charging was performed at a constant current and constant voltage of 0.8 A and an upper limit of 4.2 V, and discharging was performed at a constant current of 0.8 A up to a final voltage of 3.0 V. The initial efficiency was obtained from the ratio of the discharge capacity to the charge capacity at the first cycle, that is, (discharge capacity at the first cycle / charge capacity at the first cycle) × 100 (%). The high-temperature cycle characteristics were determined from the ratio of the discharge capacity at the 500th cycle to the discharge capacity at the 5th cycle, that is, (discharge capacity at the 500th cycle / discharge capacity at the 5th cycle) × 100 (%). The results are shown in Table 1.

  As shown in Table 1, according to Examples 1-1 to 1-19 to which chalcone or a fluorinated product thereof was added, the initial efficiency and high-temperature cycle characteristics were higher than those of Comparative Example 1-1 in which they were not added. A high value was obtained. In Comparative Examples 1-2 and 1-3 in which other compounds were added, the initial efficiency was improved, but sufficient values were not obtained for the high-temperature cycle characteristics. That is, it has been found that if chalcone or a fluoride thereof is contained in the electrolytic solution, the initial efficiency and cycle characteristics can be improved even in a high temperature environment.

  Moreover, the higher effect was obtained in Examples 1-2 to 1-19 to which the fluorinated product was added than Example 1-1 to which chalcone was added. Furthermore, when the number of fluorine groups is 2 or more, higher cycle characteristics are obtained, and the fluorine groups are bonded to both the benzene ring bonded to the carbonyl group and the benzene ring bonded to the vinyl group. There was a tendency for the cycle characteristics to improve more. That is, the halide is preferable, and the halogen group is bonded to both the benzene ring bonded to the benzene ring bonded to the vinyl group and the benzene ring bonded to the carbonyl group having two or more halogen groups. The one was found to be more preferable.

(Examples 2-1 to 2-11)
A secondary battery was made in the same manner as Example 1-11 except that the content of the halogenated chalcone in the solvent was changed within the range of 0.05% by mass to 20% by mass. The added halogenated chalcone is 4,4′-difluorochalcone.

  For the fabricated secondary batteries of Examples 2-1 to 2-11, the initial efficiency and high-temperature cycle characteristics were examined in the same manner as in Examples 1-1 to 1-19. The results are shown in Table 2 together with the results of Example 1-11 and Comparative example 1-1.

  As shown in Table 2, as the halogenated chalcone content in the solvent increased, the initial efficiency and high-temperature cycle characteristics increased, and a tendency to decrease after showing the maximum value was observed. That is, the content of chalcone and halogenated chalcone in the solvent is preferably in the range of 0.1% by mass to 9% by mass, and more preferably in the range of 0.1% by mass to 7% by mass. I understood.

(Examples 3-1 to 3-6, 4-1)
In Examples 3-1 to 3-6, secondary batteries were fabricated in the same manner as in Examples 1-2 and 1-5, except that the type of halogen group of the halogenated chalcone was changed. Specifically, in Examples 3-1 and 3-2, a benzene ring bonded to the carbonyl group or a benzene ring bonded to the vinyl group at the 2 ′ position of the benzene ring is bonded to the chlorine group. In Examples 3-3 and 3-4, the benzene ring bonded to the carbonyl group was bonded to the 2-position or the benzene ring bonded to the vinyl group was bonded to the 2′-position of the bromine group. In Examples 3-5 and 3-6, those in which an iodine group was bonded to the 2-position of the benzene ring bonded to the carbonyl group or the 2′-position of the benzene ring bonded to the vinyl group were used.

  In Examples 4-1 to 4-6, except that the halogenated chalcone was substituted at the 2- or 3-position vinyl group with a halogen group, Examples 1-1 to 1- A secondary battery was produced in the same manner as in Example 19. As the halogenated chalcone, 2-fluoro-1,3-diphenyl-2-propen-1-one was used in Example 4-1, and 2-chloro-1,3-diphenyl-2-one was used in Example 4-2. Using propen-1-one, Example 4-3 uses 3-fluoro-1,3-diphenyl-2-propen-1-one, Example 4-4 uses 3-chloro-1,3-diphenyl- 2-propen-1-one was used, in Example 4-5, 3,3-difluoro-1,3-diphenyl-2-propen-1-one was used, and in Example 4-6, 3,3-dichloro- 1,3-diphenyl-2-propen-1-one was used.

  For the fabricated secondary batteries of Examples 3-1 to 3-6 and 4-1 to 4-6, the initial efficiency and the high-temperature cycle characteristics were examined in the same manner as in Examples 1-1 to 1-19. The results are shown in Tables 3 and 4 together with the results of Examples 1-2 and 1-5 and Comparative Example 1-1.

  As shown in Tables 3 and 4, whether the halogenated chalcone substituted with another halogen group or the halogenated chalcone in which the halogen group is bonded to the vinyl group was used, the initial efficiency and the high-temperature cycle were the same. The characteristics could be improved. That is, it was found that the use of a halide in which at least a part of hydrogen contained in chalcone is substituted with halogen can improve the initial efficiency and cycle characteristics in a high temperature environment.

(Examples 5-1 to 5-6)
A secondary battery was fabricated in the same manner as in Examples 1-1 to 1-19, except that the configuration of the negative electrode 34 was changed. The negative electrode 34 uses a Sn-containing material as a negative electrode active material. After mixing this Sn-containing material, artificial graphite as a conductive agent, and polyvinylidene fluoride as a binder, N-methyl-2-pyrrolidone as a solvent is mixed. Was added to the negative electrode current collector 34A made of copper foil, dried, and compression-molded with a roll press to form the negative electrode active material layer 34B. . As the Sn-containing material, a material made of tin, cobalt, and carbon was used.

  In addition, chalcone was added to the electrolytic solution in Example 5-1, and fluorinated chalcone in which a part of hydrogen bonded to the benzene ring was substituted with a fluorine group in Examples 5-2 to 5-6. did. The substitution position of the fluorine group in the fluorinated chalcone was changed as shown in Table 5 in Examples 5-2 to 5-6. The content of chalcone or fluorinated chalcone in the solvent is 1% by mass.

  As Comparative Example 5-1 with respect to Examples 5-1 to 5-6, a secondary battery was obtained in the same manner as in Examples 5-1 to 5-6 except that chalcone and halogenated chalcone were not added to the electrolytic solution. Was made.

  For the fabricated secondary batteries of Examples 5-1 to 5-6 and Comparative Example 5-1, the initial efficiency and the high-temperature cycle characteristics were examined in the same manner as in Examples 1-1 to 1-19. The results are shown in Table 5.

  As shown in Table 5, according to Examples 5-1 to 5-6 to which chalcone or halogenated chalcone was added, the initial efficiency and high-temperature cycle characteristics were improved as compared with Comparative Example 5-1 to which chalcone or halogenated chalcone was not added. I was able to. That is, it has been found that even if other negative electrode active materials are used, the initial efficiency and cycle characteristics can be improved even in a high temperature environment if chalcone or halogenated chalcone is contained in the electrolytic solution.

  Although the present invention has been described with reference to the embodiments and examples, the present invention is not limited to the above embodiments and examples, and various modifications can be made. For example, in the above-described embodiments and examples, the case where the electrolyte solution or the gel electrolyte in which the electrolyte solution is held in the polymer compound is used as the electrolyte has been described, but the electrolyte solution may be held in the inorganic conductor, Moreover, you may make it hold | maintain electrolyte solution in the mixture of a high molecular compound and an inorganic conductor. Examples of inorganic conductors include polycrystals of lithium nitride, lithium iodide or lithium hydroxide, a mixture of lithium iodide and dichromium trioxide, or a mixture of lithium iodide, thilium sulfide and diphosphorous subsulfide. The thing containing is mentioned.

Moreover, although the said embodiment and Example demonstrated the case where the positive electrodes 21 and 33 and the negative electrodes 22 and 34 were wound, you may make it fold or stack | stack a positive electrode and a negative electrode. Furthermore, in the above-described embodiments and examples, a cylindrical or laminated film type secondary battery has been described. For example, other types such as an elliptical type, a polygonal type, a coin type, a button type, a square type, or a large type are described. The present invention can also be applied to a secondary battery having a shape .

  Furthermore, in the above-described embodiments and examples, a so-called lithium ion secondary battery, that is, a secondary battery in which the capacity of the negative electrode is represented by a capacity component due to insertion and extraction of lithium has been described. The present invention can be similarly applied to the used battery. As a battery using another electrode reaction, for example, a battery in which the capacity of the negative electrode is represented by the sum of the capacity component due to insertion and extraction of lithium and the capacity component due to precipitation and dissolution of lithium, or the capacity of the negative electrode is A so-called lithium metal battery represented by a capacity component due to precipitation and dissolution of lithium can be given.

  Among these, a battery in which the capacity of the negative electrode is represented by the sum of the capacity component due to insertion and extraction of lithium and the capacity component due to precipitation and dissolution of lithium has, for example, a charge capacity of a negative electrode material capable of inserting and extracting lithium. The lithium ion secondary battery has the same configuration as the above-described lithium ion secondary battery except that lithium metal is deposited on the negative electrode during charging by being adjusted to be smaller than the charging capacity of the positive electrode. . In addition, the lithium metal battery has the same configuration as the lithium ion secondary battery described above except that the negative electrode is made of lithium metal and the like, and the precipitation and dissolution reaction of lithium is used in the negative electrode. Yes.

  Furthermore, in the above-described embodiments and examples, the case where lithium is used as the electrode reactant has been described. However, other alkali metals such as sodium (Na) or potassium (K), magnesium or calcium (Ca), etc. The present invention can also be applied to the case of using other light metals such as alkaline earth metals or aluminum.

It is sectional drawing showing the structure of the secondary battery which concerns on the 1st 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 partial exploded perspective view showing the structure of the secondary battery which concerns on the 2nd 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.

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, 40 ... exterior member, 41 ... adhesion film.

Claims (6)

The electrolyte for lithium ion secondary batteries containing the solvent containing at least 1 sort (s) of the group which consists of chalcone and its halide. 2. The electrolyte for a lithium ion secondary battery according to claim 1 , wherein a content of the chalcone and a halide thereof in a solvent is in a range of 0.1% by mass to 9% by mass. Further, containing the polymer compound according to claim 1 for a lithium ion secondary battery electrolyte according. An electrolyte is provided with a positive electrode and a negative electrode ,
The said electrolyte contains the solvent containing at least 1 sort (s) of the group which consists of chalcone and its halide , The lithium ion secondary battery. 5. The lithium ion secondary battery according to claim 4 , wherein a content of the chalcone and a halide thereof in the solvent is in a range of 0.1% by mass to 9% by mass. The electrolyte further contains a polymer compound, a lithium ion secondary battery according to claim 4, wherein.

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