JP2008305771A - Nonaqueous solution battery - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a nonaqueous electrolyte battery with its swelling restrained at high-temperature storage. <P>SOLUTION: In the nonaqueous electrolyte battery provided with electrolyte solution together with a cathode and an anode, the electrolyte solution contains chlorine-substituted carboxylate expressed in formula (1). In the formula (1), Y, Z are C<SB>m</SB>H<SB>2m+1-n</SB>X<SB>n</SB>(0≤m≤4, 0≤n≤2m+1, X is at least either F, Cl, or Br), and M is either one out of Li, Na, K, Rb, Cs, Ag, 1/2Be, 1/2Mg, and 1/2Ca, 1/2Sr, 1/2Ba, 1/2Zn, 1/2Cd, 1/2Hg, 1/2Sn, 1/2Pb. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a non-aqueous electrolyte battery using an electrolytic solution containing a chlorine-substituted carboxylate.

  In recent years, many portable electronic devices such as a camera-integrated VTR, a digital still camera, a mobile phone, a personal digital assistant, and a notebook computer have appeared, and their size and weight have been reduced. As portable power sources for these electronic devices, research and development for improving the energy density of batteries, particularly secondary batteries, are being actively promoted.

  Among secondary batteries, a lithium ion secondary battery using a non-aqueous solvent such as carbon as a negative electrode active material, a lithium-transition metal composite oxide as a positive electrode active material, and a carbonate ester mixture as an electrolyte is a conventional aqueous electrolyte. Compared to lead batteries and nickel cadmium batteries, which are secondary batteries, a large energy density is obtained, so that they are widely put into practical use. In particular, a laminated battery using a laminate film for the exterior has a high energy density because it is lightweight. In the laminate type battery, since the deformation of the laminate type battery can be suppressed by swelling the electrolyte in the polymer, the laminate polymer battery is also widely used.

In these lithium ion secondary batteries, in order to improve battery characteristics such as cycle characteristics, for example, it has been proposed to add various additives to the electrolytic solution (see Patent Documents 1 and 2).
JP 60-41774 A JP 2004-22379 A

  However, in the electronic device using the secondary battery, the power consumption tends to increase, and the heat generation amount increases accordingly. For this reason, the operating environment of the battery is also increasing in temperature, and conventional secondary batteries have problems such as thermal expansion due to self-discharge or decomposition of the electrolytic solution, and deterioration of battery characteristics such as charge / discharge efficiency. It was.

  The present invention has been made in view of such problems, and an object of the present invention is to provide an electrolytic solution capable of improving cycle characteristics by suppressing thermal expansion and improving charge / discharge efficiency even in a high temperature environment. And providing a battery using the same.

  A non-aqueous electrolyte battery according to the present invention is a non-aqueous electrolyte battery provided with an electrolyte together with a positive electrode and a negative electrode, and contains a chlorine-substituted carboxylate represented by the following formula (1): This is a non-aqueous electrolyte battery.

In formula (1), Y and Z are C _m H _{2m + 1−n} X _n (0 ≦ m ≦ 4, 0 ≦ n ≦ 2m + 1, and X is at least one of F, Cl, and Br. ), M is Li, Na, K, Rb, Cs, Ag, 1 / 2Be, 1 / 2Mg, 1 / 2Ca, 1 / 2Sr, 1 / 2Ba, 1 / 2Zn, 1 / 2Cd, 1 / 2Hg, 1 / Any one of 2Sn and 1 / 2Pb.

  According to the battery of the present invention, by including a chlorine-substituted carboxylate in the electrolytic solution, it is possible to form a good film on the surface of the positive electrode or the negative electrode, suppress the decomposition reaction of the electrolyte, and reduce the ion in the electrode. Conductivity can be improved. Therefore, even under a high temperature environment, thermal expansion can be suppressed, charge / discharge efficiency can be improved, and cycle characteristics can be improved.

  In particular, a higher effect can be obtained by setting the concentration of the chlorine-substituted carboxylate to 0.1 to 1.0% by mass and including a chlorine atom in the halogen. In addition, a higher effect can be obtained by adding a halogenated carbonate, a carbonate having a carbon-carbon multiple bond, and a polymer compound swollen by the electrolyte to the electrolyte.

  Hereinafter, the best mode for carrying out the present invention will be described with reference to the drawings, but the present invention is not limited to the following mode.

  FIG. 1 shows a cross-sectional structure of a secondary battery according to an embodiment of the present invention. This secondary battery is a so-called cylindrical type, and is a wound electrode in which a strip-like positive electrode 21 and a negative electrode 22 are laminated and wound inside a substantially hollow cylindrical battery can 11 via a separator 23. It has a body 20. 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 (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 a structure in which a positive electrode active material layer 21B is provided on both surfaces of a positive electrode current collector 21A. 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, and the negative electrode active material layer 22B and the positive electrode active material layer 21B are arranged to face each other.

  The positive electrode 21 includes, for example, a positive electrode current collector 21A having a pair of opposed surfaces and a positive electrode active material layer 21B provided on both surfaces or 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, for example, a positive electrode material that can occlude and release lithium as an electrode reactant as a positive electrode active material.

  The positive electrode current collector 21A is made of a metal material such as aluminum, nickel, and stainless steel, for example. The positive electrode active material layer 24B includes, for example, any one or more of positive electrode materials capable of occluding and releasing lithium as a positive electrode active material, and a conductive agent such as a carbon material and polyvinylidene fluoride as necessary. It may contain a binder.

Examples of the positive electrode material capable of inserting and extracting lithium include lithium cobaltate, lithium nickelate, and solid solutions thereof (Li (NiCo _y Mn _z ) O ₂ ) (x, y, and z have values of 0 <x <1, 0 <y <1, 0 ≦ z <1, x + y + z = 1.), Manganese spinel (LiMn ₂ O ₄ ) and its solid solution (Li (Mn _2−v Ni _v ) O ₄ ) (The value of v is v <2.) Lithium composite oxides and the like, and phosphate compounds having an olivine structure such as lithium iron phosphate (LiFePO ₄ ) are preferable. This is because a high energy density can be obtained. Examples of the positive electrode material capable of inserting and extracting lithium include oxides such as titanium oxide, vanadium oxide and manganese dioxide, disulfides such as iron disulfide, titanium disulfide and molybdenum sulfide, sulfur, And conductive polymers such as polyaniline and polythiophene.

  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 anode current collector 22A is made of a metal material such as copper, nickel, and stainless steel, for example.

  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 non-graphitizable carbon, graphitizable carbon, graphite, pyrolytic carbons, cokes, glassy carbons, and fired organic polymer compounds , Carbon fibers, and carbon materials such as activated carbon. Among these, examples of coke include pitch coke, needle coke, and petroleum coke. An organic polymer compound fired body is a carbonized material obtained by firing a polymer material such as a phenol resin or a furan resin at an appropriate temperature, and part of it is non-graphitizable carbon or graphitizable carbon. Some are classified as:

  The carbon material is preferable because a change in crystal structure that occurs during charge / discharge is very small, a high charge / discharge capacity can be obtained, and good cycle characteristics can be obtained. In particular, graphite is preferable because it has a high electrochemical equivalent and can provide a high energy density. Further, non-graphitizable carbon is preferable because excellent cycle characteristics can be obtained. Furthermore, those having a low charge / discharge potential, specifically, those having a charge / discharge potential close to that of lithium metal are preferable because a high energy density of the battery can be easily realized.

  Examples of the negative electrode material capable of inserting and extracting lithium include a material containing tin or silicon 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.

  Specific examples of such a negative electrode material include, for example, a simple substance of tin, an alloy, and a compound thereof, a simple substance of silicon, an alloy, and a compound thereof, and one or more phases thereof. The material which has is mentioned. In the present invention, alloys include those containing one or more kinds of metal elements and one or more kinds of metalloid elements in addition to those made of a plurality of kinds of metal elements. Moreover, the nonmetallic element may be included. Some of the structures include a solid solution, a eutectic (eutectic mixture), an intermetallic compound, or a combination thereof.

  As an alloy of tin, for example, as a second constituent element other than tin, among the group consisting of silicon, 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. 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 the silicon compound include those containing oxygen or carbon, and may contain the second constituent element described above in addition to tin or silicon.

  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. Examples of such a metal element or metalloid element include magnesium, boron, aluminum, gallium, indium, germanium, lead, bismuth, cadmium, silver, zinc, hafnium, zirconium, yttrium, palladium, platinum, and the like. .

  As a negative electrode material capable of inserting and extracting lithium, in addition to these negative electrode materials, other negative electrode materials may be mixed and used. Examples of other negative electrode materials include carbon materials such as graphite, non-graphitizable carbon, and graphitizable carbon. Such a carbon material has very little change in crystal structure due to insertion and extraction of lithium, and when used with the above-described negative electrode material, a high energy density and excellent cycle characteristics can be obtained. It is also preferable because it functions as a conductive agent.

  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 plural kinds of porous films are laminated. It may be a structure. For example, the separator 23 is impregnated with an electrolytic solution that is a liquid electrolyte.

  The electrolytic solution includes, for example, a solvent and an electrolyte salt dissolved in the solvent. The electrolytic solution contains a chlorine-substituted carboxylate represented by the following formula (1). A chlorine-substituted carboxylate is a carboxylate in which some or all of the halogens have been replaced with chlorine. These chlorine-substituted carboxylates are decomposed on the electrode surface during the initial charge to form a lithium chlorinated protective film, thereby suppressing gas generation due to the reaction between the electrolytic solution and the battery active material. Here, it is important to use a chlorine-substituted carboxylate instead of a chlorine-substituted carboxylic acid. This is because when a chlorine-substituted carboxylic acid is used instead of a chlorine-substituted carboxylate, protons of the carboxylic acid become hydrogen gas during the initial charge, and the battery expands and becomes thick.

In formula (1), Y and Z are C _m H _{2m + 1−n} X _n (0 ≦ m ≦ 4, 0 ≦ n ≦ 2m + 1, and X is at least one of F, Cl, and Br. ), M is Li, Na, K, Rb, Cs, Ag, 1 / 2Be, 1 / 2Mg, 1 / 2Ca, 1 / 2Sr, 1 / 2Ba, 1 / 2Zn, 1 / 2Cd, 1 / 2Hg, 1 / Any one of 2Sn and 1 / 2Pb. In particular, m = 0 and 1 are preferable, and n = 2m + 1 is preferable. M is preferably Li, Na, or K. This is because a higher effect can be obtained.

  The content of the chlorine-substituted carboxylate in the electrolytic solution is preferably in the range of 0.1% by mass to 1.0% by mass. It is because a higher effect is acquired by setting it as this range.

  Examples of the chlorine-substituted carboxylate include lithium trichloroacetate represented by the following formula (2), lithium dichloroacetate represented by the following formula (3), and lithium chlorodifluoroacetate represented by the following formula (4).

  The solvent used for the electrolytic solution is preferably a high dielectric constant solvent having a relative dielectric constant of 30 or more. This is because the number of lithium ions can be increased. The content of the high dielectric constant solvent in the electrolytic solution is preferably in the range of 15% by mass to 50% by mass. It is because higher charging / discharging efficiency is obtained by setting it within this range.

  Examples of the high dielectric constant solvent include cyclic carbonates having carbon-carbon multiple bonds such as vinylene carbonate, ethylene carbonate, propylene carbonate, butylene carbonate and vinyl ethylene carbonate, lactones such as γ-butyrolactone and γ-valerolactone, N -Lactams such as methyl-2-pyrrolidone; cyclic carbamates such as N-methyl-2-oxazolidinone; and sulfone compounds such as tetramethylene sulfone. Cyclic carbonates are particularly preferable, and ethylene carbonate and vinylene carbonate having a carbon-carbon double bond are more preferable. The content of the carbonic acid ester having a carbon-carbon multiple bond in the electrolytic solution is preferably in the range of 0.1% by mass to 2.0% by mass. Moreover, the said high dielectric constant solvent may be used individually by 1 type, and may mix and use multiple types.

  The high dielectric constant solvent may contain a halogenated carbonate. This is because a good film can be formed on the negative electrode 22 and the decomposition reaction of the electrolytic solution can be suppressed. Examples of halogenated carbonates include fluorinated ethylene carbonates such as 4-fluoro-1,3-dioxolan-2-one (fluoroethylene carbonate) represented by the following formula (5), 4-methyl-5-fluoro-1 , 3-dioxolan-2-one and 4,5-difluoro-1,3-dioxolan-2-one, etc., trifluoropropylene carbonate represented by the following formula (6), 4-trifluoromethyl- 1,3-dioxolane-2-one and trifluoromethylene carbonate such as trifluoromethylene ethylene carbonate, and 4-chloro-1,3-dioxolan-2-one (chloroethylene carbonate) represented by the following formula (7) A chlorinated ethylene carbonate is mentioned. The content of the halogenated carbonate in the electrolytic solution is preferably in the range of 0.1% by mass to 2% by mass. In addition, the halogenated carbonate may be used alone or in combination of two or more.

  The solvent used for the electrolytic solution is preferably used by mixing a low-viscosity solvent having a viscosity of 1 mPa · s or less with the high dielectric constant solvent. This is because high ion conductivity can be obtained. The ratio (mass ratio) of the low-viscosity solvent to the high-dielectric-constant solvent is preferably in the range of high-dielectric-constant solvent: low-viscosity solvent = 2: 8 to 5: 5. It is because a higher effect can be obtained by setting it within this range.

  Examples of the low viscosity solvent include chain carbonate esters such as dimethyl carbonate, diethyl carbonate, ethyl methyl carbonate, and methyl propyl carbonate, methyl acetate, ethyl acetate, methyl propionate, ethyl propionate, methyl butyrate, methyl isobutyrate, and trimethyl. Chain carboxylic acid esters such as methyl acetate and ethyl trimethylacetate, chain amides such as N, N-dimethylacetamide, chain carbamic acid esters such as methyl N, N-diethylcarbamate and ethyl N, N-diethylcarbamate And ethers such as 1,2-dimethoxyethane, tetrahydrofuran, tetrahydropyran and 1,3-dioxolane. These low-viscosity solvents may be used alone or in combination of two or more.

As the electrolyte salt, e.g., lithium hexafluorophosphate (LiPF _6), lithium tetrafluoroborate (LiBF _4), lithium hexafluoroarsenate (LiAsF _6), lithium hexafluoro antimonate (LiSbF ₆₎ , Inorganic lithium salts such as lithium perchlorate (LiClO ₄ ) and lithium tetrachloroaluminate (LiAlCl ₄ ), and lithium trifluoromethanesulfonate (CF ₃ SO ₃ Li), lithium bis (trifluoromethanesulfone) imide [(CF ₃ SO ₂ ) ₂ NLi], lithium bis (pentafluoroethanesulfone) imide [(C ₂ F ₅ SO ₂ ) ₂ NLi] and lithium tris (trifluoromethanesulfone) methide [(CF ₃ SO ₂ ) ₃ CLi] Of perfluoroalkanesulfonic acid derivatives Examples include thium salts. One electrolyte salt may be used alone, or a plurality of electrolyte salts may be mixed and used.

  The secondary battery shown in FIG. 1 can be manufactured as follows, for example. First, for example, the positive electrode active material layer 21B is formed on the positive electrode current collector 21A, and the positive electrode 21 is manufactured. The positive electrode active material layer 21B is prepared, for example, by mixing a positive electrode active material powder, a conductive agent, 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, the negative electrode active material layer 22B is formed on the negative electrode current collector 22A to produce the negative electrode 22.
The negative electrode active material layer 22B may be formed by, for example, any one of a vapor phase method, a liquid phase method, a baking method, and coating, or a combination of two or more thereof. When formed by a vapor phase method, a liquid phase method, or a firing method, the negative electrode active material layer 22B and the negative electrode current collector 22A may be alloyed at least at a part of the interface at the time of formation. An alloy may be formed by heat treatment under a non-oxidizing atmosphere.

  As the vapor phase method, for example, a physical deposition method, a chemical deposition method, or the like can be used. Specifically, a vacuum deposition method, a sputtering method, an ion plating method, a laser ablation method, thermal CVD (Chemical) A vapor deposition (chemical vapor deposition) method, a plasma CVD method, or the like can be used. As the liquid phase method, for example, known methods such as electrolytic plating and electroless plating can be used. Known methods can also be used for the firing method. For example, an atmospheric firing method, a reactive firing method, and a hot press firing method can be used. In the case of application, it can be formed in the same manner as the positive electrode 21.

  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 the gasket 17. Thereby, the secondary battery shown in FIG. 1 is completed.

  In this secondary battery, when charged, for example, lithium ions are released 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 separated from the negative electrode 22 and inserted into the positive electrode 21 through the electrolytic solution. At that time, since the electrolytic solution contains a halogenated carbonyl compound in which halogen is bonded to the α-position of the carbonyl group, a good film is formed on the negative electrode 22, the decomposition reaction of the electrolytic solution is suppressed, and excellent chargeability is achieved. Discharge efficiency can be obtained.

  FIG. 3 shows a configuration of a secondary battery according to another embodiment of the present invention. In this secondary battery, a wound electrode body 30 to which a positive electrode lead 31 and a negative electrode lead 32 are attached is accommodated in a film-like exterior member 40, and can be reduced in size, weight, and thickness. ing.

  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, for example, a metal material such as aluminum, copper, nickel, and 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. The exterior member 40 is disposed, for example, 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 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, and modified polypropylene.

  Note that the exterior member 40 may be configured by a laminated film having another structure, a polymer film such as polypropylene, and 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 one or 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 one side or both sides of a negative electrode current collector 34A, and the negative electrode active material layer 34B side is disposed so as to face the positive electrode active material layer 33B. Yes. The 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 respectively the positive electrode current collector 21A, the positive electrode active material layer 21B, and the negative electrode current collector 22A described above. The same as the negative electrode active material layer 22B and the separator 23.

  The electrolyte layer 36 includes the electrolytic solution. The battery of the present invention may be in the form of a gel by containing a polymer compound that swells with the electrolyte and serves as a holding body that holds the electrolyte. It is because high ion conductivity can be obtained by including a polymer compound that swells with the electrolytic solution, excellent charge / discharge efficiency can be obtained, and battery leakage can be prevented. The structure of the electrolytic solution (that is, the solvent and the electrolyte salt) is the same as that of the cylindrical secondary battery shown in FIG. When a polymer compound is added to the electrolytic solution, the content of the polymer compound in the electrolytic solution is preferably in the range of 0.5% by mass to 2.0% by mass. Moreover, when apply | coating and using a high molecular compound on both surfaces of a separator, it is preferable that the mass ratio of a high molecular compound and electrolyte solution exists in the range of 1:10 to 1:50. It is because higher charging / discharging efficiency is obtained by setting it within this range.

  Examples of the polymer compound include ether-based polymer compounds such as polyvinyl formal represented by the following formula (8), polyethylene oxide and a crosslinked product containing polyethylene oxide, and esters such as polyacrylate represented by the following formula (9). And a polymer of vinylidene fluoride such as polyvinylidene fluoride and a copolymer of vinylidene fluoride and hexafluoropropylene represented by the following formula (10). A high molecular compound may be used individually by 1 type, and multiple types may be mixed and used for it. In particular, from the viewpoint of the effect of preventing swelling during high temperature storage, it is desirable to use a fluorine-based polymer compound such as polyvinylidene fluoride.

In the formulas (8) to (10), s, t and u are each an integer of 100 to 10,000, and R is C _x H _2x-1 O _y (x is 1 to 8, y is 0 to 4). Indicated.

  The secondary battery shown in FIG. 3 can be manufactured as follows, for example. First, a precursor solution containing a solvent, an electrolyte salt, 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. After that, the positive electrode lead 31 is attached to the end of the positive electrode current collector 33A by welding, and the negative electrode lead 32 is attached to the end of the negative electrode current collector 34A by welding. Next, 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 a protective tape 37 is adhered to the outermost peripheral portion. Thus, the wound electrode body 30 is formed. Finally, for example, the wound electrode body 30 is sandwiched between the exterior members 40, and the outer edges of the exterior members 40 are sealed and sealed by heat 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, the secondary battery shown in FIG. 3 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 including a solvent, an electrolyte salt, a monomer that is a raw material of the polymer compound, a polymerization initiator, and other materials such as a polymerization inhibitor as necessary is prepared, and the exterior member Inject into 40.

  After injecting the electrolyte composition, the opening of the exterior member 40 is heat-sealed and sealed in a vacuum atmosphere. Next, heat is applied to polymerize the monomer to obtain a polymer compound, thereby forming a gel electrolyte layer 36, and assembling the secondary battery shown in FIG. The operation of this secondary battery is the same as that of the cylindrical secondary battery shown in FIG.

  Although the present invention has been described with reference to the embodiment, the present invention is not limited to the embodiment, and various modifications can be made. For example, in the above embodiment, the case where an electrolytic solution is used as the electrolyte is described, and further, the case where a gel electrolyte in which the electrolytic solution is held in a polymer compound is also described, but other electrolytes are used. May be. Other electrolytes include, for example, a mixture of an ion conductive inorganic compound such as ion conductive ceramics, ion conductive glass and 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, a battery using lithium as an electrode reactant has been described. However, other alkali metals such as sodium (Na) and potassium (K), alkaline earth metals such as magnesium and calcium (Ca), In addition, the present invention can be applied to the case of using other light metals such as aluminum.

  Furthermore, in the above embodiment, the capacity of the negative electrode is expressed by a capacity component due to insertion and extraction of lithium, or a so-called lithium ion secondary battery, or lithium metal is used for the negative electrode active material, and the capacity of the negative electrode is Although a so-called lithium metal secondary battery represented by a capacity component due to precipitation and dissolution has been described, the present invention makes the charge capacity of the negative electrode material capable of occluding and releasing lithium smaller than the charge capacity of the positive electrode. Thus, the present invention can be similarly applied to a secondary battery in which 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 expressed by the sum thereof. .

  Furthermore, in the above-described embodiment, the secondary battery has been specifically described. However, the present invention is not limited to the secondary battery, and can be similarly applied to other batteries such as a primary battery.

<Examples 1-1 to 1-11, Comparative Examples 1-1 to 1-2>
First, the positive electrode was produced as follows. 94 parts by mass of lithium-cobalt composite oxide (LiCoO ₂ ) as the positive electrode active material, 3 parts by mass of graphite as the conductive material, and 3 parts by mass of polyvinylidene fluoride (PVdF) as the binder were mixed uniformly. N-methylpyrrolidone was added to obtain a positive electrode mixture coating solution. Next, the obtained positive electrode mixture coating solution was uniformly applied on both surfaces of an aluminum foil having a thickness of 20 μm and dried to form a positive electrode mixture layer of 40 mg / cm ² per side. This was cut into a shape having a width of 50 mm and a length of 300 mm to produce a positive electrode.

Next, the negative electrode was produced as follows. A negative electrode mixture coating solution was obtained by uniformly mixing 97 parts by mass of graphite as a negative electrode active material and 3 parts by mass of PVdF as a binder and adding N-methylpyrrolidone. Next, the obtained negative electrode mixture coating liquid was uniformly applied on both sides of a 15 μm thick copper foil serving as a negative electrode current collector and dried to form a negative electrode mixture layer of 20 mg / cm ² per side. This was cut into a shape having a width of 50 mm and a length of 300 mm to prepare a negative electrode.

  The electrolytic solution was prepared by mixing at a ratio (mass ratio) of ethylene carbonate / ethyl methyl carbonate / lithium hexafluorophosphate / lithium trichloroacetate = 34/51 / 14.5 / 0.5.

  The above positive electrode and negative electrode were laminated and wound through a separator made of a microporous polyethylene film having a thickness of 9 μm, and put in a bag made of an aluminum laminate film. After 2 g of electrolyte solution was poured into this bag, the bag was heat-sealed to produce a laminate type battery. The capacity of this battery was 700 mAh.

  The physical properties of the battery produced as described above were evaluated as follows. First, after charging the battery for 3 hours under an environment of 23 ° C. and 700 mA at 4.2 V, the change in battery thickness was examined when stored at 90 ° C. for 4 hours. Here, the expansion coefficient is a value calculated using the battery thickness before storage as the denominator and the battery thickness after storage as the numerator. Further, after charging for 3 hours at 700 mA at 23 mA in a 23 ° C. environment for 3 hours, the discharge capacity retention rate was measured when 300 cycles of 3 mA at 700 mA as the lower limit were repeated.

(Examples 1-2 and 1-3)
A laminated battery was prepared in the same manner as in Example 1-1 except that the concentration of lithium trichloroacetate in the electrolytic solution was changed as shown in Table 1, and the physical properties of the battery were evaluated.

(Example 1-4)
A laminate type battery was prepared in the same manner as in Example 1-1 except that 1.0% by mass of fluoroethylene carbonate was mixed with the electrolytic solution, and the physical properties of the battery were evaluated.

(Example 1-5)
A laminate type battery was produced in the same manner as in Example 1-1 except that 1.0% by mass of vinylene carbonate was mixed with the electrolytic solution, and the physical properties of the battery were evaluated.

(Examples 1-6 to 1-8)
A laminate type battery was prepared in the same manner as in Example 1-1 except that the type of halogenated carboxylate in the electrolytic solution was changed as shown in Table 1, and the physical properties of the battery were evaluated.

(Comparative Example 1-1)
A laminate type battery was produced in the same manner as in Example 1-1 except that the halogenated carboxylate was not added to the electrolytic solution, and the physical properties of the battery were evaluated.

(Comparative Example 1-2)
A laminate type battery was prepared in the same manner as in Example 1-1 except that a non-halogenated carboxylic acid (lithium acetate) was added to the electrolytic solution instead of the halogenated carboxylate, and the physical properties of the battery were evaluated.

(Comparative Example 1-3)
A laminate type battery was prepared in the same manner as in Example 1-1 except that lithium trifluoroacetate was added to the electrolytic solution instead of lithium trichloroacetate, and the physical properties of the battery were evaluated.

  Table 1 shows the results of evaluating the physical properties of the laminate type batteries prepared in Examples 1-1 to 1-8 and Comparative Examples 1-1 to 1-3.

  As shown in Table 1, Examples 1-1 to 1 in which chlorine-substituted carboxylates (lithium trichloroacetate, lithium dichloroacetate, lithium chlorodifluoroacetate, lithium 2,2-dichloropropionate) were mixed with the electrolyte -3, 1-6 to 1-8 show a change in battery thickness when stored at 90 ° C. for 4 hours as compared with Comparative Example 1-1 using an electrolytic solution containing no chlorine-substituted carboxylate. Diminished. Further, as can be seen from Comparative Example 1-2, the non-chlorine-substituted carboxylate (lithium acetate) was not dissolved in the electrolytic solution. From this result, it was found that the battery expansion during high-temperature storage can be suppressed by mixing a chlorine-substituted carboxylate into the electrolytic solution.

  Further, when Examples 1-1 to 1-3 in which the concentration of the chlorine-substituted carboxylate in the electrolytic solution was changed and Comparative Example 1-1 were compared, Examples 1-1 to 1-3 maintained the discharge capacity. The change in battery thickness when stored at 90 ° C. for 4 hours was reduced. . From this result, it was found that good results can be obtained when the concentration of the chlorine-substituted carboxylate in the electrolytic solution is in the range of 0.1 to 1.0% by mass.

  Example 1-4 in which fluoroethylene carbonate was mixed with the electrolytic solution in addition to the chlorine-substituted carboxylate was 4 hours at 90 ° C. compared to Example 1-1 in which fluoroethylene carbonate was not included in the electrolytic solution. The change in battery thickness during storage decreased and the discharge capacity retention rate increased. Further, in Example 1-4, the change in battery thickness when stored at 90 ° C. for 4 hours is reduced as compared with Comparative Example 1-1 in which fluoroethylene carbonate and chlorine-substituted carboxylate are not included in the electrolytic solution. The discharge capacity maintenance rate was maintained. From this result, it was found that by containing a halogenated carbonate together with the chlorine-substituted carboxylate in the electrolyte, battery expansion during high-temperature storage can be suppressed and excellent charge / discharge efficiency can be maintained.

  In addition to the chlorine-substituted carboxylate, Example 1-5 in which vinylene carbonate was mixed with the electrolytic solution was stored at 90 ° C. for 4 hours as compared with Example 1-1 in which vinylene carbonate was not included in the electrolytic solution. The change in battery thickness at the time decreased, and the discharge capacity retention rate increased. Further, in Example 1-5, compared with Comparative Example 1-1 in which vinylene carbonate and chlorine-substituted carboxylate are not included in the electrolytic solution, the change in battery thickness when stored at 90 ° C. for 4 hours is reduced. The discharge capacity maintenance rate was maintained. From this result, it was found that by containing a carbonic acid ester having a carbon-carbon multiple bond together with a chlorine-substituted carboxylate in the electrolyte, battery expansion during high-temperature storage can be suppressed and excellent charge / discharge efficiency can be maintained. .

<Examples 2-1 to 2-8, Comparative Examples 2-1 to 2-3>
(Example 2-1)
A laminate type battery was produced in the same manner as in Example 1-1, except that a separator having a thickness of 7 μm and a separator coated with 2 μm of polyvinylidene fluoride on both sides was used, and the physical properties of the battery were evaluated.

(Example 2-2, 2-3)
A laminated battery was prepared in the same manner as in Example 2-1, except that the concentration of the chlorine-substituted carboxylate in the electrolytic solution was changed as shown in Table 2, and the physical properties of the battery were evaluated.

(Example 2-4)
A laminate type battery was prepared in the same manner as in Example 2-1, except that 1.0% by mass of fluoroethylene carbonate was mixed with the electrolytic solution, and the physical properties of the battery were evaluated.

(Example 2-5)
A laminate type battery was prepared in the same manner as in Example 2-1, except that 1.0% by mass of vinylene carbonate was mixed with the electrolytic solution, and the physical properties of the battery were evaluated.

(Examples 2-6 to 2-8)
A laminate type battery was produced in the same manner as in Example 2-1, except that the type of the chlorine-substituted carboxylate in the electrolytic solution was changed as shown in Table 2, and the physical properties of the battery were evaluated.

(Comparative Example 2-1)
A laminate type battery was produced in the same manner as in Example 2-1, except that no chlorine-substituted carboxylate was added to the electrolytic solution, and the physical properties of the battery were evaluated.

(Comparative Example 2-2)
A laminated battery was prepared in the same manner as in Example 2-1, except that a non-halogenated carboxylate (lithium acetate) was added to the electrolyte instead of the chlorine-substituted carboxylate, and the physical properties of the battery were evaluated. did.

(Comparative Example 2-3)
A laminate type battery was prepared in the same manner as in Example 1-1 except that lithium trifluoroacetate was added to the electrolytic solution instead of lithium trichloroacetate, and the physical properties of the battery were evaluated.

  Table 2 shows the results of evaluating the physical properties of the laminate type batteries prepared in Examples 2-1 to 2-8 and Comparative Examples 2-1 to 2-3.

  As shown in Table 2, a polymer compound (polyvinylidene fluoride) that swells with a chlorine-substituted carboxylate (lithium trichloroacetate, lithium dichloroacetate, lithium chlorodifluoroacetate, lithium 2,2-dichloropropionate) and an electrolyte. Examples 2-1 to 2-3 and 2-6 to 2-8 using an electrolytic solution in which a mixture of) is mixed at 90 ° C. compared with Example 1-1 in which polyvinylidene fluoride is not included in the electrolytic solution. The change in battery thickness when stored for 4 hours decreased. From this result, it was found that the use of a polymer compound that swells with the electrolyte together with the chlorine-substituted carboxylate improves the effect of suppressing battery expansion during high-temperature storage.

  Further, when Examples 2-1 to 2-3 in which the concentration of the chlorine-substituted carboxylate in the electrolytic solution was changed and Comparative Example 2-1 were compared, in Examples 2-1 to 2-3, the discharge capacity was maintained. The change in battery thickness when stored at 90 ° C. for 4 hours was reduced. From this result, even when the polymer compound that swells with the electrolytic solution is added to the electrolytic solution, the concentration of the chlorine-substituted carboxylate in the electrolytic solution is 0.1 to 1.0% by mass, as in the case where it is not added. It was found that good results could be obtained within the range of.

  In addition to the chlorine-substituted carboxylate, Example 2-4 in which fluoroethylene carbonate was mixed with the electrolytic solution had a discharge capacity maintenance rate as compared with Example 2-1 that did not contain fluoroethylene carbonate in the electrolytic solution. Rose. Further, in Example 2-4, the change in battery thickness when stored at 90 ° C. for 4 hours is reduced as compared with Comparative Example 2-1 in which fluoroethylene carbonate and chlorine-substituted carboxylate are not included in the electrolytic solution. The discharge capacity maintenance rate was maintained. From this result, even when a polymer compound that swells with the electrolytic solution is added to the electrolytic solution, the halogenated carbonate is contained in the electrolytic solution together with the chlorine-substituted carboxylate, as in the case where the high-molecular compound is not added. It was found that battery expansion during storage can be suppressed and excellent charge / discharge efficiency can be maintained.

  In Example 2-5, in which vinylene carbonate was mixed with the electrolyte solution in addition to the chlorine-substituted carboxylate, the discharge capacity retention rate increased compared to Example 2-1 that did not contain vinylene carbonate in the electrolyte solution. . Further, in Example 2-5, the change in battery thickness when stored at 90 ° C. for 4 hours is reduced as compared with Comparative Example 2-1 in which vinylene carbonate and chlorine-substituted carboxylate are not included in the electrolytic solution. The discharge capacity maintenance rate was maintained. From this result, even when a polymer compound that swells with an electrolytic solution is added to the electrolytic solution, a carbonic acid ester having a carbon-carbon multiple bond is contained in the electrolytic solution together with the chlorine-substituted carboxylate, as in the case of not adding it. As a result, it was found that battery expansion during high temperature storage can be suppressed and excellent charge / discharge efficiency can be maintained.

<Example 3-1 and Comparative example 3-1>
(Example 3-1)
A laminate type battery was produced in the same manner as in Example 2-1, and the physical properties of the battery (battery thickness of the initial rechargeable battery) were evaluated.

(Comparative Example 3-1)
A laminate type battery was produced in the same manner as in Example 3-1, except that an electrolytic solution to which trichloroacetic acid was added instead of lithium trichloroacetate was used, and the physical properties of the battery were evaluated.

  Table 3 shows the results of evaluating the physical properties of the laminate type batteries produced in Example 3-1 and Comparative Example 3-1.

  As shown in Table 3, Example 3-1 using an electrolytic solution to which a chlorine-substituted carboxylate was added was compared with Comparative Example 3-1 using an electrolytic solution to which a chlorine-substituted carboxylic acid was added. It was found that the battery thickness after the first charge was thin. This is because when a chlorine-substituted carboxylic acid is used instead of a chlorine-substituted carboxylate, the proton of the carboxylic acid becomes hydrogen gas during the initial charge, and the battery expands and the thickness increases.

  While the present invention has been described with reference to the embodiments, it is needless to say that the present invention is not limited to the above embodiments and can be variously modified.

It is sectional drawing showing the structure of the secondary battery 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 secondary battery which concerns on other embodiment of this invention. It is sectional drawing along the II line | wire of the winding electrode body 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, 37 ... Protective tape, 40 ... Exterior member, 41 ... Adhesion film

Claims (18)

A non-aqueous electrolyte battery comprising an electrolyte together with a positive electrode and a negative electrode,
The electrolyte solution contains a chlorine-substituted carboxylate represented by the following formula (1).

In Expression (1), Y, Z is _C m is _{H 2m + 1-n X n} (0 ≦ m ≦ 4,0 ≦ n ≦ 2m + 1, X is F, Cl, at least one one of Br M) is Li, Na, K, Rb, Cs, Ag, 1 / 2Be, 1 / 2Mg, 1 / 2Ca, 1 / 2Sr, 1 / 2Ba, 1 / 2Zn, 1 / 2Cd, 1 / 2Hg, 1 / 2Sn and 1 / 2Pb. ]   2. The nonaqueous electrolyte battery according to claim 1, wherein the content of the chlorine-substituted carboxylate in the electrolytic solution is 0.1% by mass or more and 1.0% by mass or less.   The non-aqueous electrolyte battery according to claim 1, wherein the electrolytic solution contains a halogenated carbonate.   The non-aqueous electrolyte battery according to claim 3, wherein the halogenated carbonate is fluoroethylene carbonate.   The nonaqueous electrolyte battery according to claim 4, wherein the content of the halogenated carbonate is from 0.1% by mass to 2% by mass.   The non-aqueous electrolyte battery according to claim 1, wherein the electrolytic solution contains a carbonic acid ester having a carbon-carbon multiple bond.   The nonaqueous electrolyte battery according to claim 6, wherein the carbonate ester is vinylene carbonate.   The nonaqueous electrolyte battery according to claim 7, wherein a content of the carbonic acid ester in the electrolytic solution is 0.1% by mass or more and 1.0% by mass or less.   The nonaqueous electrolyte battery according to claim 1, comprising a polymer compound that swells with the electrolyte.   The non-aqueous electrolyte battery according to claim 10, wherein the polymer compound is polyvinylidene fluoride.   The non-aqueous electrolyte battery according to claim 10, wherein a mass ratio of the polymer compound to the electrolytic solution is 1:10 to 1:50.   The battery according to claim 1, wherein the battery is formed of a container made of an aluminum laminate film. A battery electrolyte comprising a chlorine-substituted carboxylate represented by the following formula (1):

In Expression (1), Y, Z is _C m is _{H 2m + 1-n X n} (0 ≦ m ≦ 4,0 ≦ n ≦ 2m + 1, X is F, Cl, at least one one of Br M) is Li, Na, K, Rb, Cs, Ag, 1 / 2Be, 1 / 2Mg, 1 / 2Ca, 1 / 2Sr, 1 / 2Ba, 1 / 2Zn, 1 / 2Cd, 1 / 2Hg, 1 / 2Sn and 1 / 2Pb. ]   The battery electrolyte solution according to claim 13, wherein a content of the chlorine-substituted carboxylate is 0.1% by mass or more and 1.0% by mass or less.   The battery electrolyte according to claim 14, comprising a halogenated carbonate.   The battery electrolyte according to claim 15, wherein the halogenated carbonate is fluoroethylene carbonate.   The battery electrolyte according to claim 13, comprising a carbonic acid ester having a carbon-carbon multiple bond.   The battery electrolyte according to claim 17, wherein the carbonate ester is vinylene carbonate.

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