JP2010165549A - Secondary battery - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a secondary battery capable of obtaining superior high temperature cycle characteristics and voltage retention characteristics. <P>SOLUTION: The secondary battery includes a positive electrode 21, a negative electrode 22 and electrolyte solution, of which, the last is impregnated into a separator 23 fitted between the positive electrode 21 and the negative electrode 22. Since a solvent of the electrolyte solution contains a sulfone compound including a site (such as -S(=O)<SB>2</SB>-O-S(=O)<SB>2</SB>-) containing a sulfonyl group, a stable coating is formed on a surface of the positive electrode 21 or the negative electrode 22 at charging and discharging even under a high temperature environment. Further, since an insulation member 28 is arranged at least at an opposing region (a region R2) of a positive electrode collector 21A against a negative electrode active material layer 22B, local potential rise of the positive electrode 21 at its opposing region can be restrained. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a secondary battery including an electrolyte together with a positive electrode and a negative electrode capable of inserting and extracting an electrode reactant.

  In recent years, portable electronic devices such as a video camera, a digital still camera, a mobile phone, and 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, development of a battery, in particular, a secondary battery that is small and lightweight and capable of obtaining a high energy density is in progress.

  Among these, lithium ion secondary batteries that use the insertion and extraction of lithium ions for charge / discharge reactions are highly expected. This is because an energy density higher than that of a lead battery or a nickel cadmium battery can be obtained.

  The secondary battery includes an electrolyte together with a positive electrode and a negative electrode. The positive electrode has a positive electrode active material layer on the positive electrode current collector, and the negative electrode has a negative electrode active material layer on the negative electrode current collector. The electrolyte includes a solvent and an electrolyte salt.

  Since the electrolyte functioning as a medium for the charge / discharge reaction has a great influence on the performance of the secondary battery, various studies have been made on the composition of the electrolyte. Specifically, in order to improve cycle characteristics, storage characteristics, and the like, disulfonic acid anhydride, sulfonic acid carboxylic acid anhydride, and the like are included in the electrolyte (see, for example, Patent Documents 1 and 2). In addition to the composition of the electrolyte, various studies have been made on the structure of the positive electrode and the negative electrode. Specifically, in order to improve high temperature characteristics and the like, the electrolyte contains ethylene sulfite and the like, and an insulating member is disposed in a region opposite to the positive electrode current collector and the negative electrode active material layer (for example, , See Patent Document 3).

JP 2002-008718 A JP 2004-022336 A JP 2007-273438 A

  In recent years, portable electronic devices have become more sophisticated and multifunctional, and their power consumption tends to increase. Therefore, charging and discharging of secondary batteries are frequently repeated, and their cycle characteristics are likely to deteriorate. . In addition, while the portable electronic device is compact and portable, there is a possibility that it is exposed to a high temperature environment during transportation or storage, so that the cycle characteristics in the high temperature environment is a problem. In connection with this, further improvement is desired about the high temperature cycling characteristic of a secondary battery. In this case, in order to ensure the performance of the secondary battery in a high temperature environment, it is important to improve not only the high temperature cycle characteristics but also the voltage maintenance characteristics.

  The present invention has been made in view of such problems, and an object thereof is to provide a secondary battery capable of obtaining excellent high-temperature cycle characteristics and voltage maintenance characteristics.

  The secondary battery of the present invention includes a positive electrode and a negative electrode capable of occluding and releasing an electrode reactant, and an electrolyte containing a solvent and an electrolyte salt. The solvent contains at least one of the sulfone compounds represented by formula (1) and formula (2). The positive electrode has a positive electrode active material layer in a partial region on the positive electrode current collector, and the negative electrode faces a region on the negative electrode current collector that faces the positive electrode active material layer and the positive electrode current collector. The region has a negative electrode active material layer. An insulating member is disposed at least in a region where the positive electrode current collector and the negative electrode active material layer face each other.

（Ｒ１１およびＲ１２はアルキル基、アリール基、ハロゲン化アルキル基あるいはハロゲン化アリール基である。Ｘ１は−Ｓ（＝Ｏ）₂ −、−Ｓ（＝Ｏ）₂ −Ｏ−、−Ｏ−Ｓ（＝Ｏ）₂ −Ｏ−、−Ｓ（＝Ｏ）₂ −Ｏ−Ｓ（＝Ｏ）₂ −あるいは−Ｓ（＝Ｏ）₂ −Ｏ−Ｃ（＝Ｏ）−である。ｎ１は１以上４以下の整数である。）

(R11 and R12 are an alkyl group, an aryl group, a halogenated alkyl group or a halogenated aryl group. X1 represents —S (═O) ₂ —, —S (═O) ₂ —O—, —O—S ( ═O) ₂ —O—, —S (═O) ₂ —O—S (═O) ₂ — or —S (═O) ₂ —O—C (═O) —, where n1 is 1 or more and 4 The following integers.)

（Ｒ１３はアルキレン基、アリーレン基、ハロゲン化アルキレン基あるいはハロゲン化アリーレン基である。Ｘ２は−Ｓ（＝Ｏ）₂ −、−Ｓ（＝Ｏ）₂ −Ｏ−、−Ｏ−Ｓ（＝Ｏ）₂ −Ｏ−、−Ｓ（＝Ｏ）₂ −Ｏ−Ｓ（＝Ｏ）₂ −あるいは−Ｓ（＝Ｏ）₂ −Ｏ−Ｃ（＝Ｏ）−である。ｎ２は１以上４以下の整数である。）

(R13 is an alkylene group, an arylene group, a halogenated alkylene group or a halogenated arylene group. X2 is —S (═O) ₂ —, —S (═O) ₂ —O—, —O—S (═O ) ₂ —O—, —S (═O) ₂ —O—S (═O) ₂ — or —S (═O) ₂ —O—C (═O) —, where n2 is 1 or more and 4 or less. (It is an integer.)

  Note that the negative electrode active material layer may be provided in the entire region or a partial region of the region facing the positive electrode current collector on the negative electrode current collector.

  According to the secondary battery of the present invention, since the solvent of the electrolytic solution contains at least one of the sulfone compounds represented by the formulas (1) and (2), the surface of the positive electrode or the negative electrode during charging / discharging In addition, a stable film is formed even in a high temperature environment. Thereby, since the chemical stability of the electrolyte is improved, the decomposition reaction of the electrolyte is suppressed during charging and discharging even in a high temperature environment. In addition, since the insulating member is disposed at least in the facing region between the positive electrode current collector and the negative electrode active material layer, a local potential increase of the positive electrode in the facing region is suppressed. Thereby, since dissolution and precipitation of metal pieces or metal scraps present in the battery are suppressed, voltage drop in the charged state is suppressed. Accordingly, excellent high-temperature cycle characteristics and voltage maintenance characteristics can be obtained.

It is sectional drawing showing the structure of the secondary battery which concerns on one embodiment of this invention. It is sectional drawing which expands and represents a part of winding electrode body shown in FIG. It is sectional drawing which represents typically the structure of the negative electrode shown in FIG. FIG. 3 is a cross-sectional view schematically illustrating another configuration of the negative electrode illustrated in FIG. 2. FIG. 3 is an SEM photograph showing a cross-sectional structure of the negative electrode shown in FIG. 2 and a schematic diagram thereof. FIG. 3 is an SEM photograph showing another cross-sectional structure of the negative electrode shown in FIG. 2 and a schematic diagram thereof. FIG. 3 is a plan view schematically illustrating the configuration of a positive electrode and a negative electrode illustrated in FIG. 2. It is sectional drawing which expands and represents a part of winding electrode body shown in FIG. It is sectional drawing showing the 1st modification regarding the structure of a winding electrode body. It is sectional drawing showing the 2nd modification regarding the structure of a winding electrode body. It is sectional drawing showing the 3rd modification regarding the structure of a winding electrode body. It is sectional drawing showing the 4th modification regarding the structure of a winding electrode body. It is sectional drawing showing the structure of the other secondary battery which concerns on one embodiment of this invention. It is sectional drawing along the XIV-XIV line | wire of the winding electrode body shown in FIG. It is a figure showing the analysis result of the negative electrode active material (SnCoC) by XPS.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. The order of explanation is as follows.

1. Secondary battery (cylindrical type)
2. 2. Modifications related to the configuration of the wound electrode body Other secondary batteries (laminate film type)

<1. Secondary battery (cylindrical type)>
1 and 2 show a cross-sectional configuration of a secondary battery according to an embodiment of the present invention. In FIG. 2, a part of the wound electrode body 20 shown in FIG. 1 is enlarged. The secondary battery described here is a lithium ion secondary battery in which the capacity of the negative electrode is expressed by occlusion and release of electrode reactants such as lithium ions.

[Configuration of secondary battery]
In the secondary battery, a wound electrode body 20 and a pair of insulating plates 12 and 13 are mainly housed in a substantially hollow cylindrical battery can 11. A battery structure using such a battery can 11 is called a cylindrical type.

  The battery can 11 has, for example, a hollow structure in which one end is closed and the other end is opened. The battery can 11 is made of, for example, nickel, nickel alloy, aluminum alloy, iron, iron alloy, or the like. When the battery can 11 is made of iron, nickel or a nickel alloy may be plated on the surface. The pair of insulating plates 12 and 13 are arranged so as to sandwich the wound electrode body 20 from above and below and to extend perpendicularly to the wound peripheral surface.

  A battery lid 14, a safety valve mechanism 15 and a heat sensitive resistance element (Positive Temperature Coefficient: PTC element) 16 are caulked through a gasket 17 at the open end of the battery can 11. It is sealed. The battery lid 14 is made of, for example, the same material as the battery can 11. The safety valve mechanism 15 and the heat sensitive resistance element are provided inside the battery lid 14. The safety valve mechanism 15 is electrically connected to the battery lid 14 via the heat sensitive resistance element 16. In the safety valve mechanism 15, when the internal pressure becomes a certain level or more due to an internal short circuit or external heating, the disk plate 15 </ b> A is reversed and the electric power between the battery lid 14 and the wound electrode body 20 is reversed. Connection is cut off. The heat-sensitive resistance element 16 prevents abnormal heat generation caused by a large current by increasing resistance (limiting current) as the temperature rises. The gasket 17 is made of, for example, an insulating material, and the surface thereof is coated with, for example, asphalt.

  The wound electrode body 20 is obtained by laminating and winding a positive electrode 21 and a negative electrode 22 via a separator 23. A center pin 24 may be inserted in the center of the wound electrode body 20. In the wound electrode body 20, a positive electrode lead 25 made of aluminum or an aluminum alloy is connected to the positive electrode 21, and a negative electrode lead 26 made of nickel or a nickel alloy is connected to the negative electrode 22. . The positive electrode lead 25 is welded to the safety valve mechanism 15 and electrically connected to the battery lid 14, and the negative electrode lead 26 is welded to the battery can 11 and electrically connected thereto.

[Positive electrode]
The positive electrode 21 is, for example, one in which a positive electrode active material layer 21B is provided on both surfaces of a positive electrode current collector 21A. However, the positive electrode active material layer 21B may be provided only on one surface of the positive electrode current collector 21A.

  The positive electrode current collector 21A is made of, for example, aluminum, nickel, stainless steel, or the like. Examples of the positive electrode current collector 21A include a metal foil.

  The positive electrode active material layer 21B includes one or more positive electrode materials capable of inserting and extracting lithium ions as a positive electrode active material, and a positive electrode binder or a positive electrode as necessary. Other materials such as a conductive agent may be included.

As the positive electrode material, a lithium-containing compound is preferable. This is because a high energy density can be obtained. Examples of the lithium-containing compound include a composite oxide containing lithium and a transition metal element as constituent elements, and a phosphate compound containing lithium and a transition metal element as constituent elements. Especially, what contains at least 1 sort (s) of cobalt, nickel, manganese, and iron as a transition metal element is preferable. This is because a higher voltage can be obtained. The chemical formula is represented by, for example, Li _x M1O ₂ or Li _y M2PO ₄ . In the formula, M1 and M2 represent one or more transition metal elements. Moreover, the values of x and y vary depending on the charge / discharge state, and are generally 0.05 ≦ x ≦ 1.10 and 0.05 ≦ y ≦ 1.10.

Examples of the composite oxide containing lithium and a transition metal element include lithium cobalt composite oxide (Li _x CoO ₂ ), lithium nickel composite oxide (Li _x NiO ₂ ), or lithium represented by formula (16). Examples include nickel-based composite oxides. Examples of the phosphate compound containing lithium and a transition metal element include a lithium iron phosphate compound (LiFePO ₄ ) or a lithium iron manganese phosphate compound (LiFe _1-u Mn _u PO ₄ (u <1)). Is mentioned. This is because high battery capacity is obtained and excellent cycle characteristics are also obtained.

LiNi _1-x M _x O ₂ (16)
(M is cobalt, manganese, iron, aluminum, vanadium, tin, magnesium, titanium, strontium (Sr), calcium (Ca), zirconium, molybdenum, technetium (Tc), ruthenium (Ru), tantalum, tungsten, rhenium (Re ), Ytterbium (Yb), copper, zinc, barium (Ba), boron, chromium, silicon, gallium, phosphorus, antimony (Sb), and niobium, where x is 0.005 <x <0. .5.)

  In addition, examples of the positive electrode material include oxides, disulfides, chalcogenides, and conductive polymers. Examples of the oxide include titanium oxide, vanadium oxide, and manganese dioxide. Examples of the disulfide include titanium disulfide and molybdenum sulfide. An example of the chalcogenide is niobium selenide. Examples of the conductive polymer include sulfur, polyaniline, and polythiophene.

  Of course, the positive electrode material may be other than the above. Further, two or more kinds of the series of positive electrode materials may be mixed in any combination.

  Examples of the positive electrode binder include synthetic rubber or a polymer material. The synthetic rubber is, for example, styrene butadiene rubber, fluorine rubber, or ethylene propylene diene, and the polymer material is, for example, polyvinylidene fluoride. These may be single and multiple types may be mixed.

  Examples of the positive electrode conductive agent include carbon materials such as graphite, carbon black, acetylene black, ketjen black, and vapor growth carbon fiber (VGCF). These may be single and multiple types may be mixed. Note that the positive electrode conductive agent may be a metal or a conductive polymer as long as it is a conductive material.

[Negative electrode]
In the negative electrode 22, for example, a negative electrode active material layer 22B is provided on both surfaces of a negative electrode current collector 22A. However, the negative electrode active material layer 22B may be provided only on one surface of the negative electrode current collector 22A.

  The negative electrode current collector 22A is made of, for example, copper, nickel, stainless steel, or the like. Examples of the anode current collector 22A include a metal foil.

  The surface of the negative electrode current collector 22A is preferably roughened. This is because the so-called anchor effect improves the adhesion of the negative electrode active material layer 22B to the negative electrode current collector 22A. In this case, the surface of the negative electrode current collector 22A only needs to be roughened at least in a region facing the negative electrode active material layer 22B. Examples of the roughening method include a method of forming fine particles by electrolytic treatment. This electrolytic treatment is a method of providing irregularities by forming fine particles on the surface of the anode current collector 22A by an electrolytic method in an electrolytic bath. The copper foil produced by the electrolytic method is generally called “electrolytic copper foil”.

  The negative electrode active material layer 22B includes one or more negative electrode materials capable of inserting and extracting lithium ions as a negative electrode active material, and a negative electrode binder or a negative electrode as necessary. Other materials such as a conductive agent may be included. Note that details regarding the negative electrode binder and the negative electrode conductive agent are the same as, for example, the positive electrode binder and the positive electrode conductive agent, respectively. In the negative electrode active material layer 22B, for example, the chargeable capacity of the negative electrode material is preferably larger than the discharge capacity of the positive electrode 21 in order to prevent unintentional precipitation of lithium metal during charging.

  Examples of the negative electrode material include a carbon material. This is because the change in crystal structure during insertion and extraction of lithium ions is very small, so that a high energy density and excellent cycle characteristics can be obtained. In addition, it also functions as a negative electrode conductive agent. Examples of the carbon material include graphitizable carbon, non-graphitizable carbon having a (002) plane spacing of 0.37 nm or more, and graphite having a (002) plane spacing of 0.34 nm or less. is there. More specifically, there are pyrolytic carbons, cokes, glassy carbon fibers, organic polymer compound fired bodies, activated carbon or carbon blacks. Of these, the cokes include pitch coke, needle coke, petroleum coke, and the like. The organic polymer compound fired body is obtained by firing and carbonizing a phenol resin, a furan resin, or the like at an appropriate temperature. The shape of the carbon material may be any of fibrous, spherical, granular or scale-like.

  In addition, examples of the negative electrode material include a material containing at least one of a metal element and a metalloid element as a constituent element (hereinafter, also simply referred to as “metal material”). This is because a high energy density can be obtained. Such a material may be a single element, an alloy or a compound of a metal element or a metalloid element, or may be two or more of them, or may have at least a part of one or more of those phases. . The “alloy” in the present invention includes an alloy containing one or more metal elements and one or more metalloid elements in addition to an alloy composed of two or more metal elements. Further, the “alloy” may contain a nonmetallic element. The structure includes a solid solution, a eutectic (eutectic mixture), an intermetallic compound, or those in which two or more of them coexist.

  The metal element or metalloid element described above is, for example, a metal element or metalloid element capable of forming an alloy with lithium, and specifically, is at least one of the following elements. Magnesium, boron, aluminum, gallium, indium (In), silicon, germanium (Ge), tin, or lead (Pb). Bismuth (Bi), cadmium (Cd), silver (Ag), zinc, hafnium (Hf), zirconium, yttrium, palladium (Pd), or platinum (Pt). Among these, at least one of silicon and tin is preferable. This is because a high energy density can be obtained because of its excellent ability to occlude and release lithium ions.

  The material containing at least one of silicon and tin may be, for example, a simple substance, an alloy or a compound of silicon or tin, or two or more of them, or at least one of those phases or two or more phases. You may have in a part.

  Examples of silicon alloys include those containing at least one of the following elements as constituent elements other than silicon. Tin, nickel, copper, iron, cobalt, manganese, zinc, indium, silver, titanium, germanium, bismuth, antimony or chromium. Examples of silicon compounds include those containing oxygen or carbon as constituent elements other than silicon. The silicon compound may contain, for example, any one or more of the elements described for the silicon alloy as a constituent element other than silicon.

Examples of silicon alloys or compounds include at least one of the following. SiB ₄ , SiB ₆ , Mg ₂ Si, Ni ₂ Si, TiSi ₂ , MoSi ₂ , CoSi ₂ , NiSi ₂ , CaSi ₂ , CrSi ₂ , Cu ₅ Si, FeSi ₂ or MnSi ₂ . NbSi ₂ , TaSi ₂ , VSi ₂ , WSi ₂ , ZnSi ₂ , SiC, Si ₃ N ₄ , Si ₂ N ₂ O, SiO _v (0 <v ≦ 2), SnO _w (0 <w ≦ 2) or LiSiO.

Examples of the tin alloy include those containing at least one of the following elements as constituent elements other than tin. Silicon, nickel, copper, iron, cobalt, manganese, zinc, indium, silver, titanium, germanium, bismuth, antimony or chromium. Examples of tin compounds include those containing oxygen or carbon. In addition, the compound of tin may contain any 1 type (s) or 2 or more types of the element demonstrated about the alloy of tin as structural elements other than tin, for example. Examples of tin alloys or compounds include SnSiO ₃ , LiSnO, Mg ₂ Sn, and the like.

  Among these, as a material containing silicon, silicon alone is preferable. This is because a high battery capacity and excellent cycle characteristics can be obtained. Note that “single substance” is a simple substance (which may contain a small amount of impurities) in a general sense, and does not necessarily mean 100% purity.

  Moreover, as a material containing tin, for example, an Sn-containing material containing tin as a first constituent element and further containing second and third constituent elements is preferable. The second constituent element is, for example, at least one of the following elements. Cobalt, iron, magnesium, titanium, vanadium, chromium, manganese, nickel, copper, zinc, gallium or zirconium. Niobium, molybdenum, silver, indium, cerium (Ce), hafnium, tantalum, tungsten (W), bismuth, or silicon. The third constituent element is, for example, at least one of boron, carbon, phosphorus, and aluminum. This is because when the second and third constituent elements are contained together with tin, high battery capacity and excellent cycle characteristics can be obtained.

  In particular, a material containing carbon as the third constituent element (SnMC: M is at least one of the above-described cobalt and the like) is preferable, and a material containing cobalt as the second constituent element (SnCoX: X is the boron described above). Etc.) is preferred. This is because when carbon or cobalt is contained as a constituent element, a high energy density can be obtained. In this case, the carbon content is preferably 9.9 mass% to 29.7 mass%, and the content ratio of tin and cobalt (Co / (Sn + Co)) is 20 mass% to 70 mass%. % Is preferred. This is because a high energy density can be obtained in such a composition range.

  Among such materials, SnCoC-containing materials containing tin, cobalt and carbon are preferable. This is because carbon and cobalt are contained as constituent elements, so that an extremely high energy density can be obtained. In addition to this SnCoC-containing material, an SnCoFeC-containing material containing tin, cobalt, iron and carbon is also preferable. The composition of the SnCoFeC-containing material can be arbitrarily set. For example, the composition when the content of iron is set to be small is as follows. The carbon content is 9.9 mass% to 29.7 mass%, the iron content is 0.3 mass% to 5.9 mass%, and the ratio of tin and cobalt content (Co / (Sn + Co)) is 30% by mass to 70% by mass. For example, the composition in the case where the content of iron is set to be large is as follows. Carbon content is 11.9 mass%-29.7 mass%. Further, the content ratio of tin, cobalt and iron ((Co + Fe) / (Sn + Co + Fe)) is 26.4 mass% to 48.5 mass%, and the ratio of content of cobalt and iron (Co / (Co + Fe)) is It is 9.9 mass%-79.5 mass%. This is because a high energy density can be obtained in such a composition range.

  The SnCoC-containing material or the SnCoFeC-containing material may further contain other constituent elements as necessary. Examples of such other constituent elements include at least one of silicon, nickel, chromium, indium, niobium, germanium, titanium, molybdenum, aluminum, phosphorus, gallium, and bismuth.

  The Sn-containing material has a phase containing second and third constituent elements together with tin which is the first constituent element, and the phase is preferably low crystalline or amorphous. This phase is a reaction phase capable of reacting with lithium, and excellent characteristics can be obtained by the presence of the reaction phase. The half width of the diffraction peak obtained by X-ray diffraction of this phase is 1.0 ° or more at a diffraction angle 2θ when CuKα ray is used as the specific X-ray and the drawing speed is 1 ° / min. It is preferable. This is because lithium ions are occluded and released more smoothly, and the reactivity with the electrolyte and the like is reduced. Note that the Sn-containing material may include a phase containing a simple substance or a part of each constituent element in addition to the low crystalline or amorphous phase.

  Whether the diffraction peak obtained by X-ray diffraction corresponds to the reaction phase capable of reacting with lithium can be easily determined by comparing X-ray diffraction charts before and after the electrochemical reaction with lithium. can do. For example, if the position of the diffraction peak changes before and after the electrochemical reaction with lithium, it corresponds to a reaction phase capable of reacting with lithium. In this case, for example, a diffraction peak of a low crystalline or amorphous reaction phase is observed between 2θ = 20 ° and 50 °. Such a reaction phase includes, for example, each of the above-described constituent elements, and is considered to be low-crystallized or amorphized mainly due to the presence of the third constituent element (carbon or the like). It is done.

  In the Sn-containing material, it is preferable that at least a part of carbon or the like as the third constituent element is bonded to a metal element or a metalloid element as another constituent element. This is because aggregation or crystallization of tin or the like is suppressed. The bonding state of elements can be confirmed by, for example, X-ray photoelectron spectroscopy (XPS). In a commercially available apparatus, for example, Al—Kα ray or Mg—Kα ray is used as the soft X-ray.

  Taking SnMC as an example of the Sn-containing material, when at least a part of carbon is bonded to a metal element or a metalloid element, the peak of the synthetic wave of carbon 1s orbital (C1s) is from 284.5 eV. Appear in the lower area. It is assumed that the energy calibration is performed so that the peak of 4f orbit (Au4f) of gold atom is obtained at 84.0 eV. At this time, since the surface contamination carbon usually exists on the surface of the substance, the C1s peak of the surface contamination carbon is set to 284.8 eV, which is used as the energy standard. In XPS measurement, the waveform of the C1s peak is obtained in a form that includes the surface contamination carbon peak and the carbon peak in the SnCoC-containing material. Isolate. 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).

  Moreover, as a negative electrode material, a metal oxide or a high molecular compound is mentioned, for example. Examples of the metal oxide include iron oxide, ruthenium oxide, and molybdenum oxide. Examples of the polymer compound include polyacetylene, polyaniline, and polypyrrole.

  Of course, the negative electrode material may be other than the above. Further, two or more kinds of the series of negative electrode materials may be mixed in any combination.

  The negative electrode active material layer 22B is formed by, for example, a coating method, a gas phase method, a liquid phase method, a thermal spraying method, a firing method (sintering method), or two or more methods thereof. The application method is, for example, a method in which a particulate negative electrode active material is mixed with a binder and then dispersed in a solvent and applied. Examples of the vapor phase method include a physical deposition method or a chemical deposition method. Specifically, a vacuum deposition method, a sputtering method, an ion plating method, a laser ablation method, a thermal chemical vapor deposition (CVD) method, a plasma chemical vapor deposition method, or the like. Examples of the liquid phase method include an electrolytic plating method and an electroless plating method. The thermal spraying method is a method in which a negative electrode active material is sprayed and deposited in a molten state or a semi-molten state. The baking method is, for example, a method in which heat treatment is performed at a temperature higher than the melting point of a binder or the like after being applied in the same procedure as the application method. A known method can be used for the firing method. As an example, an atmosphere firing method, a reaction firing method, a hot press firing method, or the like can be given.

  The negative electrode active material is, for example, a plurality of particles. That is, the negative electrode active material layer 22B includes a plurality of particulate negative electrode active materials (hereinafter simply referred to as “negative electrode active material particles”). The negative electrode active material particles in the case where a coating method or the like is used as a method of forming the negative electrode active material layer 22B is the particulate negative electrode active material itself used for preparing a slurry for coating. On the other hand, the negative electrode active material particles when vapor phase method or thermal spraying method is used as the method of forming the negative electrode active material layer 22B are evaporated or melted and deposited on the negative electrode current collector 22A. The negative electrode active material.

  When the negative electrode active material particles are formed by a deposition method such as a vapor phase method, the negative electrode active material particles may have a single-layer structure formed by a single deposition process, It may have a multilayer structure formed by the deposition process. However, when using a vapor deposition method with high heat during deposition, the negative electrode active material particles preferably have a multilayer structure. Since the deposition process of the negative electrode material is performed in a plurality of times (the negative electrode material is sequentially formed and deposited thinly), the negative electrode current collector 22A is exposed to higher heat than when the deposition process is performed once. This is because the time to be saved is shortened. As a result, the negative electrode current collector 22A is less susceptible to thermal damage.

  The negative electrode active material particles grow from the surface of the negative electrode current collector 22A in the thickness direction of the negative electrode active material layer 22B, and are preferably connected to the negative electrode current collector 22A at the root. This is because the expansion and contraction of the negative electrode active material layer 22B are suppressed during charging and discharging. The negative electrode active material particles are formed by a vapor phase method, a liquid phase method, a firing method, or the like, and are preferably alloyed at least at a part of the interface with the negative electrode current collector 22A. In this case, the constituent element of the negative electrode current collector 22A may be diffused into the negative electrode active material particles at the interface between them, or the constituent element of the negative electrode active material particles may be diffused into the negative electrode current collector 22A. Alternatively, both constituent elements may be diffused.

  In particular, the negative electrode active material layer 22B includes an oxide-containing film that covers the surface of the negative electrode active material particles (a region that will be in contact with the electrolyte if no oxide-containing film is provided), if necessary. Preferably it is. This is because the oxide-containing film functions as a protective film against the electrolyte, so that the decomposition reaction of the electrolyte is suppressed during charging and discharging. Thereby, cycle characteristics and storage characteristics are improved. The oxide-containing film may cover the entire surface of the negative electrode active material particles, or may cover only a part of the surface, but it is preferable to cover the entire surface. This is because the decomposition reaction of the electrolyte is further suppressed.

  The oxide-containing film includes, for example, at least one of a silicon oxide, a germanium oxide, and a tin oxide, and preferably includes a silicon oxide. This is because the entire surface of the negative electrode active material particles can be easily covered and an excellent protective function can be obtained. Of course, the oxide-containing film may contain an oxide other than the above.

  The oxide-containing film is formed by, for example, a gas phase method or a liquid phase method, and among these, it is preferably formed by a liquid phase method. This is because the surface of the negative electrode active material particles can be easily covered over a wide range. Examples of the liquid phase method include a liquid phase precipitation method, a sol-gel method, a coating method, or a dip coating method. Among these, the liquid phase precipitation method, the sol-gel method, or the dip coating method is preferable, and the liquid phase precipitation method is more preferable. This is because a higher effect can be obtained. Note that the oxide-containing film may be formed by a single formation method among the above-described series of formation methods, or may be formed by two or more types of formation methods.

  Further, the negative electrode active material layer 22B has a metal material containing a metal element that does not alloy with lithium as a constituent element in the gap inside the negative electrode active material layer 22B as necessary (hereinafter simply referred to as “metal material”). It is preferable that it contains. This is because the plurality of negative electrode active material particles are bound via a metal material and the porosity in the negative electrode active material layer 22B is reduced, so that the expansion and contraction of the negative electrode active material layer 22B are suppressed. Thereby, cycle characteristics and storage characteristics are improved. The details of the “gap inside the negative electrode active material layer 22B” will be described later (see FIGS. 5 and 6).

  Examples of the metal element described above include at least one selected from the group consisting of iron, cobalt, nickel, zinc, and copper, and among these, cobalt is preferable. This is because the metal material can easily enter the gap in the negative electrode active material layer 22B and an excellent binding action can be obtained. Of course, the metal element may be a metal element other than the above. However, the “metal material” referred to here is not limited to a simple substance but is a broad concept including an alloy or a metal compound.

  The metal material is formed by, for example, a gas phase method or a liquid phase method, and it is preferable that the metal material is formed by a liquid phase method. This is because the metal material easily enters the gap in the negative electrode active material layer 22B. Examples of the liquid phase method include an electrolytic plating method and an electroless plating method, among which the electrolytic plating method is preferable. This is because the metal material is more likely to enter the gaps and the formation time thereof can be shortened. In addition, the metal material may be formed by a single forming method among the above-described series of forming methods, or may be formed by two or more kinds of forming methods.

  Note that the negative electrode active material layer 22B may include only one of the oxide-containing film and the metal material, or may include both. However, in order to improve the cycle characteristics and the like, it is preferable to include both. In the case where only one of them is included, it is preferable that an oxide-containing film is included in order to further improve cycle characteristics and the like. Note that when both the oxide-containing film and the metal material are included, whichever may be formed first, in order to improve the cycle characteristics and the like, the oxide-containing film may be formed first. preferable.

  Here, the detailed configuration of the negative electrode 22 will be described with reference to FIGS.

  First, the case where the negative electrode active material layer 22B includes an oxide-containing film together with a plurality of negative electrode active material particles will be described. 3 and 4 schematically show a cross-sectional structure of the negative electrode 22. Here, the case where the negative electrode active material particles have a single layer structure is shown.

  In the case shown in FIG. 3, for example, when a negative electrode material is deposited on the negative electrode current collector 22A by a vapor phase method such as a vapor deposition method, a plurality of negative electrode active material particles 221 are formed on the negative electrode current collector 22A. It is formed. In this case, when the surface of the negative electrode current collector 22A is roughened and a plurality of protrusions (for example, fine particles formed by electrolytic treatment) exist on the surface, the negative electrode active material particles 221 are thickened for each protrusion. Grows in the right direction. Therefore, the plurality of negative electrode active material particles 221 are arranged on the negative electrode current collector 22A and connected to the negative electrode current collector 22A at the root thereof. After that, for example, when the oxide-containing film 222 is formed on the surface of the negative electrode active material particles 221 by a liquid phase method such as a liquid phase deposition method, the oxide-containing film 222 is applied to the surface of the negative electrode active material particles 221. Cover almost entirely. In this case, a wide range from the top of the negative electrode active material particle 221 to the root is covered. This wide covering state is a characteristic obtained when the oxide-containing film 222 is formed by a liquid phase method. That is, when the oxide-containing film 222 is formed by using the liquid phase method, the covering action extends not only to the top of the negative electrode active material particles 221 but also to the root, and thus the base is covered with the oxide-containing film 222.

  On the other hand, in the case shown in FIG. 4, for example, after the plurality of negative electrode active material particles 221 are formed by the vapor phase method, the oxide-containing film 223 is similarly formed by the vapor phase method. The oxide-containing film 223 covers only a part (the top part) of the negative electrode active material particles 221. This narrow coverage state is a characteristic obtained when the oxide-containing film 223 is formed by a vapor phase method. That is, when the oxide-containing film 223 is formed using the vapor phase method, the covering action does not reach the root of the negative electrode active material particles 221, but the base is not covered with the oxide-containing film 223.

  3 illustrates the case where the negative electrode active material layer 22B is formed by a vapor phase method, but the negative electrode active material layer 22B may be formed by another forming method such as a coating method or a sintering method. Similar results are obtained. That is, the oxide-containing film 222 is formed so as to cover almost the entire surface of the plurality of negative electrode active material particles.

  Next, the case where the negative electrode active material layer 22B includes a metal material together with a plurality of negative electrode active material particles will be described. 5 and 6 show an enlarged cross-sectional structure of the negative electrode 22. 5 and 6, (A) is a scanning electron microscope (SEM) photograph (secondary electron image), and (B) is a schematic picture of the SEM image shown in (A). Here, a case where a plurality of negative electrode active material particles 221 have a multilayer structure is shown.

  As shown in FIG. 5, when the negative electrode active material particles 221 have a multilayer structure, a plurality of gaps 224 are generated inside the negative electrode active material layer 22B due to the arrangement structure, the multilayer structure, and the surface structure. ing. The gap 224 mainly includes two types of gaps 224A and 224B classified according to the cause of occurrence. The gap 224 </ b> A is generated between the negative electrode active material particles 221, and the gap 224 </ b> B is generated between the layers in the negative electrode active material particles 221. However, there may be a gap 224 caused by another cause.

  Note that a void 225 may be formed on the exposed surface (outermost surface) of the negative electrode active material particles 221. The voids 225 are generated between the protrusions because fine whisker-like protrusions (not shown) are formed on the surface of the negative electrode active material particles 221. The void 225 may be generated over the entire exposed surface of the negative electrode active material particles 221 or may be generated only in part. However, since the whisker-like protrusions are generated on the surface every time the negative electrode active material particles 221 are formed, the voids 225 may be generated not only between the exposed surfaces of the negative electrode active material particles 221 but also between the layers. .

  As shown in FIG. 6, the negative electrode active material layer 22B has a metal material 226 in the gaps 224A and 224B. In this case, the metal material 226 may be provided in only one of the gaps 224A and 224B, but it is preferable that the metal material 226 is provided in both of them. This is because a higher effect can be obtained.

  The metal material 226 enters the gap 224 </ b> A between the negative electrode active material particles 221. Specifically, when the negative electrode active material particles 221 are formed by a vapor phase method or the like, as described above, the negative electrode active material particles 221 grow for each protrusion existing on the surface of the negative electrode current collector 22A. A gap 224A is generated between the negative electrode active material particles 221. Since the gap 224A causes a decrease in the binding property of the negative electrode active material layer 22B, a metal material 226 is embedded in the gap 224A in order to improve the binding property. In this case, it is sufficient that a part of the gap 224A is filled, but the larger the filling amount, the better. This is because the binding property of the negative electrode active material layer 22B is further improved. The filling amount (filling amount) of the metal material 226 is preferably 20% or more, more preferably 40% or more, and further preferably 80% or more.

  In addition, the metal material 226 enters the gap 224 </ b> B in the negative electrode active material particles 221. Specifically, when the negative electrode active material particles 221 have a multilayer structure, a gap 224B is generated between the layers. Like the gap 224A, the gap 224B causes a decrease in the binding property of the negative electrode active material layer 22B. Therefore, in order to improve the binding property, the metal material 226 is embedded in the gap 224B. In this case, it is sufficient that a part of the gap 224B is buried, but it is preferable that the amount of filling is large. This is because the binding property of the negative electrode active material layer 22B is further improved.

  Note that the negative electrode active material layer 22B is provided in order to prevent negative whisker-like protrusions (not shown) generated on the exposed surface of the uppermost negative electrode active material particles 221 from adversely affecting the performance of the secondary battery. A metal material 226 may be provided in the gap 225. Specifically, when the negative electrode active material particles 221 are formed by a vapor phase method or the like, fine whisker-like protrusions are formed on the surface thereof, and voids 225 are generated between the protrusions. The voids 225 increase the surface area of the negative electrode active material particles 221 and increase the amount of irreversible film formed on the surface of the negative electrode active material particles 221, which may cause a reduction in the progress of the charge / discharge reaction. . Therefore, a metal material 226 is embedded in the gap 225 in order to suppress a decrease in the progress of the charge / discharge reaction. In this case, it is sufficient that a part of the gap 225 is buried, but the larger the amount of filling, the better. This is because the progress of the charge / discharge reaction can be further suppressed. In FIG. 6, the fact that the metal material 226 is scattered on the surface of the uppermost negative electrode active material particle 221 indicates that the above-described fine protrusions are present at the spot. Of course, the metal material 226 does not necessarily have to be scattered on the surface of the negative electrode active material particle 221, and may cover the entire surface.

  In particular, the metal material 226 that has entered the gap 224B also functions to fill the gap 225 in each layer. Specifically, when the negative electrode material is deposited a plurality of times, a fine protrusion is generated on the surface of the negative electrode active material particle 221 for each deposition. For this reason, the metal material 226 is not only embedded in the gap 224B in each layer, but also embedded in the gap 225 in each layer.

  5 and 6, the case where the negative electrode active material particles 221 have a multilayer structure and the gaps 224A and 224B exist in the negative electrode active material layer 22B has been described. For this reason, the negative electrode active material layer 22B has the metal material 226 in the gaps 224A and 224B. On the other hand, when the negative electrode active material particles 221 have a single layer structure and only the gap 224A exists in the negative electrode active material layer 22B, the negative electrode active material layer 22B has a metal material only in the gap 224A. 226. Of course, since the gap 225 is generated in both cases, the gap 225 has the metal material 226 in either case.

[Detailed configuration of wound electrode body]
Next, a detailed configuration of the wound electrode body 20 will be described with reference to FIGS. 7 and 8. FIG. 7 schematically illustrates a planar configuration of the positive electrode 21 and the negative electrode 22, and FIG. 8 illustrates an enlarged part of the spirally wound electrode body 20 illustrated in FIG. In FIG. 7, the formation range of the positive electrode active material layer 21B and the negative electrode active material layer 22B is shaded.

  In the positive electrode 21, the positive electrode active material layer 21 </ b> B is provided, for example, in a partial region on the strip-shaped positive electrode current collector 21 </ b> A. Here, the positive electrode active material layer 21B is provided, for example, in a central region in the longitudinal direction (winding direction) of the positive electrode current collector 21A. As a result, the central portion of the positive electrode current collector 21A is covered with the positive electrode active material layer 21B, whereas both end portions are exposed. This is because a space for attaching the positive electrode lead 25 is secured and the heat dissipation of the positive electrode 21 is enhanced.

  On the other hand, in the negative electrode 22, the negative electrode active material layer 22B includes, for example, a region on the strip-shaped negative electrode current collector 22A that faces the positive electrode active material layer 21B and a region that does not face the region (region that faces the positive electrode current collector 21A). ). The negative electrode active material layer 22B may be provided in the entire region or a part of the region on the negative electrode current collector 22A facing the positive electrode current collector 21A. Good. However, in order to secure a space for attaching the negative electrode lead 26 and improve the heat dissipation of the negative electrode 22, the negative electrode active material layer 22 </ b> B is preferably provided in a partial region. Here, the negative electrode active material layer 22B is provided, for example, in a central region in the longitudinal direction (winding direction) of the negative electrode current collector 22A. Thereby, while the center part of 22 A of negative electrode collectors is coat | covered with the negative electrode active material layer 22B, both ends are exposed.

  That is, the negative electrode active material layer 22B is not provided in the region R3 located at both ends on the negative electrode current collector 22A, but is provided in the regions R1 and R2 located in the center. This is to prevent unintentional precipitation of lithium metal due to current concentration at both ends of the negative electrode active material layer 22B. Thereby, an internal short circuit becomes difficult to occur. This region R2 is a region where the positive electrode current collector 21A and the negative electrode active material layer 22B face each other.

  An insulating member 28 is disposed at least in the region R2. The insulating member 28 serves to suppress the local increase in the potential of the positive electrode 21 in the region R2. In the region R1 where the positive electrode active material layer 21B and the negative electrode active material layer 22B face each other, when lithium ions are occluded in the negative electrode active material layer 22B during charging, the potential of the negative electrode active material layer 22B becomes low. . On the other hand, in the region R2 where the positive electrode current collector 21A and the negative electrode active material layer 22B face each other, lithium ions are not occluded in the negative electrode active material layer 22B. Therefore, the potential of the negative electrode active material layer 22B is It becomes higher in the region R2 than in the region R1. Accordingly, the potential of the positive electrode active material layer 21B also becomes higher in the region R2 than in the region R1. In order to suppress a local potential increase of the positive electrode active material layer 21B in the region R2, an insulating member 28 is provided.

  Here, let us consider a case where the insulating member 28 is not disposed on the assumption that the carbon material is used as the negative electrode active material and the battery is charged until the battery voltage becomes 4.2V. In this case, the lithium metal potential of the negative electrode active material layer 22B in the region R1 is about 0.05V, and the lithium metal potential of the positive electrode active material layer 21B is about 4.25V. On the other hand, the lithium metal potential of the negative electrode active material layer 22B in the region R2 is about 0.4 V to 2 V, and the lithium metal potential of the positive electrode active material layer 21B is about 4.6 V to 6.2 V. . As a result, metal pieces or metal scraps in the battery are easily dissolved, and they are liable to precipitate again at the time of potential fluctuation, which may cause an internal short circuit. The metal pieces are those that have been peeled off from the battery container 11, and the metal scraps are those that are generated when the positive electrode lead 25 or the negative electrode lead 26 is attached.

The constituent material of the insulating member 28 may be any material as long as it can electrically insulate between the positive electrode current collector 21A and the negative electrode active material layer 22B. Among them, those capable of inhibiting or blocking ion migration are preferable, and those having an air permeability specified in JIS P8117 of 5000 s / 100 cm ³ or more are more preferable. Examples of the constituent material of the insulating member 28 include synthetic resins such as polyethylene, polypropylene, polyimide, or polyethylene terephthalate. However, the constituent material of the insulating member 28 may be other.

  The insulating member 28 may be provided on the positive electrode 21 or on the negative electrode 22 as long as it can electrically insulate between the positive electrode current collector 21A and the negative electrode active material layer 22B. It may be provided on both sides. In FIG. 8, for example, a case where the insulating member 28 is provided on the positive electrode 22 is illustrated. In this case, the insulating member 28 may be attached via an adhesive or the like, or may be heat-sealed. Of course, the insulating member 28 may be fixed by other methods.

  The arrangement range of the insulating member 28 can be arbitrarily set as long as it exists in at least the region R2. For example, FIG. 8 shows a case where the arrangement range of the insulating member 28 is extended to the regions R1 and R3. In this case, the central portion of the insulating member 28 covers the positive electrode current collector 21A in the region R2. One end portion of the insulating member 28 covers the positive electrode active material layer 21B in the region R1, and the other end portion covers the positive electrode current collector 21A in the region R3.

[Separator]
The separator 23 separates the positive electrode 21 and the negative electrode 22 and allows lithium ions to pass through while preventing a short circuit of current due to contact between the two electrodes. The separator 23 is made of, for example, a porous film made of synthetic resin or ceramic, and may be a laminate of two or more porous films. The synthetic resin is, for example, polytetrafluoroethylene, polypropylene, or polyethylene.

[Electrolytes]
The separator 23 is impregnated with an electrolytic solution that is a liquid electrolyte. This electrolytic solution is obtained by dissolving an electrolyte salt in a solvent, and may contain other materials such as various additives as necessary.

  The solvent contains at least one of the sulfone compounds represented by formula (1) and formula (2) (hereinafter simply referred to as “sulfone compound”). This is because the chemical stability of the electrolytic solution is improved. Moreover, it is because a stable film is formed on the surface of the positive electrode 21 or the negative electrode 22 even in a high temperature environment during charging and discharging. Thereby, the decomposition reaction of electrolyte solution is suppressed at the time of charging / discharging.

（Ｒ１１およびＲ１２はアルキル基、アリール基、ハロゲン化アルキル基あるいはハロゲン化アリール基である。Ｘ１は−Ｓ（＝Ｏ）₂ −、−Ｓ（＝Ｏ）₂ −Ｏ−、−Ｏ−Ｓ（＝Ｏ）₂ −Ｏ−、−Ｓ（＝Ｏ）₂ −Ｏ−Ｓ（＝Ｏ）₂ −あるいは−Ｓ（＝Ｏ）₂ −Ｏ−Ｃ（＝Ｏ）−である。ｎ１は１以上４以下の整数である。）

(R11 and R12 are an alkyl group, an aryl group, a halogenated alkyl group or a halogenated aryl group. X1 represents —S (═O) ₂ —, —S (═O) ₂ —O—, —O—S ( ═O) ₂ —O—, —S (═O) ₂ —O—S (═O) ₂ — or —S (═O) ₂ —O—C (═O) —, where n1 is 1 or more and 4 The following integers.)

（Ｒ１３はアルキレン基、アリーレン基、ハロゲン化アルキレン基あるいはハロゲン化アリーレン基である。Ｘ２は−Ｓ（＝Ｏ）₂ −、−Ｓ（＝Ｏ）₂ −Ｏ−、−Ｏ−Ｓ（＝Ｏ）₂ −Ｏ−、−Ｓ（＝Ｏ）₂ −Ｏ−Ｓ（＝Ｏ）₂ −あるいは−Ｓ（＝Ｏ）₂ −Ｏ−Ｃ（＝Ｏ）−である。ｎ２は１以上４以下の整数である。）

(R13 is an alkylene group, an arylene group, a halogenated alkylene group or a halogenated arylene group. X2 is —S (═O) ₂ —, —S (═O) ₂ —O—, —O—S (═O ) ₂ —O—, —S (═O) ₂ —O—S (═O) ₂ — or —S (═O) ₂ —O—C (═O) —, where n2 is 1 or more and 4 or less. (It is an integer.)

  The sulfone compound represented by the formula (1) is a chain compound having X1 as a site containing a sulfonyl group. R11 and R12 may be the same type of group or different types of groups. R11 and R12 may be a derivative such as an alkyl group described above (a group in which one or two or more substituents are introduced into an alkyl group or the like). The “halogenated alkyl group or halogenated aryl group” is a group in which at least a part of hydrogen in the alkyl group or aryl group is substituted with halogen. The type of halogen is not particularly limited, but among these, fluorine (F) is preferable. This is because the stability of the coating becomes higher. n1 is not particularly limited as long as it is 1 to 4, but 1 is particularly preferable. This is because excellent solubility and compatibility can be obtained.

  The sulfone compound represented by the formula (2) is a cyclic compound having X2 as a site containing a sulfonyl group. R13 may be a derivative such as the above-described alkylene group (a group in which one or more substituents are introduced into the alkylene group or the like). The “halogenated alkylene group or halogenated arylene group” is a group in which at least a part of hydrogen in the alkylene group or arylene group is substituted with halogen. In addition, the kind of halogen and the appropriate value of n2 are the same as the case where the sulfone compound (n1) shown in Formula (1) is demonstrated.

  Especially, it is preferable that a sulfone compound is what is represented by Formula (3) or Formula (4). This is because a stable film can be formed and excellent solubility and compatibility can be obtained. Moreover, it is because it can obtain easily.

（Ｙ１は炭素数＝２〜４のアルキレン基あるいはハロゲン化アルキレン基、炭素数＝２〜４のアルケニレン基あるいはハロゲン化アルケニレン基、アリーレン基あるいはハロゲン化アリーレン基、またはそれらの誘導体である。）

(Y1 is an alkylene group or halogenated alkylene group having 2 to 4 carbon atoms, an alkenylene group or halogenated alkenylene group having 2 to 4 carbon atoms, an arylene group or a halogenated arylene group, or a derivative thereof.)

（Ｙ２は炭素数＝２〜４のアルキレン基あるいはハロゲン化アルキレン基、炭素数＝２〜４のアルケニレン基あるいはハロゲン化アルケニレン基、アリーレン基あるいはハロゲン化アリーレン基、またはそれらの誘導体である。）

(Y2 is an alkylene group or halogenated alkylene group having 2 to 4 carbon atoms, an alkenylene group or halogenated alkenylene group having 2 to 4 carbon atoms, an arylene group or a halogenated arylene group, or a derivative thereof.)

The sulfone compound represented by formula (3) is a cyclic compound having —S (═O) ₂ —O—S (═O) ₂ — as the moiety (X2) containing a sulfonyl group. The sulfone compound represented by Formula (4) is a cyclic compound having —S (═O) ₂ —O—C (═O) — as the moiety (X2) containing a sulfonyl group. The reason why Y1 or Y2 has 2 to 4 carbon atoms is that better solubility and compatibility than the case where the number of carbon atoms is 5 or more can be obtained. Y1 and Y2 may be a derivative such as the above-described alkylene group (a group in which one or two or more substituents are introduced into the alkylene group or the like).

  Examples of such sulfone compounds include those represented by formula (3-1) to formula (3-22) or formula (4-1) to formula (4-20). These sulfone compounds also include geometric isomers.

  Among these, the compounds shown in Formula (3-1), Formula (3-2), Formula (3-22), Formula (4-1), Formula (4-16), or Formula (4-17) are preferable. This is because it can be easily obtained and a high effect can be obtained.

  However, as long as the sulfone compound has the structure shown in Formula (1) or Formula (2), Formula (3) or Formula (4) (Formula (3-1) to Formula (3-22) is not necessarily used. Or it is not restricted to what was shown to Formula (4-1)-Formula (4-20)), Other things may be sufficient.

  The content of the sulfone compound in the solvent is not particularly limited. The content of the sulfone compound can be arbitrarily set according to conditions such as the type of the negative electrode active material. For example, when the negative electrode 22 includes a carbon material as a negative electrode active material, the content of the sulfone compound in the solvent is preferably 0.001% by mass to 5% by mass, and 0.005% by mass. More preferably, it is -3 mass%. Moreover, when the negative electrode 22 contains a metal-type material as a negative electrode active material, it is preferable that content of the sulfone compound in a solvent is 0.1 mass%-5 mass%, and 0.5 mass%-3 More preferably, it is mass%. This is because the decomposition reaction of the electrolyte is sufficiently suppressed during charging and discharging.

  The solvent may contain other materials as long as it contains the above-described sulfone compound. Examples of such other materials include any one or more of a series of materials described below (excluding those corresponding to sulfone compounds).

  The solvent includes, for example, a nonaqueous solvent such as an organic solvent. Examples of the non-aqueous solvent include the following. Ethylene carbonate, propylene carbonate, butylene carbonate, dimethyl carbonate, diethyl carbonate, ethyl methyl carbonate, methyl propyl carbonate, γ-butyrolactone, γ-valerolactone, 1,2-dimethoxyethane or tetrahydrofuran. Also, 2-methyltetrahydrofuran, tetrahydropyran, 1,3-dioxolane, 4-methyl-1,3-dioxolane, 1,3-dioxane, or 1,4-dioxane. Further, methyl acetate, ethyl acetate, methyl propionate, ethyl propionate, methyl butyrate, methyl isobutyrate, methyl trimethyl acetate or ethyl trimethyl acetate. Acetonitrile, glutaronitrile, adiponitrile, methoxyacetonitrile, 3-methoxypropionitrile, N, N-dimethylformamide, N-methylpyrrolidinone or N-methyloxazolidinone. Further, N, N'-dimethylimidazolidinone, nitromethane, nitroethane, sulfolane, trimethyl phosphate or dimethyl sulfoxide. This is because excellent battery capacity, cycle characteristics, storage characteristics, and the like can be obtained.

  Among these, at least one of ethylene carbonate, propylene carbonate, dimethyl carbonate, diethyl carbonate, and ethyl methyl carbonate is preferable. This is because excellent battery capacity, cycle characteristics, storage characteristics, and the like can be obtained. In this case, a high viscosity (high dielectric constant) solvent such as ethylene carbonate or propylene carbonate (for example, a relative dielectric constant ε ≧ 30) and a low viscosity solvent such as dimethyl carbonate, ethyl methyl carbonate or diethyl carbonate (for example, viscosity ≦ 1 mPas). -A combination with s) is more preferred. This is because the dissociation property of the electrolyte salt and the ion mobility are improved.

  In particular, the solvent preferably contains at least one of unsaturated carbon-bonded cyclic carbonates (cyclic carbonates having an unsaturated bond) represented by formulas (5) to (7). This is because a stable protective film is formed on the surface of the positive electrode 21 or the negative electrode 22 during charging / discharging, so that the decomposition reaction of the electrolytic solution is suppressed. This unsaturated carbon-bonded cyclic carbonate includes geometric isomers. Content of unsaturated carbon bond cyclic carbonate in a solvent is 0.01 mass%-10 mass%, for example. However, the type of unsaturated carbon bond cyclic ester carbonate is not necessarily limited to the one described below as long as it has the structure shown in Formula (5) to Formula (7), and other types may be used.

（Ｒ２１およびＲ２２は水素基あるいはアルキル基である。）

(R21 and R22 are a hydrogen group or an alkyl group.)

（Ｒ２３〜Ｒ２６は水素基、アルキル基、ビニル基あるいはアリル基であり、それらのうちの少なくとも１つはビニル基あるいはアリル基である。）

(R23 to R26 are a hydrogen group, an alkyl group, a vinyl group, or an allyl group, and at least one of them is a vinyl group or an allyl group.)

（Ｒ２７はアルキレン基である。）

(R27 is an alkylene group.)

  The unsaturated carbon bond cyclic carbonate represented by the formula (5) is a vinylene carbonate compound. Examples of the vinylene carbonate-based compound include the following. Vinylene carbonate (1,3-dioxol-2-one), methyl vinylene carbonate (4-methyl-1,3-dioxol-2-one) or ethyl vinylene carbonate (4-ethyl-1,3-dioxol-2-one) ). 4,5-dimethyl-1,3-dioxol-2-one, 4,5-diethyl-1,3-dioxol-2-one, 4-fluoro-1,3-dioxol-2-one or 4- Trifluoromethyl-1,3-dioxol-2-one. Among these, vinylene carbonate is preferable. This is because it is easily available and a high effect can be obtained.

  The unsaturated carbon bond cyclic carbonate shown in Formula (6) is a vinyl ethylene carbonate compound. Examples of the vinyl carbonate-based compound include the following. Vinyl ethylene carbonate (4-vinyl-1,3-dioxolan-2-one), 4-methyl-4-vinyl-1,3-dioxolan-2-one or 4-ethyl-4-vinyl-1,3-dioxolane -2-one. Further, 4-n-propyl-4-vinyl-1,3-dioxolan-2-one, 5-methyl-4-vinyl-1,3-dioxolan-2-one, 4,4-divinyl-1,3- Dioxolan-2-one or 4,5-divinyl-1,3-dioxolan-2-one. Of these, vinyl ethylene carbonate is preferred. This is because it is easily available and a high effect can be obtained. Of course, as R23 to R26, all may be vinyl groups, all may be allyl groups, or vinyl groups and allyl groups may be mixed.

  The unsaturated carbon bond cyclic carbonate represented by the formula (7) is a methylene ethylene carbonate compound. Examples of the methylene ethylene carbonate compound include the following. 4-methylene-1,3-dioxolan-2-one, 4,4-dimethyl-5-methylene-1,3-dioxolan-2-one or 4,4-diethyl-5-methylene-1,3-dioxolane- 2-one. As this methylene ethylene carbonate compound, one having two methylene groups may be used in addition to one having one methylene group (compound shown in Formula (7)).

  In addition, as unsaturated carbon bond cyclic carbonate ester, the catechol carbonate (catechol carbonate) etc. which have a benzene ring other than what was shown to Formula (5)-Formula (7) may be sufficient.

  Moreover, it is preferable that the solvent contains at least 1 sort (s) of the halogenated chain carbonate represented by Formula (8) and the halogenated cyclic carbonate represented by Formula (9). This is because a stable protective film is formed on the surface of the negative electrode 22 at the time of charge and discharge, so that the decomposition reaction of the electrolytic solution is suppressed. “Halogenated chain carbonate ester” is a chain carbonate ester containing halogen as a constituent element, and “halogenated cyclic carbonate ester” is a cyclic carbonate ester containing halogen as a constituent element. This halogenated cyclic carbonate includes geometric isomers. In addition, the same kind of group may be sufficient as R31-R36 in Formula (8), and a different kind of group may be sufficient as it. The same applies to R37 to R40 in the formula (9). The content of the halogenated chain carbonate and the halogenated cyclic carbonate in the solvent is, for example, 0.1% by mass to 80% by mass. However, the types of the halogenated chain carbonate and the halogenated cyclic carbonate are not necessarily limited to those described below as long as they have the structures shown in Formula (8) and Formula (9). It may be a thing.

（Ｒ３１〜Ｒ３６は水素基、ハロゲン基、アルキル基あるいはハロゲン化アルキル基であり、それらのうちの少なくとも１つはハロゲン基あるいはハロゲン化アルキル基である。）

(R31 to R36 are a hydrogen group, a halogen group, an alkyl group or a halogenated alkyl group, and at least one of them is a halogen group or a halogenated alkyl group.)

（Ｒ３７〜Ｒ４０は水素基、ハロゲン基、アルキル基あるいはハロゲン化アルキル基であり、それらのうちの少なくとも１つはハロゲン基あるいはハロゲン化アルキル基である。）

(R37 to R40 are a hydrogen group, a halogen group, an alkyl group or a halogenated alkyl group, and at least one of them is a halogen group or a halogenated alkyl group.)

  The type of halogen is not particularly limited, but among them, fluorine, chlorine (Cl) or bromine (Br) is preferable, and fluorine is more preferable. This is because an effect higher than that of other halogens can be obtained. However, the number of halogens is preferably two rather than one, and may be three or more. This is because the ability to form a protective film is increased and a stronger and more stable protective film is formed, so that the decomposition reaction of the electrolytic solution is further suppressed.

  Examples of the halogenated chain carbonate include fluoromethyl methyl carbonate, bis (fluoromethyl) carbonate, difluoromethyl methyl carbonate, and the like.

  Examples of the halogenated cyclic carbonate include those represented by formula (9-1) to formula (9-21). Among them, 4-fluoro-1,3-dioxolan-2-one represented by the formula (9-1) or 4,5-difluoro-1,3-dioxolan-2-one represented by the formula (9-3) is preferable. The latter is preferred and the latter is more preferred. In particular, 4,5-difluoro-1,3-dioxolan-2-one is preferably a trans isomer rather than a cis isomer. This is because it is easily available and a high effect can be obtained.

  Moreover, it is preferable that the solvent contains sultone (cyclic sulfonate ester). This is because the chemical stability of the electrolytic solution is further improved. Examples of sultone include propane sultone and propene sultone. The sultone content in the solvent is, for example, 0.5% by mass to 5% by mass.

  Furthermore, it is preferable that the solvent contains an acid anhydride (excluding those corresponding to the above sulfone compounds). This is because the chemical stability of the electrolytic solution is further improved. Examples of the acid anhydride include carboxylic acid anhydrides such as succinic anhydride, glutaric anhydride, and maleic anhydride. The content of the acid anhydride in the solvent is, for example, 0.5% by mass to 5% by mass.

  The electrolyte salt includes, for example, any one or more of light metal salts such as lithium salts. The series of electrolyte salts described below may be used alone or in combination of two or more.

Examples of the lithium salt include the following. Lithium hexafluorophosphate, lithium tetrafluoroborate, lithium perchlorate or lithium hexafluoroarsenate. Further, lithium tetraphenylborate (LiB (C ₆ H ₅ ) ₄ ), lithium methanesulfonate (LiCH ₃ SO ₃ ), lithium trifluoromethanesulfonate (LiCF ₃ SO ₃ ) or lithium tetrachloroaluminate (LiAlCl ₄ ) It is. Further, dilithium hexafluorosilicate (Li ₂ SiF ₆ ), lithium chloride (LiCl) or lithium bromide (LiBr). This is because excellent battery capacity, cycle characteristics, storage characteristics, and the like can be obtained.

  Among these, at least one of lithium hexafluorophosphate, lithium tetrafluoroborate, lithium perchlorate, and lithium hexafluoroarsenate is preferable, and lithium hexafluorophosphate is more preferable. This is because a higher effect can be obtained because the internal resistance is lowered. Note that lithium tetrafluoroborate is preferable in order to further suppress the local increase in the potential of the positive electrode 21 in the region R2.

  In particular, the electrolyte salt preferably contains at least one of the compounds represented by the formulas (10) to (12). This is because a higher effect can be obtained. In this case, in particular, it is possible to further suppress the local increase in the potential of the positive electrode 21 in the region R2. In addition, R51 and R53 in the formula (10) may be the same type of group or different types of groups. The same applies to R61 to R63 in formula (11) and R71 and R72 in formula (12).

（Ｘ５１は短周期型周期表における１Ａ族元素あるいは２Ａ族元素、またはアルミニウムである。Ｍ５１は遷移金属、または短周期型周期表における３Ｂ族元素、４Ｂ族元素あるいは５Ｂ族元素である。Ｒ５１はハロゲン基である。Ｙ５１は−Ｃ（＝Ｏ）−Ｒ５２−Ｃ（＝Ｏ）−、−Ｃ（＝Ｏ）−ＣＲ５３₂ −あるいは−Ｃ（＝Ｏ）−Ｃ（＝Ｏ）−である。ただし、Ｒ５２はアルキレン基、ハロゲン化アルキレン基、アリーレン基あるいはハロゲン化アリーレン基である。Ｒ５３はアルキル基、ハロゲン化アルキル基、アリール基あるいはハロゲン化アリール基である。なお、ａ５は１〜４の整数であり、ｂ５は０、２あるいは４の整数であり、ｃ５、ｄ５、ｍ５およびｎ５は１〜３の整数である。）

(X51 is a 1A group element or 2A group element or aluminum in the short period type periodic table. M51 is a transition metal, or a 3B group element, 4B group element or 5B group element in the short period type periodic table. R51 is R51. Y51 is —C (═O) —R52—C (═O) —, —C (═O) —CR53 ₂ — or —C (═O) —C (═O) —. R52 is an alkylene group, a halogenated alkylene group, an arylene group or a halogenated arylene group, R53 is an alkyl group, a halogenated alkyl group, an aryl group or a halogenated aryl group, and a5 is 1 to 4. (It is an integer, b5 is an integer of 0, 2 or 4, and c5, d5, m5 and n5 are integers of 1 to 3.)

（Ｘ６１は短周期型周期表における１Ａ族元素あるいは２Ａ族元素である。Ｍ６１は遷移金属、または短周期型周期表における３Ｂ族元素、４Ｂ族元素あるいは５Ｂ族元素である。Ｙ６１は−Ｃ（＝Ｏ）−（ＣＲ６１₂ ）_b6−Ｃ（＝Ｏ）−、−Ｒ６３₂ Ｃ−（ＣＲ６２₂ ）_c6−Ｃ（＝Ｏ）−、−Ｒ６３₂ Ｃ−（ＣＲ６２₂ ）_c6−ＣＲ６３₂ −、−Ｒ６３₂ Ｃ−（ＣＲ６２₂ ）_c6−Ｓ（＝Ｏ）₂ −、−Ｓ（＝Ｏ）₂ −（ＣＲ６２₂ ）_d6−Ｓ（＝Ｏ）₂ −あるいは−Ｃ（＝Ｏ）−（ＣＲ６２₂ ）_d6−Ｓ（＝Ｏ）₂ −である。ただし、Ｒ６１およびＲ６３は水素基、アルキル基、ハロゲン基あるいはハロゲン化アルキル基であり、それぞれのうちの少なくとも１つはハロゲン基あるいはハロゲン化アルキル基である。Ｒ６２は水素基、アルキル基、ハロゲン基あるいはハロゲン化アルキル基である。なお、ａ６、ｅ６およびｎ６は１あるいは２の整数であり、ｂ６およびｄ６は１〜４の整数であり、ｃ６は０〜４の整数であり、ｆ６およびｍ６は１〜３の整数である。）

(X61 is a group 1A element or a group 2A element in the short period type periodic table. M61 is a transition metal, or a group 3B element, a group 4B element or a group 5B element in the short period type periodic table. Y61 is -C ( _{= O) - (CR61 2)} b6 -C (= O) -, - R63 2 C- (CR62 2) c6 -C (= O) -, - R63 2 C- (CR62 2) c6 -CR63 2 -, _{-R63 2 C- (CR62 2) c6} -S (= O) 2 -, - S (= O) 2 - (CR62 2) d6 -S (= O) 2 - or -C (= O) - (CR62 ₂ ) _d6 —S (═O) ₂ —, wherein R61 and R63 are a hydrogen group, an alkyl group, a halogen group or a halogenated alkyl group, and at least one of each is a halogen group or a halogenated alkyl group. R62 is a hydrogen group, alkyl A6, e6 and n6 are integers of 1 or 2, b6 and d6 are integers of 1 to 4, c6 is an integer of 0 to 4, and f6 is a halogen group or a halogenated alkyl group. And m6 is an integer of 1 to 3.)

（Ｘ７１は短周期型周期表における１Ａ族元素あるいは２Ａ族元素である。Ｍ７１は遷移金属、または短周期型周期表における３Ｂ族元素、４Ｂ族元素あるいは５Ｂ族元素である。Ｒｆはフッ素化アルキル基あるいはフッ素化アリール基であり、いずれの炭素数も１〜１０である。Ｙ７１は−Ｃ（＝Ｏ）−（ＣＲ７１₂ ）_d7−Ｃ（＝Ｏ）−、−Ｒ７２₂ Ｃ−（ＣＲ７１₂ ）_d7−Ｃ（＝Ｏ）−、−Ｒ７２₂ Ｃ−（ＣＲ７１₂ ）_d7−ＣＲ７２₂ −、−Ｒ７２₂ Ｃ−（ＣＲ７１₂ ）_d7−Ｓ（＝Ｏ）₂ −、−Ｓ（＝Ｏ）₂ −（ＣＲ７１₂ ）_e7−Ｓ（＝Ｏ）₂ −あるいは−Ｃ（＝Ｏ）−（ＣＲ７１₂ ）_e7−Ｓ（＝Ｏ）₂ −である。ただし、Ｒ７１は水素基、アルキル基、ハロゲン基あるいはハロゲン化アルキル基である。Ｒ７２は水素基、アルキル基、ハロゲン基あるいはハロゲン化アルキル基であり、そのうちの少なくとも１つはハロゲン基あるいはハロゲン化アルキル基である。なお、ａ７、ｆ７およびｎ７は１あるいは２の整数であり、ｂ７、ｃ７およびｅ７は１〜４の整数であり、ｄ７は０〜４の整数であり、ｇ７およびｍ７は１〜３の整数である。）

(X71 is a group 1A element or a group 2A element in the short period type periodic table. M71 is a transition metal, or a group 3B element, a group 4B element, or a group 5B element in the short period type periodic table. Rf is a fluorinated alkyl. Or a fluorinated aryl group, each having 1 to 10 carbon atoms, Y71 is —C (═O) — (CR71 ₂ ) _d7 —C (═O) —, —R72 ₂ C— (CR71 _{2 D7} -C (= O)-, -R72 ₂ C- (CR71 ₂ ) _d7 -CR72 _2- , -R72 ₂ C- (CR71 ₂ ) _d7 -S (= O) _2-, -S (= O) ₂ — (CR71 ₂ ) _e7 —S (═O) ₂ — or —C (═O) — (CR71 ₂ ) _e7 —S (═O) ₂ —, wherein R71 is a hydrogen group, alkyl group, halogen R72 represents a hydrogen group or an alkyl group. A halogen group or a halogenated alkyl group, at least one of which is a halogen group or a halogenated alkyl group, wherein a7, f7 and n7 are integers of 1 or 2, and b7, c7 and e7 are 1 And d7 is an integer of 0 to 4, and g7 and m7 are integers of 1 to 3.)

  Group 1 elements are hydrogen, lithium, sodium, potassium, rubidium, cesium, and francium. Group 2 elements are beryllium, magnesium, calcium, strontium, barium and radium. Group 13 elements are boron, aluminum, gallium, indium and thallium. Group 14 elements are carbon, silicon, germanium, tin and lead. Group 15 elements are nitrogen, phosphorus, arsenic, antimony and bismuth.

  Examples of the compound represented by the formula (10) include compounds represented by the formula (10-1) to the formula (10-6). Examples of the compound represented by Formula (11) include compounds represented by Formula (11-1) to Formula (11-8). Examples of the compound represented by the formula (12) include a compound represented by the formula (12-1). Needless to say, the compound is not limited to the above-described compound as long as it has a structure represented by Formula (10) to Formula (12).

  Moreover, it is preferable that electrolyte salt contains at least 1 sort (s) of the compounds represented by Formula (13)-Formula (15). This is because a higher effect can be obtained. In addition, m and n in Formula (13) may be the same or different. The same applies to p, q and r in the formula (15).

_{LiN (C m F 2m + 1} SO 2) (C n F 2n + 1 SO 2) ... (13)
(M and n are integers of 1 or more.)

（Ｒ８１は炭素数が２以上４以下の直鎖状あるいは分岐状のパーフルオロアルキレン基である。）

(R81 is a linear or branched perfluoroalkylene group having 2 to 4 carbon atoms.)

_{LiC (C p F 2p + 1} SO 2) (C q F 2q + 1 SO 2) (C r F 2r + 1 SO 2) ... (15)
(P, q and r are integers of 1 or more.)

The compound represented by the formula (13) is a chain imide compound, and examples of such a compound include the following. Bis (trifluoromethanesulfonyl) imide lithium (LiN (CF ₃ SO ₂ ) ₂ ) or bis (pentafluoroethanesulfonyl) imide lithium (LiN (C ₂ F ₅ SO ₂ ) ₂ ). Further, it is (trifluoromethanesulfonyl) (pentafluoroethanesulfonyl) imidolithium (LiN (CF ₃ SO ₂ ) (C ₂ F ₅ SO ₂ )). Further, it is (trifluoromethanesulfonyl) (heptafluoropropanesulfonyl) imidolithium (LiN (CF ₃ SO ₂ ) (C ₃ F ₇ SO ₂ )). Further, (trifluoromethanesulfonyl) (nonafluorobutanesulfonyl) imidolithium (LiN (CF ₃ SO ₂ ) (C ₄ F ₉ SO ₂ )).

  The compound represented by Formula (14) is a cyclic imide compound, and examples of such a compound include compounds represented by Formula (14-1) to Formula (14-4).

The compound represented by the formula (15) is a chain methide compound, and examples of such a compound include lithium tris (trifluoromethanesulfonyl) methide (LiC (CF ₃ SO ₂ ) ₃ ).

The content of the electrolyte salt is preferably 0.3 mol / kg to 3.0 mol / kg, or 0.3 mol / dm ^{3 to} 3.0 mol / dm ³ with respect to the solvent. This is because high ionic conductivity is obtained. Further, when the electrolyte salt is lithium tetrafluoroborate or a compound represented by formula (10) to formula (12), the content in the solvent is 0.001% by mass to 5% by mass. Is preferable, and it is more preferable that it is 0.005 mass%-3 mass%. This is because a local increase in the potential of the positive electrode 21 in the region R2 is further suppressed.

[Operation of secondary battery]
In this secondary battery, at the time of charging, for example, lithium ions are released from the positive electrode 21 and inserted in the negative electrode 22 through the electrolytic solution impregnated in the separator 23. On the other hand, at the time of discharging, for example, lithium ions are released from the negative electrode 22 and inserted in the positive electrode 21 through the electrolytic solution impregnated in the separator 23.

[Method for producing secondary battery]
This secondary battery is manufactured by the following procedure, for example.

  First, the positive electrode 21 is produced. First, a positive electrode active material and, if necessary, a positive electrode binder and a positive electrode conductive agent are mixed to form a positive electrode mixture, and then dispersed in an organic solvent to obtain a paste-like positive electrode mixture slurry. Subsequently, the positive electrode mixture slurry is uniformly applied to both surfaces of the positive electrode current collector 21A and then dried to form the positive electrode active material layer 21B. Finally, the positive electrode active material layer 21B is compression-molded using a roll press or the like while being heated as necessary. In this case, the compression molding may be repeated a plurality of times.

  Next, the negative electrode 22 is produced by the same procedure as that of the positive electrode 21 described above. In this case, a negative electrode mixture obtained by mixing a negative electrode active material and, if necessary, a negative electrode binder and a negative electrode conductive agent is dispersed in an organic solvent to obtain a paste-like negative electrode mixture slurry. After that, the negative electrode mixture slurry is uniformly applied to both surfaces of the negative electrode current collector 22A to form the negative electrode active material layer 22B, and then the negative electrode active material layer 22B is compression molded.

  Note that the negative electrode 22 may be manufactured by a procedure different from that of the positive electrode 21. In this case, a plurality of negative electrode active material particles are formed by depositing a negative electrode material on both surfaces of the negative electrode current collector 22A using a vapor phase method such as an evaporation method. After that, if necessary, an oxide-containing film is formed using a liquid phase method such as a liquid phase deposition method, or a metal material is formed using a liquid phase method such as an electrolytic plating method, or both are formed. Thus, the negative electrode active material layer 22B is formed.

  Next, an electrolyte salt is dissolved in a solvent containing a sulfone compound to prepare an electrolytic solution.

  Finally, a secondary battery is assembled using the positive electrode 21 and the negative electrode 22. First, the insulating member 28 is attached to at least a facing region of the positive electrode 21 between the positive electrode current collector 21A and the negative electrode active material layer 22B using an adhesive. Subsequently, the positive electrode lead 25 is attached to the positive electrode current collector 21A by welding or the like, and the negative electrode lead 26 is attached to the negative electrode current collector 22A by welding or the like. Subsequently, after the positive electrode 21 and the negative electrode 22 are stacked and wound through the separator 23 to produce the wound electrode body 20, the center pin 24 is inserted into the winding center. Subsequently, the wound electrode body 20 is accommodated in the battery can 11 while being sandwiched between the pair of insulating plates 12 and 13. In this case, the tip of the positive electrode lead 25 is attached to the safety valve mechanism 15 by welding or the like, and the tip of the negative electrode lead 26 is attached to the battery can 11 by welding or the like. Subsequently, an electrolytic solution is injected into the battery can 11 and impregnated in the separator 23. Finally, the battery lid 14, the safety valve mechanism 15, and the heat sensitive resistance element 16 are caulked to the opening end of the battery can 11 through the gasket 17. Thereby, the secondary battery shown in FIGS. 1-8 is completed.

  According to this secondary battery, since the solvent of the electrolytic solution contains at least one of the sulfone compounds represented by the formula (1) and the formula (2), the surface of the positive electrode 21 or the negative electrode 22 is charged and discharged. A stable film is formed even in a high temperature environment. Thereby, since the chemical stability of the electrolytic solution is improved, the decomposition reaction of the electrolytic solution is suppressed during charging and discharging even in a high temperature environment. In addition, since the insulating member 28 is disposed in at least the facing region (region R2) between the positive electrode current collector 21A and the negative electrode active material layer 22B in the positive electrode 21, the local potential of the positive electrode 21 in the region R2 The rise is suppressed. Thereby, since dissolution and precipitation of metal pieces or metal scraps existing in the battery are suppressed, a voltage drop during charging is suppressed. Accordingly, excellent high-temperature cycle characteristics and voltage maintenance characteristics can be obtained.

  In particular, if the sulfone compound is represented by the formula (3) or the formula (4), a high effect can be obtained. Moreover, if the content of the sulfone compound in the solvent is optimized according to the type of the negative electrode active material, a high effect can be obtained.

  Further, if the solvent contains at least one of unsaturated carbon bond cyclic carbonate, halogenated chain carbonate, halogenated cyclic carbonate, sultone and acid anhydride, higher effects can be obtained. . Further, the electrolyte salt is at least one of lithium hexafluorophosphate, lithium tetrafluoroborate, lithium perchlorate, lithium hexafluoroarsenate, and compounds represented by formulas (10) to (15). If it contains, a higher effect can be acquired. In this case, the electrolyte salt may contain at least one of lithium tetrafluoroborate or the compounds shown in the formulas (10) to (12) (especially those containing boron and fluorine as constituent elements). Thus, the voltage maintenance characteristic can be further improved.

  Furthermore, if a metal-based material advantageous for increasing the capacity is used as the negative electrode active material, higher effects can be obtained than when a carbon material or the like is used.

<2. Modification regarding configuration of wound electrode body>
In FIG. 8, in the case where the insulating member 28 is disposed on the positive electrode 21, the range of the expansion is extended to both the regions R1 and R3, but this is not necessarily limited thereto. For example, as shown in FIG. 9, the arrangement range of the insulating member 28 may be expanded only to the region R3 without extending to the region R1. Further, for example, as shown in FIG. 10, the range of the insulating member 28 may not be expanded to the regions R1 and R3, but may be disposed only in the region R2. In these cases, the same effect as that shown in FIG. 8 can be obtained. Although not specifically shown here, the arrangement range of the insulating member 28 may be expanded only to the region R1.

  In FIG. 8, the insulating member 28 is disposed on the positive electrode 21, but the present invention is not limited thereto. For example, an insulating member 28 may be disposed on the negative electrode 22 as shown in FIG. Further, for example, as shown in FIG. 12, insulating members 28 may be disposed on both the positive electrode 21 and the negative electrode 22. In this case, the arrangement range of the insulating member 28 can be arbitrarily set as described with reference to FIGS. In these cases, the same effect as that shown in FIG. 8 can be obtained. In addition, as a place where the insulating member 28 is disposed, the negative electrode 22 is preferable. This is because the alignment of the insulating member 28 is facilitated.

  Moreover, about the arrangement | positioning position and arrangement | positioning range of the insulating member 28, you may combine 2 or more types of the aspect shown in FIGS. Further, the insulating member 28 may be disposed on the separator 23. Of course, the insulating member 28 may be disposed on the positive electrode 21 and the separator 23, disposed on the negative electrode 22 and the separator 23, or disposed on the positive electrode 21, the negative electrode 22, and the separator 23.

<3. Other secondary batteries (laminate film type)>
In addition, although FIGS. 1-12 demonstrated the case where the battery structure was a cylindrical type, it is not necessarily restricted to this. Below, for example, a laminated film type is taken as an example of another battery structure, and the configuration of another secondary battery will be described.

[Configuration of other secondary batteries]
FIG. 13 shows an exploded perspective configuration of another secondary battery, and FIG. 14 shows an enlarged cross section taken along line XIV-XIV of the spirally wound electrode body 30 shown in FIG.

  This secondary battery is a lithium ion secondary battery similar to the above-described cylindrical secondary battery, and is mainly a winding in which a positive electrode lead 31 and a negative electrode lead 32 are attached inside a film-shaped exterior member 40. The rotating electrode body 30 is accommodated. A battery structure using such an exterior member 40 is called a laminate film type.

  For example, the positive electrode lead 31 and the negative electrode lead 32 are led out in the same direction from the inside of the exterior member 40 toward the outside. However, the installation position of the positive electrode lead 31 and the negative electrode lead 32 with respect to the spirally wound electrode body 30, the lead-out direction thereof, and the like are not particularly limited. The positive electrode lead 31 is made of, for example, aluminum, and the negative electrode lead 32 is made of, for example, copper, nickel, stainless steel, or the like. These materials have, for example, a thin plate shape or a mesh shape.

  The exterior member 40 is, for example, a laminate film in which a fusion layer, a metal layer, and a surface protective layer are laminated in this order. In this case, for example, the outer edges of the fusion layers of the two films are bonded together by an adhesive or the like so that the fusion layer faces the wound electrode body 30. Examples of the fusion layer include a film of polyethylene or polypropylene. Examples of the metal layer include aluminum foil. Examples of the surface protective layer include films of nylon or polyethylene terephthalate.

  Among these, as the exterior member 40, an aluminum laminated film in which a polyethylene film, an aluminum foil, and a nylon film are laminated in this order is preferable. However, the exterior member 40 may be a laminated film having another laminated structure instead of the aluminum laminated film, or may be a polymer film such as polypropylene or a metal film.

  An adhesive film 41 is inserted between the exterior member 40 and the positive electrode lead 31 and the negative electrode lead 32 to prevent intrusion of outside air. The adhesion film 41 is made of a material having adhesion to the positive electrode lead 31 and the negative electrode lead 32. Examples of such a material include polyolefin resins such as polyethylene, polypropylene, modified polyethylene, and modified polypropylene.

  The wound electrode body 30 is obtained by laminating and winding a positive electrode 33 and a negative electrode 34 via a separator 35 and an electrolyte layer 36, and an outermost peripheral portion thereof is protected by a protective tape 37. In the positive electrode 33, for example, a positive electrode active material layer 33B is provided on both surfaces of a positive electrode current collector 33A. The configurations of the positive electrode current collector 33A and the positive electrode active material layer 33B are the same as those of the positive electrode current collector 21A and the positive electrode active material layer 21B in the cylindrical secondary battery, respectively. In the negative electrode 34, for example, a negative electrode active material layer 34B is provided on both surfaces of a negative electrode current collector 34A. The configurations of the negative electrode current collector 34A and the negative electrode active material layer 34B are the same as the configurations of the negative electrode current collector 22A and the negative electrode active material layer 22B in the cylindrical secondary battery, respectively. In this wound electrode body 30, an insulating member is disposed at least in a region where the positive electrode current collector 33A and the negative electrode active material layer 34B face each other. The details regarding the constituent material, the arrangement location, the arrangement range, and the like of the insulating member are the same as those described for the cylindrical secondary battery. The configuration of the separator 35 is the same as the configuration of the separator 23 in the cylindrical secondary battery.

  The electrolyte layer 36 is one in which an electrolytic solution is held by a polymer compound, and may contain other materials such as various additives as necessary. The electrolyte layer 36 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 of the electrolyte is prevented.

  Examples of the polymer compound include at least one of the following polymer materials. Polyacrylonitrile, polyvinylidene fluoride, polytetrafluoroethylene, polyhexafluoropropylene, polyethylene oxide, polypropylene oxide, polyphosphazene, polysiloxane, or polyvinyl fluoride. Polyvinyl acetate, polyvinyl alcohol, polymethyl methacrylate, polyacrylic acid, polymethacrylic acid, styrene-butadiene rubber, nitrile-butadiene rubber, polystyrene or polycarbonate. Further, it is a copolymer of vinylidene fluoride and hexafluoropyrene. These may be single and multiple types may be mixed. Among these, polyvinylidene fluoride or a copolymer of vinylidene fluoride and hexafluoropyrene is preferable. This is because it is electrochemically stable.

  The composition of the electrolytic solution is the same as the composition of the electrolytic solution in the cylindrical secondary battery, and the electrolytic solution contains at least one of the sulfone compounds represented by the formulas (1) and (2). . However, in the electrolyte layer 36 which is a gel electrolyte, the solvent of the electrolytic solution is a wide concept including not only a liquid solvent but also a material having ion conductivity capable of dissociating the electrolyte salt. Therefore, when using a polymer compound having ion conductivity, the polymer compound is also included in the solvent.

  Instead of the gel electrolyte layer 36 in which the electrolyte is held by the polymer compound, the electrolyte may be used as it is. In this case, the separator 35 is impregnated with the electrolytic solution.

  In this secondary battery, at the time of charging, for example, lithium ions are released from the positive electrode 33 and inserted in the negative electrode 34 through the electrolyte layer 36. On the other hand, at the time of discharging, for example, lithium ions are released from the negative electrode 34 and inserted in the positive electrode 53 through the electrolyte layer 36.

[Other secondary battery manufacturing methods]
The secondary battery provided with the gel electrolyte layer 36 is manufactured by, for example, the following three types of procedures.

  In the first manufacturing method, first, the positive electrode 33 and the negative electrode 34 are manufactured by the same procedure as the positive electrode 21 and the negative electrode 22 in the cylindrical secondary battery. Specifically, the positive electrode active material layer 33B is formed on both surfaces of the positive electrode current collector 33A to produce the positive electrode 33, and the negative electrode active material layer 34B is formed on both surfaces of the negative electrode current collector 34A to produce the negative electrode 34. To do. Subsequently, an insulating member is disposed at least in a region where the positive electrode current collector 33A and the negative electrode active material layer 34B are opposed to each other. Subsequently, the positive electrode lead 31 is attached to the positive electrode current collector 33A by welding or the like, and the negative electrode lead 32 is attached to the negative electrode current collector 34A by welding or the like. Then, after preparing the precursor solution containing electrolyte solution, a high molecular compound, and a solvent and apply | coating to the positive electrode 33 and the negative electrode 34, the solvent is volatilized and the gel electrolyte layer 36 is formed. Subsequently, the positive electrode 33 and the negative electrode 34 on which the electrolyte layer 36 is formed are stacked and wound via a separator 35, and then a protective tape 37 is adhered to the outermost peripheral portion to produce the wound electrode body 30. Finally, after sandwiching the wound electrode body 30 between the two film-shaped exterior members 40, the outer edge portions of the exterior member 40 are bonded to each other by heat fusion or the like, and the wound electrode body 30 is enclosed. . At this time, the adhesion film 41 is inserted between the positive electrode lead 31 and the negative electrode lead 32 and the exterior member 40. Thereby, the secondary battery shown in FIGS. 13 and 14 is completed.

  In the second manufacturing method, first, the positive electrode lead 31 is attached to the positive electrode 33 and the negative electrode lead 32 is attached to the negative electrode 34. Subsequently, after the positive electrode 33 and the negative electrode 34 are laminated and wound via the separator 35, a protective tape 37 is adhered to the outermost peripheral portion thereof, and a wound body that is a precursor of the wound electrode body 30. Is made. Subsequently, after sandwiching the wound body between the two film-shaped exterior members 40, the remaining outer peripheral edge except for the outer peripheral edge on one side is adhered by heat fusion or the like, thereby forming a bag-shaped exterior The wound body is accommodated in the member 40. 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 to form a bag-shaped exterior member. After injecting into the inside of 40, the opening of the exterior member 40 is sealed by heat fusion or the like. Finally, the monomer is thermally polymerized to obtain a polymer compound, and the gel electrolyte layer 36 is formed. Thereby, the secondary battery is completed.

  In the third manufacturing method, a wound body is formed by forming a wound body in the same manner as in the second manufacturing method described above except that the separator 35 coated with the polymer compound on both sides is used first. 40 is housed inside. Examples of the polymer compound applied to the separator 35 include a polymer (such as a homopolymer, a copolymer, or a multi-component copolymer) containing vinylidene fluoride as a component. Specifically, polyvinylidene fluoride, a binary copolymer containing vinylidene fluoride and hexafluoropropylene as components, and a ternary copolymer containing vinylidene fluoride, hexafluoropropylene and chlorotrifluoroethylene as components. Such as coalescence. 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 40, the opening of the exterior member 40 is sealed by heat fusion or the like. Finally, the exterior member 40 is heated while applying a load to bring the separator 35 into close contact with the positive electrode 33 and the negative electrode 34 via 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 layer 36, thereby completing the secondary battery.

  In the third manufacturing method, battery swelling is suppressed more than in the first manufacturing method. Further, in the third manufacturing method, almost no monomer or solvent, which is a raw material of the polymer compound, remains in the electrolyte layer 36 and the formation process of the polymer compound is better controlled than in the second manufacturing method. . For this reason, sufficient adhesion is obtained between the positive electrode 33, the negative electrode 34 and the separator 35 and the electrolyte layer 36.

  According to the other secondary battery, the solvent of the electrolytic solution contains at least one of the sulfone compounds represented by the formulas (1) and (2), and at least the positive electrode current collector 33A and the negative electrode active material. An insulating member is disposed in a region facing the material layer 34B. Therefore, excellent high-temperature cycle characteristics and voltage maintenance characteristics can be obtained by the same action as the cylindrical secondary battery. Other effects of the secondary battery other than those described above are the same as those of the cylindrical secondary battery.

  Specific examples of the present invention will be described in detail.

(Experimental Examples 1-1 to 1-9)
The cylindrical lithium ion secondary battery shown in FIG. 1, FIG. 2, FIG. 7, FIG. 8, and FIG.

First, the positive electrode 21 was produced. In this case, first, 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 890 ° C. for 5 hours. A cobalt composite oxide (LiCoO ₂ ) was obtained. When the obtained LiCoO ₂ was analyzed by X-ray diffraction, it was in good agreement with the LiCoO ₂ peak registered in the JCPDS (joint committee of powder diffraction standard) file. Subsequently, LiCoO ₂ was pulverized into a powder (average particle diameter (median diameter) = 10 μm). Subsequently, 95 parts by mass of LiCoO ₂ and 5 parts by mass of Li ₂ CO ₃ were mixed to obtain a positive electrode active material. Subsequently, 91 parts by mass of the positive electrode active material, 6 parts by mass of artificial graphite (KS-15 manufactured by Lonza) as the positive electrode conductive agent, and 3 parts by mass of polyvinylidene fluoride as the positive electrode binder were mixed, did. Subsequently, the positive electrode mixture was dispersed in N-methyl-2-pyrrolidone to obtain a paste-like positive electrode mixture slurry. Subsequently, a positive electrode mixture slurry is uniformly applied to both surfaces of a positive electrode current collector 21A made of a strip-shaped aluminum foil (thickness = 20 μm) using a coating apparatus, and then dried to form a positive electrode active material layer 21B. Formed. Finally, the positive electrode active material layer 21B was compression molded using a roll press.

  Next, the negative electrode 22 was produced. In this case, first, 94 parts by mass of artificial graphite (manufactured by JFE) as a negative electrode active material, 1 part by mass of VGCF as a negative electrode conductive agent, and 5 parts by mass of polyvinylidene fluoride as a negative electrode binder are mixed. A mixture was prepared. Subsequently, the negative electrode mixture was dispersed in N-methyl-2-pyrrolidone to obtain a paste-like negative electrode mixture slurry. Subsequently, the negative electrode mixture slurry is uniformly applied to both surfaces of the negative electrode current collector 22A made of a strip-shaped electrolytic copper foil (thickness = 15 μm) using a coating apparatus, and then dried, and the negative electrode active material layer 22B Formed. Finally, the negative electrode active material layer 22B was compression molded using a roll press.

Next, an electrolytic solution that is a liquid electrolyte was prepared. In this case, first as a solvent,
Ethylene carbonate (EC), propylene carbonate (PC), vinylene carbonate (VC), dimethyl carbonate (DMC), ethyl methyl carbonate (EMC), and a sulfone compound were mixed. When the content of the sulfone compound in the solvent is Z, the composition of the solvent (EC: PC: VC: DMC: EMC: sulfone compound) is 30-Z: 5: 1: 60: 4: Z by mass ratio. did. The type and content of the sulfone compound are as shown in Table 1. After that, lithium hexafluorophosphate (LiPF ₆ ) was dissolved in a solvent as an electrolyte salt. The content of the electrolyte salt was 1 mol / dm ³ with respect to the solvent.

Finally, a secondary battery was assembled using the electrolyte together with the positive electrode 21 and the negative electrode 22. First, in the positive electrode 21 or the negative electrode 22, the insulating member 28 was attached to the opposing region of the positive electrode current collector 21 </ b> A and the negative electrode active material layer 22 </ b> B and its peripheral region using an adhesive. As this insulating member 28, a polypropylene film (air permeability = 5000 s / 100 cm ³ ) was used. Subsequently, the positive electrode lead 25 made of aluminum was welded to the positive electrode current collector 21A, and the negative electrode lead 26 made of nickel was welded to the negative electrode current collector 22A. Subsequently, after laminating and winding the positive electrode 21 and the negative electrode 22 through a separator 23 made of a polyethylene film (thickness = 16 μm), the winding electrode 20 is fixed by fixing the winding end portion using an adhesive tape. Produced. Subsequently, the center pin 24 was inserted into the winding center of the wound electrode body 20. Subsequently, the wound electrode body 20 was housed in an iron battery can 11 (diameter 18 mm × height 65 mm) plated with nickel while being sandwiched between a pair of insulating plates 12 and 13. In this case, the tip of the positive electrode lead 25 was welded to the safety valve mechanism 15 and the tip of the negative electrode lead 26 was welded to the battery can 11. Subsequently, an electrolytic solution was injected into the battery can 11 by a reduced pressure method to impregnate the separator 23. Finally, the battery lid 14, the safety valve mechanism 15, and the heat sensitive resistance element 16 were caulked to the opening end of the battery can 11 through the gasket 17. Thereby, a cylindrical secondary battery was completed. When producing this secondary battery, the thickness of the positive electrode active material layer 21B was adjusted so that lithium metal did not deposit on the negative electrode 22 during full charge.

(Experimental Examples 1-10 to 1-19)
As shown in Table 1, the same procedure as in Experimental Examples 1-1 to 1-8 was performed, except that both the sulfone compound and the insulating member 28 were not used in combination.

(Experimental Examples 1-20 to 1-23)
As shown in Table 1, Experimental Examples 1-6 and 1-16 except that ethylene sulfite (ES) or 1,3-perfluoropropane disulfonylimide lithium (LiPFSI) was used instead of the sulfone compound. The same procedure was followed.

  When the high temperature cycle characteristics and voltage maintenance characteristics of the secondary batteries of Examples 1-1 to 1-23 were examined, the results shown in Table 1 were obtained.

  When investigating the high-temperature cycle characteristics, first, charging and discharging were performed for 1 cycle in a high temperature environment of 50 ° C., and the discharge capacity at the first cycle was measured. Subsequently, the battery was repeatedly charged and discharged in the same atmosphere until the total number of cycles reached 150 cycles, and the discharge capacity at the 150th cycle was measured. Finally, discharge capacity retention rate (%) = (discharge capacity at the 150th cycle / discharge capacity at the first cycle) × 100 was calculated. At the time of charging, constant current and constant voltage charging was performed up to an upper limit voltage of 4.2 V at a current of 2500 mA. At the time of discharge, constant current discharge was performed with a current of 2000 mA to a final voltage of 2.5V.

  When examining the voltage maintenance characteristics, first, the battery was charged in an atmosphere at 25 ° C. In this case, constant current and constant voltage charging was performed up to an upper limit voltage of 4.2 V at a current of 500 mA. Subsequently, the battery was left in the same atmosphere for 2 weeks while being charged. Subsequently, the open circuit voltage after standing was measured. In this case, it was determined that a significant voltage drop occurred when the open circuit potential was less than 4.1 V, and no significant pressure drop occurred when the open circuit potential was 4.1 V or more. Finally, as a ratio of occurrence of a significant voltage drop, a voltage drop occurrence rate (%) = (number of occurrence of significant voltage drop / total number) × 100 was calculated. In this case, the total number is 60 to 130.

  The procedure and conditions for examining the above-described high-temperature cycle characteristics and voltage maintenance characteristics are the same in the following series of experimental examples.

  In the secondary battery using artificial graphite as the negative electrode active material, when the sulfone compound and the insulating member 28 are used in combination, the discharge capacity maintenance rate and voltage drop generation are better than when they are not used in combination. The rate was obtained. Specifically, when the sulfone compound and the insulating member 28 were used in combination, the discharge capacity retention rate was higher while the voltage drop occurrence rate was kept low in the first half of the single digit range. Such a tendency was similarly obtained when compared with the case where ES or LiPFSI was used instead of the sulfone compound. In particular, when the sulfone compound and the insulating member 28 were used in combination, a better result was obtained when the sulfone compound was 0.005 mass% to 3 mass% in the solvent.

  Before the confirmation, after checking the discharge capacity maintenance rate and the voltage drop occurrence rate, the secondary batteries of Experimental Examples 1-1 to 1-18 in which the insulating member 28 is not disposed are disassembled, and the positive electrode current collector is collected. The state of the opposing region between the body 21A and the negative electrode active material layer 22B was examined visually. As a result, in most of the secondary batteries determined to have a significant voltage drop, nickel metal was deposited on the portion of the separator 23 corresponding to the facing region. An internal short circuit occurred due to the deposition of this nickel metal, which seems to have caused a significant voltage drop. The nickel metal is considered to be deposited after the nickel powder generated when the negative electrode lead 26 is welded or the nickel plating peeled off from the battery can 11 is dissolved.

  Therefore, in the secondary battery of the present invention, when artificial graphite is used as the negative electrode active material, the electrolyte solution contains the sulfone compound, and the positive electrode current collector 21A and the negative electrode active material layer 22B An insulating member 28 is disposed in the opposite region. Thereby, excellent high-temperature cycle characteristics and voltage maintenance characteristics can be obtained.

(Experimental examples 2-1 to 2-10)
As shown in Table 2, the same procedures as in Experimental Examples 1-5 and 1-15 were performed except that the type of the sulfone compound was changed. When the high-temperature cycle characteristics and voltage maintenance characteristics of the secondary batteries of Examples 2-1 to 2-10 were examined, the results shown in Table 2 were obtained.

  Even when the type of the sulfone compound was changed, the same results as in Table 1 were obtained. Therefore, in the secondary battery of the present invention using artificial graphite as the negative electrode active material, excellent high-temperature cycle characteristics and voltage maintenance / storage characteristics can be obtained even if the type of the sulfone compound is changed.

(Experimental examples 3-1 to 3-6)
As shown in Table 3, the same procedure as in Experimental Examples 1-5 and 1-15 was performed, except that the composition of the solvent was changed. In this case, 4-fluoro-1,3-dioxolan-2-one (FEC) or trans-4,5-difluoro-1,3-dioxolan-2-one (DFEC) or the like was used as a solvent. In addition, when using FEC etc., they were replaced with EC and content was 10 mass%. When the high-temperature cycle characteristics and the voltage maintenance characteristics of the secondary batteries of Examples 3-1 to 3-6 were examined, the results shown in Table 3 were obtained.

  Even when the composition of the solvent was changed, the same results as in Table 1 were obtained. In this case, when VC or the like is used, the discharge capacity maintenance rate is increased while the voltage drop occurrence rate is substantially maintained as compared with the case where they are not used. From these facts, in the secondary battery of the present invention using artificial graphite as the negative electrode active material, excellent high-temperature cycle characteristics and voltage maintenance and storage characteristics can be obtained even if the composition of the solvent is changed. Moreover, if an unsaturated bond cyclic carbonate or a halogenated cyclic carbonate is used as a solvent, the high-temperature cycle characteristics are further improved.

(Experimental examples 4-1 to 4-6)
As shown in Table 4, the same procedures as in Experimental Examples 1-5 and 1-15 were performed except that the composition of the electrolyte salt was changed. In this case, as the electrolyte salt, lithium tetrafluoroborate (LiBF ₄ ), lithium difluorooxalate borate (LiFOB) represented by formula (10-1), or lithium bisoxalate represented by formula (10-6) Rate borate (LiBOB) or the like was used. Incidentally, in the case of using a LiBF ₄ was them with 0.5 wt% and the content is replaced with EC. When the high-temperature cycle characteristics and the voltage maintenance characteristics of the secondary batteries of Examples 4-1 to 4-6 were examined, the results shown in Table 4 were obtained.

Even when the composition of the electrolyte salt was changed, the same results as in Table 1 were obtained. In this case, when LiBF ₄ or the like was used, the voltage drop occurrence rate was lower while the discharge capacity maintenance rate was substantially maintained. For these reasons, in the secondary battery of the present invention using artificial graphite as the negative electrode active material, excellent high-temperature cycle characteristics and voltage maintenance characteristics can be obtained even if the composition of the electrolyte salt is changed. Further, when an electrolyte salt (such as LiBF ₄ ) containing boron and fluorine as constituent elements is used, the voltage maintaining characteristics are further improved.

(Experimental examples 5-1 to 5-6)
As shown in Table 5, the same procedure as in Experimental Example 4-1 was performed except that the content of the electrolyte salt was changed. When the high-temperature cycle characteristics and voltage maintenance characteristics of the secondary batteries of Examples 5-1 to 5-6 were examined, the results shown in Table 5 were obtained.

  Even when the content of the electrolyte salt was changed, the same results as in Table 1 were obtained. In this case, good results were obtained when the content of the electrolyte salt was 0.005% by mass to 3% by mass. For these reasons, in the secondary battery of the present invention using artificial graphite as the negative electrode active material, excellent high-temperature cycle characteristics and voltage maintenance characteristics can be obtained even if the content of the electrolyte salt is changed.

(Experimental examples 6-1 to 6-49)
As shown in Tables 6 and 7, Experimental Example 1-5 except that SnMC (M is one or more of transition metal elements such as cobalt) which is a Sn-containing material was used as the negative electrode active material. , 1-10, 1-15.

  When preparing SnMC, first, tin powder and transition metal powder were alloyed to form tin-containing alloy powder, and then carbon powder was added and dry mixed. Subsequently, 10 g of the above mixture was set together with about 400 g of steel balls having a diameter of 9 mm in a reaction vessel of a planetary ball mill manufactured by Ito Seisakusho. Subsequently, after replacing the inside of the reaction vessel with an argon atmosphere, an operation for 10 minutes and a pause for 10 minutes at a rotation speed of 250 revolutions per minute were repeated until the total operation time reached 20 hours. Subsequently, after the reaction vessel was cooled to room temperature and SnMC was taken out, coarse powder was removed through a 280 mesh sieve.

  When the composition of the obtained SnMC was analyzed, the composition (mass ratio) was as shown in Table 6 and Table 7. In this case, the content of tin and transition metal was measured using an inductively coupled plasma (ICP) emission analyzer, and the content of carbon was measured using a carbon / sulfur analyzer. Further, when SnMC was analyzed by the X-ray diffraction method, a diffraction peak having a half-value width of 1.0 ° or more at a diffraction angle 2θ was observed in a diffraction angle 2θ = 20 ° to 50 °. Further, when SnCoC was analyzed on behalf of SnMC by XPS, peak P1 was obtained as shown in FIG. When this peak P1 was analyzed, a peak P2 of surface contamination carbon and a peak P3 of C1s in SnCoC on the lower energy side (region lower than 284.5 eV) were obtained. From this result, it was confirmed that carbon in SnCoC was bonded to other elements.

(Experimental examples 7-1 to 7-4)
As shown in Table 8, the same procedure as in Experimental Examples 6-1 and 6-25 was performed, except that the composition of SnCoC was changed. Also in this case, when SnCoC was analyzed by X-ray diffraction and XPS, the same results as in Experimental Examples 6-1 to 6-49 were obtained.

(Experimental examples 8-1 to 8-6)
As shown in Table 9, the same procedure as in Experimental Examples 6-1 and 6-25 was performed, except that SnCoX (X is boron or the like) which is a Sn-containing material was used as the negative electrode active material. The procedure for preparing SnCoX is the same as that for preparing SnMC except that boron powder or the like is used instead of carbon powder. Also in this case, when SnCoX was analyzed by X-ray diffraction and XPS, the same results as in Experimental Examples 6-1 to 6-49 were obtained.

  The secondary batteries of Examples 6-1 to 6-49, 7-1 to 7-4, and 8-1 to 8-6 were examined for high-temperature cycle characteristics and voltage maintenance characteristics. The results shown are obtained.

  Even when SnMC or SnCoX was used as the negative electrode active material, the same results as in Table 1 were obtained. For these reasons, in the secondary battery of the present invention, when the Sn-containing material is used as the negative electrode active material, the solvent of the electrolytic solution contains the sulfone compound, and the positive electrode current collector 21A and the negative electrode active material layer 22B. An insulating member 28 is disposed in a region facing the surface. Thereby, excellent high-temperature cycle characteristics and voltage maintenance characteristics can be obtained.

(Experimental examples 9-1 to 9-11)
As shown in Table 10, except that the negative electrode active material layer 22B was formed using silicon as the negative electrode active material, and the composition of the solvent and the content of the electrolyte salt were changed, Experimental Examples 1-1 to 1- 23, 2-1 to 2-10. In the case of forming the negative electrode active material layer 22B, a plurality of negative electrode active material particles were formed by depositing silicon on the surface of the negative electrode current collector 22A using a vapor deposition method (electron beam vapor deposition method). In this case, the deposition process was repeated 10 times so that the total thickness of the negative electrode active material layer 22B was 6 μm. EC and diethyl carbonate (DEC) were used as the solvent, and their composition (EC: DEC) was 30:70 by mass ratio. The content of the electrolyte salt was 1 mol / kg with respect to the solvent. When the high-temperature cycle characteristics and voltage maintenance characteristics of the secondary batteries of Examples 9-1 to 9-11 were examined, the results shown in Table 10 were obtained.

  Even when silicon was used as the negative electrode active material, the same results as in Table 1 were obtained. In this case, better results were obtained when the content of the sulfone compound in the solvent was 0.1% by mass to 5% by mass. For these reasons, in the secondary battery of the present invention, when silicon is used as the negative electrode active material, the solvent of the electrolytic solution contains the sulfone compound, and the positive electrode current collector 21A and the negative electrode active material layer 22B An insulating member 28 is disposed in the facing region. Thereby, excellent high-temperature cycle characteristics and voltage maintenance characteristics can be obtained.

(Experimental examples 10-1 to 10-13)
As shown in Table 11, the same procedures as in Experimental Examples 9-3 and 9-10 were performed except that the composition of the solvent was changed. In this case, bis (fluoromethyl) carbonate (DFDMC), propene sultone (PRS), succinic anhydride (SCAH), or the like was used as a solvent. The composition of the solvent (EC: PC: DEC) was 10:20:70 by mass ratio. Moreover, content of VC etc. in the solvent was 5 mass%. When the high-temperature cycle characteristics and the voltage maintenance characteristics of the secondary batteries of Examples 10-1 to 10-13 were examined, the results shown in Table 11 were obtained.

  Even when the composition of the solvent was changed, the same results as in Table 10 were obtained. In this case, when VC or the like is used, the discharge capacity maintenance rate is increased while the voltage drop occurrence rate is substantially maintained as compared to the case where they are not used. For these reasons, in the secondary battery of the present invention using silicon as the negative electrode active material, excellent high-temperature cycle characteristics and voltage maintenance and storage characteristics can be obtained even if the composition of the solvent is changed. Moreover, if unsaturated bond cyclic carbonate or halogenated cyclic carbonate is used as the solvent, the high-temperature cycle characteristics are further improved.

(Experimental examples 11-1 to 11-4)
As shown in Table 12, the same procedures as in Experimental Examples 9-3 and 9-10 were performed except that the composition of the electrolyte salt was changed. In this case, bis (trifluoromethanesulfonyl) imide lithium (LiTFSI) or the like was used as the electrolyte salt. Incidentally, in the case of using a LiBF ₄ is, 0.9 mol / kg content of LiPF _6, the content of such LiBF ₄ was 0.1 mol / kg. When the high-temperature cycle characteristics and voltage maintenance characteristics of the secondary batteries of Examples 11-1 to 11-4 were examined, the results shown in Table 12 were obtained.

Even when the composition of the electrolyte salt was changed, the same results as in Table 10 were obtained. In this case, when LiBF ₄ or the like was used, the discharge capacity maintenance rate increased while the voltage drop occurrence rate was substantially maintained. For these reasons, in the secondary battery of the present invention using silicon as the negative electrode active material, excellent high-temperature cycle characteristics and voltage maintenance characteristics can be obtained even if the composition of the electrolyte salt is changed.

  From the results shown in Tables 1 to 12, in the secondary battery of the present invention, the solvent of the electrolytic solution contains at least one of the sulfone compounds represented by Formula (1) and Formula (2). An insulating member is disposed at least in a region where the positive electrode current collector of the positive electrode and the negative electrode active material layer of the negative electrode face each other. Thus, excellent high-temperature cycle characteristics and voltage maintenance characteristics can be obtained without depending on the type of the negative electrode active material, the composition of the solvent, the composition of the electrolyte salt, or the like.

  In this case, when the metal material (silicon, SnMC or SnCoX) was used as the negative electrode active material, the increase rate of the discharge capacity retention rate was larger than when the carbon material (artificial graphite) was used. Therefore, a higher effect can be obtained when a metal-based material is used than when a carbon material is used. This result shows that the use of a metal material that is advantageous for increasing the capacity as the negative electrode active material makes the electrolyte solution more easily decomposed than when a carbon material is used. it is conceivable that.

  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, in the above-described embodiments and examples, the lithium ion secondary battery has been described as the type of the secondary battery, but the present invention is not necessarily limited thereto. The secondary battery of the present invention also includes a secondary battery in which the capacity of the negative electrode includes a capacity due to insertion and extraction of lithium ions and a capacity due to precipitation and dissolution of lithium metal, and is represented by the sum of these capacities. , As well as applicable. In this case, a negative electrode material capable of inserting and extracting lithium ions is used as the negative electrode active material, and the chargeable capacity of the negative electrode material is set to be smaller than the discharge capacity of the positive electrode. .

  In the above-described embodiments and examples, the case where the battery structure is a cylindrical type or a laminate film type and the case where the battery element has a winding structure have been described as examples, but the present invention is not necessarily limited thereto. . The secondary battery of the present invention can be similarly applied to a case where it has another battery structure such as a square shape, a coin shape or a button shape, and a case where the battery element has another structure such as a laminated structure.

  In the above-described embodiments and examples, the case where lithium is used as the element of the electrode reactant is described, but the present invention is not necessarily limited thereto. The electrode reactant may be, for example, another group 1 element such as sodium (Na) or potassium (K), a group 2 element such as magnesium or calcium, or another light metal such as aluminum. Since the effect of the present invention should be obtained without depending on the type of the electrode reactant, the same effect can be obtained even if the type of the electrode reactant is changed.

  In the above-described embodiments and examples, the appropriate range derived from the results of the examples is described for the content of the sulfone compound. However, the description may be outside the above-described range. It does not completely deny sex. In other words, the appropriate range described above is a particularly preferable range for obtaining the effects of the present invention. Therefore, as long as the effects of the present invention can be obtained, the content may slightly deviate from the above ranges.

  DESCRIPTION OF SYMBOLS 11 ... Battery can, 12, 13 ... Insulation board, 14 ... Battery cover, 15 ... Safety valve mechanism, 15A ... Disc board, 16 ... Heat sensitive resistance element, 17 ... Gasket, 20, 30 ... Winding electrode body, 21, 33 ... Positive electrode, 21A, 33A ... Positive electrode current collector, 21B, 33B ... Positive electrode active material layer, 22, 34 ... Negative electrode, 22A, 34A ... Negative electrode current collector, 22B, 34B ... Negative electrode active material layer, 23, 35 ... Separator 24 ... Center pin, 25, 31 ... Positive electrode lead, 26, 32 ... Negative electrode lead, 28 ... Insulating member, 36 ... Electrolyte layer, 37 ... Protective tape, 40 ... Exterior member, 41 ... Adhesive film, 221 ... Negative electrode active material Particles 222 ... Oxide-containing film, 224 (224A, 224B) ... gap, 225 ... gap, 226 ... metal material.

Claims (18)

A positive electrode and a negative electrode capable of occluding and releasing an electrode reactant, and an electrolyte containing a solvent and an electrolyte salt;
The solvent includes at least one of the sulfone compounds represented by formula (1) and formula (2),
The positive electrode has a positive electrode active material layer in a partial region on the positive electrode current collector, and the negative electrode is formed on a region of the negative electrode current collector facing the positive electrode active material layer and the positive electrode current collector. Having a negative electrode active material layer in the opposing region;
A secondary battery in which an insulating member is disposed at least in a region where the positive electrode current collector and the negative electrode active material layer face each other.

(R11 and R12 are an alkyl group, an aryl group, a halogenated alkyl group or a halogenated aryl group. X1 represents —S (═O) ₂ —, —S (═O) ₂ —O—, —O—S ( ═O) ₂ —O—, —S (═O) ₂ —O—S (═O) ₂ — or —S (═O) ₂ —O—C (═O) —, where n1 is 1 or more and 4 The following integers.)

(R13 is an alkylene group, an arylene group, a halogenated alkylene group or a halogenated arylene group. X2 is —S (═O) ₂ —, —S (═O) ₂ —O—, —O—S (═O ) ₂ —O—, —S (═O) ₂ —O—S (═O) ₂ — or —S (═O) ₂ —O—C (═O) —, where n2 is 1 or more and 4 or less. (It is an integer.) The secondary battery according to claim 1, wherein the sulfone compound is represented by Formula (3) or Formula (4).

(Y1 is an alkylene group or halogenated alkylene group having 2 to 4 carbon atoms, an alkenylene group or halogenated alkenylene group having 2 to 4 carbon atoms, an arylene group or a halogenated arylene group, or a derivative thereof.)

(Y2 is an alkylene group or halogenated alkylene group having 2 to 4 carbon atoms, an alkenylene group or halogenated alkenylene group having 2 to 4 carbon atoms, an arylene group or a halogenated arylene group, or a derivative thereof.) The secondary battery according to claim 1, wherein the sulfone compound is represented by Formula (3-1) to Formula (3-22) or Formula (4-1) to Formula (4-20).

  The sulfone compound is represented by formula (3-1), formula (3-2), formula (3-22), formula (4-1), formula (4-16) or formula (4-17). The secondary battery according to claim 3.   The secondary battery according to claim 1, wherein the negative electrode includes a carbon material as a negative electrode active material, and the content of the sulfone compound in the solvent is 0.001% by mass to 5% by mass.   The secondary battery according to claim 1, wherein the negative electrode includes a material containing at least one of silicon (Si) and tin (Sn) as a constituent element as a negative electrode active material.   The secondary battery according to claim 6, wherein the material containing at least one of silicon and tin as a constituent element is a simple substance of silicon.   The material containing at least one of silicon and tin as a constituent element is tin, cobalt (Co), iron (Fe), magnesium (Mg), titanium (Ti), vanadium (V), chromium (Cr), Manganese (Mn), Nickel (Ni), Copper (Cu), Zinc (Zn), Gallium (Ga), Zirconium (Zr), Niobium (Nb), Molybdenum (Mo), Silver (Ag), Indium (In), At least one of cerium (Ce), hafnium (Hf), tantalum (Ta), tungsten (W), bismuth (Bi) and silicon, and boron (B), carbon (C), phosphorus (P) and aluminum A material containing at least one of (Al) as a constituent element, in which the half-value width of a diffraction peak obtained by X-ray diffraction is 1.0 ° or more. Secondary battery is claimed in claim 6, wherein.   The material containing at least one of silicon and tin as a constituent element is a material containing tin, cobalt, and carbon as constituent elements, and in the material, the carbon content is 9.9 mass% or more 29 0.7 mass% or less, the ratio of tin and cobalt (Co / (Sn + Co)) is 20 mass% or more and 70 mass% or less, and the half width of the diffraction peak obtained by X-ray diffraction is 1.0 ° or more. The secondary battery according to claim 6.   The secondary battery according to claim 6, wherein the content of the sulfone compound in the solvent is 0.1% by mass or more and 5% by mass or less.   The secondary battery according to claim 1, wherein the insulating member is disposed on at least one of the positive electrode and the negative electrode.   The secondary battery according to claim 1, wherein the insulating member is a synthetic resin. The solvent is an unsaturated carbon bond cyclic ester carbonate represented by formula (5) to formula (7), a halogenated chain carbonate ester represented by formula (8), or a halogenation represented by formula (9). The secondary battery according to claim 1, comprising at least one of cyclic carbonate, sultone, and acid anhydride.

(R21 and R22 are a hydrogen group or an alkyl group.)

(R23 to R26 are a hydrogen group, an alkyl group, a vinyl group, or an allyl group, and at least one of them is a vinyl group or an allyl group.)

(R27 is an alkylene group.)

(R31 to R36 are a hydrogen group, a halogen group, an alkyl group or a halogenated alkyl group, and at least one of them is a halogen group or a halogenated alkyl group.)

(R37 to R40 are a hydrogen group, a halogen group, an alkyl group or a halogenated alkyl group, and at least one of them is a halogen group or a halogenated alkyl group.)   The unsaturated carbon-bonded cyclic ester carbonate is vinylene carbonate, vinyl ethylene carbonate or methylene ethylene carbonate, the halogenated chain ester carbonate is fluoromethyl methyl carbonate or bis (fluoromethyl) carbonate, and the halogenated cyclic ester carbonate The secondary battery according to claim 13, wherein the carbonate is 4-fluoro-1,3-dioxolan-2-one or 4,5-difluoro-1,3-dioxolan-2-one. The electrolyte salt includes lithium hexafluorophosphate (LiPF ₆ ), lithium tetrafluoroborate (LiBF ₄ ), lithium perchlorate (LiClO ₄ ), lithium hexafluoroarsenate (LiAsF ₆ ), and a formula ( The secondary battery according to claim 1, comprising at least one of compounds represented by 10) to formula (15).

(X51 is a 1A group element or 2A group element or aluminum in the short period type periodic table. M51 is a transition metal, or a 3B group element, 4B group element or 5B group element in the short period type periodic table. R51 is R51. Y51 is —C (═O) —R52—C (═O) —, —C (═O) —CR53 ₂ — or —C (═O) —C (═O) —. R52 is an alkylene group, a halogenated alkylene group, an arylene group or a halogenated arylene group, R53 is an alkyl group, a halogenated alkyl group, an aryl group or a halogenated aryl group, and a5 is 1 to 4. (It is an integer, b5 is an integer of 0, 2 or 4, and c5, d5, m5 and n5 are integers of 1 to 3.)

(X61 is a group 1A element or a group 2A element in the short period type periodic table. M61 is a transition metal, or a group 3B element, a group 4B element or a group 5B element in the short period type periodic table. Y61 is -C ( _{= O) - (CR61 2)} b6 -C (= O) -, - R63 2 C- (CR62 2) c6 -C (= O) -, - R63 2 C- (CR62 2) c6 -CR63 2 -, _{-R63 2 C- (CR62 2) c6} -S (= O) 2 -, - S (= O) 2 - (CR62 2) d6 -S (= O) 2 - or -C (= O) - (CR62 ₂ ) _d6 —S (═O) ₂ —, wherein R61 and R63 are a hydrogen group, an alkyl group, a halogen group or a halogenated alkyl group, and at least one of each is a halogen group or a halogenated alkyl group. R62 is a hydrogen group, alkyl A6, e6 and n6 are integers of 1 or 2, b6 and d6 are integers of 1 to 4, c6 is an integer of 0 to 4, and f6 is a halogen group or a halogenated alkyl group. And m6 is an integer of 1 to 3.)

(X71 is a group 1A element or a group 2A element in the short period type periodic table. M71 is a transition metal, or a group 3B element, a group 4B element, or a group 5B element in the short period type periodic table. Rf is a fluorinated alkyl. Or a fluorinated aryl group, each having 1 to 10 carbon atoms, Y71 is —C (═O) — (CR71 ₂ ) _d7 —C (═O) —, —R72 ₂ C— (CR71 _{2 D7} -C (= O)-, -R72 ₂ C- (CR71 ₂ ) _d7 -CR72 _2- , -R72 ₂ C- (CR71 ₂ ) _d7 -S (= O) _2-, -S (= O) ₂ — (CR71 ₂ ) _e7 —S (═O) ₂ — or —C (═O) — (CR71 ₂ ) _e7 —S (═O) ₂ —, wherein R71 is a hydrogen group, alkyl group, halogen R72 represents a hydrogen group or an alkyl group. A halogen group or a halogenated alkyl group, at least one of which is a halogen group or a halogenated alkyl group, wherein a7, f7 and n7 are integers of 1 or 2, and b7, c7 and e7 are 1 And d7 is an integer of 0 to 4, and g7 and m7 are integers of 1 to 3.)
_{LiN (C m F 2m + 1} SO 2) (C n F 2n + 1 SO 2) ... (13)
(M and n are integers of 1 or more.)

(R81 is a linear or branched perfluoroalkylene group having 2 to 4 carbon atoms.)
LiC (C _p F _{2p + 1} SO ₂ ) (C _q F _{2q + 1} SO ₂ ) (C _r F _{2r + 1} SO ₂ ) (15)
(P, q and r are integers of 1 or more.) The compound represented by formula (10) is represented by formula (10-1) to formula (10-6), and the compound represented by formula (11) is represented by formula (11-1) to The secondary battery according to claim 15, wherein the secondary battery is represented by the formula (11-8), and the compound represented by the formula (12) is represented by the formula (12-1).

  The electrolyte salt is lithium tetrafluoroborate or a compound represented by formula (10) to formula (12), and the content thereof in the solvent is 0.005 mass% or more and 3 mass% or less. The secondary battery according to claim 15.   The secondary battery according to claim 1, wherein the electrode reactant is lithium ion.

Images