JP2008147117A - Electrolyte and battery - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a battery capable of preventing bulging characteristics while surely keeping cycle characteristics. <P>SOLUTION: A battery is equipped with a positive electrode 21, a negative electrode 22, an electrolyte, and a separator 23 interposed between the positive electrode 21 and the negative electrode 22, and the separator 23 is impregnated with a liquid-state electrolyte (an electrolyte solution). A solvent of the electrolyte solution contains ethylene carbonate, diethyl carbonate having a content in the solvent of 30-80 wt.%, and a sulfone compound such as 2-sulfobenzoic acid anhydride having a content in the solvent of 0.1-1 wt.%. Since sufficient ionic conductivity in the electrolyte solution can be obtained, decomposition reaction is suppressed, discharge capacity is difficult to drop, and bulging of the secondary battery is difficult to bulge. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to an electrolyte containing a solvent and an electrolyte salt and a battery using the electrolyte.

  In recent years, portable electronic devices such as a camera-integrated VTR (video tape recorder), a mobile phone, or a laptop computer have been widely used, and there is a strong demand for miniaturization, weight reduction, and long life. Accordingly, as a power source for portable electronic devices, development of a battery, in particular, a secondary battery that is lightweight and capable of obtaining a high energy density is underway.

  Among them, secondary batteries that use lithium storage and release for charge / discharge reactions (so-called lithium ion secondary batteries) and secondary batteries that use lithium precipitation and dissolution (so-called lithium metal secondary batteries) Compared to batteries and nickel-cadmium batteries, a large energy density can be obtained and a high capacity can be realized.

  As a lithium ion secondary battery, a carbon material is used as a negative electrode material, a composite material of lithium (Li) and a transition metal is used as a positive electrode material, and a liquid electrolyte (so-called electrolytic solution) containing a carbonate is used as an electrolyte. Things are known. Since carbonate ester is excellent in oxidation resistance and reduction resistance compared with water and other organic solvents, a high voltage can be obtained.

  As such a lithium ion secondary battery, since it is lightweight and has high energy density, a battery using a laminate film as an exterior member (so-called laminate film type secondary battery) has been put into practical use. In particular, a so-called gel-like material in which an electrolytic solution is held in a polymer compound is widely used because deformation of the exterior member can be suppressed. Since this laminate film type secondary battery has a large proportion of the active material in the battery, it can cope with higher capacity.

Regarding the composition of the electrolytic solution used for these secondary batteries, several techniques have already been proposed for the purpose of improving various performances. Specifically, in order to improve the storage characteristics and cycle characteristics at high temperatures, a technique of incorporating a chain or cyclic sulfone compound in the electrolyte is known (see, for example, Patent Documents 1 and 2). . In addition, in order to suppress the generation of gas in the battery in a high temperature state and the swelling associated therewith, a technique is known in which the electrolyte contains 2-sulfobenzoic anhydride (see, for example, Patent Documents 3 and 4). ).
JP 2002-008718 A JP 2002-151144 A JP 2002-313418 A JP-A-2005-502179

  In recent electronic devices, high performance and multi-functionality tend to progress more and more, and therefore, the discharge capacity tends to decrease due to frequent charge and discharge of the secondary battery. In addition, the amount of heat generation tends to increase with factors such as higher performance of electronic components typified by CPU (central processing unit), so that secondary batteries tend to swell when exposed to high-temperature atmospheres. is there. For this reason, further improvement is desired regarding the cycle characteristics and swelling characteristics of the secondary battery.

  However, the conventional secondary battery still has a problem that sufficient cycle characteristics and swelling characteristics cannot be obtained.

  Specifically, in the technique of Patent Document 2, since a mixed solvent in which ethylene carbonate, propylene carbonate, and diethyl carbonate are mixed at a volume ratio of 1: 1: 1 is used as the solvent, a sufficient cycle is achieved. Characteristics are not obtained. This is because the ratio of diethyl carbonate in the solvent (33% by volume and 28% by weight) is small. Further, since diethyl carbonate has a higher viscosity than dimethyl carbonate and ethyl methyl carbonate, the electrolyte solution is less likely to be impregnated when the anode active material layer is thickened.

  In the technique of Patent Document 3, since a low-viscosity solvent such as a chain carbonate is not used as a solvent, when using propylene carbonate or γ-butyrolactone that is liquid at room temperature together with ethylene carbonate that is solid at room temperature, carbonic acid in the solvent is used. It is necessary to set the composition of the electrolyte so that the ratio of propylene and γ-butyrolactone is increased. However, since propylene carbonate and γ-butyrolactone easily react with graphite, when graphite is used as the negative electrode material, the electrolytic solution having the above composition cannot be used.

  In the technique of Patent Document 4, since a mixed solvent in which ethylene carbonate, dimethyl carbonate, and ethylmethyl carbonate are mixed at a weight ratio of 1: 1: 1 is used as the solvent, 2-sulfobenzoate is used as the electrolyte. Even if an acid anhydride is contained, it is difficult to sufficiently suppress swelling. This is because dimethyl carbonate and ethyl methyl carbonate have the property of promoting swelling at high temperatures.

  The present invention has been made in view of such problems, and an object thereof is to provide an electrolyte and a battery that can improve the swollenness characteristics while ensuring the cycle characteristics.

（Ｒ１はＣ_m Ｈ_2m-nＸ_n であり、Ｘはハロゲンを表す。ただし、ｍは２以上４以下の範囲内の整数であり、ｎは０あるいは１以上２ｍ以下の範囲内の整数である。）

（Ｒ２、Ｒ３、Ｒ４およびＲ５はＣ_j Ｈ_2j+1-k Ｘ_kであり、互いに同一でもよいし異なってもよい。Ｘはハロゲンを表す。ただし、ｊは０あるいは１以上３以下の範囲内の整数であり、ｋは０あるいは１以上２ｊ＋１以下の範囲内の整数である。） The electrolyte of the present invention contains a solvent and an electrolyte salt, and the solvent contains ethylene carbonate, diethyl carbonate, and at least one of the sulfone compounds represented by Chemical Formula 1 and Chemical Formula 2, In the solvent, the content of diethyl carbonate is in the range of 30% by weight to 80% by weight, and the content of the sulfone compound in the solvent is in the range of 0.1% by weight to 1% by weight.

(R1 is a _{C m H 2m-n X n} , X represents a halogen. However, m is an integer ranging from 2 to 4, n represents an integer in the range of 0 or 1 or more 2m is there.)

(R2, R3, R4 and R5 are _{C j H 2j + 1-k} X k, good .X be different may be mutually the same halogen. However, j is 0 or 1 to 3 range And k is an integer in the range of 0 or 1 to 2j + 1.)

（Ｒ１はＣ_m Ｈ_2m-nＸ_n であり、Ｘはハロゲンを表す。ただし、ｍは２以上４以下の範囲内の整数であり、ｎは０あるいは１以上２ｍ以下の範囲内の整数である。）

（Ｒ２、Ｒ３、Ｒ４およびＲ５はＣ_j Ｈ_2j+1-k Ｘ_kであり、互いに同一でもよいし異なってもよい。Ｘはハロゲンを表す。ただし、ｊは０あるいは１以上３以下の範囲内の整数であり、ｋは０あるいは１以上２ｊ＋１以下の範囲内の整数である。） The battery of the present invention includes an electrolyte together with a positive electrode and a negative electrode. The electrolyte includes a solvent and an electrolyte salt, and the solvent is represented by ethylene carbonate, diethyl carbonate, Chemical Formula 3 and Chemical Formula 4. At least one of the sulfone compounds, the content of diethyl carbonate in the solvent is in the range of 30 wt% to 80 wt%, and the content of the sulfone compound in the solvent is 0.1 wt% % Or more and 1% by weight or less.

(R1 is a _{C m H 2m-n X n} , X represents a halogen. However, m is an integer ranging from 2 to 4, n represents an integer in the range of 0 or 1 or more 2m is there.)

(R2, R3, R4 and R5 are _{C j H 2j + 1-k} X k, good .X be different may be mutually the same halogen. However, j is 0 or 1 to 3 range And k is an integer in the range of 0 or 1 to 2j + 1.)

  According to the electrolyte of the present invention, it contains at least one of the sulfone compounds shown in Chemical Formula 1 or Chemical Formula 2 together with ethylene carbonate and diethyl carbonate, and the content of diethyl carbonate in the solvent is 30 wt% or more and 80 wt% or less. And the content of the sulfone compound is in the range of 0.1% by weight or more and 1% by weight or less, so that sufficient ion conductivity is obtained and the decomposition reaction is sufficiently suppressed. Thereby, in the battery using the electrolyte of the present invention, the swollenness characteristics can be improved while ensuring the cycle characteristics.

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

  An electrolyte according to an embodiment of the present invention is used for an electrochemical device such as a battery, and includes a solvent and an electrolyte salt. The electrolyte containing these solvent and electrolyte salt is a liquid electrolyte (so-called electrolytic solution).

  The solvent contains ethylene carbonate, diethyl carbonate, and at least one of the sulfone compounds represented by Chemical formula 5 and Chemical formula 6. The content of diethyl carbonate in the solvent is in the range of 30 wt% to 80 wt%, and the content of the sulfone compound in the solvent is in the range of 0.1 wt% to 1 wt%. Examples of X (halogen) shown in Chemical formula 5 and Chemical formula 6 include fluorine (F), chlorine (Cl), bromine (Br), and the like.

（Ｒ１はＣ_m Ｈ_2m-nＸ_n であり、Ｘはハロゲンを表す。ただし、ｍは２以上４以下の範囲内の整数であり、ｎは０あるいは１以上２ｍ以下の範囲内の整数である。）

（Ｒ２、Ｒ３、Ｒ４およびＲ５はＣ_j Ｈ_2j+1-k Ｘ_kであり、互いに同一でもよいし異なってもよい。Ｘはハロゲンを表す。ただし、ｊは０あるいは１以上３以下の範囲内の整数であり、ｋは０あるいは１以上２ｊ＋１以下の範囲内の整数である。）

(R1 is a _{C m H 2m-n X n} , X represents a halogen. However, m is an integer ranging from 2 to 4, n represents an integer in the range of 0 or 1 or more 2m is there.)

(R2, R3, R4 and R5 are _{C j H 2j + 1-k} X k, good .X be different may be mutually the same halogen. However, j is 0 or 1 to 3 range And k is an integer in the range of 0 or 1 to 2j + 1.)

  Solvents contain ethylene carbonate and diethyl carbonate because dissociation of electrolyte salt and ion transfer can be achieved by using a high viscosity (high dielectric constant) solvent (ethylene carbonate) and a low viscosity solvent (diethyl carbonate) in combination. This is because sufficient ion conductivity can be obtained because the degree is improved. In addition, the content of diethyl carbonate in the solvent is within the above-mentioned range because the content of diethyl carbonate that contributes to the cycle characteristics and swelling characteristics of the electrochemical device using the electrolyte is optimized. It is because it becomes difficult to fall and an electrochemical device becomes difficult to swell. Thereby, excellent cycle characteristics and swelling characteristics can be obtained.

  The reason why the solvent contains the sulfone compound is that the decomposition reaction of the electrolyte is suppressed and the electrolyte is electrochemically stabilized. Thereby, the tendency for the discharge capacity to decrease is suppressed, and the electrochemical device is less likely to swell. In addition, the content of the sulfone compound in the solvent is within the above-described range, as in the case of the above-described ethylene carbonate and diethyl carbonate, because the content of the sulfone compound is optimized, so that the discharge capacity is reduced. It is because it becomes difficult and an electrochemical device becomes difficult to swell.

  Examples of the sulfone compound shown in Chemical Formula 5 include 2-sulfopropionic anhydride. These may be used alone or in combination of two or more.

  Examples of the sulfone compound shown in Chemical Formula 6 include 2-sulfobenzoic anhydride represented by Chemical Formula 7. Other examples of the sulfone compound shown in Chemical Formula 6 include 4-fluoro-2-sulfobenzoic anhydride, 4,5-difluoro-2-sulfobenzoic anhydride, and 6-fluoro-2-sulfobenzoic acid. Anhydride, 3,4,5,6-tetrafluoro-2-sulfobenzoic anhydride, 3-methyl-2-sulfobenzoic anhydride, 3-ethyl-2-sulfobenzoic anhydride, 3,6- Examples thereof include dimethyl-2-sulfobenzoic anhydride, 3,4-dimethyl-2-sulfobenzoic anhydride, and 3,5-dimethyl-2-sulfobenzoic anhydride. These may be used alone or in combination of two or more. Especially, it is preferable that the sulfone compound shown in Chemical formula 6 contains 2-sulfobenzoic anhydride. This is because a sufficient effect can be obtained.

  Needless to say, the sulfone compound is not limited to the series of compounds described above as long as it has the structure shown in Chemical Formula 5 or Chemical Formula 6.

  The solvent may further contain dimethyl carbonate or ethyl methyl carbonate which is a low viscosity solvent. The content of dimethyl carbonate in the solvent is preferably in the range of 5% by weight to 35% by weight, and the content of ethyl methyl carbonate in the solvent is preferably in the range of 5% by weight to 50% by weight. In this case, the solvent may contain only one of dimethyl carbonate or ethyl methyl carbonate, or may contain both. The reason why the solvent contains dimethyl carbonate or ethyl methyl carbonate is that the tendency of the electrochemical device to swell is suppressed, and the discharge capacity is less likely to decrease. In addition, the content of dimethyl carbonate or ethyl methyl carbonate in the solvent is within the above range, as in the case of ethylene carbonate and diethyl carbonate described above, the content of dimethyl carbonate or ethyl methyl carbonate is optimized. For this reason, the discharge capacity is less likely to decrease, and the electrochemical device is less likely to swell. As a result, the cycle characteristics are improved while the swelling characteristics are substantially maintained.

  The solvent preferably further contains a cyclic ester carbonate having an unsaturated bond. This is because the capacity characteristics of the electrochemical device are improved. Thereby, cycle characteristics are improved. Examples of the cyclic carbonate having an unsaturated bond include vinylene carbonate and vinyl ethylene carbonate. These may be used alone or in combination of two or more.

  In addition, the solvent may contain the other solvent with the above-mentioned series of solvents, for example. Examples of other solvents include non-aqueous solvents such as organic solvents. Specifically, examples of the high-viscosity solvent include cyclic carbonates such as propyne carbonate and butylene carbonate, lactones such as γ-butyrolactone and γ-valerolactone, lactams such as N-methylpyrrolidone, and N-methyloxazolidinone. And a sulfone compound such as tetramethylene sulfone. Examples of the low-viscosity solvent include chain carbonates such as methylpropyl carbonate, methyl acetate, ethyl acetate, methyl propionate, ethyl propionate, methyl butyrate, methyl isobutyrate, methyl trimethylacetate, and ethyl trimethylacetate. A chain carboxylic acid ester, a chain amide such as N, N′-dimethylacetamide, a chain carbamic acid ester such as methyl N, N′-diethylcarbamate or ethyl N, N′-diethylcarbamate, , 2-dimethoxyethane, tetrahydrofuran, tetrahydropyran or ether such as 1,3-dioxolane. This is because, in an electrochemical device using an electrolyte, excellent capacity characteristics and cycle characteristics can be obtained. These may be used alone or in combination of two or more. Among them, the solvent preferably contains propylene carbonate. This is because the swelling characteristics are improved because the electrochemical device is less likely to swell.

  The other solvent is preferably at least one selected from the group consisting of a chain carbonate having halogen as a constituent element and a cyclic carbonate having halogen as a constituent element. This is because the cycle characteristics are further improved.

  Examples of the chain carbonate having halogen as a constituent element include fluoromethyl methyl carbonate, bis (fluoromethyl) carbonate, difluoromethyl methyl carbonate, and the like. These may be used alone or in combination of two or more.

  Examples of the cyclic carbonate having a halogen as a constituent element include 4-fluoro-1,3-dioxolan-2-one, 4-chloro-1,3-dioxolan-2-one, 4,5-difluoro-1, Examples include 3-dioxolan-2-one and 4-trifluoromethyl-1,3-dioxolan-2-one. These may be used alone or in combination of two or more. Among these, 4-fluoro-1,3-dioxolan-2-one is preferable as the cyclic carbonate having halogen as a constituent element, and 4,5-difluoro-1,3-dioxolan-2-one is more preferable. This is because they are easily available and higher effects can be obtained. In particular, as 4,5-difluoro-1,3-dioxolan-2-one, a trans isomer is preferable to a cis isomer in order to obtain a higher effect.

The electrolyte salt includes, for example, a light metal salt such as a lithium salt. Examples of the lithium salt include lithium hexafluorophosphate (LiPF _6), lithium tetrafluoroborate (LiBF _4), lithium hexafluoroarsenate (LiAsF _6), lithium hexafluoro antimonate (LiSbF ₆ ), Lithium lithium perchlorate (LiClO ₄ ) or lithium tetrachloroaluminate (LiAlCl ₄ ), lithium trifluoromethanesulfonate, lithium bis (trifluoromethanesulfone) imide, lithium bis (pentafluoromethanesulfone) And lithium salts of perfluoroalkanesulfonic acid derivatives such as methide or lithium tris (trifluoromethanesulfone) methide. This is because, in an electrochemical device using an electrolyte, excellent capacity characteristics and cycle characteristics can be obtained. These may be used alone or in combination of two or more. Among these, the electrolyte salt preferably contains lithium hexafluorophosphate. This is because the internal resistance is lowered and the capacity characteristics and cycle characteristics are further improved.

  The content of the electrolyte salt is preferably in the range of 0.3 mol / kg to 3.0 mol / kg with respect to the solvent, for example. Outside this range, the ionic conductivity is extremely lowered, so that there is a possibility that sufficient capacity characteristics and the like may not be obtained.

  The electrolyte may further contain a polymer compound that holds the above-described solvent and electrolyte salt (so-called electrolytic solution). An electrolyte containing a polymer compound together with these solvent and electrolyte salt is a so-called gel electrolyte. A gel electrolyte is preferable because high ion conductivity (for example, 1 mS / cm or more at room temperature) is obtained and leakage is prevented in an electrochemical device using the electrolyte. The solvent in this case is not only a liquid solvent but also a broad concept including those having ionic conductivity capable of dissociating electrolyte salts. Accordingly, when a polymer compound having ion conductivity is used, the polymer compound is also included in the solvent.

  Examples of the polymer compound include a polymer of vinylidene fluoride such as polyvinylidene fluoride having a structural unit represented by Chemical formula 8, and a copolymer of vinylidene fluoride and hexafluoropropylene. This is because the redox stability is high.

  Examples of the polymer compound include those formed by polymerizing a polymerizable compound. Examples of the polymerizable compound include those containing a vinyl group or a group obtained by substituting a part of hydrogen with a substituent such as a methyl group. Specifically, monofunctional acrylates such as acrylic acid esters, monofunctional methacrylates such as methacrylic acid esters, polyfunctional acrylates such as diacrylic acid esters or triacrylic acid esters, and polyfunctional acrylates such as dimethacrylic acid esters or trimethacrylic acid esters. There are functional methacrylate, acrylonitrile, methacrylonitrile, and the like. Among them, ester having acrylate group or methacrylate group is preferable. This is because the polymerization proceeds easily and the reaction rate of the polymerizable compound is high. Moreover, as a polymeric compound, what does not contain an ether group is preferable. This is because, when an ether group is present, lithium ions are coordinated to the ether group, resulting in a decrease in ionic conductivity. As such a polymer compound, for example, a polyacrylic acid ester having the structural unit shown in Chemical Formula 9 can be given.

（Ｒ６はＣ_g Ｈ_2h-1Ｏ_h である。ただし、ｇは１以上８以下の範囲内の整数であり、ｈは０あるいは１以上４以下の範囲内の整数である。）

(R6 is _{C g H 2h-1 O h} . However, g is an integer in the range of 1 to 8, h is an integer in the range of 0 or 1 to 4.)

  Any one of the polymerizable compounds may be used alone, but it is desirable to mix a monofunctional compound and a polyfunctional compound, or to use a polyfunctional compound singly or in combination of two or more. . This is because such a configuration makes it easy to achieve both the mechanical strength of the polymer compound formed by polymerization and the electrolyte solution retention.

  Furthermore, as a high molecular compound, what has polyvinyl formal which has the structural unit shown to Chemical formula 10 is also preferable. Polyvinyl formal is a polymer compound having an acetal group as a structural unit.

  The proportion of acetal groups in the polyvinyl formal is preferably in the range of 60 mol% or more and 80 mol% or less. This is because the solubility with the solvent can be improved within this range, and the stability of the electrolyte can be further increased. Moreover, it is preferable that the weight average molecular weight of polyvinyl formal exists in the range of 10,000 or more and 500,000 or less. This is because if the molecular weight is too low, the polymerization reaction does not proceed easily, and if it is too high, the viscosity of the electrolytic solution increases.

  The above-described polymer compound may be used alone or may be a copolymer used by mixing a plurality of types. Moreover, what was polymerized with the crosslinking agent may be used.

  According to this electrolyte, the solvent contains at least one of the sulfone compounds shown in Chemical Formula 5 or Chemical Formula 6 together with ethylene carbonate and diethyl carbonate, and the content of diethyl carbonate in the solvent is 30% by weight or more and 80% by weight. %, And the content of the sulfone compound in the solvent is in the range of 0.1% by weight or more and 1% by weight or less, so that sufficient ion conductivity is obtained and the decomposition reaction is sufficiently suppressed. Is done. Therefore, in the electrochemical device using the electrolyte, the swollenness characteristics can be improved while ensuring the cycle characteristics.

  In this case, the solvent further contains dimethyl carbonate, and the content of dimethyl carbonate in the solvent is in the range of 5 wt% to 35 wt%, or the solvent further contains ethyl methyl carbonate, and the carbonic acid in the solvent If the ethylmethyl content is in the range of 5 wt% or more and 50 wt% or less, the cycle characteristics can be improved while the swelling characteristics are substantially maintained. Moreover, if the solvent further contains a cyclic carbonate having an unsaturated bond, the cycle characteristics can be further improved.

  Next, usage examples of the above-described electrolyte will be described. Here, when a battery is given as an example of an electrochemical device, the electrolyte is used in the battery as follows.

(First battery)
1 shows an exploded perspective configuration of the first battery, and FIG. 2 shows an enlarged cross-sectional configuration along the line II-II of the main part of the battery shown in FIG. The first battery is a lithium ion secondary battery in which the capacity of the negative electrode 22 is represented by a capacity component based on insertion and extraction of lithium, and is a so-called laminate film type secondary battery. In the secondary battery, a wound electrode body 20 to which a positive electrode lead 11 and a negative electrode lead 12 are attached is housed in a film-shaped exterior member 30.

  For example, the positive electrode lead 11 and the negative electrode lead 12 are led out in the same direction from the inside of the exterior member 30 toward the outside. The positive electrode lead 11 is made of, for example, a metal material such as aluminum (Al), and the negative electrode lead 12 is made of, for example, a metal material such as copper (Cu), nickel (Ni), or stainless steel. These have, for example, a thin plate-like or mesh-like structure.

  The exterior member 30 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 30 has, for example, a structure in which outer edges of two rectangular aluminum laminate films are adhered to each other by fusion or an adhesive so that a polyethylene film faces the wound electrode body 20. Yes.

  An adhesion film 31 is inserted between the exterior member 30 and the positive electrode lead 11 and the negative electrode lead 12 to prevent intrusion of outside air. The adhesion film 31 is made of a material having adhesion to the positive electrode lead 11 and the negative electrode lead 12. Examples of this type of material include polyolefin resins such as polyethylene, polypropylene, modified polyethylene, and modified polypropylene.

  In addition, the exterior member 30 may be composed of a laminate film having another laminated structure instead of the above-described aluminum laminate film, or may be composed of a polymer film such as polypropylene or a metal film.

  The wound electrode body 20 is obtained by winding a positive electrode 21 and a negative electrode 22 after being laminated with a separator 23 and an electrolyte 24 interposed therebetween.

  The positive electrode 21 has, for example, a structure in which a positive electrode active material layer 21B is provided on one or both surfaces of a positive electrode current collector 21A having a pair of opposed surfaces. The positive electrode current collector 21A is made of, for example, a metal material such as aluminum. The positive electrode active material layer 21B includes, for example, any one or more of positive electrode materials capable of inserting and extracting lithium as an electrode reactant as a positive electrode active material. An agent and a binder may be included.

As a cathode material capable of inserting and extracting lithium, for example, lithium cobalt oxide, lithium nickel oxide or a solid solution containing them _{(Li (Ni p Co q Mn} r) O 2)) (p, of q and r The values are respectively 0 <p <1, 0 <q <1, 0 <r <1, p + q + r = 1), or lithium manganate having a spinel structure (LiMn ₂ O ₄ ) or its solid solution (Li (Mn _2-z Ni _z ) O ₄ : The value of z is z <2.) Or a phosphate compound having an olivine structure such as lithium iron phosphate (LiFePO ₄ ) is preferable. This is because a high energy density can be obtained. Other positive electrode materials that can occlude and release lithium include, for example, oxides such as titanium oxide, vanadium oxide, and manganese dioxide, and disulfides such as iron disulfide, titanium disulfide, and molybdenum sulfide. And conductive polymers such as sulfur, polyaniline or polythiophene.

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

  The negative electrode active material layer 22B includes, for example, any one or more of negative electrode materials capable of inserting and extracting lithium, which is an electrode reactant, as a negative electrode active material. An agent and a binder may be included. Examples of the negative electrode material capable of inserting and extracting lithium include carbon materials such as graphite, graphitizable carbon, and non-graphitizable carbon. Since the carbon material has very little change in crystal structure due to insertion and extraction of lithium, for example, when used with other negative electrode materials, a high energy density can be obtained and excellent cycle characteristics can be obtained. In addition, it also functions as a conductive agent, which is preferable.

  In addition, as a negative electrode material capable of inserting and extracting lithium, for example, a material that can store and release lithium and includes at least one of a metal element and a metalloid element as a constituent element is used. Can be mentioned. Use of such a negative electrode material is preferable because a high energy density can be obtained. 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. 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. This structure includes a solid solution, a eutectic (eutectic mixture), an intermetallic compound, or a mixture of two or more of them.

  Examples of the metal element or metalloid element constituting the negative electrode material include a metal element or metalloid element capable of forming an alloy with lithium. Specifically, magnesium (Mg), boron (B), aluminum, gallium (Ga), indium (In), silicon (Si), germanium (Ge), tin (Sn), lead (Pb), bismuth (Bi) ), Cadmium (Cd), silver (Ag), zinc (Zn), hafnium (Hf), zirconium (Zr), yttrium (Y), palladium (Pd) or platinum (Pt). Among these, at least one of tin and silicon is particularly preferable. This is because the ability to occlude and release lithium is particularly large, and a high energy density can be obtained.

  As the negative electrode material containing at least one of tin and silicon, specifically, a simple substance, an alloy, or a compound of tin, a simple substance, an alloy, or a compound of silicon, or one or more of these Examples thereof include materials having a phase at least partially. Examples of the tin alloy include, as the second constituent element other than tin, silicon, nickel, copper, iron, cobalt (Co), manganese (Mn), zinc, indium, silver, titanium (Ti), germanium, and bismuth. And at least one selected from the group consisting of antimony (Sb) and chromium (Cr). As an alloy of silicon, for example, as a second constituent element other than silicon, among the group consisting of tin, nickel, copper, iron, cobalt, manganese, zinc, indium, silver, titanium, germanium, bismuth, antimony and chromium The thing containing at least 1 sort (s) of these is mentioned.

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

  Among these, as the negative electrode material, for example, a material containing tin as the first constituent element and containing the second constituent element and the third constituent element in addition to the tin is preferable. The second constituent element is cobalt, iron, magnesium, titanium, vanadium (V), chromium, manganese, nickel, copper, zinc, gallium, zirconium, niobium (Nb), molybdenum (Mo), silver, indium, cerium ( Ce), hafnium, tantalum (Ta), tungsten (W), bismuth and silicon. The third constituent element is at least one selected from the group consisting of boron, carbon, aluminum, and phosphorus (P). This is because the cycle characteristics are improved by including the second element and the third element.

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

  This CoSnC-containing material may further contain other constituent elements as necessary. As other constituent elements, for example, silicon, iron, nickel, chromium, indium, niobium, germanium, titanium, molybdenum, aluminum, phosphorus, gallium, bismuth, and the like are preferable, and two or more of them may be included. This is because the capacity or cycle characteristics are further improved.

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

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

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

  In addition, examples of the negative electrode material capable of inserting and extracting lithium include metal oxides and polymer compounds capable of inserting and extracting lithium. Examples of the metal oxide include iron oxide, ruthenium oxide, and molybdenum oxide. Examples of the polymer compound include polyaniline, polythiophene, and polypyrrole.

  Examples of the conductive agent include carbon materials such as graphite, carbon black, and ketjen black. These may be used alone or in combination of two or more. Note that the conductive agent may be a metal material or a conductive polymer as long as it is a conductive material.

  Examples of the binder include synthetic rubbers such as styrene butadiene rubber, fluorine rubber or ethylene propylene diene, and polymer materials such as polyvinylidene fluoride. These may be used alone or in combination of two or more.

  In this secondary battery, the charge capacity of the negative electrode active material is larger than the charge capacity of the positive electrode active material by adjusting the amount between the positive electrode active material and the negative electrode active material. This prevents lithium metal from being deposited on the negative electrode 22 even during full charge.

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

  The electrolyte 24 is the electrolyte of the present invention having the above-described configuration, and is provided between the positive electrode 21 and the separator 23 and between the negative electrode 22 and the separator 23. The electrolyte 24 may be a liquid electrolyte containing a solvent and an electrolyte salt (so-called electrolyte solution), or may be a gel electrolyte containing a polymer compound that holds the solvent and the electrolyte salt together.

  The secondary battery provided with the gel electrolyte 24 can be manufactured by, for example, the following three types of manufacturing methods.

  In the first manufacturing method, first, the positive electrode 21 is manufactured by forming the positive electrode active material layers 21B on both surfaces of the positive electrode current collector 21A. When forming the positive electrode active material layer 21B, a positive electrode mixture obtained by mixing a powder of a positive electrode active material, a conductive agent, and a binder is dispersed in a solvent such as N-methyl-2-pyrrolidone. A paste-like positive electrode mixture slurry is formed, and the positive electrode mixture slurry is applied to the positive electrode current collector 21A and dried, followed by compression molding. For example, the negative electrode 22 is produced by forming the negative electrode active material layer 22B on both surfaces of the negative electrode current collector 22A according to the same procedure as that of the positive electrode 21.

  Subsequently, a precursor solution containing an electrolytic solution, a polymer compound, and a solvent is prepared, applied to the positive electrode 21 and the negative electrode 22, and then the solvent is volatilized to form the gel electrolyte 24. Subsequently, the positive electrode lead 11 and the negative electrode lead 12 are attached to the positive electrode current collector 21A and the negative electrode current collector 22A, respectively. Subsequently, after the positive electrode 21 and the negative electrode 22 provided with the electrolyte 24 are laminated via the separator 23, the positive electrode 21 and the negative electrode 22 are wound in the longitudinal direction, and the protective tape 25 is adhered to the outermost peripheral portion thereof. Form. Subsequently, for example, the wound electrode body 20 is sandwiched between two film-shaped exterior members 30 and then the outer edge portions of the exterior member 30 are bonded to each other by heat fusion or the like. Enclose. At that time, the adhesion film 31 is inserted between the positive electrode lead 11 and the negative electrode lead 12 and the exterior member 30. Thereby, the secondary battery shown in FIGS. 1 and 2 is completed.

  In the second manufacturing method, first, the positive electrode lead 11 and the negative electrode lead 12 are attached to the positive electrode 21 and the negative electrode 22, respectively, and then the positive electrode 21 and the negative electrode 22 are stacked and wound via the separator 23 and By adhering the protective tape 25, a wound body that is a precursor of the wound electrode body 20 is formed. Subsequently, after sandwiching the wound body between the two film-like exterior members 30, the remaining outer peripheral edge portion excluding the outer peripheral edge portion on one side is bonded by thermal fusion or the like, thereby forming a bag-like exterior. Housed in the member 30. Subsequently, an electrolyte composition containing an electrolytic solution, 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 a bag-shaped exterior member After injecting into the interior of 30, the opening of the exterior member 30 is sealed by heat fusion or the like. Finally, the gel electrolyte 24 is formed by thermally polymerizing the monomer to obtain a polymer compound. Thereby, the secondary battery shown in FIGS. 1 and 2 is completed.

  In the third manufacturing method, first, a wound body is formed by forming a wound body in the same manner as in the first manufacturing method described above except that the separator 23 coated with the polymer compound on both sides is used. Store inside. Examples of the polymer compound applied to the separator 23 include a polymer containing vinylidene fluoride as a component, that is, a homopolymer, a copolymer, or a multi-component copolymer. Specifically, a binary copolymer (PVDF-HFP) containing polyvinylidene fluoride (PVDF), vinylidene fluoride and hexafluoropropylene as components, or vinylidene fluoride, hexafluoropropylene and chlorotrifluoroethylene as components. And a terpolymer (PVDF-HFP-CTFE). In addition, the high molecular compound may contain the other 1 type, or 2 or more types of high molecular compound with the polymer which uses the above-mentioned vinylidene fluoride as a component. Subsequently, after the electrolytic solution is prepared and injected into the exterior member 30, the opening of the exterior member 30 is sealed by heat fusion or the like. Finally, the exterior member 30 is heated while applying a load, and the separator 23 is brought into close contact with the positive electrode 21 and the negative electrode 22 through the polymer compound. As a result, the electrolytic solution is impregnated into the polymer compound, and the polymer compound is gelled to form the electrolyte 24. Thus, the secondary battery shown in FIGS. 1 and 2 is completed. In the third manufacturing method, the swollenness characteristics are improved as compared with the first manufacturing method. Further, in the third manufacturing method, compared to the second manufacturing method, there are hardly any monomers or solvents that are raw materials for the polymer compound remaining in the electrolyte 24, and the formation process of the polymer compound is well controlled. Therefore, sufficient adhesion is obtained between the positive electrode 21, the negative electrode 22 and the separator 23 and the electrolyte 24.

  In this secondary battery, when charged, for example, lithium ions are extracted from the positive electrode 21 and inserted into the negative electrode 22 via the electrolyte 24. On the other hand, when discharging is performed, lithium ions are released from the negative electrode 22 and inserted into the positive electrode 21 via the electrolyte 24.

  According to this secondary battery, when the capacity of the negative electrode 22 is expressed by a capacity component based on insertion and extraction of lithium, the electrolyte of the present invention is provided as the electrolyte 24. The characteristics can be improved.

  Next, although the form of the 2nd and 3rd battery is demonstrated, about the same component as a 1st battery, the same code | symbol is attached | subjected and the description is abbreviate | omitted.

(Second battery)
The second battery has the same configuration, operation and effect as the first battery except that the configuration of the negative electrode 22 is different, and is manufactured by the same procedure.

  The negative electrode 22 has a negative electrode active material layer 22B provided on both surfaces of a negative electrode current collector 22A, as in the first battery. The negative electrode active material layer 22B contains, for example, a negative electrode active material containing silicon or tin as a constituent element. Silicon and tin have a large ability to occlude and release lithium, and a high energy density can be obtained. In particular, silicon is preferred because of its higher theoretical capacity. Specifically, for example, it contains a silicon simple substance, an alloy or a compound, or a tin simple substance, an alloy or a compound, and may contain two or more of them.

  The negative electrode active material layer 22B is formed using, for example, a vapor phase method, a liquid phase method, a thermal spraying method, a firing method, or two or more of these methods. The electrical conductor 22A is preferably alloyed at least at a part of the interface. Specifically, the constituent elements of the negative electrode current collector 22A diffuse into the negative electrode active material layer 22B at the interface, the constituent elements of the negative electrode active material layer 22B diffuse into the negative electrode current collector 22A, or the constituent elements thereof It is preferable that they diffuse to each other. This is because breakage due to expansion and contraction of the negative electrode active material layer 22B due to charging / discharging can be suppressed, and electronic conductivity between the negative electrode active material layer 22B and the negative electrode current collector 22A can be improved. .

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

(Third battery)
The third battery is a so-called lithium metal secondary battery in which the capacity of the negative electrode 22 is represented by a capacity component based on precipitation and dissolution of lithium. This secondary battery has the same configuration as that of the first battery except that the negative electrode active material layer 22B is made of lithium metal, and is manufactured by the same procedure.

  This secondary battery uses lithium metal as a negative electrode active material, and can thereby obtain a high energy density. The negative electrode active material layer 22B may already be provided from the time of assembly, but may not be present at the time of assembly, and may be composed of lithium metal deposited during charging. Further, the negative electrode current collector 22A may be omitted by using the negative electrode active material layer 22B as a current collector.

  In this secondary battery, when charged, for example, lithium ions are released from the positive electrode 21 and deposited as lithium metal on the surface of the negative electrode current collector 22A. On the other hand, when discharge is performed, for example, lithium metal is eluted as lithium ions from the negative electrode active material layer 22 </ b> B and is occluded in the positive electrode 21.

  According to this secondary battery, when the capacity of the negative electrode is expressed by a capacity component based on the precipitation and dissolution of lithium, the electrolyte of the present invention is provided as the electrolyte 24, so that the swelling characteristics are ensured while ensuring the cycle characteristics. Can be improved.

  Examples of the present invention will be described in detail.

(Example 1-1)
The laminated film type secondary battery shown in FIGS. 1 and 2 was produced by the third manufacturing method described for the first battery. At this time, a lithium ion secondary battery in which the capacity of the negative electrode 22 was expressed by a capacity component based on insertion and extraction of lithium was made.

First, the positive electrode 21 was produced. That is, lithium carbonate (Li ₂ CO ₃ ) and cobalt carbonate (CoCO ₃ ) are mixed at a molar ratio of 0.5: 1 and then calcined in air at 900 ° C. for 5 hours. The product (LiCoO ₂ ) was obtained. Subsequently, 94 parts by mass of a lithium / cobalt composite oxide as a positive electrode active material, 3 parts by mass of graphite as a conductive agent, and 3 parts by mass of polyvinylidene fluoride as a binder were mixed to form a positive electrode mixture. -A paste-like positive electrode mixture slurry was prepared by dispersing in methyl-2-pyrrolidone. Subsequently, the positive electrode mixture slurry was uniformly applied to both surfaces of the positive electrode current collector 21A made of aluminum foil (20 μm thick) and dried, and then the positive electrode active material layer 21B was formed by compression molding with a roll press machine. Formed. At this time, the density of the positive electrode active material layer 21B per one side was set to 40 mg / cm ² . Finally, it was cut into a strip shape so that the width was 50 mm and the length was 300 nm. After that, the positive electrode lead 11 made of aluminum was welded and attached to one end of the positive electrode current collector 21A.

Subsequently, the negative electrode 22 was produced. That is, 97 parts by mass of graphite powder as a negative electrode active material and 3 parts by mass of polyvinylidene fluoride as a binder were mixed to form a negative electrode mixture, which was then dispersed in N-methyl-2-pyrrolidone to obtain a paste form. Negative electrode mixture slurry. Subsequently, the negative electrode mixture slurry was uniformly applied to both surfaces of the negative electrode current collector 22A made of copper foil (15 μm thick), dried, and then compression molded with a roll press to form the negative electrode active material layer 22B. Formed. At this time, the density of the negative electrode active material layer 22B per one side was set to 20 mg / cm ² . Finally, it was cut into a strip shape so as to have a width of 50 mm and a length of 300 mm. After that, the negative electrode lead 12 made of nickel was welded to one end of the negative electrode current collector 22A.

  Subsequently, the positive electrode 21, the separator 23 made of a microporous polyethylene film (7 μm thickness) coated with polyvinylidene fluoride as a polymer compound on both sides, and the negative electrode 22 are laminated in this order and spirally formed in the longitudinal direction. After being wound a number of times, the winding end portion was fixed with a protective tape 25 made of an adhesive tape to form a wound body that was a precursor of the wound electrode body 20. At this time, the thickness of the polymer compound on one side of the separator 23 was set to 2 μm. Subsequently, between the exterior member 30 made of a laminate film of a three-layer structure (total thickness 100 μm) in which nylon (30 μm thickness), aluminum (40 μm thickness), and unstretched polypropylene (30 μm) are laminated from the outside. After sandwiching the wound body, the wound body was housed inside the bag-shaped exterior member 30 by heat-sealing the outer edges except for one side. Subsequently, after a liquid electrolyte (electrolytic solution) was injected into the inside through the opening of the exterior member 30, the opening of the exterior member 30 was heat-sealed and sealed in a vacuum atmosphere.

As an electrolytic solution, ethylene carbonate (EC), diethyl carbonate (DEC), vinylene carbonate (VC), which is a cyclic carbonate having an unsaturated bond, and a sulfone compound shown in Chemical Formula 5 or Chemical Formula 6 are used as solvents. A mixed solvent mixed with a certain 2-sulfobenzoic anhydride (SBAH) was used, and lithium hexafluorophosphate (LiPF ₆ ) was used as an electrolyte salt. At this time, the composition ratio of the mixed solvent was EC: DEC: VC: SBAH = 69: 30: 0.5: 0.5 by weight. The composition of the electrolytic solution was mixed solvent: electrolyte salt = 86: 14 by weight ratio.

  Finally, the exterior member 30 is sandwiched between iron plates and heated at 70 ° C. for 3 minutes while applying a load to gel the polymer compound applied to the separator 23 to form the electrolyte 24, thereby forming a laminate film type. The secondary battery was completed. The capacity of this secondary battery is 700 mAh.

(Examples 1-2 to 1-4)
The composition ratio of the solvent (EC: DEC: VC: SBAH) was 39: 60: 0.5: 0.5 (Example 1-2) and 29: 70: 0.5: 0.5 (Example) by weight ratio. 1-3), 19: 80: 0.5: 0.5 (Example 1-4), except that the procedure was the same as Example 1-1.

(Example 1-5)
VC is not contained in the solvent, and the composition ratio of the solvent (EC: DEC: VC: SBAH) is the same as that of Example 1-1 except that the weight ratio is 39.5: 60: 0: 0.5. I went through the procedure.

(Comparative Examples 1-1 and 1-2)
The composition ratio of the solvent (EC: DEC: VC: SBAH) was 74: 25: 0.5: 0.5 (Comparative Example 1-1) by weight ratio, 14: 85: 0.5: 0.5 (Comparative Example). Except for 1-2), the same procedure as in Example 1-1 was performed.

  When the swelling characteristics and cycle characteristics of the secondary batteries of Examples 1-1 to 1-5 and Comparative Examples 1-1 and 1-2 were examined, the results shown in Table 1 were obtained.

  When examining the swollenness characteristics, the swollenness was determined by storing the secondary battery at a high temperature according to the following procedure. First, the thickness of the secondary battery was measured in an atmosphere at 23 ° C. Subsequently, the battery was charged to an upper limit voltage of 4.2 V at a charging current of 700 mA, and further charged at a constant voltage of 4.2 V until the time from the start of charging was 3 hours. Then, after storing for 4 hours in a 90 degreeC thermostat with a charge condition, the thickness of the secondary battery was measured again. Finally, the swelling (mm) was calculated as the amount of change in thickness by subtracting the thickness before storage from the thickness after storage. In evaluating the swelling characteristics, the evaluation standard was set to 0.6 mm or less, preferably 0.5 mm or less.

  When examining the cycle characteristics, the secondary battery was repeatedly charged and discharged by the following procedure to obtain the discharge capacity retention rate. First, the discharge capacity at the first cycle was measured by charging and discharging in an atmosphere at 23 ° C. Subsequently, the discharge capacity at the 300th cycle was measured by repeating charge and discharge until the total number of charge and discharge was 300 times. Finally, discharge capacity retention ratio (%) = (discharge capacity at the 300th cycle / discharge capacity at the first cycle) × 100 was calculated. The charge condition for one cycle was the same as the case where the swelling characteristics were examined, and the discharge condition for one cycle was a discharge current of 700 mA and a discharge voltage of 3.0 V. In evaluating the cycle characteristics, the evaluation criterion was set to 50% or more, preferably 60% or more.

  The procedures, conditions, evaluation criteria, and the like for examining the above-described swelling characteristics and cycle characteristics are the same for the evaluation of the same characteristics regarding the series of examples and comparative examples.

  As shown in Table 1, when the results of Examples 1-1 to 1-4 and Comparative Examples 1-2 and 1-2 are seen, blistering gradually decreases as the content of DEC in the solvent increases. However, the discharge capacity retention rate increased and then decreased. In this case, in Comparative Example 1-1 in which the content of DEC is 25% by weight and Comparative Example 1-2 in which the content of DEC is 85% by weight, the swelling satisfies the evaluation criteria (0.6 mm or less). The maintenance rate decreased significantly and did not meet the evaluation criteria (50% or more). On the other hand, in Examples 1-1 to 1-4 in which the content of DEC is 30% by weight, 60% by weight, 70% by weight, and 80% by weight, the swelling satisfies the evaluation standard (0.6 mm or less). The discharge capacity retention rate also satisfied the evaluation criteria (50% or more). Therefore, in the secondary battery containing the sulfone compound shown in Chemical Formula 5 or Chemical Formula 6 together with EC, DEC and VC as a solvent, the content of DEC in the solvent is in the range of 30 wt% to 80 wt%. As a result, it was confirmed that the cycle characteristics were secured and the swelling characteristics were improved.

  Moreover, in Example 1-2 in which the solvent contains VC, the discharge capacity maintenance rate increased while the swelling was substantially maintained as compared with Example 1-5 in which VC was not included. From this, it was confirmed that the cycle characteristics were improved when the electrolyte contained a cyclic carbonate having an unsaturated bond as a solvent.

(Examples 2-1 and 2-2)
Example 1 except that the content of SBAH in the solvent was 0.1% by weight (Example 2-1) and 1% by weight (Example 2-2), and the EC content was adjusted accordingly. The same procedure as in -3 was performed.

(Comparative Examples 2-1 to 2-4)
The same procedure as in Examples 1-1 to 1-4 was performed, except that SBAH was not contained in the solvent and the EC content was adjusted accordingly.

  When the swelling characteristics and cycle characteristics of the secondary batteries of Examples 2-1 and 2-2 and Comparative Examples 2-1 to 2-4 were examined, the results shown in Table 2 were obtained. In Table 2, various characteristics of Examples 1-1 to 1-4 are also shown.

  As shown in Table 2, in Examples 1-1 to 1-4 in which the solvent contains SBAH, blistering was significantly reduced as compared with Comparative Examples 2-1 to 2-4 not containing SBAH. In addition, in Examples 1-1 to 1-4, the discharge capacity retention rate was slightly decreased as compared with Comparative Examples 2-1 to 2-4, and the discharge capacity retention rate was substantially the same. It was. Therefore, in a secondary battery in which the electrolyte contains EC, DEC, and VC as solvents, the solvent includes the sulfone compound shown in Chemical Formula 5 or Chemical Formula 6, thereby ensuring cycle characteristics and improving swelling characteristics. It was confirmed that

  Further, in Example 2-1 in which the content of SBAH is 0.1% by weight, Example 1-3 in which the content is 0.5% by weight, and Example 2-2 in which the content is 1% by weight, swelling is evaluated as a criterion ( 0.6 mm or less), particularly 0.5 mm or less, and the discharge capacity maintenance rate also satisfies the evaluation criteria (50% or more). In this case, as the SBAH content increased, the swelling decreased and the discharge capacity retention rate tended to decrease. Therefore, in order to improve the swelling characteristics while ensuring the cycle characteristics in the secondary battery containing the sulfone compound shown in Chemical Formula 5 or Chemical Formula 6 together with EC, DEC and VC as a solvent, the electrolyte contains It was confirmed that the amount should be in the range of 0.1 wt% to 1 wt%.

(Examples 3-1 to 3-8)
Dimethyl carbonate (DMC) was added to the solvent, and the solvent composition ratio (EC: DEC: DMC: VC: SBAH) was 39: 55: 5: 0.5: 0.5 (Example 3-1) by weight ratio, 29: 65: 5: 0.5: 0.5 (Example 3-2), 19: 75: 5: 0.5: 0.5 (Example 3-3), 39: 30: 30: 0. 5: 0.5 (Example 3-4), 29: 40: 30: 0.5: 0.5 (Example 3-5), 19: 50: 30: 0.5: 0.5 (Example) 3-6), 29: 35: 35: 0.5: 0.5 (Example 3-7), 19: 45: 35: 0.5: 0.5 (Example 3-8). Except for this, the same procedure as in Example 1-1 was performed.

(Comparative Examples 3-1 to 3-6)
The same procedure as in Examples 3-1 to 3-6 was performed, except that SBAH was not contained in the solvent and the EC content was adjusted accordingly.

(Example 3-7)
The same procedure as in Examples 3-7 and 3-8 was performed, except that the content of DEC in the solvent was 25% by weight and the content of EC was adjusted accordingly.

  When the swelling characteristics and cycle characteristics of the secondary batteries of Examples 3-1 to 3-8 and Comparative examples 3-1 to 3-7 were examined, the results shown in Table 3 were obtained.

  As shown in Table 3, in Examples 3-1 to 3-6 in which the solvent contains SBAH, as compared with Comparative Examples 3-1 to 3-6 not containing SBAH, the blistering was greatly reduced. The discharge capacity retention rate was almost the same. Therefore, in the secondary battery in which the electrolyte contains EC, DEC, DMC and VC as the solvent, the solvent contains the sulfone compound shown in Chemical Formula 5 or Chemical Formula 6, so that the cycle characteristics are secured and the swelling characteristics are improved. It was confirmed that it improved.

  Further, Examples 3-1 to 3-3 having a DMC content of 5% by weight, Examples 3-4 to 3-6 having 30% by weight, and Examples 3-7 and 3- In No. 8, the swelling satisfied the evaluation criterion (0.6 mm or less), and the discharge capacity maintenance rate also satisfied the evaluation criterion (50% or more), and particularly reached 60% or more. In this case, as the DMC content increased, the swelling increased and the discharge capacity retention rate tended to increase. In addition, although the solvent contains DMC and SBAH, in Comparative Example 3-7 in which the content of DEC is 25% by weight, the discharge capacity retention rate satisfied the evaluation criterion, but the swelling did not satisfy the evaluation criterion. . The increase in blistering in Comparative Example 3-7 indicates that blistering has become prominent because the DMC content is too high and the DEC content is too low. From this, in order to improve the swelling characteristics while ensuring the cycle characteristics in the secondary battery containing the sulfone compound shown in Chemical Formula 5 or Chemical Formula 6 together with EC, DEC, DMC and VC as the solvent, It was confirmed that the content should be in the range of 5 wt% to 35 wt%.

  In particular, Examples 1-2 to 1-4 in which the solvent does not contain DMC, and Examples 3-1 to 3-3 in which a part of DEC in Examples 1-2 to 1-4 is replaced with DMC. In comparison, the bulge increased only slightly in the latter than the former, and the bulges were almost the same, but the discharge capacity maintenance rate increased significantly in the latter than in the former. From this, it was confirmed that when the solvent contains DMC, the cycle characteristics are improved while the swelling characteristics are substantially maintained.

(Examples 4-1 to 4-6)
Ethyl methyl carbonate (EMC) was added to the solvent, and the composition ratio of the solvent (EC: DEC: EMC: VC: SBAH) was 39: 55: 5: 0.5: 0.5 by weight ratio (Example 4-1). 29: 65: 5: 0.5: 0.5 (Example 4-2), 19: 75: 5: 0.5: 0.5 (Example 4-3), 39: 30: 30: 0 5: 0.5 (Example 4-4), 29: 30: 40: 0.5: 0.5 (Example 4-5), 19: 30: 50: 0.5: 0.5 (implementation) A procedure similar to that of Example 1-1 was performed except that Example 4-6) was adopted.

(Comparative Examples 4-1 to 4-6)
The same procedure as in Examples 4-1 to 4-6 was performed except that SBAH was not contained in the solvent and the EC content was adjusted accordingly.

(Comparative Examples 4-7 to 4-9)
The same procedure as in Examples 4-1 to 4-3 was performed except that the content of DEC in the solvent was 25% by weight and the content of EMC was adjusted accordingly.

  When the swelling characteristics and cycle characteristics of the secondary batteries of Examples 4-1 to 4-6 and Comparative Examples 4-1 to 4-9 were examined, the results shown in Table 4 were obtained.

  As shown in Table 4, in Examples 4-1 to 4-6 in which the solvent contains SBAH, as compared with Comparative Examples 4-1 to 4-6 that does not contain SBAH, the blistering was significantly reduced. The discharge capacity retention rate was almost the same. From this, in the secondary battery in which the electrolyte contains EC, DEC, EMC and VC as the solvent, the solvent contains the sulfone compound shown in Chemical Formula 5 or Chemical Formula 6, thereby ensuring cycle characteristics and swelling characteristics. It was confirmed that it improved.

  Further, Examples 4-1 to 4-3 having an EMC content of 5% by weight, Examples 4-4 having 30% by weight, Examples 4-5 having 40% by weight, and Examples having 50% by weight In Example 4-6, the swelling satisfies the evaluation criteria (0.6 mm or less), particularly 0.5 mm or less, and the discharge capacity maintenance rate also satisfies the evaluation criteria (50% or more), particularly 60% or more. did. In this case, as the EMC content increased, the swelling increased while the discharge capacity retention rate increased and then decreased. In Comparative Examples 4-7 to 4-9, in which the solvent contains EMC and SBAH, but the DEC content is 25% by weight, the discharge capacity retention rate reached 60% or more, but the swelling was 0. It did not reach below 5mm. The increase in blisters in Comparative Examples 4-7 to 4-9 indicates that blistering has become prominent because the EMC content is too large and the DEC content is too small. From this, in order to improve the swelling characteristics while ensuring the cycle characteristics in the secondary battery containing the sulfone compound shown in Chemical Formula 5 or Chemical Formula 6 together with EC, DEC, EMC and VC as the solvent, the EMC is used. It has been confirmed that the content of C should be in the range of 5 wt% to 50 wt%.

  In particular, Examples 1-2 to 1-4 in which the solvent does not contain EMC and Examples 4-1 to 4-3 in which a part of DEC in Examples 1-2 to 1-4 was replaced with EMC were used. In comparison, the swelling was almost the same between the former and the latter, but the discharge capacity retention rate was significantly increased in the latter than in the former. From this, it was confirmed that when the solvent contains EMC, the cycle characteristics are improved while the swelling characteristics are substantially maintained.

  In addition, when Examples 3-1 to 3-3 in which the solvent contains DMC and Examples 4-1 to 4-3 in which EMC was used instead of DMC were compared, swelling was reduced in the latter than in the former. The discharge capacity retention rate increased in the former than in the latter. From this, it was confirmed that when DMC and EMC were compared, EMC was advantageous for improving the swelling characteristics and DMC was advantageous for improving the cycle characteristics.

(Examples 5-1 to 5-5)
DMC and EMC were added to the solvent, and the composition ratio of the solvent (EC: DEC: DMC: EMC: VC: SBAH) was 39: 50: 5: 5: 0.5: 0.5 by weight (Example 5-1 ), 29: 60: 5: 5: 0.5: 0.5 (Example 5-2), 19: 70: 5: 5: 0.5: 0.5 (Example 5-3), 29: 30: 20: 20: 0.5: 0.5 (Example 5-4), 19: 30: 25: 25: 0.5: 0.5 (Example 5-5) The same procedure as in Example 1-1 was performed.

(Comparative Examples 5-1 to 5-5)
The same procedure as in Examples 5-1 to 5-5 was performed, except that SBAH was not contained in the solvent and the EC content was adjusted accordingly.

(Comparative Examples 5-6 to 5-9)
The same procedure as in Examples 5-1 to 5-7 was performed, except that the content of DEC in the solvent was 25% by weight and the contents of DMC and EMC were adjusted accordingly. In this case, the solvent composition ratio (EC: DEC: DMC: EMC: VC: SBAH) was 39: 25: 30: 5: 0.5: 0.5 (Comparative Example 5-6) by weight ratio, 39 : 25: 5: 30: 0.5: 0.5 (Comparative Example 5-7), 29: 25: 5: 40: 0.5: 0.5 (Comparative Example 5-8), 19: 25: 5 : 50: 0.5: 0.5 (Comparative Example 5-9).

  When the swelling characteristics and cycle characteristics of the secondary batteries of Examples 5-1 to 5-5 and Comparative Examples 5-1 to 5-9 were examined, the results shown in Table 5 were obtained.

  As shown in Table 5, in Examples 5-1 to 5-5 in which the solvent contains SBAH, as compared with Comparative Examples 5-1 to 5-5 that does not contain SBAH, the blistering was significantly reduced. The discharge capacity retention rate was almost the same. In this case, the swelling reached 0.5 mm or less, and the discharge capacity retention rate reached 60% or more. In Comparative Examples 5-6 to 5-9 in which the solvent contains DMC, EMC, and SBAH, but the DEC content is 25% by weight, the discharge capacity retention rate reached 60% or more, but the swelling Did not reach 0.5 mm or less. Therefore, in a secondary battery using an electrolyte containing EC, DEC, DMC, EMC and VC as a solvent, the cycle characteristics are secured by including the sulfone compound shown in Chemical Formula 5 or Chemical Formula 6. It was confirmed that the swelling characteristics were improved as well.

(Examples 6-1 to 6-4)
Propylene carbonate (PC) was added to the solvent, and the composition ratio of the solvent (EC: DEC: VC: PC: SBAH) was 59: 30: 0.5: 10: 0.5 by weight ratio (Example 6-1), 29: 60: 0.5: 10: 0.5 (Example 6-2), 19: 70: 0.5: 10: 0.5 (Example 6-3), 9: 80: 0.5: The procedure was similar to that of Example 1-1 except that 10: 0.5 (Example 6-4).

(Example 6-5)
While adding PC to the solvent, VC was not contained, and the composition ratio of the solvent (EC: DEC: VC: PC: SBAH) was 29.5: 60: 0: 10: 0.5 by weight ratio. Except for this, the same procedure as in Example 1-1 was performed.

(Comparative Examples 6-1 and 6-2)
The composition ratio of the solvent (EC: DEC: VC: PC: SBAH) was 64: 25: 0.5: 10: 0.5 (Comparative Example 6-1) by weight ratio, 4: 85: 0.5: 10: A procedure similar to that of Example 1-1 was performed except that 0.5 (Comparative Example 6-2) was used.

  When the swelling characteristics and cycle characteristics of the secondary batteries of Examples 6-1 to 6-5 and Comparative Examples 6-1 and 6-2 were examined, the results shown in Table 6 were obtained.

  As shown in Table 6, when the results of Examples 6-1 to 6-4 and Comparative Examples 6-1 and 6-2 are seen, in Comparative Examples 6-1 and 6-2, swelling is evaluated as an evaluation criterion (0 0.6 mm or less), but the discharge capacity retention rate was significantly reduced and the evaluation criteria (50% or more) were not satisfied. On the other hand, in Examples 6-1 to 6-4, the swelling satisfied the evaluation criteria, and the discharge capacity retention rate also satisfied the evaluation criteria. Therefore, in the secondary battery in which the electrolyte includes the sulfone compound shown in Chemical Formula 5 or Chemical Formula 6 together with EC, DEC, VC and PC as a solvent, the content of DEC in the solvent is 30 wt% or more and 80 wt% or less. It was confirmed that by making it within the range, the cycle characteristics were ensured and the swollen characteristics were improved.

  Further, in Example 6-2 in which the solvent contains VC, the discharge capacity maintenance rate increased while the swelling was substantially maintained as compared with Example 6-5 in which VC was not included. From this, it was confirmed that the cycle characteristics were improved when the electrolyte contained a cyclic carbonate having an unsaturated bond as a solvent.

(Examples 7-1 and 7-2)
Example 6 except that the content of SBAH in the solvent was 0.1% by weight (Example 7-1) and 1% by weight (Example 7-2), and the EC content was adjusted accordingly. The same procedure as in -3 was performed.

(Comparative Examples 7-1 to 7-4)
The same procedure as in Examples 6-1 to 6-4 was performed except that SBAH was not contained in the solvent and the EC content was adjusted accordingly.

  When the swelling characteristics and cycle characteristics of the secondary batteries of Examples 7-1 and 7-2 and Comparative Examples 7-1 to 7-4 were examined, the results shown in Table 7 were obtained. Table 7 also shows various characteristics of Examples 6-1 to 6-4.

  As shown in Table 7, in Examples 6-1 to 6-4, as compared with Comparative Examples 7-1 to 7-4, the blistering was significantly reduced and the discharge capacity retention rate was substantially the same. It was. Therefore, in the secondary battery in which the electrolyte contains EC, DEC, VC, and PC as the solvent, the solvent includes the sulfone compound shown in Chemical Formula 5 or Chemical Formula 6, so that the cycle characteristics are secured and the swelling characteristics are improved. It was confirmed that it improved.

  Further, in Examples 7-1, 6-3, and 7-2, the swelling satisfied the evaluation standard (0.6 mm or less), particularly reached 0.5 mm, and the discharge capacity maintenance rate was also evaluated standard (50% or more). ) Therefore, in order to improve the swelling characteristics while securing the cycle characteristics in the secondary battery including the sulfone compound shown in Chemical Formula 5 or Chemical Formula 6 together with EC, DEC, VC and PC as the solvent, the sulfone compound It has been confirmed that the content of N should be in the range of 0.1 wt% to 1 wt%.

(Examples 8-1 to 8-8)
DMC was added to the solvent, and the composition ratio of the solvent (EC: DEC: DMC: VC: PC: SBAH) was 29: 55: 5: 0.5: 10: 0.5 by weight ratio (Example 8-1), 19: 65: 5: 0.5: 10: 0.5 (Example 8-2), 9: 75: 5: 0.5: 10: 0.5 (Example 8-3), 29:30: 30: 0.5: 10: 0.5 (Example 8-4), 19: 40: 30: 0.5: 10: 0.5 (Example 8-5), 9: 50: 30: 0. 5: 10: 0.5 (Example 8-6), 19: 35: 35: 0.5: 10: 0.5 (Example 8-7), 9: 45: 35: 0.5: 10: A procedure similar to that of Examples 6-1 to 6-4 was performed, except that the value was 0.5 (Example 8-8).

(Comparative Examples 8-1 to 8-6)
The same procedure as in Examples 8-1 to 8-6 was performed, except that SBAH was not contained in the solvent and the EC content was adjusted accordingly.

(Comparative Example 8-7)
A procedure similar to that in Examples 8-7 and 8-8 was performed, except that the content of DEC in the solvent was 25% by weight and the EC content was adjusted accordingly.

  When the swelling characteristics and cycle characteristics of the secondary batteries of Examples 8-1 to 8-8 and Comparative Examples 8-1 to 8-7 were examined, the results shown in Table 8 were obtained.

  As shown in Table 8, in Examples 8-1 to 8-6, as compared with Comparative Examples 8-1 to 8-6, the blistering was significantly reduced and the discharge capacity maintenance ratio was substantially the same. It was. From this, in the secondary battery in which the electrolyte contains EC, DEC, DMC, VC and PC as a solvent, the solvent includes the sulfone compound shown in Chemical Formula 5 or Chemical Formula 6, thereby ensuring cycle characteristics and swelling. It was confirmed that the characteristics were improved.

  Further, in Examples 8-1 to 8-8, the swelling satisfied the evaluation criterion (0.6 mm or less), and the discharge capacity maintenance rate also satisfied the evaluation criterion (50% or more), and particularly reached 60% or more. . In addition, although the solvent contains DMC and SBAH, in Comparative Example 8-7 in which the content of DEC is 25% by weight, the discharge capacity retention rate satisfied the evaluation criterion, but the swelling did not satisfy the evaluation criterion. . From this, in order to improve the swelling characteristics while securing the cycle characteristics in the secondary battery containing the sulfone compound shown in Chemical Formula 5 or Chemical Formula 6 together with EC, DEC, DMC, VC and PC as the solvent, It was confirmed that the content of DMC should be in the range of 5 wt% to 35 wt%.

  In particular, when Examples 6-2 to 6-4 in which the solvent does not contain DMC and Examples 8-1 to 8-3 containing DMC were compared, the swelling was almost the same between the former and the latter. However, the discharge capacity retention rate was significantly increased in the latter than in the former. From this, it was confirmed that when the solvent contains DMC, the cycle characteristics are improved while the swelling characteristics are substantially maintained.

(Examples 9-1 to 9-6)
EMC was added to the solvent, and the composition ratio of the solvent (EC: DEC: EMC: VC: PC: SBAH) was 29: 55: 5: 0.5: 10: 0.5 by weight ratio (Example 9-1), 19: 65: 5: 0.5: 10: 0.5 (Example 9-2), 9: 75: 5: 0.5: 10: 0.5 (Example 9-3), 29:30: 30: 0.5: 10: 0.5 (Example 9-4), 19: 30: 40: 0.5: 10: 0.5 (Example 9-5), 9: 30: 50: 0. The same procedure as in Examples 6-1 to 6-4 was performed except that the ratio was 5: 10: 0.5 (Example 9-6).

(Comparative Examples 9-1 to 9-6)
The same procedure as in Examples 9-1 to 9-6 was performed, except that the solvent did not contain SBAH and the EC content was adjusted accordingly.

(Comparative Examples 9-7 to 9-9)
The same procedure as in Examples 9-4 to 9-6 was performed except that the content of DEC in the solvent was 25% by weight and the content of EMC was adjusted accordingly.

  When the swelling characteristics and cycle characteristics of the secondary batteries of Examples 9-1 to 9-6 and Comparative Examples 9-1 to 9-9 were examined, the results shown in Table 9 were obtained.

  As shown in Table 9, in Examples 9-1 to 9-6, as compared with Comparative Examples 9-1 to 9-6, the blistering was significantly reduced and the discharge capacity maintenance ratio was substantially the same. It was. From this, in the secondary battery in which the electrolyte contains EC, DEC, EMC, VC and PC as the solvent, the solvent includes the sulfone compound shown in Chemical Formula 5 or Chemical Formula 6, so that the cycle characteristics are secured and the swelling is achieved. It was confirmed that the characteristics were improved.

  Further, in Examples 9-1 to 9-6, the swelling satisfies the evaluation standard (0.6 mm or less), particularly 0.5 mm or less, and the discharge capacity maintenance ratio satisfies the evaluation standard (50% or more). Especially reached 60% or more. In Comparative Examples 9-7 to 9-9 in which the solvent contains EMC and SBAH, but the DEC content is 25% by weight, the discharge capacity retention rate reached 60% or more, but the swelling was 0 It did not reach below 5mm. From this, in order to improve the swelling characteristics while securing the cycle characteristics in the secondary battery containing the sulfone compound shown in Chemical Formula 5 or Chemical Formula 6 together with EC, DEC, EMC, VC and PC as a solvent, It was confirmed that the EMC content should be in the range of 5 wt% to 50 wt%.

  In particular, when Examples 6-2 to 6-4 where the solvent does not contain EMC and Examples 9-1 to 9-3 containing EMC were compared, the swelling was almost the same between the former and the latter. However, the discharge capacity retention rate increased more or less in the latter than in the former. From this, it was confirmed that by including EMC in the solvent, the cycle characteristics are improved while the swelling characteristics are substantially maintained.

  Moreover, when Examples 8-1 to 8-3 containing DMC and Examples 9-1 to 9-3 containing EMC were compared, the swelling decreased in the latter rather than the former, but the discharge capacity retention rate Increased in the former than in the latter. From this, it was confirmed that EMC is advantageous for improving the swelling characteristics, and DMC is advantageous for improving the cycle characteristics.

(Examples 10-1 to 10-5)
DMC and EMC were added to the solvent, and the solvent composition ratio (EC: DEC: DMC: EMC: VC: PC: SBAH) was 29: 50: 5: 5: 0.5: 10: 0.5 by weight ratio (implementation) Example 10-1), 19: 60: 5: 5: 0.5: 10: 0.5 (Example 10-2), 9: 70: 5: 5: 0.5: 10: 0.5 (implementation) Example 10-3), 19: 30: 20: 20: 0.5: 10: 0.5 (Example 10-4), 9: 30: 25: 25: 0.5: 10: 0.5 (implementation) The same procedure as in Examples 6-1 to 6-4 was performed, except that Example 10-5) was used.

(Comparative Examples 10-1 to 10-5)
The same procedure as in Examples 10-1 to 10-5 was performed except that SBAH was not contained in the solvent and the EC content was adjusted accordingly.

(Comparative Examples 10-6 to 10-9)
A procedure similar to that in Examples 10-1 to 10-7 was performed except that the content of DEC in the solvent was 25% by weight and the contents of DMC and EMC were adjusted accordingly. In this case, the composition ratio of the solvent (EC: DEC: DMC: EMC: VC: PC: SBAH) was 29: 25: 30: 5: 0.5: 10: 0.5 by weight ratio (Comparative Example 10- 6), 29: 25: 5: 30: 0.5: 10: 0.5 (Comparative Example 10-7), 19: 25: 5: 40: 0.5: 10: 0.5 (Comparative Example 10-) 8), 9: 25: 5: 50: 0.5: 10: 0.5 (Comparative Example 10-9).

  When the swelling characteristics and cycle characteristics of the secondary batteries of Examples 10-1 to 10-7 and Comparative Examples 10-1 to 10-9 were examined, the results shown in Table 10 were obtained.

  As shown in Table 10, in Examples 10-1 to 10-5, as compared with Comparative Examples 10-1 to 10-5, the swelling was significantly reduced and the discharge capacity retention rate was substantially the same. It was. In this case, the swelling reached 0.5 mm or less, and the discharge capacity retention rate reached 60% or more. In Comparative Examples 10-6 to 10-9 in which the solvent contains DMC, EMC, and SBAH, but the DEC content is 25% by weight, the discharge capacity retention rate reached 60% or more, but the swelling Did not reach 0.5 mm or less. Therefore, in the secondary battery in which the electrolyte includes EC, DEC, DMC, EMC, VC and PC as a solvent, the cycle characteristics are ensured by including the sulfone compound shown in Chemical Formula 5 or Chemical Formula 6 as the solvent. In addition, it was confirmed that the swelling characteristics were improved.

  Here, when the case where the solvent does not contain PC (see Tables 1 to 5) and the case where PC contains (see Tables 6 to 10) are compared, the discharge capacity retention rate slightly decreases in the latter than in the former. However, blistering decreased in the latter than in the former. From this, it was confirmed that the swollenness characteristics were improved when the solvent contained PC.

(Examples 11 and 12)
The same procedure as in Examples 1-2 and 6-2 was performed, except that the electrolyte 24 was formed by the first manufacturing method described for the first battery. In forming the electrolyte 24, a precursor solution containing an electrolytic solution, polyvinylidene fluoride as a polymer compound, and N-methyl-2-pyrrolidone as a solvent is prepared and applied to the positive electrode 21 and the negative electrode 22. The solvent was volatilized.

  When the swelling characteristics and cycle characteristics of the secondary batteries of Examples 1-2 and 11 were examined, the results shown in Table 11 were obtained. Further, when the swelling characteristics and cycle characteristics of the secondary batteries of Examples 6-2 and 12 were examined, the results shown in Table 12 were obtained.

As shown in Table 11 and Table 12, in Examples 1-2 and 6-2 (presence or absence of the polymer compound applied to the separator; yes) using the separator 23 coated with the polymer compound on both sides, Compared with Examples 11 and 12 (the presence or absence of the polymer compound applied to the separator; none) using the separator 23 in which the polymer compound was not applied to both surfaces, the discharge capacity retention rate was substantially maintained. The blistering has been greatly reduced. From this, it was confirmed that the swelling characteristics are improved by forming the electrolyte 24 using the separator 23 coated with the polymer compound on both sides.

  The present invention has been described with reference to the embodiments and examples. However, the present invention is not limited to the embodiments described in the above embodiments and examples, and various modifications can be made. For example, the application of the electrolyte of the present invention is not necessarily limited to a battery, but may be an electrochemical device other than a battery. Examples of other electrochemical devices include capacitors.

  In the above-described embodiments and examples, the case where a liquid electrolyte or a gel electrolyte is used as the electrolyte of the present invention has been described. However, other types of electrolytes may be used. Other electrolytes include, for example, a mixture of an ion conductive inorganic compound such as ion conductive ceramics, ion conductive glass or ionic crystal and an electrolyte, or a mixture of another inorganic compound and an electrolyte. Or a mixture of these inorganic compounds and a gel electrolyte.

  In the above-described embodiments and examples, the battery of the present invention is a lithium ion secondary battery in which the capacity of the negative electrode is represented by a capacity component based on insertion and extraction of lithium, or lithium metal is used for the negative electrode active material. The lithium metal secondary battery in which the capacity of the negative electrode is represented by a capacity component based on the precipitation and dissolution of lithium has been described, but is not necessarily limited thereto. The secondary battery of the present invention has a negative electrode material capable of occluding and releasing lithium with a charge capacity smaller than the charge capacity of the positive electrode, so that the capacity of the negative electrode is based on the insertion and release of lithium. The present invention can be similarly applied to a secondary battery including a capacity component based on the precipitation and dissolution of the metal and expressed by the sum of the capacity components.

  In the above-described embodiments and examples, the case where lithium is used as the electrode reactant has been described. However, other Group 1A elements such as sodium (Na) or potassium (K), magnesium or calcium (Ca), etc. Other light metals such as 2A group elements and aluminum may be used. Also in this case, the negative electrode material described in the above embodiment can be used as the negative electrode active material.

  In the above-described embodiment or example, the laminate film type is given as an example of the battery structure of the battery of the present invention, and the winding structure is taken as an example of the structure of the battery element. The present invention can be similarly applied to a battery having another battery structure such as a cylindrical shape, a coin shape, a button shape, or a square shape, or a battery having a laminated structure of battery elements. In addition, the battery of the present invention is not limited to the secondary battery, but can be similarly applied to other batteries such as a primary battery.

  Further, in the above-described embodiments and examples, the numerical range derived from the results of the examples for the composition ratio of the solvent (diethyl carbonate, dimethyl carbonate, ethyl methyl carbonate, sulfone compound) in the electrolyte of the present invention is an appropriate range. However, the explanation does not completely deny the possibility that the content is outside the above range. In other words, the appropriate range described above is a particularly preferable range for obtaining the effect of the present invention, and the content may be slightly deviated from the above range as long as the effect of the present invention is obtained.

It is a disassembled perspective view showing the structure of the battery which concerns on one embodiment of this invention. It is sectional drawing showing the structure along the II-II line of the winding electrode body shown in FIG.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 11 ... Positive electrode lead, 12 ... Negative electrode lead, 20 ... Winding electrode body, 21 ... Positive electrode, 21A ... Positive electrode collector, 21B ... Positive electrode active material layer, 22 ... Negative electrode, 22A ... Negative electrode collector, 22B ... Negative electrode active Material layer, 23 ... separator, 24 ... electrolyte, 25 ... protective tape, 30 ... exterior member, 31 ... adhesion film.

Claims (15)

A solvent and an electrolyte salt,
The solvent contains ethylene carbonate, diethyl carbonate, and at least one of the sulfone compounds represented by Chemical Formula 1 and Chemical Formula 2,
The diethyl carbonate content in the solvent is in the range of 30 wt% to 80 wt%, and the sulfone compound content in the solvent is in the range of 0.1 wt% to 1 wt%. The electrolyte characterized by being.

(R1 is a _{C m H 2m-n X n} , X represents a halogen. However, m is an integer ranging from 2 to 4, n represents an integer in the range of 0 or 1 or more 2m is there.)

(R2, R3, R4 and R5 are _{C j H 2j + 1-k} X k, good .X be different may be mutually the same halogen. However, j is 0 or 1 to 3 range And k is an integer in the range of 0 or 1 to 2j + 1.) The electrolyte according to claim 1, wherein the sulfone compound contains 2-sulfobenzoic anhydride represented by Chemical Formula 3.

  The electrolyte according to claim 1, wherein the solvent further contains dimethyl carbonate, and the content of the dimethyl carbonate in the solvent is in the range of 5 wt% to 35 wt%.   The electrolyte according to claim 1, wherein the solvent further contains ethyl methyl carbonate, and the content of the ethyl methyl carbonate in the solvent is in the range of 5 wt% to 50 wt%.   The electrolyte according to claim 1, wherein the solvent further contains a cyclic carbonate having an unsaturated bond.   The electrolyte according to claim 1, wherein the solvent further contains propylene carbonate.   The electrolyte according to claim 1, further comprising a polymer compound that holds the solvent and the electrolyte salt. A battery comprising an electrolyte together with a positive electrode and a negative electrode,
The electrolyte includes a solvent and an electrolyte salt,
The solvent contains ethylene carbonate, diethyl carbonate, and at least one of sulfone compounds represented by Chemical formula 4 and Chemical formula 5,
The diethyl carbonate content in the solvent is in the range of 30 wt% to 80 wt%, and the sulfone compound content in the solvent is in the range of 0.1 wt% to 1 wt%. The battery characterized by being.

(R1 is a _{C m H 2m-n X n} , X represents a halogen. However, m is an integer ranging from 2 to 4, n represents an integer in the range of 0 or 1 or more 2m is there.)

(R2, R3, R4 and R5 are _{C j H 2j + 1-k} X k, good .X be different may be mutually the same halogen. However, j is 0 or 1 to 3 range And k is an integer in the range of 0 or 1 to 2j + 1.) The battery according to claim 8, wherein the sulfone compound includes 2-sulfobenzoic anhydride represented by Chemical Formula 6.

  The battery according to claim 8, wherein the solvent further contains dimethyl carbonate, and the content of the dimethyl carbonate in the solvent is in the range of 5 wt% to 35 wt%.   The battery according to claim 8, wherein the solvent further contains ethyl methyl carbonate, and the content of the ethyl methyl carbonate in the solvent is in the range of 5 wt% to 50 wt%.   The battery according to claim 8, wherein the solvent further contains a cyclic carbonate having an unsaturated bond.   The battery according to claim 8, wherein the solvent further contains propylene carbonate.   The battery according to claim 8, wherein the electrolyte further includes a polymer compound that holds the solvent and the electrolyte salt.   The battery according to claim 8, wherein the positive electrode, the negative electrode, and the electrolyte are housed in a film-shaped exterior member.

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