JP6565323B2 - Non-aqueous secondary battery - Google Patents

Description

  The present invention relates to a non-aqueous secondary battery.

  So far, the present inventors have formed an organic skeleton layer containing an aromatic compound that is a dicarboxylic acid anion having an aromatic ring structure and an alkali metal element coordinated with oxygen contained in the carboxylic acid anion to form a skeleton. An electrode active material provided with an alkali metal element layer to be formed, and a non-aqueous secondary battery provided with such an electrode active material have been proposed (see Patent Documents 1 and 2, etc.).

JP 2012-221754 A JP 2013-225413 A

  However, in the non-aqueous secondary battery provided with the electrode active material of Patent Documents 1 and 2, the charge / discharge characteristics can be improved, but the internal resistance may be large. For this reason, it has been desired to further reduce the internal resistance.

  The present invention has been made to solve such problems, and a main object of the present invention is to provide a non-aqueous secondary battery capable of further reducing internal resistance.

  In order to achieve the above-mentioned object, the present inventors have found that when a non-aqueous secondary battery is produced using a non-aqueous electrolyte containing a predetermined amount of a predetermined compound, the internal resistance can be further reduced. The invention has been completed.

That is, the non-aqueous secondary battery of the present invention is
An organic skeleton layer containing an aromatic compound that is a dicarboxylic acid anion having an aromatic ring structure; and an alkali metal element layer in which an alkali metal element coordinates to oxygen contained in the carboxylic acid anion to form a skeleton. A layered structure-containing electrode comprising a layered structure;
A non-aqueous electrolyte solution containing the anionic compound represented by the general formula (1) in an amount of more than 0.5% by mass based on the non-aqueous solvent in which the supporting salt is dissolved;
It is equipped with.

(However, M represents a transition element, a group 13, 14 or 15 element of the periodic table; A ^{a +} is a metal ion proton or onium ion, a is an integer of 1 to 3, p is b / a; An integer of 1 to 3, m is an integer of 1 to 4, n is an integer of 0 to 8, q represents 0 or 1; R ¹ is alkylene having 1 to 10 carbons, halogenated having 1 to 10 carbons Alkylene, arylene having 6 to 20 carbon atoms, or halogenated arylene having 6 to 20 carbon atoms (these alkylene and arylene may have a substituent or a hetero atom in the structure, and q is 1 and m is 2) -4 represents m R ^{1 s} may be bonded to each other); R ² represents halogen, alkyl having 1 to 10 carbons, alkyl halide having 1 to 10 carbons, 6 to 6 carbons 20 aryls, aryl halides having 6 to 20 carbon atoms (this Et alkyl and aryl substituents in their structure, may form a ring of n R ² are each bonded to when the may have a hetero atom, and n is 2-8) or -X ³ R ³ represents a; X ^1, X ² and X ^3, O each independently represents S or NR ^4; R ³ and R ⁴ are each hydrogen independently, having 1 to 10 carbon atoms Alkyl, halogenated alkyl having 1 to 10 carbon atoms, aryl having 6 to 20 carbon atoms, aryl halide having 6 to 20 carbon atoms (these alkyl and aryl may have a substituent or a hetero atom in the structure thereof). Well, when there are a plurality of R ³ or R ⁴ , each may be bonded to form a ring)

  In this non-aqueous secondary battery, the internal resistance can be reduced. The reason why such an effect is obtained is that, for example, by using a non-aqueous electrolyte solution containing a predetermined amount or more of the anion compound represented by the general formula (1), a stable film is formed on the surface of the layer structure, and the layer structure It is inferred that the charge / discharge reaction on the surface is performed smoothly.

Explanatory drawing which shows an example of the structure of a layered structure. An explanatory view showing an example of nonaqueous system rechargeable battery. The graph which shows IV resistance of Experimental Examples 1-6. The graph which shows the cycling characteristics of Experimental Examples 1-6. The graph showing the relationship between the ratio of CMC and the maximum capacity. The graph showing the relationship between the ratio of CMC and initial efficiency. The graph showing the relationship between the ratio of CMC and a capacity maintenance rate.

  The non-aqueous secondary battery of this invention is equipped with the non-aqueous electrolyte containing the compound represented by General formula (1), and a layered structure containing electrode. Hereinafter, a preferred embodiment of the non-aqueous secondary battery of the present invention will be described. The non-aqueous secondary battery of this embodiment is a lithium secondary battery that includes a layered structure-containing electrode as a negative electrode and uses lithium as a charge carrier. More specifically, the non-aqueous secondary battery according to the present embodiment includes a positive electrode capable of inserting and extracting lithium, a layered structure-containing electrode as a negative electrode capable of inserting and extracting lithium, and a positive electrode and a negative electrode. And the above-described non-aqueous electrolyte that conducts lithium.

  The nonaqueous electrolytic solution contains a compound represented by the general formula (1). In the general formula (1), M is a transition element, a group 13, 14 or 15 element of the periodic table, among which Al, B, V, Ti, Si, Zr, Ge, Sn, Cu, Y, Zn, Ga, Nb, Ta, Bi, P, As, Sc, Hf or Sb are preferable, and Al, B or P is more preferable. When M is Al, B or P, the synthesis of anions contained in the compound becomes relatively easy, and the production cost can be suppressed. The valence b of the anion is 1 to 3, of which 1 is preferable. When the valence b is larger than 3, it is not preferable because the salt of the compound tends to be hardly dissolved in the mixed organic solvent. The constants m and n are values related to the number of ligands and are determined by the type of M. m is an integer of 1 to 4, and n is an integer of 0 to 8. The constant q is 0 or 1. When q is 0, the chelate ring is a five-membered ring.

Wherein, R ¹ represents an alkylene having 1 to 10 carbon atoms, a halogenated alkylene of 1 to 10 carbon atoms, a halogenated arylene having 6-20 arylene carbon atoms or 6 to 20 carbon atoms. These alkylene and arylene may have a substituent or a hetero atom in the structure. Specifically, instead of hydrogen on alkylene and arylene, halogen, chain or cyclic alkyl group, aryl group, alkenyl group, alkoxy group, aryloxy group, sulfonyl group, amino group, cyano group, carbonyl group, acyl It may have a group, an amide group or a hydroxyl group as a substituent, or may have a structure in which nitrogen, sulfur or oxygen is introduced instead of carbon on alkylene and arylene. When q is 1 and m is 2 to 4, m R ^{1 s} may be bonded to each other. Examples thereof include a ligand such as ethylenediaminetetraacetic acid.

R ² is halogen, alkyl having 1 to 10 carbon atoms, alkyl halide having 1 to 10 carbon atoms, aryl having 6 to 20 carbon atoms, aryl halide having 6 to 20 carbon atoms, or —X ³ R ³ (X ³ , R ³ will be described later. Alkyl and aryl here may also have a substituent or a hetero atom in the structure in the same manner as R ^1, and when n is 2 to 8, n R ² are bonded to each other to form a ring. May be formed. R ² is preferably an electron-withdrawing group, particularly preferably a fluorine atom. This is because in the case of a fluorine atom, the solubility and dissociation degree of the salt of the anion compound are improved, and the ionic conductivity is improved accordingly. Moreover, it is because oxidation resistance improves and generation | occurrence | production of a side reaction can be suppressed by this.

X ¹ , X ² and X ³ each independently represent O, S or NR ⁴ . That is, the ligand is bonded to M through these heteroatoms.

R ³ and R ⁴ each independently represent hydrogen, an alkyl having 1 to 10 carbon atoms, an alkyl halide having 1 to 10 carbon atoms, an aryl having 6 to 20 carbon atoms, or an aryl halide having 6 to 20 carbon atoms. . Similarly to R ¹ , these alkyls and aryls may have a substituent or a hetero atom in the structure. Further, when a plurality of R ³ or R ⁴ are present, they may be bonded to each other to form a ring.

In the cation (A ^{a +} ) of the compound represented by the general formula (1), a is 1 to 3, and p is b / a. Examples of the cation include lithium, sodium, potassium, magnesium, calcium, barium, cesium, rubidium, silver, zinc, copper, cobalt, iron, nickel, manganese, titanium, lead, chromium, vanadium, ruthenium, yttrium, lanthanoid, In addition to cations such as actinides, tetraalkylammonium (wherein alkyl is methyl, ethyl, butyl, etc.), ammonium cations such as triethylammonium, pyridinium, imidazolium, protons, and the like. Among these, a lithium cation, a sodium cation, or a potassium cation is preferable. In particular, a compound containing lithium or potassium is preferable because it is easily dissolved in a non-aqueous solvent.

  The compound represented by the general formula (1) preferably contains one or more anions of PTFO, PFO, PO, BFO and BOB represented by the formulas (2) to (6). The reason is that it is easy to form a stable film on the surface of the negative electrode active material. The compound represented by the general formula (1) is more preferably a compound containing lithium or potassium as a cation and PFO or BOB as an anion. Among these, a compound containing lithium as a cation and PFO as an anion is more preferable. In such a case, the internal resistance can be further reduced, and the cycle characteristics can be further improved.

As a method for synthesizing such a compound, for example, in the case of PFO, after reacting LiPF ₆ with 4 times moles of lithium alkoxide in a non-aqueous solvent, oxalic acid is added and alkoxide bonded to phosphorus. There is a method of substituting with oxalic acid. In the case of BFO, a method of reacting LiBF ₄ with 2 moles of lithium alkoxide in a non-aqueous solvent and then adding oxalic acid to replace the alkoxide bonded to boron with oxalic acid. Etc. In these cases, the compound represented by the general formula (1) can be obtained as an anion lithium salt.

  It is considered that when this compound is charged at least once in a non-aqueous secondary battery, all or part of the compound (for example, anion) is decomposed and coated on the surface of the negative electrode active material to form a film. This coating can be detected by, for example, X-ray photoelectron spectroscopy (XPS) or IR analysis.

  The non-aqueous electrolyte comprises a compound represented by the general formula (1) from 0.5% by mass with respect to the non-aqueous solvent in which the supporting salt is dissolved, that is, the total amount of the supporting salt and the non-aqueous solvent. Including many. If this compound is contained in an amount of more than 0.5% by mass, the internal resistance can be reduced. The content of this compound is preferably 0.6% by mass or more, more preferably 0.8 or more, and still more preferably 1.0 or more. The upper limit of the content of this compound is not particularly limited, but may be, for example, a saturation amount or less, 5.0 mass% or less, 4.0 mass% or less, or 3.0 mass%. It is good also as follows.

  Examples of the non-aqueous solvent include carbonates, esters, ethers, nitriles, furans, sulfolanes and dioxolanes, and these can be used alone or in combination. Specifically, as carbonates, cyclic carbonates such as ethylene carbonate, propylene carbonate, vinylene carbonate, dimethyl carbonate, ethyl methyl carbonate, diethyl carbonate, ethyl-n-butyl carbonate, methyl-t-butyl carbonate, di- chain carbonates such as i-propyl carbonate and t-butyl-i-propyl carbonate, cyclic esters such as γ-butyllactone and γ-valerolactone, chain esters such as methyl formate and ethyl acetate, dimethoxyethane, Ethers such as ethoxymethoxyethane, nitriles such as acetonitrile and benzonitrile, furans such as tetrahydrofuran and methyltetrahydrofuran, sulfolanes such as sulfolane and tetramethylsulfolane Examples include holanes, dioxolanes such as 1,3-dioxolane and methyldioxolane. Among these, the combination of cyclic carbonates and chain carbonates is preferable. According to this combination, not only the cycle characteristics representing the battery characteristics in repeated charge and discharge are excellent, but also the viscosity of the non-aqueous electrolyte, the electric capacity of the obtained battery, the battery output, etc. are balanced. be able to. The cyclic carbonates are considered to have a relatively high relative dielectric constant and increase the dielectric constant of the non-aqueous electrolyte, and the chain carbonates are considered to suppress the viscosity of the non-aqueous electrolyte.

Examples of the supporting salt include LiPF ₆ , LiBF ₄ , LiAsF ₆ , LiCF ₃ SO ₃ , LiN (CF ₃ SO ₂ ) ₂ , LiC (CF ₃ SO ₂ ) ₃ , LiSbF ₆ , LiSiF ₆ , LiAlF ₄ , LiSCN, Examples include LiClO ₄ , LiCl, LiF, LiBr, LiI, and LiAlCl ₄ . Among these, from the group consisting of inorganic salts such as LiPF ₆ , LiBF ₄ , LiAsF ₆ , LiSbF ₆ and organic salts such as LiCF ₃ SO ₃ , LiN (CF ₃ SO ₂ ) ₂ , LiC (CF ₃ SO ₂ ) _3. It is preferable from the viewpoint of electrical characteristics to use a combination of one or two or more selected salts. Of these, LiPF ₆ is preferred. The supporting salt does not include the compound represented by the general formula (1). The concentration of the supporting salt in the non-aqueous solvent in which the supporting salt is dissolved is preferably 0.1 mol / L or more and 5 mol / L or less, and more preferably 0.5 mol / L or more and 2 mol / L or less. If it is 0.1 mol / L or more, a sufficient current density can be obtained, and if it is 5 mol / L or less, the non-aqueous electrolyte can be made more stable. Moreover, you may add flame retardants, such as a phosphorus type and a halogen type, to this non-aqueous non-aqueous electrolyte.

A layered structure-containing electrode as a negative electrode includes an organic skeleton layer containing an aromatic compound that is a dicarboxylic acid anion having an aromatic ring structure, and an alkali metal element coordinated to oxygen contained in the carboxylic acid anion. A layered structure having an alkali metal element layer to be formed (hereinafter also referred to as a layered structure of the present invention) is provided as an active material. FIG. 1 is an explanatory view showing an example of the structure of the layered structure of the present invention. It is structurally stable that this layered structure has a monoclinic crystal structure that is formed in layers by π-electron interaction of an aromatic compound and is assigned to the space group P2 ₁ / c. Yes, it is preferable. Moreover, it is structurally stable that the layered structure has a structure of the following formula (7) in which four oxygen atoms of different dicarboxylic acid anions and an alkali metal element form a four-coordination. preferable. However, in this formula (7), R has one or more aromatic ring structures, and two or more of a plurality of Rs may be the same or one or more may be different. A is an alkali metal element. Thus, it is preferable to have a structure in which the organic skeleton layer is bonded by an alkali metal element.

  The organic skeleton layer contains an aromatic compound that is a dicarboxylic acid anion having one or more aromatic ring structures. The aromatic compound may have one aromatic ring structure, but preferably has two or more aromatic ring structures. That is, R in the formula (7) preferably has two or more aromatic ring structures. This is because a layered structure is easily formed when the aromatic ring structure is 2 or more. The two or more aromatic ring structures may be, for example, an aromatic polycyclic compound in which two or more aromatic rings such as biphenyl are bonded, or a condensed polycycle in which two or more aromatic rings such as naphthalene, anthracene, and pyrene are condensed. It may be a compound. The aromatic compound preferably has an aromatic ring structure of 5 or less. This is because if the aromatic ring structure is 5 or less, the energy density can be further increased. This aromatic ring may be a 5-membered ring, a 6-membered ring or an 8-membered ring, and a 6-membered ring is preferred. This organic skeleton layer preferably contains an aromatic compound in which one of the dicarboxylic acid anions and the other of the carboxylic acid anions are bonded to diagonal positions of the aromatic ring structure. By doing so, it is easy to form a layered structure of the organic skeleton layer and the alkali metal element layer. The diagonal position to which the carboxylic acid is bonded may be the farthest position from the bonding position of one carboxylic acid to the bonding position of the other carboxylic acid. For example, if the aromatic ring structure is benzene, 1, 4 The position (para position) can be mentioned, and naphthalene includes the 2nd and 6th positions, and pyrene includes the 2nd and 7th positions. This organic skeleton layer may be composed of an aromatic compound including a structure represented by the formula (8). However, R may be the above aromatic ring structure having one or more aromatic ring structures. Specifically, the organic skeleton layer may include any one or more aromatic compounds of the following formulas (9) to (11). However, in the formulas (9) to (11), n is preferably an integer of 1 to 5, and m is an integer of 0 to 3. When n is 1 or more and 5 or less, the size of the organic skeleton layer is suitable, and the charge / discharge capacity can be further increased. Moreover, when m is 0 or more and 3 or less, the size of the organic skeleton layer is suitable, and the charge / discharge capacity can be further increased. In the formulas (9) to (11), these aromatic compounds may have a substituent or a hetero atom in the structure. Specifically, instead of hydrogen of an aromatic compound, a halogen, a chain or cyclic alkyl group, an aryl group, an alkenyl group, an alkoxy group, an aryloxy group, a sulfonyl group, an amino group, a cyano group, a carbonyl group, an acyl group Further, it may have an amide group or a hydroxyl group as a substituent, or may have a structure in which nitrogen, sulfur or oxygen is introduced instead of carbon of the aromatic compound. Note that Li in the formulas (8) to (11) indicates Li constituting the alkali metal element layer.

For example, as shown in FIG. 1, the alkali metal element layer has a skeleton formed by coordination of an alkali metal element with oxygen contained in a carboxylate anion. The alkali metal element may be any one or more of Li, Na, and K, and among these, Li is preferable. Since the alkali metal element contained in the alkali metal element layer forms the skeleton of the layered structure, it is presumed that the alkali metal element does not participate in ion migration accompanying charge / discharge, that is, is not occluded / released during charge / discharge. As shown in FIG. 1, the layered structure thus configured is formed by an organic skeleton layer and a Li layer (alkali metal element layer) existing between the organic skeleton layers. In the energy storage mechanism, the organic skeleton layer of the layered structure is considered to function as a redox (e ⁻ ) site, while the Li layer functions as a Li ⁺ storage site. That is, this layered structure is considered to store and release energy as shown in the following formula (12). Further, in this layered structure, a space where Li can enter may be formed in the organic skeleton layer, and Li can be occluded and released also in portions other than the alkali metal layer in Formula (12). It is assumed that the discharge capacity can be further increased.

  A layered structure-containing electrode is prepared by mixing an active material (the layered structure described above) and other materials and adding a suitable solvent to form a paste-like electrode mixture on the surface of the current collector. It may be dried and compressed to increase the electrode density as necessary.

  The electrode mixture preferably contains a water-soluble polymer. The water-soluble polymer may be at least one of carboxymethyl cellulose and polyvinyl alcohol. This water-soluble polymer may serve as a binder that binds the active material particles and the conductive material particles. Carboxymethyl cellulose may be, for example, an inorganic salt having a carboxymethyl group terminated with sodium or calcium, or an ammonium salt having a carboxymethyl group terminated with ammonium. When the electrode mixture includes a water-soluble polymer, the electrode mixture is preferably included in the range of 2% by mass to 8% by mass. When the water-soluble polymer is contained in the range of 2% by mass or more, the capacity retention rate can be further increased. Moreover, in the thing containing a water-soluble polymer in 8 mass% or less, the adhesiveness of electrode materials or an electrode material and a collector is high. Among these, what contains a water-soluble polymer in 7 mass% or less is preferable, and what contains in 6 mass% or less is more preferable.

  The electrode mixture may contain a styrene-butadiene copolymer in addition to the water-soluble polymer. The styrene-butadiene copolymer may serve as a binding material that binds the active material particles and the conductive material particles. A material containing a styrene-butadiene copolymer is preferable in that the active material particles can be bound more strongly. When the electrode mixture includes a styrene-butadiene copolymer, the electrode mixture preferably includes the styrene-butadiene copolymer in a range of 8% by mass or less. If the amount is 8% by mass or less, the amount of the active material, the conductive material, and the water-soluble polymer does not decrease too much, so that the functions of the active material, the conductive material, and the water-soluble polymer can be sufficiently exhibited.

  The electrode mixture preferably includes a conductive material. The conductive material is not particularly limited as long as it is an electron conductive material that does not adversely affect battery performance. For example, graphite such as natural graphite (scale-like graphite, scale-like graphite) or artificial graphite, acetylene black, carbon black, ketjen A mixture of one or more of carbon materials such as black, carbon whisker, needle coke and carbon fiber, and metals (copper, nickel, aluminum, silver, gold, etc.) can be used. Among these, as the conductive material, carbon black and acetylene black are preferable from the viewpoints of electron conductivity and coatability. When the electrode mixture includes a conductive material, the electrode material preferably includes the conductive material in a range of 5% by mass to 15% by mass. If it is 5 mass% or more, sufficient electroconductivity can be given to an electrode and deterioration of a charge / discharge characteristic can be suppressed. Moreover, if it is 15 mass% or less, since an active material and a water-soluble polymer do not decrease too much, the function of an active material and a water-soluble polymer can fully be exhibited.

  The electrode mixture preferably contains the active material in the range of 70% by mass to 90% by mass. In an electrode using an organic active material, since the conductivity is generally low and it is necessary to improve the conductivity by adding a large amount of a conductive material, the amount of the active material is less than 70% by mass. , Which is preferable in that the active material can be increased to 70% by mass or more. In the case where the active material is contained in the range of 90% by mass or less, the amount of the conductive material and the water-soluble polymer is not decreased too much, so that the functions of the conductive material and the water-soluble polymer can be sufficiently exhibited.

  The electrode mixture may include a binder instead of or in addition to the above-described water-soluble polymer or styrene-butadiene copolymer. The binder serves to bind the active material particles and the conductive material particles. For example, polytetrafluoroethylene (PTFE), polyvinylidene fluoride (PVdF), a fluorine-containing resin such as fluororubber, polypropylene, A thermoplastic resin such as polyethylene, ethylene-propylene-diene-monomer (EPDM) rubber, sulfonated EPDM rubber, natural butyl rubber (NBR), or the like may be used. These can be used alone or as a mixture of two or more.

  As a solvent for dispersing the active material and other materials, water may be used. For example, N-methylpyrrolidone, dimethylformamide, dimethylacetamide, methyl ethyl ketone, cyclohexanone, methyl acetate, methyl acrylate, diethylenetriamine, N, N -You may use organic solvents, such as a dimethylamino propylamine, ethylene oxide, and tetrahydrofuran. In addition, water is suitable when the water-soluble polymer or styrene butadiene copolymer described above is used as the binder. Examples of the application method include roller coating such as applicator roll, screen coating, doctor blade method, spin coating, bar coater, and the like, and any of these can be used to obtain an arbitrary thickness and shape.

  Current collectors include copper, nickel, stainless steel, titanium, aluminum, calcined carbon, conductive polymer, conductive glass, Al-Cd alloy, etc., for the purpose of improving adhesion, conductivity and reduction resistance. For example, the surface of copper or the like treated with carbon, nickel, titanium, silver, or the like can also be used. Of these, the current collector of the negative electrode is more preferably aluminum metal. That is, the layered structure is preferably formed on an aluminum metal current collector. This is because aluminum is abundant and has excellent corrosion resistance. For these, the surface can be oxidized. Examples of the shape of the current collector include foil, film, sheet, net, punched or expanded, lath, porous, foam, and formed fiber group. The thickness of the current collector is, for example, 1 to 500 μm.

  The layered structure-containing electrode has an organic skeleton layer containing an aromatic compound that is a dicarboxylic acid anion having an aromatic ring structure (preferably a naphthalene skeleton or a benzene skeleton) and an alkali metal element coordinated to oxygen contained in the carboxylic acid anion. After forming an electrode mixture containing a layered structure including an alkali metal element layer that forms a skeleton and a conductive material on a current collector, 250 ° C to 450 ° C in an inert atmosphere It is good also as what is baked in the temperature range. In this way, the crystal structure can be made more suitable, the π-electron interaction of the aromatic compound can be increased, and the exchange of electrons can be facilitated, so that the charge / discharge characteristics can be further improved. In this firing treatment, when the firing temperature is 250 ° C. or higher, charge / discharge characteristics can be improved, and when the firing temperature is 450 ° C. or lower, structural breakdown of the layered structure can be further suppressed. The firing temperature is preferably 275 ° C. or higher, more preferably 350 ° C. or lower, and further preferably about 300 ° C. Moreover, although baking time is suitably selected according to baking temperature, the range of 2 hours or more and 24 hours or less is preferable, for example. The inert atmosphere may be, for example, a rare gas such as nitrogen gas, He, or Ar, and among these, Ar is preferable.

For example, the positive electrode is prepared by mixing a positive electrode active material, a conductive material, and a binder, adding a suitable solvent to form a paste-like positive electrode mixture, applying and drying on the surface of the current collector, and if necessary You may compress and form in order to raise an electrode density. As the positive electrode active material, a sulfide containing a transition metal element, an oxide containing lithium and a transition metal element, or the like can be used. Specifically, transition metal sulfides such as TiS ₂ , TiS ₃ , MoS ₃ , FeS ₂ , Li _(1-a) MnO ₂ (0 <a <1, etc., the same shall apply hereinafter), Li _(1-a) Mn Lithium manganese composite oxide such as ₂ O ₄ , lithium cobalt composite oxide such as Li _(1-a) CoO ₂ , lithium nickel composite oxide such as Li _(1-a) NiO ₂ , lithium such as LiV ₂ O ₃ Vanadium composite oxides, transition metal oxides such as V ₂ O _{5, and the} like can be used. Of these, lithium transition metal composite oxides such as LiCoO ₂ , LiNiO ₂ , LiMnO ₂ , and LiV ₂ O ₃ are preferable. Moreover, what was illustrated by the layered structure containing electrode can respectively be used for the electrically conductive material, binder, solvent, etc. which are used for a positive electrode. In addition to aluminum, titanium, stainless steel, nickel, iron, calcined carbon, conductive polymer, conductive glass, etc., the positive electrode current collector includes aluminum and titanium for the purpose of improving adhesion, conductivity, and oxidation resistance. What processed the surface of copper etc. with carbon, nickel, titanium, silver, etc. can be used. For these, the surface can be oxidized. The shape of the current collector can be the same as that of the layered structure-containing electrode. The positive electrode current collector may be the same as the negative electrode current collector.

  The nonaqueous secondary battery of the present invention may include a separator between the positive electrode and the negative electrode. The separator is not particularly limited as long as it is a composition that can withstand the range of use of the non-aqueous secondary battery. For example, a polymer nonwoven fabric such as a polypropylene nonwoven fabric or a polyphenylene sulfide nonwoven fabric, or a thin olefin resin such as polyethylene or polypropylene is thin. A microporous membrane is mentioned. These may be used alone or in combination.

  The shape of the nonaqueous secondary battery of the present invention is not particularly limited, and examples thereof include a coin type, a button type, a sheet type, a laminated type, a cylindrical type, a flat type, and a square type. Moreover, you may apply to the large sized thing etc. which are used for an electric vehicle etc. FIG. 2 is a schematic diagram illustrating an example of the non-aqueous secondary battery 10 according to the above-described embodiment. The non-aqueous secondary battery 10 includes a positive electrode sheet 13 in which a positive electrode mixture 12 is formed on a current collector 11, a negative electrode sheet 18 in which a negative electrode mixture 17 is formed on the surface of a current collector 14, a positive electrode sheet 13 and a negative electrode A separator 19 provided between the sheet 18 and a nonaqueous electrolytic solution 20 that fills between the positive electrode sheet 13 and the negative electrode sheet 18 are provided. In this nonaqueous secondary battery 10, a separator 19 is sandwiched between a positive electrode sheet 13 and a negative electrode sheet 18, and these are wound and inserted into a cylindrical case 22, and a positive electrode terminal 24 and a negative electrode sheet connected to the positive electrode sheet 13. And a negative electrode terminal 26 connected to each other. The negative electrode composite material includes an organic skeleton layer containing an aromatic compound that is a dicarboxylic acid anion having an aromatic ring structure, and an alkali metal element that forms a skeleton by coordination of an alkali metal element with oxygen contained in the carboxylic acid anion. And a layered structure having a layer. The nonaqueous electrolytic solution is a nonaqueous electrolytic solution containing 1.0% by mass or more of the compound represented by the general formula (1) with respect to the nonaqueous solvent in which the supporting salt is dissolved.

  In the non-aqueous secondary battery of this embodiment, the internal resistance can be further reduced. The reason why such an effect can be obtained is assumed as follows. For example, by using a non-aqueous electrolyte solution containing a predetermined amount or more of the anion compound represented by the general formula (1), a stable film is formed on the surface of the negative electrode active material (layered structure), and the surface of the negative electrode active material is filled. It is assumed that the discharge reaction (for example, lithium occlusion / release reaction) is performed smoothly.

  It should be noted that the present invention is not limited to the above-described embodiment, and it goes without saying that the present invention can be implemented in various modes as long as it belongs to the technical scope of the present invention.

  For example, in the embodiment described above, the layered structure-containing electrode is a negative electrode, but the layered structure-containing electrode may be a positive electrode. In this case, as the negative electrode, for example, metal lithium, a lithium alloy, a graphite negative electrode, or the like can be provided as an active material.

  In the above-described embodiment, the lithium secondary battery using lithium as a charge carrier is used. However, a battery other than lithium may be used as a charge carrier. For example, an alkali metal other than lithium, such as sodium or potassium, may be used as the charge carrier. In this case, at least one of the support salt contained in the non-aqueous electrolyte and the compound represented by the general formula (1) may contain an alkali metal ion other than lithium ion as a cation. Note that the type of alkali metal element forming the skeleton of the layered structure is not particularly limited because it is not inserted / desorbed by charge / discharge.

  Below, the example which produced the non-aqueous secondary battery of this invention concretely is demonstrated. Experimental examples 1, 2, and 6 correspond to examples of the present invention, and experimental examples 3 to 5 correspond to comparative examples. The present invention is not limited to the following examples, and it goes without saying that the present invention can be carried out in various modes as long as they belong to the technical scope of the present invention.

[Experimental Example 1]
(Synthesis of dilithium 2,6-naphthalenedicarboxylate)
For the synthesis of lithium 2,6-naphthalenedicarboxylate, 2,6-naphthalenedicarboxylic acid and lithium hydroxide monohydrate (LiOH.H ₂ O) were used as starting materials. Methanol (100 mL) was added to lithium hydroxide monohydrate (0.556 g) and stirred. After the lithium hydroxide monohydrate was dissolved, 2,6-naphthalenedicarboxylic acid (1.0 g) was added and stirred for 1 hour. After stirring, the solvent was removed, and the mixture was dried at 150 ° C. for 16 hours under vacuum to synthesize white 2,6-naphthalenedicarboxylate (formula (13)) as a white powder sample.

(Production of lithium 2,6-naphthalenedicarboxylate negative electrode)
73.9% by mass of lithium 2,6-naphthalenedicarboxylate prepared by the above method, 13.0% by mass of carbon black (Tokai Carbon, TB5500 (diameter of about 50 nm)) as a particulate carbon conductive material, a water-soluble polymer Mixing 5.2% by mass of a certain carboxymethyl cellulose (CMC) (Daicel Finechem, CMC Daicel 1120) and 7.8% by mass of styrene butadiene copolymer (SBR) (Nippon Zeon, BM-400B) as a dispersant An appropriate amount of water was added and dispersed to form a slurry composite. This slurry-like mixture was uniformly applied to a 10 μm thick copper foil current collector and dried by heating to prepare a coated sheet. Thereafter, the coated sheet was pressure-pressed and punched out to an area of 2.05 cm ² to prepare a disk-shaped electrode.

(Preparation of bipolar evaluation cell)
Lithium hexafluorophosphate was added to a non-aqueous solvent in which ethylene carbonate, dimethyl carbonate, and ethyl methyl carbonate were mixed at a volume ratio of 30:40:30 so as to be 1 mol / L. Furthermore, 1.0% by mass of a lithium salt (LPFO) containing an anion represented by the formula (3) was added to a non-aqueous solvent in which lithium hexafluorophosphate was dissolved to prepare a non-aqueous electrolyte. . Using the above 2,6-naphthalenedicarboxylate electrode as a working electrode, a lithium metal foil (thickness 300 μm) as a counter electrode, and sandwiching a separator (manufactured by Toray Tonen) impregnated with the above non-aqueous electrolyte between both electrodes A bipolar evaluation cell was prepared.

(Charge / discharge test)
Using the above bipolar evaluation cell, the battery was discharged at 0.3 mA to 0.5 V in a temperature environment of 20 ° C., and then charged to 1.5 V at 0.3 mA. This charging / discharging was performed 10 cycles. Polarization was calculated | required from the difference of the charging voltage and average voltage in that case, and IV resistance was computed from the polarization difference and electric current value. Thereafter, the charge / discharge current was set to 0.6 mA at the same charge / discharge voltage, 50 cycles of charge / discharge tests were performed, and the cycle characteristics were confirmed.

[Experimental Examples 2 to 5]
A cell of Experimental Example 2 was prepared in the same manner as Experimental Example 1 except that the amount of LPFO added was 3.0% by mass, and a charge / discharge test was performed. A cell of Experimental Example 3 was prepared in the same manner as Experimental Example 1 except that LPFO was not added, and a charge / discharge test was performed. A cell of Experimental Example 4 was prepared in the same manner as Experimental Example 1 except that the amount of LPFO added was 0.3 mass%, and a charge / discharge test was performed. A cell of Experimental Example 5 was produced in the same manner as Experimental Example 1 except that the amount of LPFO added was 0.5 mass%, and a charge / discharge test was performed.

[Experimental Example 6]
A cell of Experimental Example 6 was prepared in the same manner as in Experimental Example 1 except that 1.0% by mass of a lithium salt (LBOB) containing an anion represented by Formula (6) was added instead of LPFO, and a charge / discharge test was performed. Went.

  Table 1 shows the results of the types and addition ratios of additives in Examples 1 to 6, IV resistance, and capacity retention ratio after cycling. FIG. 3 shows the measurement results of IV resistance, and FIG. 4 shows the measurement results of cycle characteristics. In Experimental Examples 1, 2, and 6 using a nonaqueous electrolytic solution containing more than 0.5% by mass of a lithium salt containing an anion of formula (3) or formula (6), a reduction in IV resistance was confirmed.

  From the above, it was found that the internal resistance can be further reduced by using the nonaqueous electrolytic solution containing the compound represented by the general formula (1) (FIG. 3). The reason why such an effect is obtained is that it is suitable for the charge / discharge reaction due to the interaction between the dicarboxylic acid group contained in the layered structure and the oxalate dianion skeleton contained in the compound represented by the general formula (1). This is probably because an interface was formed.

  Furthermore, in Experimental Examples 1 and 2 containing more than 0.5% by mass of a lithium salt containing an anion of formula (3), improvement in cycle characteristics was confirmed (FIG. 4). From this, in Experimental Examples 1 and 2, the lithium salt containing the anion of formula (3) undergoes reductive decomposition on the surface of the negative electrode active material, and a stable film is formed by the reduction product. It was inferred that the ion conductivity necessary for lithium ion insertion / deinsertion reaction can be obtained while suppressing the reduction reaction. Although not shown, when the charge / discharge curves of Experimental Examples 1, 2, 4 to 6 were confirmed, a flat portion was confirmed near 0.7 V during the discharge of the first cycle, and the additive was added near 2 V. A flat portion presumed to be due to decomposition was confirmed, and only a flat portion near 0.7 V was confirmed in the subsequent cycles. From these facts, it was inferred that the coating was formed during the first cycle discharge.

  Below, it examined as a reference example about the compounding ratio of the electrode compound material in the non-aqueous secondary battery using the layered structure mentioned above.

[Reference Example 1]
(Charge / discharge test)
After reducing (discharging) to 0.5 V at 0.14 mA in a temperature environment of 20 ° C. using a bipolar evaluation cell prepared in the same manner as in Experimental Example 1 except that LPFO was not added to the non-aqueous electrolyte. And oxidized (charged) to 2.0 V at 0.14 mA. In this charge / discharge operation, the first reduction capacity is Q (1st) red, the oxidation capacity is Q (1st) oxi, the 10th reduction capacity is Q (10th) red, and the oxidation capacity is Q (10th) oxi. . Then, the initial efficiency was calculated from the equation of (Q (1st) oxi / Q (1st) red) × 100. Further, the capacity retention rate after 10 cycles was calculated from the formula of (Q (10th) oxi / Q (1st) oxi) × 100. The maximum capacity was the maximum of the first to tenth oxidation capacities.

[Reference Examples 2 to 12]
A cell was prepared in the same manner as in Reference Example 1 except that the configuration of the negative electrode was changed to that shown in Table 2 in the preparation of the coated electrode, and a charge / discharge test was performed. In Reference Example 12, fibrous carbon (vapor-grown carbon fiber, manufactured by Showa Denko, VGCF (diameter: about 150 nm, length: about 10 to 20 μm)) is used as the fibrous conductive material, and polyfluoride is used as the binder. Vinylidene was used and N-methyl-2-pyrrolidone was used as a dispersant.

[Results and discussion]
Table 2 shows the results of the maximum capacity, initial efficiency, and capacity retention rate of Reference Examples 1 to 12. Moreover, the graph showing the relationship between the ratio of CMC, maximum capacity | capacitance, initial efficiency, and a capacity | capacitance maintenance factor in FIGS. From Table 2, the CMC-based binder was compared with Reference Example 10 in which the CMC-based binder was not used, Reference Example 11 in which the CMC-based binder was excessive, and Reference Example 12 in which the PVdF-based binder was used. In Reference Examples 1 to 8 in which the dressing material was used at a ratio of 2% by mass or more and 8% by mass or less, it was found that all of the maximum capacity, the initial efficiency, and the capacity maintenance rate were excellent. In this regard, when the cross section of the electrode was observed with a scanning electron microscope (SEM), in Reference Examples 1 to 8, the entire electrode mixture was blackish, and the active material, conductive material, and water-soluble polymer were uniformly mixed and collected. It was in close contact with the electrical body. On the other hand, in Reference Example 10, a white portion and a black portion were mixed in the electrode mixture, and phase separation occurred. In Reference Examples 11 and 12, many portions where the electrode mixture was not in close contact with the current collector were observed. Therefore, in Reference Examples 1 to 8 using an appropriate amount of the CMC binder, Reference Example 10 without using the CMC binder, Reference Example 11 using excessive CMC binder, and PVdF binder. Compared to Reference Example 12 using a dressing material, the active material and the conductive material are more uniformly mixed and closely adhered to the current collector, so that the occurrence of a heterogeneous reaction in the electrode can be suppressed. It was inferred that the discharge characteristics could be further improved. 5 and 6 show that the maximum capacity and the initial efficiency can be further increased if the CMC in the electrode is 8.0 mass% or less. Further, FIG. 7 shows that the capacity retention ratio can be further increased when the CMC in the electrode is 2.0 mass% or more and 8.0 mass% or less. In Reference Example 9 in which the CMC in the electrode is 1.9% by mass, the maximum capacity and initial efficiency are equivalent to those of Reference Examples 1 to 8, but the capacity retention rate is 10% or more than that of Reference Examples 1 to 8. The value was low. Therefore, it has been found that the electrode exhibits a better expression capacity, initial efficiency, and capacity retention rate by containing the water-soluble polymer in the range of 2 mass% to 8 mass%. In addition, since the reference examples 1-12 mentioned above used the non-aqueous electrolyte solution which does not contain the compound represented by General formula (1), it was set as the reference example. However, also in the present invention, the charging / discharging characteristics can be further enhanced by setting the mixture of the electrode mixture as in Reference Examples 1 to 8 as compared with the case of Reference Examples 9 to 12. It was guessed.

  The present invention can be used in the field of the battery industry.

  DESCRIPTION OF SYMBOLS 10 Nonaqueous secondary battery, 11 Current collector, 12 Positive electrode mixture, 13 Positive electrode sheet, 14 Current collector, 17 Negative electrode mixture, 18 Negative electrode sheet, 19 Separator, 20 Nonaqueous electrolyte, 22 Cylindrical case, 24 Positive electrode Terminal, 26 Negative terminal.

Claims (11)

An organic skeleton layer containing an aromatic compound that is a dicarboxylic acid anion having an aromatic ring structure; and an alkali metal element layer in which an alkali metal element coordinates to oxygen contained in the carboxylic acid anion to form a skeleton. A layered structure-containing electrode comprising a layered structure;
A compound represented by the general formula (1), and one or more in a supporting salt of _{LiPF 6, LiBF 4, LiAsF 6} , LiSbF 6, ethylene carbonate, propylene carbonate, dimethyl carbonate, ethyl methyl carbonate, diethyl carbonate a non-aqueous solvent is one or more of which consists, the above formula (1) compound, a non-water containing more than 0.5% by weight relative to the nonaqueous solvent dissolving the support salt An electrolyte,
A non-aqueous secondary battery comprising:
(However, M represents a transition element, a group 13, 14 or 15 element of the periodic table; A ^{a +} is a metal ion , proton or onium ion, a is an integer of 1 to 3, p is b / a; b Is an integer of 1 to 3, m is an integer of 1 to 4, n is an integer of 0 to 8, q is 0 or 1, R ¹ is alkylene having 1 to 10 carbons, and halogen having 1 to 10 carbons Alkylene, aryl having 6 to 20 carbon atoms or halogenated arylene having 6 to 20 carbon atoms (these alkylene and arylene may have a substituent or a hetero atom in the structure, and q is 1 and m is each the m R ¹ represents may be bound) is when 2 to 4; R ² is halogen, alkyl having 1 to 10 carbon atoms, a halogenated alkyl having 1 to 10 carbon atoms, 6 carbon atoms -20 aryl, C6-20 aryl halide ( These alkyl and aryl substituents in their structures, may have a hetero atom, and n may form a ring of n R ² are each bonded to at the time of 2 to 8) Or -X ³ R ³ ; X ¹ , X ² and X ³ each independently represent O, S or NR ⁴ ; R ³ and R ⁴ each independently represent hydrogen, 1 to 10 carbon atoms Alkyls, halogenated alkyls having 1 to 10 carbon atoms, aryls having 6 to 20 carbon atoms, aryl halides having 6 to 20 carbon atoms (these alkyls and aryls have substituents and heteroatoms in their structures) Or a plurality of R ³ or R ⁴ may be bonded to each other to form a ring).   The non-aqueous secondary battery according to claim 1, wherein the non-aqueous electrolyte includes the compound represented by the general formula (1) in a range of 0.6 mass% to 5.0 mass%.   In the non-aqueous electrolyte, in the compound represented by the general formula (1), the A is at least one of Li and K, and the M is Al, B, V, Ti, Si, Zr, Ge, Sn. The non-aqueous secondary battery according to claim 1, which is at least one selected from the group consisting of Cu, Y, Zn, Ga, Nb, Ta, Bi, P, As, Sc, Hf, and Sb. In the non-aqueous electrolyte, the compound represented by the general formula (1) includes one or more selected from PTFO, PFO, PO, BFO and BOB represented by the formulas (2) to (6) as anions. The non-aqueous secondary battery according to any one of claims 1 to 3.
The layered structure is formed in a layer shape by π-electron interaction of the aromatic compound and has a monoclinic crystal structure belonging to the space group P ₂ 1 / c. The non-aqueous secondary battery according to item. The said layered structure is equipped with the structure of Formula (7) in which four oxygen of the said different dicarboxylate anion and the said alkali metal element form a 4-coordination. Non-aqueous secondary battery.
The non-aqueous secondary battery according to any one of claims 1 to 6, wherein the organic skeleton layer is composed of an aromatic compound including a structure represented by the formula (8).
The non-aqueous system according to any one of claims 1 to 7, wherein the organic skeleton layer is provided with an aromatic compound including one or more structures selected from the group consisting of formulas (9) to (11). Secondary battery.
  The said layered structure containing electrode is equipped with the electrode compound material which contains the water-soluble polymer which is at least one among carboxymethylcellulose and polyvinyl alcohol in the range of 2 mass% or more and 8 mass% or less. The non-aqueous secondary battery according to any one of claims.   The non-aqueous secondary battery according to any one of claims 1 to 9, wherein the layered structure-containing electrode includes an electrode mixture containing a conductive material in a range of 5 mass% to 15 mass%.   The said layered structure containing electrode is a non-aqueous secondary battery of any one of Claims 1-10 provided with the electrode compound material which contains a styrene butadiene copolymer in 8 mass% or less.