JP2013058402A - Electrolyte for secondary battery, secondary battery, battery pack, electric vehicle, power storage system, electric power tool and electronic apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a secondary battery capable of obtaining excellent battery characteristics.SOLUTION: A secondary battery includes a positive electrode, a negative electrode and an electrolyte. The electrolyte includes: an alkyl lithium carbonate represented as R1-O-C(=O)-O-Li (R1 represents an alkyl group having 1-5 carbon atoms); at least one of reactive cyclic carbonate esters having a halogen group, a vinyl group or the like; and at least one of LiPFOand LiPFO.

Description

  The present technology relates to an electrolyte for a secondary battery, a secondary battery using the electrolyte for the secondary battery, and a battery pack, an electric vehicle, an electric power storage system, an electric tool, and an electronic device using the secondary battery.

  In recent years, various electronic devices such as mobile phones and personal digital assistants (PDAs) have become widespread, and further downsizing, weight reduction, and long life have been strongly demanded. 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. Recently, the secondary battery is typified by a battery pack that is detachably mounted on an electronic device, an electric vehicle such as an electric vehicle, an electric power storage system such as a household electric power server, or an electric tool such as an electric drill. Application to various uses is also being considered.

  As secondary batteries, those utilizing various charge / discharge principles have been widely proposed, and among them, those utilizing the storage and release of electrode reactants are considered promising. This is because higher energy density can be obtained than lead batteries and nickel cadmium batteries.

  The secondary battery includes an electrolytic solution together with a positive electrode and a negative electrode. The positive electrode includes a positive electrode active material capable of occluding and releasing an electrode reactant, and the negative electrode includes a negative electrode active material capable of occluding and releasing an electrode reactant. The electrolytic solution contains a solvent and an electrolyte salt. In order to obtain a high battery capacity, a mixed solvent of a cyclic carbonate which is a high dielectric constant solvent and a chain carbonate which is a low viscosity solvent is used as a solvent for the electrolytic solution.

  Since the composition of the electrolytic solution greatly affects the performance of the secondary battery, various studies have been made on the composition. Specifically, in order to improve cycle characteristics and the like, it has been proposed to use a reactive cyclic carbonate having a halogen or unsaturated carbon bond (see, for example, Patent Document 1). This is because a coating film is formed on the surface of the negative electrode, so that the decomposition reaction of the electrolytic solution is suppressed. In this case, it has also been proposed to use a difluorophosphate in order to improve cycle characteristics and the like even if the amount of the cyclic carbonate having an unsaturated carbon bond is small (see, for example, Patent Document 2).

  However, when a reactive cyclic carbonate is used, a film is formed on the surface of the negative electrode, but the resistance of the surface of the negative electrode increases. As a result, the discharge capacity decreases when discharging with a large current or when charging and discharging are repeated many times. Further, at the time of the first charge when the coating film is formed on the surface of the negative electrode, the electrode reactant released from the positive electrode is inactivated on the surface or inside of the negative electrode active material. Thereby, since the discharge capacity is relatively decreased with respect to the charge capacity at the first charge / discharge, the battery capacity is lower than the theoretical capacity.

  Therefore, in order to suppress a decrease in battery capacity when using a reactive cyclic carbonate, it has been proposed to use lithium oxalate, lithium formate, ammonium oxalate, lithium alkyl carbonate, or the like (for example, (See Patent Documents 3 to 6.) In this case, not only the electrolytic solution but also the positive electrode or the negative electrode contains lithium alkyl carbonate.

JP 2006-086058 A JP 2007-141830 A JP-A-1995-254436 JP 1997-283181 A JP 1999-339807 A Japanese Patent No. 4270904

  In recent years, electronic devices equipped with secondary batteries have become more sophisticated and multifunctional, and therefore, charging and discharging of secondary batteries tend to be repeated as the power consumption of the electronic devices increases. . Therefore, further improvements regarding battery characteristics are required.

  The present technology has been made in view of such problems, and the purpose thereof is an electrolyte solution for a secondary battery, a secondary battery, a battery pack, an electric vehicle, an electric power storage system, an electric motor that can obtain excellent battery characteristics. To provide tools and electronics.

  The electrolytic solution for a secondary battery of the present technology includes at least one of lithium alkyl carbonate represented by the following formula (1) and reactive carbonates represented by the following formulas (2) to (5). It contains a seed and at least one of lithium fluorophosphate represented by the following formula (6) and formula (7).

R1-O—C (═O) —O—Li (1)
(R1 is an alkyl group having 1 to 5 carbon atoms.)

（Ｒ２〜Ｒ５は水素基、ハロゲン基、アルキル基またはハロゲン化アルキル基であり、Ｒ２〜Ｒ５のうちの少なくとも１つはハロゲン基またはハロゲン化アルキル基である。Ｒ６およびＲ７は水素基またはアルキル基である。Ｒ８〜Ｒ１１は水素基、アルキル基、ビニル基またはアリル基であり、Ｒ８〜Ｒ１１のうちの少なくとも１つはビニル基またはアリル基である。Ｒ１２は＝ＣＨ−Ｒ１３で表される基であり、Ｒ１３は水素基またはアルキル基である。）

(R2 to R5 are a hydrogen group, a halogen group, an alkyl group or a halogenated alkyl group, and at least one of R2 to R5 is a halogen group or a halogenated alkyl group. R6 and R7 are a hydrogen group or an alkyl group. R8 to R11 are a hydrogen group, an alkyl group, a vinyl group or an allyl group, and at least one of R8 to R11 is a vinyl group or an allyl group, and R12 is a group represented by ═CH—R13. And R13 is a hydrogen group or an alkyl group.)

Li ₂ PFO ₃ (6)
LiPF ₂ O ₂ (7)

  Moreover, the secondary battery of this technique is equipped with electrolyte solution with a positive electrode and a negative electrode, and the electrolyte solution has a composition similar to the electrolyte solution for secondary batteries mentioned above. Furthermore, the battery pack, the electric vehicle, the power storage system, the electric tool, and the electronic device of the present technology use the above-described secondary battery of the present technology.

  According to the secondary battery electrolytic solution or secondary battery of the present technology, the electrolytic solution contains the above-described lithium alkyl carbonate, reactive cyclic carbonate, and lithium fluorophosphate, so that excellent battery characteristics can be obtained. Can do. Moreover, the same effect can be acquired also in the battery pack using the secondary battery of this technique, an electric vehicle, an electric power storage system, an electric tool, and an electronic device.

It is sectional drawing showing the structure of the secondary battery (cylindrical type) of one Embodiment of this technique. It is sectional drawing which expands and represents a part of winding electrode body shown in FIG. It is a perspective view showing the structure of the other secondary battery (laminate film type) of one Embodiment of this technique. It is sectional drawing along the IV-IV line of the wound electrode body shown in FIG. It is a block diagram showing the structure of the application example (battery pack) of a secondary battery. It is a block diagram showing the structure of the application example (electric vehicle) of a secondary battery. It is a block diagram showing the structure of the application example (electric power storage system) of a secondary battery. It is a block diagram showing the structure of the application example (electric tool) of a secondary battery.

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

1. 2. Electrolyte for secondary battery and secondary battery 1-1. Cylindrical type 1-2. Laminated film type 2. Use of secondary battery 2-1. Battery pack 2-2. Electric vehicle 2-3. Electric power storage system 2-4. Electric tool

<1. Secondary battery electrolyte and secondary battery / 1-1. Cylindrical type>
1 and 2 show a cross-sectional configuration of a secondary battery using an electrolyte for a secondary battery according to an embodiment of the present technology. In FIG. 2, one of the wound electrode bodies 20 shown in FIG. The department is expanding.

[Overall structure of secondary battery]
This secondary battery is, for example, a lithium ion secondary battery (hereinafter, simply referred to as “secondary battery”) in which battery capacity is obtained by occlusion and release of lithium ions that are electrode reactants.

  The secondary battery described here is a so-called cylindrical type. In this secondary battery, a spirally wound electrode body 20 and a pair of insulating plates 12 and 13 are housed inside a substantially hollow cylindrical battery can 11. The wound electrode body 20 is obtained by, for example, laminating and winding a positive electrode 21 and a negative electrode 22 with a separator 23 interposed therebetween.

  The battery can 11 has a hollow structure in which one end is closed and the other end is opened, and is formed of, for example, Fe, Al, or an alloy thereof. Note that Ni or the like may be plated on the surface of the battery can 11. The pair of insulating plates 12 and 13 are disposed 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 (PTC element) 16 are caulked through a gasket 17 at the open end of the battery can 11. Thereby, the battery can 11 is sealed. The battery lid 14 is formed of the same material as the battery can 11, for example. The safety valve mechanism 15 and the thermal resistance element 16 are provided inside the battery lid 14, and the safety valve mechanism 15 is electrically connected to the battery lid 14 via the thermal 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 15A is reversed and the electrical connection between the battery lid 14 and the wound electrode body 20 is established. It is designed to cut. The heat sensitive resistance element 16 prevents abnormal heat generation caused by a large current. In the heat sensitive resistor element 16, when the temperature rises, the resistance increases accordingly. The gasket 17 is made of, for example, an insulating material, and asphalt may be applied to the surface thereof.

  A center pin 24 may be inserted in the center of the wound electrode body 20. For example, a positive electrode lead 25 formed of a conductive material such as Al is connected to the positive electrode 21, and a negative electrode lead 26 formed of a conductive material such as Ni is connected to the negative electrode 22. ing. The positive electrode lead 25 is welded to the safety valve mechanism 15 and is electrically connected to the battery lid 14, and the negative electrode lead 26 is welded to the battery can 11 and is electrically connected to the battery can 11. It is connected to the.

[Positive electrode]
The positive electrode 21 is, for example, one in which a positive electrode active material layer 21B is provided on one side or both sides of a positive electrode current collector 21A. The positive electrode current collector 21A is formed of a conductive material such as Al, Ni, or stainless steel, for example.

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

The positive electrode material is preferably a lithium-containing compound. This is because a high energy density can be obtained. Examples of the lithium-containing compound include a composite oxide containing Li and a transition metal element as constituent elements, and a phosphate compound containing Li and a transition metal element as constituent elements. Among them, the transition metal element is preferably one or more of Co, Ni, Mn, and Fe. 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. The values of x and y vary depending on the charge / discharge state, but are generally 0.05 ≦ x ≦ 1.10 and 0.05 ≦ y ≦ 1.10.

Examples of the composite oxide containing Li and a transition metal element include Li _x CoO ₂ , Li _x NiO ₂ , and a lithium nickel composite oxide represented by the formula (10). This is because high battery capacity is obtained and excellent cycle characteristics are also obtained.

LiNi _1-m M _m O ₂ (10)
(M is Co, Mn, Fe, Al, V, Sn, Mg, Ti, Sr, Ca, Zr, Mo, Tc, Ru, Ta, W, Re, Yb, Cu, Zn, Ba, B, Cr, Si , Ga, P, Sb and Nb, and m is 0.005 <m <0.5.)

The phosphate compound containing Li and a transition metal element is, for example, a lithium iron phosphate compound represented by the following formula (8). This is because high battery capacity is obtained and excellent cycle characteristics are also obtained. This lithium iron phosphate compound is, for example, LiFePO ₄ or LiFe _a Mn _1-a O ₄ .

LiFe _a M1 _1-a O ₄ (8)
(M1 is at least one of Mg, Al, Ca, Ti, V, Mn, Co, Ni, Cu, Zn, Zr, and Ba, and a is 0 <a ≦ 1.)

  In addition, the positive electrode material may be, for example, an oxide, disulfide, chalcogenide, or conductive polymer. 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.

Especially, as a positive electrode material, the positive electrode material which shows a predetermined charging / discharging characteristic is preferable. This positive electrode material has a charge / discharge curve (vertical axis: potential (V), horizontal axis: charge / discharge capacity (mAh)) with a potential of 1 V to 5 V (vs. lithium metal potential) and a full charge / discharge capacity. A potential flat portion where the amount of change in potential is within 25 mV is shown in a region where the capacitance is 50% or more. This is because excellent battery characteristics can be obtained when used in combination with an electrolytic solution containing lithium alkyl carbonate, reactive cyclic carbonate and lithium fluorophosphate described below. The charge / discharge curve described here is a charge / discharge curve of the positive electrode material itself, and the potential range of 1 V to 5 V is a potential range in which lithium ions can be occluded and released in the secondary battery. A specific example of the positive electrode material is any one or more of lithium iron phosphate compounds shown in Formula (8). For example, a potential flat portion is set at a potential = about 1.55 V in the charge / discharge curve. Such as LiFePO ₄ .

  The positive electrode binder is, for example, any one kind or two kinds or more of synthetic rubber or polymer material. Examples of the synthetic rubber include styrene butadiene rubber, fluorine rubber, and ethylene propylene diene. The polymer material is, for example, polyvinylidene fluoride or polyimide.

  The positive electrode conductive agent is, for example, any one type or two or more types of carbon materials. Examples of the carbon material include graphite, carbon black, acetylene black, and ketjen black. The positive electrode conductive agent may be a metal material 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 one or both surfaces of a negative electrode current collector 22A.

  The negative electrode current collector 22A is formed of, for example, a conductive material such as Cu, Ni, or stainless steel. 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. A copper foil produced by an electrolytic method is generally called an electrolytic copper foil.

  The negative electrode active material layer 22B includes one or more negative electrode materials capable of occluding and releasing lithium ions as a negative electrode active material, and a negative electrode binder or a negative electrode conductive agent as necessary. Other materials 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 this 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 deposition of Li metal during charging and discharging.

  The negative electrode material is, for example, a carbon material. This is because the change in crystal structure at the time of occlusion and release 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. This carbon material is, for example, graphitizable carbon, non-graphitizable carbon having a (002) plane spacing of 0.37 nm or more, or graphite having a (002) plane spacing of 0.34 nm or less. . More specifically, pyrolytic carbons, cokes, glassy carbon fibers, organic polymer compound fired bodies, activated carbon or carbon blacks. Among these, the cokes include pitch coke, needle coke, petroleum coke and the like. The organic polymer compound fired body is obtained by firing (carbonizing) a polymer compound such as a phenol resin or a furan resin at an appropriate temperature. In addition, the carbon material may be low crystalline carbon or amorphous carbon heat-treated at about 1000 ° C. or less. The shape of the carbon material may be any of a fibrous shape, a spherical shape, a granular shape, and a scale shape.

  The negative electrode material is, for example, a material (metal material) containing any one or two of a metal element and a metalloid element as a constituent element. This is because a high energy density can be obtained. The metal-based material may be a simple substance, an alloy or a compound, or two or more of them, or one having at least a part of one or more of those phases. The alloy includes a material including one or more metal elements and one or more metalloid elements in addition to a material composed of two or more metal elements. The alloy may contain a nonmetallic element. The structure includes a solid solution, a eutectic (eutectic mixture), an intermetallic compound, or a coexistence of two or more kinds thereof.

  The metal element or metalloid element described above is, for example, a metal element or metalloid element capable of forming an alloy with Li, and specifically, one or more of the following elements. Mg, B, Al, Ga, In, Si, Ge, Sn, Pb, Bi, Cd, Ag, Zn, Hf, Zr, Y, Pd, or Pt. Among these, at least one of Si and Sn is preferable. This is because the ability to occlude and release lithium ions is excellent, and a high energy density can be obtained.

  The material containing at least one of Si and Sn may be a simple substance, an alloy, or a compound of Si or Sn, or may be two or more of them, or at least a part of one or more of those phases. You may have. The simple substance is a simple substance in a general sense (may contain a small amount of impurities), and does not necessarily mean 100% purity.

  An alloy of Si is, for example, a material containing one or more of the following elements as a constituent element other than Si. Sn, Ni, Cu, Fe, Co, Mn, Zn, In, Ag, Ti, Ge, Bi, Sb or Cr. Examples of the Si compound include a material containing C or O as a constituent element other than Si. Note that the Si compound may include, for example, one or more of the elements described for the Si alloy as a constituent element other than Si.

Examples of the Si alloy or compound include the following materials. SiB _4, a _{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, MnSi 2, NbSi 2 or TaSi _2. VSi ₂ , WSi ₂ , ZnSi ₂ , SiC, Si ₃ N ₄ , Si ₂ N ₂ O, SiO _v (0 <v ≦ 2) or LiSiO. Note that _v in SiO _v may be 0.2 <v <1.4.

The Sn alloy is, for example, a material containing one or more of the following elements as a constituent element other than Sn. Si, Ni, Cu, Fe, Co, Mn, Zn, In, Ag, Ti, Ge, Bi, Sb or Cr. Examples of the Sn compound include a material containing C or O as a constituent element. The Sn compound may contain, for example, one or more of the elements described for the Sn alloy as a constituent element other than Sn. Examples of the alloy or compound of Sn include SnO _w (0 <w ≦ 2), SnSiO ₃ , LiSnO, or Mg ₂ Sn.

  Moreover, as a material containing Sn, for example, a material containing Sn as the first constituent element and the second and third constituent elements in addition thereto is preferable. The second constituent element is, for example, one or more of the following elements. Co, Fe, Mg, Ti, V, Cr, Mn, Ni, Cu, Zn, Ga, Zr, Nb, Mo, Ag, In, Ce, Hf, Ta, W, Bi, or Si. The third constituent element is, for example, one type or two or more types of B, C, Al, and P. This is because when the second and third constituent elements are included, a high battery capacity and excellent cycle characteristics can be obtained.

  Among these, a material containing Sn, Co and C (SnCoC-containing material) is preferable. As the composition of the SnCoC-containing material, for example, the C content is 9.9 mass% to 29.7 mass%, and the Sn and Co content ratio (Co / (Sn + Co)) is 20 mass% to 70 mass%. % By mass. This is because a high energy density can be obtained in such a composition range.

  This SnCoC-containing material has a phase containing Sn, Co, and C, and the phase is preferably low crystalline or amorphous. This phase is a reaction phase capable of reacting with Li, and excellent characteristics can be obtained due to the presence of the reaction phase. The half width of the diffraction peak obtained by X-ray diffraction of this phase is preferably 1 ° or more at a diffraction angle 2θ when CuKα ray is used as the specific X-ray and the drawing speed is 1 ° / min. . This is because lithium ions are occluded and released more smoothly, and the reactivity with the electrolytic solution is reduced. Note that the SnCoC-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 a diffraction peak obtained by X-ray diffraction corresponds to a reaction phase capable of reacting with Li can be easily determined by comparing X-ray diffraction charts before and after electrochemical reaction with Li. . For example, if the position of the diffraction peak changes before and after the electrochemical reaction with Li, it corresponds to a reaction phase capable of reacting with Li. 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 has, for example, each of the above-described constituent elements, and is considered to be low crystallization or amorphous mainly due to the presence of C.

  In the SnCoC-containing material, it is preferable that at least a part of C that is a constituent element is bonded to a metal element or a metalloid element that is another constituent element. This is because aggregation or crystallization of Sn 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. When at least a part of C is bonded to a metal element, a metalloid element, or the like, the peak of the synthesized wave of C 1s orbital (C1s) appears in a region lower than 284.5 eV. It is assumed that energy calibration is performed so that a peak of 4f orbit (Au4f) of Au atoms 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 the XPS measurement, the waveform of the C1s peak is obtained in a form including the surface contamination carbon peak and the C peak in the SnCoC-containing material. Therefore, for example, by analyzing using commercially available software, both peaks 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).

  Note that the SnCoC-containing material may further contain other constituent elements as necessary. Such other constituent elements are, for example, one or more of Si, Fe, Ni, Cr, In, Nb, Ge, Ti, Mo, Al, P, Ga, and Bi.

  In addition to this SnCoC-containing material, a material containing Sn, Co, Fe and C (SnCoFeC-containing material) is also preferable. The composition of the SnCoFeC-containing material can be arbitrarily set. For example, the composition when the Fe content is set to be small is as follows. The content of C is 9.9 mass% to 29.7 mass%, the content of Fe is 0.3 mass% to 5.9 mass%, and the ratio of the content of Sn and Co (Co / (Sn + Co)) is 30% by mass to 70% by mass. For example, the composition in the case where the Fe content is set to be large is as follows. The content of C is 11.9 mass% to 29.7 mass%, and the ratio of the content of Sn, Co and Fe ((Co + Fe) / (Sn + Co + Fe)) is 26.4 mass% to 48.5 mass%, Co The ratio of the Fe content (Co / (Co + Fe)) is 9.9 mass% to 79.5 mass%. This is because a high energy density can be obtained in such a composition range. The physical properties (half width, etc.) of this SnCoFeC-containing material are the same as those of the above-described SnCoC-containing material.

  Further, the negative electrode material is, for example, at least one of lithium-titanium composite oxides represented by the following formulas (9) to (11). A lithium composite oxide containing Ti as a constituent element together with Li is more electrochemically stable (low reactivity) than a carbon material (for example, graphite), and therefore the decomposition reaction of the electrolyte solution due to the reactivity of the anode 22 This is because it is suppressed. Thereby, even if charging / discharging is repeated, the resistance of the negative electrode 22 hardly increases.

Li [Li _x M 2 _{(1-3x) / 2} Ti _{(3 + x) / 2} ] O ₄ (9)
(M2 is at least one of Mg, Ca, Cu, Zn and Sr, and x satisfies 0 ≦ x ≦ 1/3.)

Li [Li _y M3 _1-3y Ti _{1 + 2y} ] O ₄ (10)
(M3 is at least one of Al, Sc, Cr, Mn, Fe, Ga and Y, and y satisfies 0 ≦ y ≦ 1/3.)

Li [Li _1/3 M4 _z Ti _{(5/3) -z} ] O 4 (11)
(M4 is at least one of V, Zr and Nb, and z satisfies 0 ≦ z ≦ 2/3.)

M2 in the formula (9) is a metal element that can be a divalent ion, M3 in the formula (10) is a metal element that can be a trivalent ion, and M4 in the formula (11) is a metal element that can be a tetravalent ion. Specific examples of the lithium titanium composite oxide represented by the formula (9) include Li _3.75 Ti _4.875 Mg _0.375 O ₁₂ . A specific example of the lithium titanium composite oxide represented by the formula (10) is LiCrTiO ₄ or the like. Specific examples of the lithium titanium composite oxide represented by the formula (11) include Li ₄ Ti ₅ O ₁₂ or Li ₄ Ti _4.95 Nb _0.05 O ₁₂ .

  In addition, the negative electrode material may be, for example, a metal oxide or a polymer compound. Examples of the metal oxide include iron oxide, ruthenium oxide, and molybdenum oxide. Examples of the polymer compound include polyacetylene, polyaniline, and polypyrrole.

Especially, as a negative electrode material, the material which shows a predetermined charging / discharging characteristic for the same reason as a positive electrode material is preferable. That is, in the charge / discharge curve, the potential is 1 V to 5 V (vs. lithium metal potential), and the potential flatness is within 25 mV in the region where the charge / discharge capacity is 50% or more of the total charge / discharge capacity. Material. The charge / discharge curve described here is a charge / discharge curve of the negative electrode material itself. Specific examples of the negative electrode material include one or more of lithium titanium composite oxides represented by the formulas (9) to (11). For example, in the charge / discharge curve, the potential is about 3.4 V. Li ₄ Ti ₅ O ₁₂ or the like showing the flat portion of the battery.

  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 kinds thereof. The coating 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 such as an organic solvent. Examples of the vapor phase method include a physical deposition method and a chemical deposition method. Specific examples include vacuum deposition, sputtering, ion plating, laser ablation, thermal chemical vapor deposition, chemical vapor deposition (CVD), and plasma chemical vapor deposition. 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 the negative electrode active material is sprayed 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.

  In this secondary battery, as described above, in order to prevent unintentional deposition of Li metal on the negative electrode 22 during charging, the electrochemical equivalent of the negative electrode material capable of occluding and releasing lithium ions is It is larger than the electrochemical equivalent. In addition, when the open circuit voltage (that is, the battery voltage) at the time of full charge is 4.25 V or more, the amount of lithium ions released per unit mass increases even when the same positive electrode active material is used compared to the case of 4.20 V. Accordingly, the amounts of the positive electrode active material and the negative electrode active material are adjusted accordingly. Thereby, a high energy density can be obtained.

[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, for example, a porous film made of synthetic resin or ceramic, and may be a laminated film in which two or more kinds of porous films are laminated. The synthetic resin is, for example, polytetrafluoroethylene, polypropylene, or polyethylene.

  In particular, the separator 23 may include, for example, a base material layer made of the porous film described above and a polymer compound layer provided on at least one surface of the base material layer. This is because the adhesion of the separator 23 to the positive electrode 21 and the negative electrode 22 is improved, so that the distortion of the wound electrode body 20 is suppressed. As a result, the decomposition reaction of the electrolytic solution is suppressed, and the leakage of the electrolytic solution impregnated in the base material layer is also suppressed. Therefore, the resistance of the secondary battery is hardly increased even when charging and discharging are repeated, and the battery swells. Is suppressed.

  The polymer compound layer includes, for example, a polymer material such as polyvinylidene fluoride. This is because it has excellent physical strength and is electrochemically stable. However, the polymer material may be a material other than polyvinylidene fluoride. This polymer compound layer is prepared by, for example, preparing a solution in which a polymer material is dissolved and then applying the solution to the surface of the base material layer, or immersing the base material layer in the solution and then drying it. It is formed.

[Electrolyte]
The separator 23 is impregnated with an electrolytic solution that is a liquid electrolyte. This electrolytic solution, together with a solvent and an electrolyte salt, is at least one of lithium alkyl carbonate represented by the following formula (1) and reactive cyclic carbonates represented by the following formulas (2) to (5). 1 type and at least one of the lithium fluorophosphates represented by the following formula (6) and formula (7) are included. However, the electrolytic solution may further contain other materials such as additives as necessary.

R1-O—C (═O) —O—Li (1)
(R1 is an alkyl group having 1 to 5 carbon atoms.)

（Ｒ２〜Ｒ５は水素基、ハロゲン基、アルキル基またはハロゲン化アルキル基であり、Ｒ２〜Ｒ５のうちの少なくとも１つはハロゲン基またはハロゲン化アルキル基である。Ｒ６およびＲ７は水素基またはアルキル基である。Ｒ８〜Ｒ１１は水素基、アルキル基、ビニル基またはアリル基であり、Ｒ８〜Ｒ１１のうちの少なくとも１つはビニル基またはアリル基である。Ｒ１２は＝ＣＨ−Ｒ１３で表される基であり、Ｒ１３は水素基またはアルキル基である。）

(R2 to R5 are a hydrogen group, a halogen group, an alkyl group or a halogenated alkyl group, and at least one of R2 to R5 is a halogen group or a halogenated alkyl group. R6 and R7 are a hydrogen group or an alkyl group. R8 to R11 are a hydrogen group, an alkyl group, a vinyl group or an allyl group, and at least one of R8 to R11 is a vinyl group or an allyl group, and R12 is a group represented by ═CH—R13. And R13 is a hydrogen group or an alkyl group.)

Li ₂ PFO ₃ (6)
LiPF ₂ O ₂ (7)

  The alkyl lithium carbonate represented by the formula (1) is lithium carbonate having an alkyl group (R1) having a predetermined carbon number. The reactive cyclic carbonate represented by the formula (2) is a cyclic carbonate (halogenated cyclic carbonate) containing one or more halogens as constituent elements. The reactive cyclic carbonates represented by the formulas (3) to (5) are cyclic carbonates (unsaturated carbon bond cyclic carbonates) having an unsaturated carbon bond (carbon-carbon double bond). Here, the formula (3) is a vinylene carbonate compound, the formula (4) is a vinyl ethylene carbonate compound, and the formula (5) is a methylene ethylene carbonate compound. The lithium fluorophosphate represented by formula (4) is lithium monofluorophosphate, and the lithium fluorophosphate represented by formula (5) is lithium difluorophosphate.

The reason why the electrolytic solution contains three components of lithium alkyl carbonate, reactive cyclic carbonate and lithium fluorophosphate is that the decomposition reaction of the electrolytic solution is specifically suppressed by the synergistic action of the three. Specifically, first, a strong coating is formed on the surface of the negative electrode 22 mainly by the reactive cyclic carbonate during the first charge, so that the decomposition reaction of the electrolytic solution due to the reactivity of the negative electrode 22 is not caused. It is suppressed. Second, the presence of alkyl lithium carbonate having a structure similar to that of the main solvent (a chain or cyclic carbonate described later) in the electrolytic solution suppresses the decomposition reaction of the solvent in the vicinity of the surface of the anode 22. The Third, the presence of lithium fluorophosphate having a structure similar to an electrolyte salt (such as LiPF ₆ described later) in the electrolytic solution suppresses the decomposition reaction of the electrolyte salt in the vicinity of the surface of the anode 22. For these reasons, even when the secondary battery is charged / discharged or stored, the decomposition reaction of the electrolytic solution is remarkably suppressed, and the tendency becomes remarkable particularly in a high temperature environment.

In the alkyl lithium carbonate, the type of R1 is not particularly limited as long as it is an alkyl group having 1 to 5 carbon atoms. This is because if the carbon number of R1 (alkyl group) in the alkyl lithium carbonate is 1 to 5, the above-described advantages can be obtained without depending on the type of R1. This R1 is a methyl group (—CH ₃ ), an ethyl group (—C ₂ H ₅ ), a propyl group (—C ₃ H ₇ ), a butyl group (—C ₄ H ₉ ) or a pentyl group (—C ₅ H _11). ). However, the propyl group, butyl group and pentyl group may be linear or branched. More specifically, the propyl group is an n-propyl group or an i-propyl group. The butyl group is an n-butyl group, an s-butyl group, an i-butyl group or a t-butyl group. The pentyl group is an n-pentyl group, an s-pentyl group, an i-pentyl group, a t-pentyl group, or a neopentyl group (2,2-dimethylpropyl group).

  Specific examples of this lithium alkyl carbonate include methyl lithium carbonate, ethyl lithium carbonate, n-propyl lithium carbonate, i-propyl lithium carbonate, n-butyl lithium carbonate, t-butyl lithium carbonate, n-pentyl lithium carbonate or t-pentyl. Such as lithium carbonate. However, the alkyl lithium carbonate may be another compound corresponding to the formula (1), or may be one type or two or more types.

  The content of lithium alkyl carbonate in the electrolytic solution is not particularly limited, but is preferably 5 ppm to 2000 ppm. This is because the decomposition reaction of the electrolytic solution is further suppressed.

  In the halogenated cyclic carbonate, the types of R2 to R5 are not particularly limited as long as they are a hydrogen group, a halogen group, an alkyl group, or a halogenated alkyl group. This is because when at least one of R2 to R5 is a halogen group or a halogenated alkyl group, the above-described advantages can be obtained without depending on the type of R2 to R5. The number of carbon atoms of the alkyl group and the halogenated alkyl group is not particularly limited, but is preferably not too large to ensure solubility and compatibility, for example, 3 or less. Note that R2 to R5 may be the same type of group, different types of groups, or a part of R2 to R5 may be the same type of group. The kind of halogen group is, for example, -F, -Cl, -Br or -I. The halogenated alkyl group is a group in which at least a part of H in the alkyl group is substituted with one kind or two or more kinds of halogens. The number of halogens is preferably two rather than one, and may be three or more. This is because a stronger and more stable protective film is formed, so that the decomposition reaction of the electrolytic solution is further suppressed.

  Specific examples of the halogenated cyclic carbonate include 4-fluoro-1,3-dioxolan-2-one, 4-chloro-1,3-dioxolan-2-one, 4,5-difluoro-1,3-dioxolane. 2-one, tetrafluoro-1,3-dioxolan-2-one, 4-fluoro-5-chloro-1,3-dioxolan-2-one, 4,5-dichloro-1,3-dioxolane-2- ON, tetrachloro-1,3-dioxolan-2-one, 4,5-bistrifluoromethyl-1,3-dioxolan-2-one, 4-trifluoromethyl-1,3-dioxolan-2-one, 4 , 5-difluoro-4,5-dimethyl-1,3-dioxolan-2-one, 4-methyl-5,5-difluoro-1,3-dioxolan-2-one, 4-ethyl-5,5-diflu B-1,3-dioxolan-2-one, 4-trifluoromethyl-5-fluoro-1,3-dioxolan-2-one, 4-trifluoromethyl-5-methyl-1,3-dioxolane-2- ON, 4-fluoro-4,5-dimethyl-1,3-dioxolan-2-one, 4,4-difluoro-5- (1,1-difluoroethyl) -1,3-dioxolan-2-one, 4, , 5-dichloro-4,5-dimethyl-1,3-dioxolan-2-one, 4-ethyl-5-fluoro-1,3-dioxolan-2-one, 4-ethyl-4,5-difluoro-1 , 3-dioxolan-2-one, 4-ethyl-4,5,5-trifluoro-1,3-dioxolan-2-one, or 4-fluoro-4-methyl-1,3-dioxolan-2-one Etc. However, the halogenated cyclic carbonate may be another compound corresponding to the formula (2), or one kind or two or more kinds.

  In the unsaturated carbon bond cyclic carbonate represented by the formula (3), the type of R6 and R7 is not particularly limited as long as it is a hydrogen group or an alkyl group. This is because the above-described advantages can be obtained without depending on the types of R6 and R7 because the carbon-carbon double bond is already present inside the five-membered ring. The number of carbon atoms of the alkyl group is not particularly limited, but is preferably not too large to ensure solubility and compatibility, for example, 3 or less. R6 and R7 may be the same type of group or different types of groups.

  In the unsaturated carbon bond cyclic ester carbonate represented by the formula (4), the type of R8 to R11 is not particularly limited as long as it is a hydrogen group, an alkyl group, a vinyl group, or an allyl group. If at least one of R8 to R11 is a vinyl group or an allyl group, the above-described advantages can be obtained without depending on the type of R8 to R11 because it has a carbon-carbon double bond outside the five-membered ring. It is. The number of carbon atoms of the alkyl group, vinyl group or allyl group is not particularly limited, but is preferably not too large to ensure solubility and compatibility, for example, 3 or less. Note that R8 to R11 may be the same type of group, different types of groups, or a part of R8 to R11 may be the same type of group.

  In the unsaturated carbon bond cyclic carbonate represented by the formula (5), the type of R12 is not particularly limited as long as it is a group represented by CH—R13 (R13 is a hydrogen group or an alkyl group). This is because the above-described advantages can be obtained without depending on the type of R12 because the carbon-carbon double bond is already present outside the five-membered ring. The number of carbon atoms of R12 is not particularly limited, but is preferably not too large to ensure solubility and compatibility, for example, 3 or less.

  Specific examples of this unsaturated carbon bond cyclic ester carbonate are as follows. Examples of the vinylene carbonate-based compound include vinylene carbonate (1,3-dioxol-2-one), methyl vinylene carbonate (4-methyl-1,3-dioxol-2-one), and 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- Such as dioxol-2-one or 4-trifluoromethyl-1,3-dioxol-2-one; Examples of the vinyl ethylene carbonate compound include vinyl ethylene carbonate (4-vinyl-1,3-dioxolan-2-one), 4-methyl-4-vinyl-1,3-dioxolan-2-one, 4-ethyl- 4-vinyl-1,3-dioxolan-2-one, 4-n-propyl-4-vinyl-1,3-dioxolan-2-one, 5-methyl-4-vinyl-1,3-dioxolane-2-one ON, 4,4-divinyl-1,3-dioxolan-2-one, or 4,5-divinyl-1,3-dioxolan-2-one. Examples of the methylene ethylene carbonate compound include methylene ethylene carbonate (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-dioxolan-2-one and the like. However, the unsaturated carbon bond cyclic ester carbonate may be another compound corresponding to Formula (3) to Formula (5), or may be one type or two or more types.

  The content of the reactive cyclic carbonate in the electrolytic solution is not particularly limited, but is preferably 0.5% by weight to 10% by weight. This is because the decomposition reaction of the electrolytic solution is further suppressed.

  Although content of lithium fluorophosphate in electrolyte solution is not specifically limited, Especially, it is preferable that they are 5 ppm-3000 ppm. This is because the decomposition reaction of the electrolytic solution is further suppressed.

  The solvent includes, for example, any one kind or two or more kinds of nonaqueous solvents such as organic solvents. Examples of the non-aqueous solvent include ethylene carbonate, propylene carbonate, butylene carbonate, dimethyl carbonate, diethyl carbonate, ethyl methyl carbonate, methyl propyl carbonate, γ-butyrolactone, γ-valerolactone, 1,2-dimethoxyethane, tetrahydrofuran, 2 -Methyltetrahydrofuran, tetrahydropyran, 1,3-dioxolane, 4-methyl-1,3-dioxolane, 1,3-dioxane, 1,4-dioxane, methyl acetate, ethyl acetate, methyl propionate, ethyl propionate, butyric acid Methyl, methyl isobutyrate, methyl trimethylacetate, ethyl trimethylacetate, acetonitrile, glutaronitrile, adiponitrile, methoxyacetonitrile, 3-methoxypropionitrile, N, N-dimethylformamide, N-methylpyrrolidinone, N-methyl Examples include oxazolidinone, N, N'-dimethylimidazolidinone, nitromethane, nitroethane, sulfolane, trimethyl phosphate, and 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 more excellent characteristics 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 a chain carbonate (halogenated chain carbonate) containing one or more halogens as a constituent element. This is because a stable coating is formed on the surface of the negative electrode 22 during charging and discharging, and thus the decomposition reaction of the electrolytic solution is suppressed. The kind and number of halogen groups are the same as, for example, halogenated cyclic carbonate. Examples of the halogenated chain carbonate ester include fluoromethyl methyl carbonate, bis (fluoromethyl) carbonate, and difluoromethyl methyl carbonate. The content of the halogenated chain carbonate in the solvent is not particularly limited, but is, for example, 0.01 wt% to 50 wt%. This is because the decomposition reaction of the electrolytic solution is suppressed without excessively reducing the battery capacity.

  The solvent may contain sultone (cyclic sulfonic acid ester). This is because the chemical stability of the electrolytic solution is improved. The sultone is, for example, propane sultone or propene sultone. In addition, although content of sultone in a solvent is not specifically limited, For example, it is 0.5 weight%-5 weight%. This is because the decomposition reaction of the electrolytic solution is suppressed without excessively reducing the battery capacity.

  Furthermore, the solvent may contain an acid anhydride. This is because the chemical stability of the electrolytic solution is further improved. Examples of the acid anhydride include dicarboxylic acid anhydride, disulfonic acid anhydride, and carboxylic acid sulfonic acid anhydride. Examples of the dicarboxylic acid anhydride include succinic anhydride, glutaric anhydride, and maleic anhydride. Examples of the disulfonic anhydride include ethanedisulfonic anhydride and propanedisulfonic anhydride. Examples of the carboxylic acid sulfonic acid anhydride include anhydrous sulfobenzoic acid, anhydrous sulfopropionic acid, and anhydrous sulfobutyric acid. In addition, although content of the acid anhydride in a solvent is not specifically limited, For example, they are 0.5 weight%-5 weight%. This is because the decomposition reaction of the electrolytic solution is suppressed without excessively reducing the battery capacity.

[Electrolyte salt]
The electrolyte salt includes, for example, any one or more of lithium salts described below. However, the electrolyte salt may be a salt other than the lithium salt (for example, a light metal salt other than the lithium salt).

Examples of the lithium salt include LiPF ₆ , LiBF ₄ , LiClO ₄ , LiAsF ₆ , LiB (C ₆ H ₅ ) ₄ , LiCH ₃ SO ₃ , LiCF ₃ SO ₃ , LiAlCl ₄ , Li ₂ SiF ₆ , LiCl, or LiBr. It is. This is because excellent battery capacity, cycle characteristics, storage characteristics, and the like can be obtained.

Among these, at least one of LiPF ₆ , LiBF ₄ , LiClO ₄ and LiAsF ₆ is preferable, and LiPF ₆ is more preferable. This is because a higher effect can be obtained because the internal resistance is lowered.

  The content of the electrolyte salt is preferably 0.3 mol / kg or more and 3.0 mol / kg or less with respect to the solvent. This is because high ionic conductivity is obtained.

[Operation of secondary battery]
In this secondary battery, for example, during charging, lithium ions released from the positive electrode 21 are occluded in the negative electrode 22 through the electrolytic solution, and during discharging, lithium ions released from the negative electrode 22 are used as the electrolytic solution. And inserted in the positive electrode 21.

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

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

  In addition, the negative electrode 22 is prepared by the same procedure as that of the positive electrode 21 described above. A negative electrode mixture in which a negative electrode active material and, if necessary, a negative electrode binder and a negative electrode conductive agent are mixed is dispersed in an organic solvent or the like to obtain a paste-like negative electrode mixture slurry. Subsequently, the negative electrode mixture slurry is applied to both surfaces of the negative electrode current collector 22A and then dried to form the negative electrode active material layer 22B, and then the negative electrode active material layer 22B is compression molded as necessary.

  Moreover, after electrolyte salt is disperse | distributed to a solvent, alkyl lithium carbonate, reactive cyclic carbonate, and lithium fluorophosphate are added, and electrolyte solution is prepared.

  Finally, a secondary battery is assembled using the positive electrode 21 and the negative electrode 22. First, using a welding method or the like, the positive electrode lead 25 is attached to the positive electrode current collector 21A, and the negative electrode lead 26 is attached to the negative electrode current collector 22A. Subsequently, after the positive electrode 21 and the negative electrode 22 are laminated via the separator 23 and wound 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 and the tip of the negative electrode lead 26 is attached to the battery can 11 using a welding method or the like. Subsequently, an electrolytic solution is injected into the battery can 11 and impregnated in the separator 23. Subsequently, 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.

[Operation and effect of secondary battery]
According to this cylindrical secondary battery, the electrolyte contains lithium alkyl carbonate, reactive cyclic carbonate, and lithium fluorophosphate. In this case, as described above, the decomposition reaction of the electrolytic solution is specifically suppressed by the synergistic action of the three parties, so that the electrolytic solution is extremely difficult to decompose even when the secondary battery is charged / discharged or stored. Therefore, excellent battery characteristics can be obtained.

  In particular, if the content of lithium alkyl carbonate in the electrolyte is 5 ppm to 2000 ppm, the content of reactive cyclic carbonate is 0.5 wt% to 10 wt%, and the content of lithium fluorophosphate is 5 ppm to 3000 ppm. Higher effects can be obtained.

In addition, if the positive electrode active material or the negative electrode active material is a material that shows a potential flat portion in the charge / discharge curve, the above-described synergistic effect is more exhibited, and thus a higher effect can be obtained. Specifically, this material is a lithium iron phosphate compound such as LiFePO ₄ shown in Formula (8) as the positive electrode active material, and is shown in Formulas (9) to (11) as the negative electrode active material. Lithium titanium composite oxide such as Li ₄ Ti ₅ O ₁₂ .

<1-2. Laminate film type>
FIG. 3 illustrates an exploded perspective configuration of another secondary battery according to an embodiment of the present technology, and FIG. 4 is an enlarged view of the wound electrode body 30 illustrated in FIG. 3 taken along line VI-VI. As shown. In the following, the components of the cylindrical secondary battery already described will be referred to as needed.

[Overall structure of secondary battery]
The secondary battery described here is a so-called laminate film type lithium ion secondary battery. In this secondary battery, a wound electrode body 30 is housed inside a film-shaped exterior member 40, and the wound electrode body 30 has a positive electrode 33 and a negative electrode 34 with a separator 35 and an electrolyte layer 36 interposed therebetween. Laminated and wound. A positive electrode lead 31 is attached to the positive electrode 33, and a negative electrode lead 32 is attached to the negative electrode 34. The outermost periphery of the wound electrode body 30 is protected by a protective tape 37.

  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. The positive electrode lead 31 is made of, for example, a conductive material such as Al, and the negative electrode lead 32 is made of, for example, a conductive material such as Cu, Ni, or stainless steel. 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 laminated film, for example, the outer peripheral edge portions of the fusion layers of the two films are bonded together with an adhesive or the like so that the fusion layer faces the wound electrode body 30. The fusing layer is, for example, a film of polyethylene or polypropylene. The metal layer is, for example, an Al foil. The surface protective layer is, for example, a film such as 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 laminate film having another laminated structure, a polymer film such as polypropylene, or a metal film.

  An adhesion film 41 is inserted between the exterior member 40 and the positive electrode lead 31 and the negative electrode lead 32 in order to prevent intrusion of outside air. The adhesion film 41 is formed of a material having adhesion to the positive electrode lead 31 and the negative electrode lead 32. Such a material is, for example, a polyolefin resin such as polyethylene, polypropylene, modified polyethylene, or modified polypropylene.

  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. 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 positive electrode current collector 33A, the positive electrode active material layer 33B, the negative electrode current collector 34A, and the negative electrode active material layer 34B are respectively the positive electrode current collector 21A, the positive electrode active material layer 21B, the negative electrode current collector 22A, and the negative electrode active material layer. The configuration is the same as 22B. The configuration of the separator 35 is the same as the configuration of the separator 23.

  The electrolyte layer 36 is one in which an electrolytic solution is held by a polymer compound, and may contain other materials such as additives as necessary. The electrolyte layer 36 is a so-called gel electrolyte. This is because high ionic conductivity (for example, 1 mS / cm or more at room temperature) is obtained and leakage of the electrolytic solution is prevented.

  Examples of the polymer compound include polyacrylonitrile, polyvinylidene fluoride, polytetrafluoroethylene, polyhexafluoropropylene, polyethylene oxide, polypropylene oxide, polyphosphazene, polysiloxane, polyvinyl fluoride, polyvinyl acetate, polyvinyl alcohol, polymethacryl. One or more of methyl acid, polyacrylic acid, polymethacrylic acid, styrene-butadiene rubber, nitrile-butadiene rubber, polystyrene, polycarbonate, or a copolymer of vinylidene fluoride and hexafluoropyrene . . Among these, polyvinylidene fluoride or a copolymer of vinylidene fluoride and hexafluoropyrene is preferable, and polyvinylidene fluoride is more preferable. This is because it is electrochemically stable.

  The composition of the electrolytic solution is the same as that of the cylindrical type, and the electrolytic solution contains lithium alkyl carbonate, reactive cyclic carbonate, and lithium fluorophosphate. 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, the electrolytic solution may be used as it is. In this case, the separator 35 is impregnated with the electrolytic solution.

[Operation of secondary battery]
In this secondary battery, for example, at the time of charging, lithium ions released from the positive electrode 33 are occluded by the negative electrode 34 through the electrolyte layer 36, and at the time of discharging, lithium ions released from the negative electrode 34 are absorbed by the electrolyte layer. It is occluded by the positive electrode 33 via 36.

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

  In the first procedure, the positive electrode 33 and the negative electrode 34 are manufactured by the same manufacturing procedure as that of the positive electrode 21 and the negative electrode 22. In this case, 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, after preparing a precursor solution containing an electrolytic solution, a polymer compound, and a solvent such as an organic solvent, the precursor solution is applied to the positive electrode 33 and the negative electrode 34 to form a gel electrolyte layer 36. Subsequently, the positive electrode lead 31 is attached to the positive electrode current collector 33A and the negative electrode lead 32 is attached to the negative electrode current collector 34A by a welding method or the like. Subsequently, after the positive electrode 33 and the negative electrode 34 on which the electrolyte layer 36 is formed are stacked via the separator 35 and wound to produce the wound electrode body 30, a protective tape 37 is attached to the outermost peripheral portion thereof. wear. When this separator 35 is prepared, a coating layer containing an organosilicon compound is formed on the surface of the base material layer as necessary. Subsequently, the wound electrode body 30 is sandwiched between the two film-shaped exterior members 40, and then the outer peripheral edge portions of the exterior member 40 are bonded to each other using a heat fusion method or the like. Enclose. In this case, the adhesion film 41 is inserted between the positive electrode lead 31 and the negative electrode lead 32 and the exterior member 40.

  In the second procedure, the positive electrode lead 31 is attached to the positive electrode 33 and the negative electrode lead 52 is attached to the negative electrode 34. Subsequently, after the positive electrode 33 and the negative electrode 34 are laminated via the separator 35 and wound to produce a wound body that is a precursor of the wound electrode body 30, a protective tape 37 is attached to the outermost peripheral portion thereof. wear. Subsequently, after sandwiching the wound body between the two film-like exterior members 40, the remaining outer peripheral edge portion excluding the outer peripheral edge portion on one side is adhered by a heat fusion method or the like, and the bag-shaped outer member 40 is bonded. The wound body is accommodated in the exterior 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 exterior member 40 is sealed using a heat sealing method or the like. Subsequently, the monomer is thermally polymerized. Thereby, since a high molecular compound is formed, the gel electrolyte layer 36 is formed.

  In the third procedure, a wound body is produced and stored in the bag-shaped exterior member 40 in the same manner as in the second procedure described above except that the separator 35 coated with the polymer compound on both sides is used. 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, a binary copolymer comprising polyvinylidene fluoride, vinylidene fluoride and hexafluoropropylene as components, or a ternary copolymer comprising vinylidene fluoride, hexafluoropropylene and chlorotrifluoroethylene as components. Etc. One or two or more other polymer compounds may be used together with the polymer containing 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 using a thermal fusion method or the like. Subsequently, the exterior member 40 is heated while applying a load, and the separator 35 is brought into close contact with the positive electrode 33 and the negative electrode 34 through the polymer compound. Thereby, since the electrolytic solution impregnates the polymer compound, the polymer compound is gelled to form the electrolyte layer 36.

  In the third procedure, the swelling of the secondary battery is suppressed more than in the first procedure. In the third procedure, since the monomer or solvent that is a raw material of the polymer compound hardly remains in the electrolyte layer 36 than in the second procedure, the formation process of the polymer compound is controlled well. 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.

[Operation and effect of secondary battery]
According to the laminate film type secondary battery, the electrolyte solution of the electrolyte layer 36 contains lithium alkyl carbonate, reactive cyclic carbonate, and lithium fluorophosphate. Therefore, excellent battery characteristics can be obtained for the same reason as the cylindrical secondary battery. Other operations and effects are the same as those of the cylindrical type.

<2. Applications of secondary batteries>
Next, application examples of the above-described secondary battery will be described.

  The secondary battery can be used as long as it is a machine, device, instrument, device or system (an assembly of multiple devices) that can be used as a power source for driving or a power storage source for power storage. There is no particular limitation. When a secondary battery is used as a power source, it may be a main power source (a power source used preferentially) or an auxiliary power source (a power source used in place of or switched from the main power source). The type of the main power source is not limited to the secondary battery.

  Examples of uses of the secondary battery include the following uses. It is a portable electronic device such as a video camera, a digital still camera, a mobile phone, a notebook computer, a cordless phone, a headphone stereo, a portable radio, a portable TV, or a portable information terminal. It is a portable living device such as an electric shaver. A storage device such as a backup power supply or a memory card. An electric tool such as an electric drill or an electric saw. A battery pack used as a power source for a notebook computer or the like. Medical electronic devices such as pacemakers or hearing aids. An electric vehicle such as an electric vehicle (including a hybrid vehicle). It is an electric power storage system such as a home battery system that stores electric power in case of an emergency. Of course, applications other than those described above may be used.

  Among them, it is effective that the secondary battery is applied to a battery pack, an electric vehicle, an electric power storage system, an electric tool, an electronic device, or the like. This is because excellent battery characteristics are required, and the characteristics can be effectively improved by using the secondary battery of the present technology. The battery pack is a power source using a secondary battery, and is a so-called assembled battery. The electric vehicle is a vehicle that operates (runs) using a secondary battery as a driving power source, and may be an automobile (such as a hybrid automobile) that includes a drive source other than the secondary battery as described above. The power storage system is a system that uses a secondary battery as a power storage source. For example, in a household power storage system, power is stored in a secondary battery that is a power storage source, and the power is consumed as necessary, so that household electrical products can be used. An electric power tool is a tool in which a movable part (for example, a drill etc.) moves, using a secondary battery as a driving power source. An electronic device is a device that exhibits various functions using a secondary battery as a driving power source.

  Here, some application examples of the secondary battery will be specifically described. In addition, since the structure of each application example demonstrated below is an example to the last, it can change suitably.

<2-1. Battery Pack>
FIG. 5 shows a block configuration of the battery pack. For example, as shown in FIG. 5, the battery pack includes a control unit 61, a power source 62, a switch unit 63, a current measuring unit 64, a temperature, and the like inside a housing 60 formed of a plastic material or the like. A detection unit 65, a voltage detection unit 66, a switch control unit 67, a memory 68, a temperature detection element 69, a current detection resistor 70, a positive electrode terminal 71, and a negative electrode terminal 72 are provided.

  The control unit 61 controls the operation of the entire battery pack (including the usage state of the power supply 62), and includes, for example, a central processing unit (CPU). The power source 62 includes one or more secondary batteries (not shown). The power source 62 is, for example, an assembled battery including two or more secondary batteries, and the connection form thereof may be in series, in parallel, or a mixture of both. For example, the power source 62 includes six secondary batteries connected in two parallel three series.

  The switch unit 63 switches the usage state of the power source 62 (whether or not the power source 62 can be connected to an external device) according to an instruction from the control unit 61. The switch unit 63 includes, for example, a charge control switch, a discharge control switch, a charging diode, a discharging diode (all not shown), and the like. The charge control switch and the discharge control switch are semiconductor switches such as a field effect transistor (MOSFET) using a metal oxide semiconductor, for example.

  The current measurement unit 64 measures current using the current detection resistor 70 and outputs the measurement result to the control unit 61. The temperature detection unit 65 measures the temperature using the temperature detection element 69 and outputs the measurement result to the control unit 61. This temperature measurement result is used, for example, when the control unit 61 performs charge / discharge control during abnormal heat generation, or when the control unit 61 performs correction processing when calculating the remaining capacity. The voltage detector 66 measures the voltage of the secondary battery in the power source 62, converts the measured voltage analog / digital conversion (A / D), and supplies the converted voltage to the controller 61.

  The switch control unit 67 controls the operation of the switch unit 63 in accordance with signals input from the current measurement unit 66 and the voltage measurement unit 66.

  For example, when the battery voltage reaches the overcharge detection voltage, the switch control unit 67 disconnects the switch unit 67 (charge control switch) and controls the charging current not to flow through the current path of the power source 62. It is like that. As a result, the power source 62 can only discharge through the discharging diode. The switch control unit 67 is configured to cut off the charging current when a large current flows during charging, for example.

  Further, the switch control unit 67 controls the switch unit 67 (discharge control switch) to be disconnected so that the discharge current does not flow in the current path of the power source 62 when the battery voltage reaches the overdischarge detection voltage, for example. It is supposed to be. As a result, the power source 62 can only be charged via the charging diode. For example, the switch control unit 67 is configured to cut off the discharge current when a large current flows during discharging.

  In the secondary battery, for example, the overcharge detection voltage is 4.20 V ± 0.05 V, and the overdischarge detection voltage is 2.4 V ± 0.1 V.

  The memory 68 is, for example, an EEPROM that is a nonvolatile memory. The memory 68 stores, for example, numerical values calculated by the control unit 61 and information (for example, internal resistance in an initial state) of the secondary battery measured in the manufacturing process stage. If the full charge capacity of the secondary battery is stored in the memory 68, the control unit 10 can grasp information such as the remaining capacity.

  The temperature detection element 69 measures the temperature of the power supply 62 and outputs the measurement result to the control unit 61, and is, for example, a thermistor.

  The positive electrode terminal 71 and the negative electrode terminal 72 are connected to an external device (for example, a notebook personal computer) operated using a battery pack or an external device (for example, a charger) used to charge the battery pack. Terminal. Charging / discharging of the power source 62 is performed via the positive terminal 71 and the negative terminal 72.

<2-2. Electric vehicle>
FIG. 6 shows a block configuration of a hybrid vehicle which is an example of an electric vehicle. For example, as shown in FIG. 6, the electric vehicle includes a control unit 74, an engine 75, a power source 76, a driving motor 77, and a differential device 78 in a metal housing 73. , A generator 79, a transmission 80 and a clutch 81, inverters 82 and 83, and various sensors 84. In addition, the electric vehicle includes, for example, a front wheel drive shaft 85 and a front wheel 86 connected to the differential device 78 and the transmission 80, and a rear wheel drive shaft 87 and a rear wheel 88.

  This electric vehicle can run using either the engine 75 or the motor 77 as a drive source. The engine 75 is a main power source, such as a gasoline engine. When the engine 75 is used as a power source, the driving force (rotational force) of the engine 75 is transmitted to the front wheels 86 or the rear wheels 88 via, for example, a differential device 78 that is a driving unit, a transmission 80, and a clutch 81. The rotational force of the engine 75 is also transmitted to the generator 79. The generator 79 generates AC power by the rotational force, and the AC power is converted into DC power via the inverter 83 and stored in the power source 76. Is done. On the other hand, when the motor 77 serving as a conversion unit is used as a power source, power (DC power) supplied from the power source 76 is converted into AC power via the inverter 82, and the motor 77 is driven by the AC power. The driving force (rotational force) converted from electric power by the motor 77 is transmitted to the front wheels 86 or the rear wheels 88 via, for example, a differential device 78, a transmission 80, and a clutch 81, which are driving units.

  When the electric vehicle is decelerated by a braking mechanism (not shown), the resistance force at the time of deceleration may be transmitted as a rotational force to the motor 77, and the motor 77 may generate AC power by the rotational force. This AC power is preferably converted into DC power via the inverter 82, and the DC regenerative power is preferably stored in the power source 76.

  The control unit 74 controls the operation of the entire electric vehicle, and includes, for example, a CPU. The power source 76 includes one or more secondary batteries (not shown). The power source 76 may be connected to an external power source and can store power by receiving power supply from the external power source. The various sensors 84 are used, for example, to control the rotational speed of the engine 75 or to control the opening (throttle opening) of a throttle valve (not shown). The various sensors 84 include, for example, a speed sensor, an acceleration sensor, an engine speed sensor, and the like.

  In the above description, the hybrid vehicle is described as the electric vehicle. However, the electric vehicle may be a vehicle (electric vehicle) that operates using only the power source 76 and the motor 77 without using the engine 75.

<2-3. Power storage system>
FIG. 7 shows a block configuration of the power storage system. This power storage system includes, for example, a control unit 90, a power source 91, a smart meter 92, and a power hub 93 in a house 89 such as a general house or a commercial building as shown in FIG. Yes.

  Here, the power source 91 is connected to, for example, an electric device 94 installed inside the house 89 and can be connected to an electric vehicle 96 stopped outside the house 89. The power source 91 is connected to, for example, a private generator 95 installed in a house 89 via a power hub 93 and can be connected to an external centralized power system 97 via the smart meter 92 and the power hub 93. It has become.

  Note that the electric device 94 includes one or more home appliances such as a refrigerator, an air conditioner, a television, or a water heater. The private power generator 95 is, for example, one type or two or more types such as a solar power generator or a wind power generator. The electric vehicle 96 is, for example, one type or two or more types such as an electric vehicle, an electric motorcycle, or a hybrid vehicle. The centralized power system 97 is, for example, one type or two or more types such as a thermal power plant, a nuclear power plant, a hydroelectric power plant, or a wind power plant.

  The control unit 90 controls the operation of the entire power storage system (including the usage state of the power supply 91), and includes, for example, a CPU. The power source 91 includes one or more secondary batteries (not shown). The smart meter 92 is, for example, a network-compatible power meter installed in a house 89 on the power demand side, and can communicate with the power supply side. Accordingly, for example, the smart meter 92 controls the balance between supply and demand in the house 89 while communicating with the outside as necessary, thereby enabling efficient and stable energy supply.

  In this power storage system, for example, power is accumulated in the power source 91 from the centralized power system 97 that is an external power source via the smart meter 92 and the power hub 93, and the power hub 93 is connected from the solar power generator 95 that is an independent power source. Power is accumulated in the power source 91 through the power source 91. The electric power stored in the power source 91 is supplied to the electric device 94 or the electric vehicle 96 as required in accordance with an instruction from the control unit 91, so that the electric device 94 can be operated and the electric vehicle 96. Can be charged. In other words, the power storage system is a system that makes it possible to store and supply power in the house 89 using the power source 91.

  The power stored in the power supply 91 can be used arbitrarily. For this reason, for example, power is stored in the power source 91 from the centralized power system 97 at midnight when the amount of electricity used is low, and the power stored in the power source 91 is used during the day when the amount of electricity used is high. it can.

  The power storage system described above may be installed for each house (one household), or may be installed for each of a plurality of houses (multiple households).

<2-4. Electric tool>
FIG. 8 shows a block configuration of the electric power tool. For example, as illustrated in FIG. 8, the electric power tool is an electric drill, and includes a control unit 99 and a power source 100 inside a tool main body 98 formed of a plastic material or the like. For example, a drill portion 101 which is a movable portion is attached to the tool body 98 so as to be operable (rotatable).

  The control part 99 controls operation | movement (including the use condition of the power supply 100) of the whole electric tool, and contains CPU etc., for example. The power supply 100 includes one or more secondary batteries (not shown). This controlled object 99 is moved by supplying electric power from the power supply 100 to the drill unit 101 as necessary in accordance with operation of an operation switch (not shown).

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

(Experimental Examples 1-1 to 1-29)
The cylindrical lithium ion secondary battery shown in FIGS. 1 and 2 was produced by the following procedure.

In producing the positive electrode 21, 91 parts by mass of a positive electrode active material (LiCoO ₂ ), 3 parts by mass of a positive electrode binder (polyvinylidene fluoride: PVDF), and 6 parts by mass of a positive electrode conductive agent (graphite) are mixed. Thus, a positive electrode mixture was obtained. Subsequently, the positive electrode mixture was dispersed in an organic solvent (N-methyl-2-pyrrolidone: NMP) 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 (Al foil: thickness = 12 μm) using a coating apparatus, and then dried to be positive electrode active material layer 21B (positive electrode current collector 21A). The thickness of one side of the film was 30 μm). Subsequently, the positive electrode active material layer 21B was compression-molded (volume density = 3.4 g / cm ³ ) using a roll press. Finally, the positive electrode current collector 21A on which the positive electrode active material layer 21B was formed was cut into a strip shape (length = 300 mm × width = 50 mm).

  When producing the negative electrode 22, 97 mass parts of negative electrode active materials (artificial graphite) and 3 mass parts of negative electrode binder (PVDF) were mixed, and it was set as the negative electrode mixture. Subsequently, the negative electrode mixture was dispersed in an organic solvent (NMP) to obtain a paste-like negative electrode mixture slurry. Subsequently, the negative electrode mixture slurry was uniformly applied to both surfaces of the negative electrode current collector 22A (electrolytic Cu foil: thickness = 15 μm) using a coating apparatus, and then dried to be used as the negative electrode active material layer 22B (negative electrode current collector). A thickness of one side of 22A = 30 μm) was formed. Subsequently, the negative electrode active material layer 22B was compression molded (press pressure = 200 MPa) using a roll press. Finally, the negative electrode current collector 22A on which the negative electrode active material layer 22B was formed was cut into a strip shape (length = 300 mm × width = 50 mm).

When preparing an electrolytic solution, after dissolving an electrolyte salt (LiPF ₆ ) in a solvent (ethylene carbonate (EC) and dimethyl carbonate (DMC)), lithium alkyl carbonate, reactive cyclic carbonate and Lithium fluorophosphate was added. In this case, the composition of the solvent was EC: DMC = 30: 70 by weight, and the content of the electrolyte salt was 1.2 mol / kg with respect to the solvent. The types and contents of lithium alkyl carbonate, reactive cyclic carbonate and lithium fluorophosphate are as shown in Tables 1 and 2.

  As the lithium alkyl carbonate, methyl lithium carbonate (MCL) was used. The “carbon number” shown in Tables 1 and 2 represents the carbon number of the alkyl group (R1) in the lithium alkyl carbonate. 4-fluoro-1,3-dioxolan-2-one (FEC) was used as the reactive cyclic carbonate. As the fluorophosphate, lithium monofluorophosphate (MFPL) was used. For comparison, lithium oxalate (SL) or lithium formate (GL), which is a lithium carboxylate, was used.

  When assembling the secondary battery, 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, the positive electrode 21 and the negative electrode 22 are laminated through the separator 23 (microporous polypropylene film: thickness = 25 μm) and then wound, and then the winding end portion is fixed with an adhesive tape and the wound electrode A body 20 was produced. Subsequently, the center pin 24 was inserted into the winding center of the wound electrode body 20. Subsequently, while being sandwiched between the pair of insulating plates 12 and 13, the wound electrode body 20 was housed inside the nickel-plated iron battery can 11. 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. In 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.

  As the characteristics of the secondary battery, the initial charge / discharge characteristics, room temperature cycle characteristics, and high temperature cycle characteristics were examined. The results shown in Table 1 and Table 2 were obtained.

  When investigating the initial charge / discharge characteristics, in order to stabilize the battery state, after charging and discharging the secondary battery for one cycle in a normal temperature environment (23 ° C.), the charge and discharge capacity is further charged and discharged for one cycle. Was measured. From this result, the initial efficiency (%) = (discharge capacity at the second cycle / charge capacity at the second cycle) × 100 was calculated. At the time of charging, the battery was charged at a constant current and a constant voltage up to an upper limit voltage of 4.2 V at a current of 0.2 C, and further charged at a constant voltage until the current reached 0.05 C. At the time of discharge, constant current discharge was performed at a current of 0.2 C until the voltage reached 3 V throughout. Here, 0.2 C and 0.05 C are current values at which the battery capacity (theoretical capacity) can be discharged in 5 hours and 20 hours, respectively.

  When investigating the normal temperature cycle characteristics, use a secondary battery whose battery state has been stabilized by the same procedure as when examining the initial charge / discharge characteristics, and charge the secondary battery for one cycle in a normal temperature environment (23 ° C.). After discharging and measuring the discharge capacity, charging and discharging were repeated until the total number of cycles reached 300 cycles, and the discharge capacity was measured. From this result, the normal temperature maintenance rate (%) = (discharge capacity at the 300th cycle / discharge capacity at the second cycle) × 100 was calculated. The charge / discharge conditions are the same as the case of examining the initial charge / discharge characteristics.

  When investigating the high-temperature cycle characteristics, use a secondary battery whose battery state has been stabilized by the same procedure as when examining the initial charge / discharge characteristics, and further recycle the secondary battery in a normal temperature environment (23 ° C.). The discharge capacity was measured by charging and discharging. Subsequently, charging and discharging were repeated until the total number of cycles reached 300 cycles in a high-temperature environment (45 ° C.), and the discharge capacity was measured. From this result, the high temperature maintenance ratio (%) = (discharge capacity at the 300th cycle / discharge capacity at the second cycle) × 100 was calculated. The charge / discharge conditions are the same as the case of examining the initial charge / discharge characteristics.

When lithium cobalt composite oxide (LiCoO ₂ ) was used as the positive electrode active material and a carbon material (artificial graphite) was used as the negative electrode active material, the following results were obtained. When alkyl lithium carbonate, reactive cyclic carbonate and lithium fluorophosphate were used together (Experimental Examples 1-1 to 1-14), when they were not used together (Experimental Examples 1-15 to 15). Compared with 1-29), the initial efficiency, the normal temperature maintenance rate, and the high temperature maintenance rate increased.

  Specifically, the case where none of the lithium alkyl carbonate, the reactive cyclic carbonate, and the lithium fluorophosphate is used (Experimental Example 1-15) is used as a reference. When only one of them was used (Experimental Examples 1-16 to 1-19), the initial efficiency increased across the board, but the normal temperature maintenance rate and the high temperature maintenance rate increased or decreased compared to the above criteria. . Moreover, when arbitrary two were used in combination (Experimental Examples 1-20 to 1-27), the room temperature maintenance rate and the high temperature maintenance rate increased compared to the above criteria. On the other hand, when three are used in combination (Experimental Examples 1-1 to 1-14), the initial efficiency is increased as compared to the above-mentioned criteria (Experimental Examples 1-15-1 to 1-27). At the same time, the room temperature maintenance rate and the high temperature maintenance rate increased significantly. This result indicates that when three are used in combination, the decomposition reaction of the electrolytic solution is remarkably suppressed as compared with the case where only one is used and any two are used in combination.

  In particular, when three were used in combination, high initial efficiency, room temperature maintenance rate, and high temperature maintenance rate were obtained when the content of lithium alkyl carbonate was 5 ppm to 2000 ppm. Such a tendency was similarly obtained even when the content of the reactive cyclic carbonate was 0.5 wt% to 10 wt% and the content of lithium fluorophosphate was 5 ppm to 3000 ppm. .

  When lithium carboxylate was used instead of lithium alkyl carbonate (Experimental Examples 1-28, 1-29), the initial efficiency, room temperature maintenance rate, and high temperature maintenance rate increased across the board compared to the above criteria. However, when using alkyl lithium carbonate (Experimental example 1-6), it was not far. This result shows that the tendency that the normal temperature maintenance rate and the high temperature maintenance rate increase greatly by combining the three is a specific advantage obtained only when lithium alkyl carbonate is used.

(Experimental examples 2-1 to 2-44)
As shown in Tables 3 to 5, the secondary reaction was performed in the same manner as in Experimental Examples 1-1 to 1-14 except that the types of lithium alkyl carbonate, reactive cyclic carbonate, and lithium fluorophosphate were changed. A battery was fabricated and various characteristics were examined.

  Examples of the lithium alkyl carbonate include ethyl lithium carbonate (ECL), n-propyl lithium carbonate (n-PRCL), i-propyl lithium carbonate (i-PRCL), n-butyl lithium carbonate (n-BCL), and t-butyl carbonate. Lithium (t-BCL), n-pentyl lithium carbonate (n-PNCL) or t-pentyl lithium carbonate (t-PNCL) was used. As the reactive cyclic carbonate, a mixture of FEC and VC was used together with vinylene carbonate (VC), vinyl ethylene carbonate (VEC) or methylene ethylene carbonate (MEC). As the fluorophosphate, lithium difluorophosphate (DFPL) was used.

  Even when the types of alkyl lithium carbonate, reactive cyclic carbonate and lithium fluorophosphate were changed, the same results as in Table 1 were obtained. That is, when an alkyl lithium carbonate, a reactive cyclic carbonate and lithium fluorophosphate were used together, high initial efficiency, normal temperature maintenance rate and high temperature maintenance rate were obtained.

(Experimental examples 3-1 to 3-50)
As shown in Tables 6 to 8, Experimental Examples 1-1 to 1-29, 2-1 to 2 except that lithium titanium composite oxide (Li ₄ Ti ₅ O ₁₂ ) was used as the negative electrode active material. A secondary battery was fabricated by the same procedure as in -44, and various characteristics were examined. In producing the negative electrode 22, 85 parts by mass of a negative electrode active material (Li ₄ Ti ₅ O ₁₂ ), ₅ parts by mass of a negative electrode binder (PVDF), and 10 parts by mass of a negative electrode conductive agent (graphite) are mixed. Thus, a negative electrode mixture was prepared.

Even when lithium cobalt composite oxide (LiCoO ₂ ) is used as the positive electrode active material and lithium titanium composite oxide (Li ₄ Ti ₅ O ₁₂ ) is used as the negative electrode active material, the same results as in Tables 1 to 5 are obtained. It was.

  Specifically, the case where none of lithium alkyl carbonate, reactive cyclic carbonate and lithium fluorophosphate is used (Experimental Example 3-44) is used as a reference. When only one of them is used (Experimental Examples 3-45 to 3-47) and when any two are used in combination (Experimental Examples 3-48 to 3-50), the above criteria are compared. The initial efficiency, the normal temperature maintenance rate, and the high temperature maintenance rate increased depending on the combination, but sometimes decreased. On the other hand, when three are used in combination (Experimental examples 3-1 to 3-43), the initial efficiency is slightly lower than that of the above-mentioned standard (Experimental examples 3-44 to 3-50). However, the room temperature maintenance rate and the high temperature maintenance rate increased significantly. This result indicates that the decomposition reaction of the electrolytic solution is drastically suppressed when the lithium titanium composite oxide is used as the negative electrode active material in combination of the three.

(Experimental examples 4-1 to 4-50)
As shown in Tables 9 to 11, the same as Experimental Examples 1-1 to 1-29 and 2-1 to 2-44, except that a lithium iron phosphate compound (LiFePO ₄ ) was used as the positive electrode active material. A secondary battery was fabricated according to the procedure described above, and various characteristics were examined. In the case of producing the positive electrode 21, 92 parts by mass of a positive electrode active material (LiFePO ₄ ), 5 parts by mass of a positive electrode binder (PVDF), and 3 parts by mass of a positive electrode conductive agent (Ketjen Black) are mixed. A mixture was prepared.

Even when a lithium iron phosphate compound (LiFePO ₄ ) was used as the positive electrode active material and a carbon material (artificial graphite) was used as the negative electrode active material, the same results as in Tables 1 to 5 were obtained.

  Specifically, the case where none of lithium alkyl carbonate, reactive cyclic carbonate and lithium fluorophosphate is used (Experimental Example 4-44) is used as a reference. When only one of them is used (Experimental Examples 4-45 to 4-47) and when any two are used in combination (Experimental Examples 4-48 to 4-50), the above criteria are compared. The initial efficiency, the room temperature maintenance rate, and the high temperature maintenance rate increased depending on the combination but decreased depending on the case. On the other hand, when three were used in combination (Experimental Examples 4-1 to 4-43), the initial efficiency was only slightly increased compared to the above criteria, but the room temperature maintenance rate And the high temperature maintenance rate increased significantly. This result shows that the decomposition reaction of the electrolytic solution is drastically suppressed when three are used in combination when a lithium iron phosphate compound is used as the positive electrode active material.

(Experimental examples 5-1 to 5-50)
As shown in Tables 12 to 14, except that lithium iron phosphate compound (LiFePO ₄ ) was used as the positive electrode active material and lithium titanium composite oxide (Li ₄ Ti ₅ O ₁₂ ) was used as the negative electrode active material. Secondary batteries were fabricated in the same procedure as in Experimental Examples 1-1 to 1-29 and 2-1 to 2-44, and various characteristics were examined. The production procedures of the positive electrode 21 and the negative electrode 22 are the same as those of Experimental Examples 3-1 to 3-50 and 4-1 to 4-50.

Even when lithium iron phosphate compound (LiFePO ₄ ) is used as the positive electrode active material and lithium titanium composite oxide (Li ₄ Ti ₅ O ₁₂ ) is used as the negative electrode active material, the same results as in Tables 1 to 5 are obtained. It was.

  Specifically, the case where none of lithium alkyl carbonate, reactive cyclic carbonate and lithium fluorophosphate is used (Experimental Example 5-44) is used as a reference. When only one of them was used (Experimental Examples 5-45 to 5-47) and when any two were used in combination (Experimental Examples 5-48 to 5-50), the above criteria were compared. The initial efficiency, the room temperature maintenance rate, and the high temperature maintenance rate increased depending on the combination but decreased depending on the case. On the other hand, when three are used in combination (Experimental Examples 5-1 to 5-43), the initial efficiency is substantially maintained and the normal temperature maintenance rate and the high temperature maintenance rate are higher than those of the above criteria. Increased significantly.

  From the results of Tables 1 to 14, it was confirmed that excellent battery characteristics can be obtained when the electrolytic solution contains lithium alkyl carbonate, reactive cyclic carbonate and lithium fluorophosphate together.

  In particular, when a material having a potential flat portion in the charge / discharge curve, such as a lithium iron phosphate compound as a positive electrode active material or a lithium titanium composite oxide as a negative electrode active material, increases in the normal temperature maintenance rate and the high temperature maintenance rate Increased significantly. From this result, it was confirmed that the battery characteristics were further improved when the above materials were used as the positive electrode active material or the negative electrode active material.

  The present technology has been described with reference to the embodiments and examples. However, the present technology is not limited to the aspects described in the embodiments and examples, and various modifications are possible. For example, the positive electrode active material of the present technology includes a lithium ion 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 expressed by the sum of these capacities. , As well as applicable. In this case, the chargeable capacity of the negative electrode material is set to be smaller than the discharge capacity of the positive electrode.

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

（Ｒ２〜Ｒ５は水素基、ハロゲン基、アルキル基またはハロゲン化アルキル基であり、Ｒ２〜Ｒ５のうちの少なくとも１つはハロゲン基またはハロゲン化アルキル基である。Ｒ６およびＲ７は水素基またはアルキル基である。Ｒ８〜Ｒ１１は水素基、アルキル基、ビニル基またはアリル基であり、Ｒ８〜Ｒ１１のうちの少なくとも１つはビニル基またはアリル基である。Ｒ１２は＝ＣＨ−Ｒ１３で表される基であり、Ｒ１３は水素基またはアルキル基である。）
Ｌｉ₂ ＰＦＯ₃ ・・・（６）
ＬｉＰＦ₂ Ｏ₂ ・・・（７）
（２）
前記アルキル炭酸リチウムは、メチル炭酸リチウム、エチル炭酸リチウム、直鎖状または分岐状のプロピル炭酸リチウム、直鎖状または分岐状のブチル炭酸リチウム、および、直鎖状または分岐状のペンチル炭酸リチウムのうちの少なくとも１種であり、
前記反応性環状炭酸エステルは、４−フルオロ−１，３−ジオキソラン−２−オン、炭酸ビニレン（１，３−ジオキソール−２−オン）、炭酸ビニルエチレン（４−ビニル−１，３−ジオキソラン−２−オン）および炭酸メチレンエチレン（４−メチレン−１，３−ジオキソラン−２−オン）のうちの少なくとも１種である、
上記（１）に記載の二次電池。
（３）
前記電解液における前記アルキル炭酸リチウムの含有量は５ｐｐｍ〜２０００ｐｐｍであり、
前記電解液における前記反応性環状炭酸エステルの含有量は０．５重量％〜１０重量％であり、
前記電解液における前記フルオロリン酸リチウムの含有量は５ｐｐｍ〜３０００ｐｐｍである、
上記（１）または（２）に記載の二次電池。
（４）
前記正極および前記負極のうちの少なくとも一方は、活物質として、充放電曲線（縦軸：電位（Ｖ），横軸：充放電容量（ｍＡｈ））において電位が１Ｖ〜５Ｖ（対リチウム金属電位）であると共に充放電容量が全充放電容量の５０％以上である領域に電位の変化量が２５ｍＶ以内である電位平坦部を示す材料を含む、
上記（１）ないし（３）のいずれかに記載の二次電池。
（５）
前記正極は前記活物質として下記の式（８）で表されるリチウム鉄リン酸化合物を含み、
前記負極は前記活物質として下記の式（９）〜式（１１）で表されるリチウムチタン複合酸化物のうちの少なくとも１種を含む、
上記（４）に記載の二次電池。
ＬｉＦｅ_a Ｍ１_1-a Ｏ₄ ・・・（８）
（Ｍ１はＭｇ、Ａｌ、Ｃａ、Ｔｉ、Ｖ、Ｍｎ、Ｃｏ、Ｎｉ、Ｃｕ、Ｚｎ、ＺｒおよびＢａのうちの少なくとも１種であり、ａは０＜ａ≦１である。）
Ｌｉ［Ｌｉ_x Ｍ２_(1-3x)/2Ｔｉ_(3+x)/2 ］Ｏ₄ ・・・（９）
（Ｍ２はＭｇ、Ｃａ、Ｃｕ、ＺｎおよびＳｒのうちの少なくとも１種であり、ｘは０≦ｘ≦１／３を満たす。）
Ｌｉ［Ｌｉ_y Ｍ３_1-3yＴｉ_1+2y］Ｏ₄ ・・・（１０）
（Ｍ３はＡｌ、Ｓｃ、Ｃｒ、Ｍｎ、Ｆｅ、ＧａおよびＹのうちの少なくとも１種であり、ｙは０≦ｙ≦１／３を満たす。）
Ｌｉ［Ｌｉ_1/3 Ｍ４_z Ｔｉ_(5/3)-z ］Ｏ４ ・・・（１１）
（Ｍ４はＶ、ＺｒおよびＮｂのうちの少なくとも１種であり、ｚは０≦ｚ≦２／３を満たす。）
（６）
前記正極の活物質はリチウム鉄リン酸化合物（ＬｉＦｅＰＯ₄ ）であり、
前記負極の活物質はチタン酸リチウム（Ｌｉ₄ Ｔｉ₅ Ｏ₁₂）である、
上記（５）に記載の二次電池。
（７）
リチウムイオン二次電池である、
上記（１）ないし（６）のいずれかに記載の二次電池。
（８）
下記の式（１）で表されるアルキル炭酸リチウムと、
下記の式（２）〜式（５）で表される反応性環状炭酸エステルのうちの少なくとも１種と、
下記の式（６）および式（７）で表されるフルオロリン酸リチウムのうちの少なくとも一方と
を含む、二次電池用電解液。
Ｒ１−Ｏ−Ｃ（＝Ｏ）−Ｏ−Ｌｉ ・・・（１）
（Ｒ１は炭素数が１〜５のアルキル基である。）

（Ｒ２〜Ｒ５は水素基、ハロゲン基、アルキル基またはハロゲン化アルキル基であり、Ｒ２〜Ｒ５のうちの少なくとも１つはハロゲン基またはハロゲン化アルキル基である。Ｒ６およびＲ７は水素基またはアルキル基である。Ｒ８〜Ｒ１１は水素基、アルキル基、ビニル基またはアリル基であり、Ｒ８〜Ｒ１１のうちの少なくとも１つはビニル基またはアリル基である。Ｒ１２は＝ＣＨ−Ｒ１３で表される基であり、Ｒ１３は水素基またはアルキル基である。）
Ｌｉ₂ ＰＦＯ₃ ・・・（６）
ＬｉＰＦ₂ Ｏ₂ ・・・（７）
（９）
上記（１）ないし（７）のいずれかに記載の二次電池と、
その二次電池の使用状態を制御する制御部と、
その制御部の指示に応じて前記二次電池の使用状態を切り換えるスイッチ部と
を備えた、電池パック。
（１０）
上記（１）ないし（７）のいずれかに記載の二次電池と、
その二次電池から供給された電力を駆動力に変換する変換部と、
その駆動力に応じて駆動する駆動部と、
前記二次電池の使用状態を制御する制御部と
を備えた、電動車両。
（１１）
上記（１）ないし（７）のいずれかに記載の二次電池と、
１または２以上の電気機器と、
前記二次電池からの前記電気機器に対する電力供給を制御する制御部と
を備えた、電力貯蔵システム。
（１２）
上記（１）ないし（７）のいずれかに記載の二次電池と、
その二次電池から電力を供給される可動部と
を備えた、電動工具。
（１３）
上記（１）ないし（７）のいずれかに記載の二次電池を電力供給源として備えた、
電子機器。 In addition, this technique can also take the following structures.
(1)
An electrolyte is provided together with the positive electrode and the negative electrode,
The electrolyte is
An alkyl lithium carbonate represented by the following formula (1):
At least one of reactive cyclic carbonates represented by the following formulas (2) to (5);
A secondary battery comprising at least one of lithium fluorophosphate represented by the following formula (6) and formula (7).
R1-O—C (═O) —O—Li (1)
(R1 is an alkyl group having 1 to 5 carbon atoms.)

(R2 to R5 are a hydrogen group, a halogen group, an alkyl group or a halogenated alkyl group, and at least one of R2 to R5 is a halogen group or a halogenated alkyl group. R6 and R7 are a hydrogen group or an alkyl group. R8 to R11 are a hydrogen group, an alkyl group, a vinyl group or an allyl group, and at least one of R8 to R11 is a vinyl group or an allyl group, and R12 is a group represented by ═CH—R13. And R13 is a hydrogen group or an alkyl group.)
Li ₂ PFO ₃ (6)
LiPF ₂ O ₂ (7)
(2)
The lithium alkyl carbonate is methyl lithium carbonate, ethyl lithium carbonate, linear or branched propyl lithium carbonate, linear or branched butyl lithium carbonate, and linear or branched lithium pentyl carbonate. At least one of
Examples of the reactive cyclic carbonate include 4-fluoro-1,3-dioxolan-2-one, vinylene carbonate (1,3-dioxol-2-one), vinyl ethylene carbonate (4-vinyl-1,3-dioxolane- 2-one) and methylene ethylene carbonate (4-methylene-1,3-dioxolan-2-one),
The secondary battery as described in said (1).
(3)
The content of the lithium alkyl carbonate in the electrolytic solution is 5 ppm to 2000 ppm,
The content of the reactive cyclic carbonate in the electrolytic solution is 0.5 wt% to 10 wt%,
The content of the lithium fluorophosphate in the electrolytic solution is 5 ppm to 3000 ppm,
The secondary battery according to (1) or (2) above.
(4)
At least one of the positive electrode and the negative electrode has, as an active material, a potential of 1 V to 5 V (vs. lithium metal potential) in a charge / discharge curve (vertical axis: potential (V), horizontal axis: charge / discharge capacity (mAh)). And a material showing a potential flat portion whose potential change amount is within 25 mV in a region where the charge / discharge capacity is 50% or more of the total charge / discharge capacity,
The secondary battery according to any one of (1) to (3).
(5)
The positive electrode includes a lithium iron phosphate compound represented by the following formula (8) as the active material,
The negative electrode contains at least one of lithium titanium composite oxides represented by the following formulas (9) to (11) as the active material,
The secondary battery as described in said (4).
LiFe _a M1 _1-a O ₄ (8)
(M1 is at least one of Mg, Al, Ca, Ti, V, Mn, Co, Ni, Cu, Zn, Zr, and Ba, and a is 0 <a ≦ 1.)
Li [Li _x M 2 _{(1-3x) / 2} Ti _{(3 + x) / 2} ] O ₄ (9)
(M2 is at least one of Mg, Ca, Cu, Zn and Sr, and x satisfies 0 ≦ x ≦ 1/3.)
Li [Li _y M3 _1-3y Ti _{1 + 2y} ] O ₄ (10)
(M3 is at least one of Al, Sc, Cr, Mn, Fe, Ga and Y, and y satisfies 0 ≦ y ≦ 1/3.)
Li [Li _1/3 M4 _z Ti _{(5/3) -z} ] O 4 (11)
(M4 is at least one of V, Zr and Nb, and z satisfies 0 ≦ z ≦ 2/3.)
(6)
The positive electrode active material is a lithium iron phosphate compound (LiFePO ₄ ),
The negative electrode active material is lithium titanate (Li ₄ Ti ₅ O ₁₂ ),
The secondary battery as described in said (5).
(7)
A lithium ion secondary battery,
The secondary battery according to any one of (1) to (6) above.
(8)
An alkyl lithium carbonate represented by the following formula (1):
At least one of reactive cyclic carbonates represented by the following formulas (2) to (5);
An electrolyte solution for a secondary battery, comprising at least one of lithium fluorophosphate represented by the following formula (6) and formula (7).
R1-O—C (═O) —O—Li (1)
(R1 is an alkyl group having 1 to 5 carbon atoms.)

(R2 to R5 are a hydrogen group, a halogen group, an alkyl group or a halogenated alkyl group, and at least one of R2 to R5 is a halogen group or a halogenated alkyl group. R6 and R7 are a hydrogen group or an alkyl group. R8 to R11 are a hydrogen group, an alkyl group, a vinyl group or an allyl group, and at least one of R8 to R11 is a vinyl group or an allyl group, and R12 is a group represented by ═CH—R13. And R13 is a hydrogen group or an alkyl group.)
Li ₂ PFO ₃ (6)
LiPF ₂ O ₂ (7)
(9)
The secondary battery according to any one of the above (1) to (7);
A control unit for controlling the usage state of the secondary battery;
A battery pack comprising: a switch unit that switches a usage state of the secondary battery in accordance with an instruction from the control unit.
(10)
The secondary battery according to any one of the above (1) to (7);
A converter that converts electric power supplied from the secondary battery into driving force;
A drive unit that drives according to the driving force;
An electric vehicle comprising: a control unit that controls a usage state of the secondary battery.
(11)
The secondary battery according to any one of the above (1) to (7);
One or more electrical devices;
And a control unit that controls power supply from the secondary battery to the electrical device.
(12)
The secondary battery according to any one of the above (1) to (7);
And a movable part to which electric power is supplied from the secondary battery.
(13)
The secondary battery according to any one of (1) to (7) is provided as a power supply source.
Electronics.

  DESCRIPTION OF SYMBOLS 11 ... Battery can, 20, 30 ... Winding electrode body, 21, 33 ... Positive electrode, 21A, 33A ... Positive electrode collector, 21B, 33B ... Positive electrode active material layer, 21C, 22C, 23C ... Covering layer, 22, 34 ... Negative electrode, 22A, 34A ... Negative electrode current collector, 22B, 34B ... Negative electrode active material layer, 23, 35 ... Separator, 23A ... Base material layer, 36 ... Electrolyte layer, 40 ... Exterior member.

Claims (13)

An electrolyte is provided together with a positive electrode and a negative electrode
The electrolyte is
An alkyl lithium carbonate represented by the following formula (1):
At least one of reactive cyclic carbonates represented by the following formulas (2) to (5);
A secondary battery comprising at least one of lithium fluorophosphate represented by the following formula (6) and formula (7).
R1-O—C (═O) —O—Li (1)
(R1 is an alkyl group having 1 to 5 carbon atoms.)

(R2 to R5 are a hydrogen group, a halogen group, an alkyl group or a halogenated alkyl group, and at least one of R2 to R5 is a halogen group or a halogenated alkyl group. R6 and R7 are a hydrogen group or an alkyl group. R8 to R11 are a hydrogen group, an alkyl group, a vinyl group or an allyl group, and at least one of R8 to R11 is a vinyl group or an allyl group, and R12 is a group represented by ═CH—R13. And R13 is a hydrogen group or an alkyl group.)
Li ₂ PFO ₃ (6)
LiPF ₂ O ₂ (7) The lithium alkyl carbonate is methyl lithium carbonate, ethyl lithium carbonate, linear or branched propyl lithium carbonate, linear or branched butyl lithium carbonate, and linear or branched lithium pentyl carbonate. At least one of
Examples of the reactive cyclic carbonate include 4-fluoro-1,3-dioxolan-2-one, vinylene carbonate (1,3-dioxol-2-one), vinyl ethylene carbonate (4-vinyl-1,3-dioxolane- 2-one) and methylene ethylene carbonate (4-methylene-1,3-dioxolan-2-one),
The secondary battery according to claim 1. The content of the lithium alkyl carbonate in the electrolytic solution is 5 ppm to 2000 ppm,
The content of the reactive cyclic carbonate in the electrolytic solution is 0.5 wt% to 10 wt%,
The content of the lithium fluorophosphate in the electrolytic solution is 5 ppm to 3000 ppm,
The secondary battery according to claim 1. At least one of the positive electrode and the negative electrode has, as an active material, a potential of 1 V to 5 V (vs. lithium metal potential) in a charge / discharge curve (vertical axis: potential (V), horizontal axis: charge / discharge capacity (mAh)). And a material showing a potential flat portion whose potential change amount is within 25 mV in a region where the charge / discharge capacity is 50% or more of the total charge / discharge capacity,
The secondary battery according to claim 1. The positive electrode includes a lithium iron phosphate compound represented by the following formula (8) as the active material,
The negative electrode contains at least one of lithium titanium composite oxides represented by the following formulas (9) to (11) as the active material,
The secondary battery according to claim 4.
LiFe _a M1 _1-a O ₄ (8)
(M1 is at least one of Mg, Al, Ca, Ti, V, Mn, Co, Ni, Cu, Zn, Zr, and Ba, and a is 0 <a ≦ 1.)
Li [Li _x M 2 _{(1-3x) / 2} Ti _{(3 + x) / 2} ] O ₄ (9)
(M2 is at least one of Mg, Ca, Cu, Zn and Sr, and x satisfies 0 ≦ x ≦ 1/3.)
Li [Li _y M3 _1-3y Ti _{1 + 2y} ] O ₄ (10)
(M3 is at least one of Al, Sc, Cr, Mn, Fe, Ga and Y, and y satisfies 0 ≦ y ≦ 1/3.)
Li [Li _1/3 M4 _z Ti _{(5/3) -z} ] O 4 (11)
(M4 is at least one of V, Zr and Nb, and z satisfies 0 ≦ z ≦ 2/3.) The positive electrode active material is a lithium iron phosphate compound (LiFePO ₄ ),
The negative electrode active material is lithium titanate (Li ₄ Ti ₅ O ₁₂ ),
The secondary battery according to claim 5. A lithium ion secondary battery,
The secondary battery according to claim 1. An alkyl lithium carbonate represented by the following formula (1):
At least one of reactive cyclic carbonates represented by the following formulas (2) to (5);
An electrolyte solution for a secondary battery, comprising at least one of lithium fluorophosphate represented by the following formula (6) and formula (7).
R1-O—C (═O) —O—Li (1)
(R1 is an alkyl group having 1 to 5 carbon atoms.)

(R2 to R5 are a hydrogen group, a halogen group, an alkyl group or a halogenated alkyl group, and at least one of R2 to R5 is a halogen group or a halogenated alkyl group. R6 and R7 are a hydrogen group or an alkyl group. R8 to R11 are a hydrogen group, an alkyl group, a vinyl group or an allyl group, and at least one of R8 to R11 is a vinyl group or an allyl group, and R12 is a group represented by ═CH—R13. And R13 is a hydrogen group or an alkyl group.)
Li ₂ PFO ₃ (6)
LiPF ₂ O ₂ (7) A secondary battery,
A control unit for controlling the usage state of the secondary battery;
A switch unit for switching the usage state of the secondary battery according to an instruction of the control unit,
The secondary battery includes an electrolyte solution together with a positive electrode and a negative electrode,
The electrolyte is
An alkyl lithium carbonate represented by the following formula (1):
At least one of reactive cyclic carbonates represented by the following formulas (2) to (5);
A battery pack comprising at least one of lithium fluorophosphate represented by the following formula (6) and formula (7).
R1-O—C (═O) —O—Li (1)
(R1 is an alkyl group having 1 to 5 carbon atoms.)

(R2 to R5 are a hydrogen group, a halogen group, an alkyl group or a halogenated alkyl group, and at least one of R2 to R5 is a halogen group or a halogenated alkyl group. R6 and R7 are a hydrogen group or an alkyl group. R8 to R11 are a hydrogen group, an alkyl group, a vinyl group or an allyl group, and at least one of R8 to R11 is a vinyl group or an allyl group, and R12 is a group represented by ═CH—R13. And R13 is a hydrogen group or an alkyl group.)
Li ₂ PFO ₃ (6)
LiPF ₂ O ₂ (7) A secondary battery,
A converter that converts electric power supplied from the secondary battery into driving force;
A drive unit that drives according to the driving force;
A control unit for controlling the usage state of the secondary battery,
The secondary battery includes an electrolyte solution together with a positive electrode and a negative electrode,
The electrolyte is
An alkyl lithium carbonate represented by the following formula (1):
At least one of reactive cyclic carbonates represented by the following formulas (2) to (5);
An electric vehicle including at least one of lithium fluorophosphate represented by the following formula (6) and formula (7).
R1-O—C (═O) —O—Li (1)
(R1 is an alkyl group having 1 to 5 carbon atoms.)

(R2 to R5 are a hydrogen group, a halogen group, an alkyl group or a halogenated alkyl group, and at least one of R2 to R5 is a halogen group or a halogenated alkyl group. R6 and R7 are a hydrogen group or an alkyl group. R8 to R11 are a hydrogen group, an alkyl group, a vinyl group or an allyl group, and at least one of R8 to R11 is a vinyl group or an allyl group, and R12 is a group represented by ═CH—R13. And R13 is a hydrogen group or an alkyl group.)
Li ₂ PFO ₃ (6)
LiPF ₂ O ₂ (7) A secondary battery,
One or more electrical devices;
A control unit for controlling power supply from the secondary battery to the electrical device,
The secondary battery includes an electrolyte solution together with a positive electrode and a negative electrode,
The electrolyte is
An alkyl lithium carbonate represented by the following formula (1):
At least one of reactive cyclic carbonates represented by the following formulas (2) to (5);
An electric power storage system comprising: at least one of lithium fluorophosphate represented by the following formula (6) and formula (7):
R1-O—C (═O) —O—Li (1)
(R1 is an alkyl group having 1 to 5 carbon atoms.)

(R2 to R5 are a hydrogen group, a halogen group, an alkyl group or a halogenated alkyl group, and at least one of R2 to R5 is a halogen group or a halogenated alkyl group. R6 and R7 are a hydrogen group or an alkyl group. R8 to R11 are a hydrogen group, an alkyl group, a vinyl group or an allyl group, and at least one of R8 to R11 is a vinyl group or an allyl group, and R12 is a group represented by ═CH—R13. And R13 is a hydrogen group or an alkyl group.)
Li ₂ PFO ₃ (6)
LiPF ₂ O ₂ (7) A secondary battery,
A movable part to which power is supplied from the secondary battery,
The secondary battery includes an electrolyte solution together with a positive electrode and a negative electrode,
The electrolyte is
An alkyl lithium carbonate represented by the following formula (1):
At least one of reactive cyclic carbonates represented by the following formulas (2) to (5);
An electric tool comprising at least one of lithium fluorophosphate represented by the following formula (6) and formula (7).
R1-O—C (═O) —O—Li (1)
(R1 is an alkyl group having 1 to 5 carbon atoms.)

(R2 to R5 are a hydrogen group, a halogen group, an alkyl group or a halogenated alkyl group, and at least one of R2 to R5 is a halogen group or a halogenated alkyl group. R6 and R7 are a hydrogen group or an alkyl group. R8 to R11 are a hydrogen group, an alkyl group, a vinyl group or an allyl group, and at least one of R8 to R11 is a vinyl group or an allyl group, and R12 is a group represented by ═CH—R13. And R13 is a hydrogen group or an alkyl group.)
Li ₂ PFO ₃ (6)
LiPF ₂ O ₂ (7) A secondary battery is provided as a power supply source,
The secondary battery includes an electrolyte solution together with a positive electrode and a negative electrode,
The electrolyte is
An alkyl lithium carbonate represented by the following formula (1):
At least one of reactive cyclic carbonates represented by the following formulas (2) to (5);
An electronic device comprising at least one of lithium fluorophosphate represented by the following formula (6) and formula (7):
R1-O—C (═O) —O—Li (1)
(R1 is an alkyl group having 1 to 5 carbon atoms.)

(R2 to R5 are a hydrogen group, a halogen group, an alkyl group or a halogenated alkyl group, and at least one of R2 to R5 is a halogen group or a halogenated alkyl group. R6 and R7 are a hydrogen group or an alkyl group. R8 to R11 are a hydrogen group, an alkyl group, a vinyl group or an allyl group, and at least one of R8 to R11 is a vinyl group or an allyl group, and R12 is a group represented by ═CH—R13. And R13 is a hydrogen group or an alkyl group.)
Li ₂ PFO ₃ (6)
LiPF ₂ O ₂ (7)

Images