JP4207932B2 - Non-aqueous secondary battery - Google Patents

Description

  The present invention relates to a non-aqueous secondary battery with improved charge / discharge capacity and cycle characteristics.

  As a negative electrode material for a non-aqueous secondary battery, lithium metal and lithium alloy are typical, but if they are used, so-called dendrites in which lithium metal grows in a dendritic shape during charge and discharge are generated, causing internal short circuit or Due to the high activity of the dendrite itself, there were dangers such as ignition.

  In contrast, calcined carbonaceous materials capable of reversibly inserting and releasing lithium have come into practical use. This carbonaceous material has the disadvantage that its capacity per volume is low due to its relatively low density. For this reason, although it is described in JP-A-5-151995 that a lithium foil is crimped or laminated on a carbon material, the above problem has not been essentially solved.

  Further, a method using an oxide such as Sn, V, Si, B, Zr or a composite oxide thereof as a negative electrode material has been proposed (JP-A-5-174818, JP-A-6-60867, and JP-A-6-275267). No. 6-325765, No. 6-338324, EP-615296). These oxide or composite oxide negative electrodes are combined with a positive electrode of a transition metal compound containing a certain kind of lithium to give a non-aqueous secondary battery having a large charge capacity of 3 to 3.6 V, and are also practically used. It is said that there is almost no dendrite generation and is extremely safe. However, a battery using these materials has a large problem that charge / discharge cycle performance is not sufficient, and charge / discharge efficiency in the initial cycle is particularly low.

  In order to solve these problems, a method of using a composite oxide containing Sn as a negative electrode material and attaching lithium metal on a negative electrode sheet (PCT / JP96 / 00527) has been proposed. Is inadequate and has not reached the product level.

  An object of the present invention is to obtain a non-aqueous secondary battery having 1) high charge / discharge capacity, good charge / discharge cycle characteristics, and 2) high energy density.

According to one aspect of the present invention, a positive electrode sheet having a layer mainly composed of a lithium-containing metal oxide, a carbonaceous compound containing a graphite structure selected from natural graphite and artificial graphite, and / or the following general formula (1) A non-aqueous secondary battery having a negative electrode sheet having a mixture layer mainly composed of a negative electrode material composed mainly of an amorphous composite compound mainly composed of tin, a non-aqueous electrolyte containing a lithium salt, and a separator, The non-aqueous electrolyte contains a combination of at least one cyclic carbonate selected from propylene carbonate, ethylene carbonate and butylene carbonate and at least one acyclic carbonate selected from dimethyl carbonate and diethyl carbonate , and further contains at least n-dodecane . Non-aqueous secondary battery characterized by containing 0.01 to 3 wt% with respect to the aqueous electrolyte. .
SnM ¹ _a O _t S u _... the general formula (1)
(In the formula, M ¹ represents two or more elements selected from Al, B, P, Si, Ge, Group 1 element, Group 2 element, Group 3 element, and halogen element in the periodic table; Is a number of 0.2 or more and 2 or less, t is a number of 1 or more and 6 or less, and u is a number of 0.5 or less.)

  According to the present invention, it is possible to provide a non-aqueous secondary battery having a large discharge capacity and excellent cycle characteristics by containing a chain hydrocarbon in the electrolytic solution.

  FIG. 1 is a cross-sectional view showing an example of a cylinder-type non-aqueous secondary battery. The shape of the battery may be a button, coin, sheet, corner, or the like. The positive electrode sheet 1 and the negative electrode sheet 2 are wound with the separator 3 interposed therebetween and inserted into the battery can 4. An electrolytic solution is injected into the battery can 4, and the battery lid 5 is caulked to the battery can 4 via the gasket 6. The battery lid 5 is electrically connected to the positive electrode sheet 1 and serves as a positive electrode terminal. The battery can 4 is electrically connected to the negative electrode sheet 2 and serves as a negative electrode terminal. The safety valve 7 can be used as a sealing plate. Furthermore, it is preferable to use a PTC (positive temperature coefficient) element in order to guarantee the safety of the battery.

A preferable electrolytic solution is composed of a solvent obtained by mixing one or more chain hydrocarbons and other aprotic organic solvents, and a lithium salt in the solvent.
The content of chain hydrocarbon in the electrolytic solution is preferably 0.01 to 3% by weight, more preferably 0.02 to 2% by weight, and particularly preferably 0.02 to 1.5% by weight. As the chain hydrocarbon, those having 7 to 25 carbon atoms are preferable, those having 7 to 20 carbon atoms are more preferable, and those having 8 to 16 carbon atoms are particularly preferable.

  Specifically, it is preferably selected from heptane, octane, nonane, decane, undecane, dodecane, tridecane, tetradecane, pentadecane, hexadecane, heptadecane, octadecane, nonadecane, eicosane, and octane, nonane, decane, undecane, dodecane, tridecane. More preferably, it is selected from tetradecane, pentadecane and hexadecane. These hydrocarbons may be linear or branched. Particularly preferred are linear or branched octane, decane, dodecane, and tetradecane.

These hydrocarbons may be one kind or an arbitrary mixture of two or more kinds, but preferably one kind.
Examples of aprotic organic solvents other than chain hydrocarbons include propylene carbonate, ethylene carbonate, butylene carbonate, dimethyl carbonate, diethyl carbonate, γ-butyrolactone, 1,2-dimethoxyethane, tetrahydrofuran, 2-methyltetrahydrofuran, dimethyl sulfone. Xoxide, 1,3-dioxolane, formamide, dimethylformamide, dioxolane, acetonitrile, nitromethane, methyl formate, methyl acetate, methyl propionate, ethyl propionate, phosphate triester, trimethoxymethane, dioxolane derivative, sulfolane, 3-methyl 2-Oxazolidinone, propylene carbonate derivatives, tetrahydrofuran derivatives, diethyl ether, 1,3-propane sultone, etc. Can. In these, carbonate ester is preferable and propylene carbonate, ethylene carbonate, butylene carbonate, dimethyl carbonate, and diethyl carbonate are more preferable.

Examples of the lithium salt dissolved in these aprotic organic solvents, for _{example, LiClO 4, LiBF 4, LiPF} 6, LiCF 3 SO 3, LiCF 3 CO 2, LiAsF 6, LiSbF 6, LiB 10 Cl 10, lower aliphatic Examples thereof include lithium carboxylate, LiAlCl ₄ , LiCl, LiBr, LiI, lithium chloroborane, and lithium tetraphenylborate. Among these, LiClO ₄ , LiBF ₄ , LiPF ₆ , and LiCF ₃ SO ₃ are particularly preferable.

Among them, an electrolytic solution containing LiCF ₃ SO ₃ , LiClO ₄ , LiBF ₄ and / or LiPF ₆ in a mixed solution of propylene carbonate or ethylene carbonate and 1,2-dimethoxyethane and / or diethyl carbonate is preferable. An electrolytic solution containing LiBF ₄ and / or LiPF ₆ in a mixed solution of ethylene carbonate and diethyl carbonate is particularly preferable.

  The amount of these electrolytes added to the battery is not particularly limited, but a necessary amount can be used depending on the amount of the positive electrode active material and the negative electrode material and the size of the battery. The concentration of the supporting electrolyte is preferably 0.2 to 3 mol per liter of the electrolytic solution. The temperature at the time of pouring the electrolytic solution is preferably in the range of -20 to + 50 ° C, more preferably -20 to + 40 ° C, and particularly preferably -10 to + 30 ° C. It is preferable to cool both the electrolytic solution and the battery can during injection.

In addition to the electrolytic solution, the following solid electrolyte can also be used. The solid electrolyte is classified into an inorganic solid electrolyte and an organic solid electrolyte. Well-known inorganic solid electrolytes include Li nitrides, halides, oxyacid salts, and the like. Among these, Li ₃ N, LiI, Li ₅ NI ₂ , Li ₃ N—LiI—LiOH, LiSiO ₄ , LiSiO ₄ —LiI—LiOH, xLi ₃ PO ₄ — (1-x) Li ₄ SiO ₄ , Li ₂ SiS _3. Phosphorus sulfide compounds are effective.

  In the organic solid electrolyte, a polyethylene oxide derivative or a polymer containing the derivative, a polypropylene oxide derivative or a polymer containing the derivative, a polymer containing an ion dissociation group, a mixture of a polymer containing an ion dissociation group and the above aprotic electrolyte, phosphoric acid Ester polymers are effective.

Furthermore, there is a method of adding polyacrylonitrile to the electrolytic solution. A method of using an inorganic and organic solid electrolyte in combination is also known.
It is also known to add the following compounds to the electrolyte for the purpose of improving discharge and charge / discharge characteristics. For example, pyridine, triethyl phosphite, triethanolamine, cyclic ether, ethylenediamine, n-glyme, hexaphosphoric acid triamide, nitrobenzene derivative, sulfur, quinoneimine dye, N-substituted oxazolidinone and N, N'-substituted imidazolidinone, ethylene glycol Dialkyl ether, quaternary ammonium salt, polyethylene glycol, pyrrole, 2-methoxyethanol, AlCl ₃ , monomer of conductive polymer electrode active material, triethylenephosphoramide, trialkylphosphine, morpholine, aryl compound having carbonyl group, Hexamethylphosphoric triamide and 4-alkylmorpholine, bicyclic tertiary amine, oil (Japanese Patent Laid-Open No. 62-287580), quaternary phosphonium salt, tertiary sulfonium salt, etc. It is below.

  In order to make the electrolyte nonflammable, a halogen-containing solvent such as carbon tetrachloride or ethylene trifluoride chloride can be contained in the electrolyte. In addition, carbon dioxide gas can be included in the electrolyte in order to make it suitable for high-temperature storage. Further, the mixture of the positive electrode and the negative electrode can contain an electrolytic solution or an electrolyte. For example, a method in which the ion conductive polymer, nitromethane, or an electrolytic solution is included is known.

  The negative electrode sheet 2 shown in FIG. 1 has a negative electrode mixture layer formed on both surfaces of a sheet-like negative electrode current collector. On the negative electrode mixture layer, a metal foil mainly composed of lithium can be attached via an auxiliary layer.

  As the metal mainly composed of lithium, lithium metal is preferably used, but a metal having a purity of 90% by weight or more is preferable, and a metal having a purity of 98% by weight or more is particularly preferable. As the overlapping pattern of lithium on the negative electrode sheet, it is preferable to superimpose on the entire surface of the sheet, but since lithium preliminarily inserted into the negative electrode material gradually diffuses into the negative electrode material by aging, it is not a full sheet, but a stripe, frame shape Also, any partial overlap of disk-like is preferable. The term “lamination” as used herein means that a metal foil mainly composed of lithium is directly bonded onto a sheet having a negative electrode mixture and an auxiliary layer. The auxiliary layer will be described later.

  The amount of lithium insertion can be arbitrarily controlled by the amount of lithium superimposed on the negative electrode sheet. The lithium pre-insertion amount is preferably 0.5 to 4.0 equivalents, more preferably 1 to 3.5 equivalents, and particularly preferably 1.2 to 3.2 equivalents with respect to the negative electrode material. When lithium less than 1.2 equivalents is preliminarily inserted into the negative electrode material, the battery capacity is low, and when more than 3.2 equivalents of lithium is preliminarily inserted, cycle performance is deteriorated.

  The coverage of the metal foil overlapping in the negative electrode sheet is preferably 10 to 100%, more preferably 15 to 100%, and particularly preferably 20 to 100%. When it is 20% or less, the preliminary insertion of lithium may become uneven, which is not preferable. Further, from the viewpoint of uniformity, the thickness of the metal foil mainly composed of lithium is preferably 5 to 150 μm, more preferably 5 to 100 μm, and particularly preferably 10 to 75 μm.

  The handling atmosphere such as cutting and sticking of the metal foil mainly composed of lithium is preferably a dry air or argon gas atmosphere having a dew point of −30 ° C. or lower and −80 ° C. or higher. In the case of dry air, −40 ° C. or lower and −80 ° C. or higher is more preferable. Carbon dioxide gas may be used in combination during handling. Particularly in the case of an argon gas atmosphere, it is preferable to use carbon dioxide in combination.

  The non-aqueous secondary battery can be uniformly inserted with lithium into the negative electrode material (negative electrode mixture) by aging after injecting the electrolyte and caulking the battery lid. The aging temperature is preferably 0 to 80 ° C, more preferably 10 to 70 ° C, and particularly preferably 20 to 60 ° C. The aging time is preferably 1 to 60 days, more preferably 5 to 50 days, and particularly preferably 8 to 30 days.

  It is more preferable to charge or charge / discharge before aging and / or during aging in order to uniformly insert lithium. In that case, it is preferable to perform partial charge or charge / discharge rather than full charge or charge / discharge.

Next, the auxiliary layer and protective layer installed on the surfaces of the electrodes (positive electrode sheet and negative electrode sheet) will be described.
Providing a layer different from the active material, such as a protective layer, on the electrode surface has been studied in the past. When lithium metal or an alloy is used as the negative electrode, a protective material made of carbon containing carbon material or metal powder is used. Providing a layer is described in JP-A-4-229562, US Pat. No. 5,387,479, and JP-A-3-297072. However, the purpose of these patents is to protect the active part of the lithium metal surface and prevent the electrolytic solution from being decomposed by contact with the electrolytic solution or the formation of a passive film due to decomposition products. The configuration is different from that of the negative electrode.

  Further, JP-A-61-263069 describes that a transition metal oxide is used as a negative electrode material and the surface thereof is coated with an ion conductive solid electrolyte. In the examples, the solid electrolyte is formed on the transition metal oxide layer. It is described that the film is provided by sputtering. The purpose of this patent is to prevent lithium dendritic precipitation and to prevent decomposition of the electrolyte, as in the above-mentioned patent, and is not necessarily applicable to metal oxide negative electrodes. Further, the ion conductive solid electrolyte is not preferable because it has solubility in water and hygroscopicity.

  Further, Japanese Patent Application Laid-Open No. 61-7777 discloses a protective layer made of a material having both electron conductivity and ion conductivity on the surface of the positive electrode, and tungsten, molybdenum as materials having electron-ion mixed conductivity. Vanadium oxide is preferred. However, these oxides are compounds capable of occluding and releasing lithium, and are not necessarily preferable for metal oxide negative electrodes.

  The auxiliary layer provided on the negative electrode sheet is composed of at least one layer, and may be composed of the same or different plural layers. These auxiliary layers are composed of water-insoluble conductive particles and a binder. The binder used when forming the electrode mixture described later can be used. The proportion of conductive particles contained in the auxiliary layer is preferably 2.5% by weight or more and 96% by weight or less, more preferably 5% by weight or more and 95% by weight or less, and particularly preferably 10% by weight or more and 93% by weight or less. .

Examples of water-insoluble conductive particles include carbon particles such as metals, metal oxides, metal fibers, carbon fibers, carbon black, and graphite. The solubility of the conductive particles in water is 100 ppm or less, preferably insoluble. Among these water-insoluble conductive particles, those having low reactivity with alkali metals, particularly lithium, are preferable, and metal powders and carbon particles are more preferable. The electrical resistivity at 20 ° C. of the elements constituting the particles is preferably 5 × 10 ⁹ Ω · m or less.

  The metal powder is preferably a metal having low reactivity with lithium, that is, a metal that is difficult to form a lithium alloy. Specifically, copper, nickel, iron, chromium, molybdenum, titanium, tungsten, and tantalum are preferable. The shape of these metal powders may be any of acicular, columnar, plate-like, and massive shapes, and the maximum diameter is preferably 0.02 μm or more and 20 μm or less, more preferably 0.1 μm or more and 10 μm or less. These metal powders are preferably those whose surfaces are not excessively oxidized, and when oxidized, heat treatment is preferably performed in a reducing atmosphere.

  As the carbon particles, a known carbon material used as a conductive material used in combination when the electrode active material is not conductive can be used. Examples of these materials include carbon black such as thermal black, furnace black, channel black, and lamp black, natural graphite such as scaly graphite, scaly graphite, and earthy graphite, artificial graphite, and carbon fiber. In order to mix and disperse these carbon particles with the binder, it is preferable to use carbon black and graphite in combination. As carbon black, acetylene black and ketjen black are preferable. The carbon particles are preferably 0.01 μm or more and 20 μm or less, and more preferably 0.02 μm or more and 10 μm or less.

  In the auxiliary layer, particles having substantially no conductivity may be mixed for the purpose of improving the strength of the coating film. Examples of these particles include fine powder of Teflon, SiC, aluminum nitride, alumina, zirconia, magnesia, mullite, forsterite, and steatite. These particles are preferably used in an amount of 0.01 to 10 times that of the conductive particles.

  In the case where the negative electrode is formed by coating a mixture on both sides of the current collector, these auxiliary layers may be coated on both sides or may be coated on only one side. . The auxiliary layer is coated on the current collector after a mixture mainly composed of a metal or semi-metal oxide, which is a material capable of reversibly occluding and releasing lithium, and then the auxiliary layer is sequentially applied. A sequential method may be used, or a simultaneous application method in which a mixture layer and an auxiliary layer are simultaneously applied.

  The positive electrode sheet to be combined may also have a protective layer. In this case, the protective layer is composed of at least one layer, and may be composed of a plurality of layers of the same type or different types. These protective layers may have substantially no electronic conductivity, that is, may be insulating layers, or may be conductive layers like the negative electrode sheet. Furthermore, the form which laminated | stacked the insulating layer and the electroconductive layer may be sufficient. The thickness of the protective layer is preferably 1 μm or more and 40 μm or less, more preferably 2 μm or more and 30 μm or less. Further, it is desirable that the protective layer containing these particles does not melt at 300 ° C. or less or does not form a new film.

  When the protective layer is composed of water-insoluble conductive particles and a binder, the conductive particles used for the auxiliary layer of the negative electrode sheet can be used. The kind and size of the conductive particles preferably used are the same as those of the negative electrode sheet.

  When the protective layer is insulative, these layers preferably contain organic or inorganic particles. These particles are preferably 0.1 μm or more and 20 μm or less, and more preferably 0.2 μm or more and 15 μm or less. Preferable organic particles are cross-linked latex or fluororesin powder, and those that do not decompose or form a film at 300 ° C. or lower are preferable. More preferred is a fine powder of Teflon.

Examples of inorganic particles include carbides, silicides, nitrides, sulfides, and oxides of metals and nonmetallic elements.
Among carbides, silicides, and nitrides, SiC, aluminum nitride (AlN), BN, and BP are preferably highly insulating and chemically stable. In particular, SiC using BeO, Be, and BN as a sintering aid. Is particularly preferred.

Among chalcogenides, oxides are preferable, and oxides that are not easily oxidized or reduced are preferable. These oxides include Al ₂ O ₃ , As ₄ O ₆ , B ₂ O ₃ , BaO, BeO, CaO, Li ₂ O, K ₂ O, Na ₂ O, In ₂ O ₃ , MgO, Sb ₂ O. _{5, SiO 2, SrO, ZrO} 4 can be mentioned. Among these, Al ₂ O ₃ , BaO, BeO, CaO, K ₂ O, Na ₂ O, MgO, SiO ₂ , SrO, and ZrO ₄ are particularly preferable. These oxides may be single or complex oxides. Preferred compounds as the composite oxide include mullite (3Al ₂ O ₃ .2SiO ₂ ), steatite (MgO.SiO ₂ ), forsterite (2MgO.SiO ₂ ), cordierite (2MgO.2Al ₂ O ₃ .5SiO _2). And the like.

  These insulating inorganic compound particles are used as particles having a size of 0.1 μm or more and 20 μm or less, particularly preferably 0.2 μm or more and 15 μm or less, by a method such as control of production conditions or pulverization.

  The protective layer is formed by using these conductive particles and / or particles having substantially no conductivity and a binder. The binder used when forming the electrode mixture described later can be used. The ratio of the particles to the binder is preferably 40% by weight or more and 96% by weight or less, more preferably 50% by weight or more and 94% by weight or less, based on the total weight of both.

  Hereinafter, other materials for producing the non-aqueous secondary battery and the manufacturing method will be described in detail. The positive and negative electrodes used in the non-aqueous secondary battery can be made by coating a positive electrode mixture or a negative electrode mixture on a current collector. In addition to the positive electrode active material or the negative electrode material, the positive electrode or the negative electrode mixture can contain a conductive agent, a binder, a dispersant, a filler, an ionic conductive agent, a pressure enhancer, and various additives, respectively.

As the negative electrode material, a carbonaceous compound, a transition metal, a metal belonging to Groups 13 to 15 of the periodic table, an oxide of a metalloid element, and / or a chalcogenide can be used. The carbonaceous compound is preferably selected from natural graphite, artificial graphite, vapor-grown carbon, baked carbon of an organic substance, and the like, and includes a graphite structure. In addition to carbon, the carbonaceous compound may contain 0 to 10% by weight of different types of compounds such as B, P, N, S, SiC, and B ₄ C.

In particular, the negative electrode material is preferably mainly composed of a transition metal, a metal of Group 13 to 15 in the periodic table, an oxide of a metalloid element and / or a chalcogenide.
As the negative electrode material, a carbonaceous compound may be used in addition to the transition metal, the metal of group 13 to 15 of the periodic table, the oxide of metalloid element and / or chalcogenide.

As the transition metal compound, V, Ti, Fe, Mn, Co, Ni, Zn, W, Mo alone or a composite oxide and / or chalcogenide are particularly preferable. More preferable compounds are Li _p Co _q V _1-q O _z described in JP-A-6-44972 (where p = 0.1 to 2.5, q = 0 to 1, z = 1.3 to 4. 5).

  The metal or metalloid compound other than the transition metal is composed of a group 13-15 element of the periodic table, Ga, Si, Sn, Ge, Pb, Sb, Bi alone or a combination of two or more thereof. A compound is selected.

For example, Ga ₂ O ₃ , SiO, GeO, GeO ₂ , SnO, SnO ₂ , SnS, SnSiO ₃ , PbO, PbO ₂ , Pb ₂ O ₃ , Pb ₂ O ₄ , Pb ₃ O ₄ , Sb ₂ O ₃ , Sb ₂ O ₄ , Sb ₂ O ₅ , Bi ₂ O ₃ , Bi ₂ O ₄ , Bi ₂ O ₅ , SnSiO _{3 and the} like are preferable. These may be composite oxides with lithium oxide, such as Li ₂ GeO ₃ and Li ₂ SnO ₂ .

  The above complex oxide and / or chalcogenide is preferably mainly amorphous when assembled into a battery. The term “amorphous” as used herein refers to an X-ray diffraction method using CuKα rays, which has a broad scattering band having an apex from 20 ° to 40 ° as a 2θ value, and has a crystalline diffraction line. Also good. Preferably, the strongest intensity of the crystalline diffraction lines seen at 2θ values of 40 ° or more and 70 ° or less is 500 of diffraction line intensities at the apexes of broad scattering bands seen at 20 ° or more and 40 ° or less of 2θ values. It is preferably not more than twice, more preferably not more than 100 times, particularly preferably not more than 5 times, and most preferably not having a crystalline diffraction line.

The complex oxide and / or chalcogenide is a complex compound of three or more elements among B, Al, Ga, In, Tl, Si, Ge, Sn, Pb, P, As, Sb, and Bi.
Particularly preferred is a composite compound composed of three or more elements of B, Al, Si, Ge, Sn, and P. These composite compounds may contain a group 1 to group 3 element or a halogen element in the periodic table mainly to modify the amorphous structure.

Among the above negative electrode materials, an amorphous composite compound mainly composed of tin is particularly preferable, and is represented by the following general formula (1).
SnM ¹ _a O _t S _u general formula (1)
In the formula, M ¹ represents two or more elements selected from Al, B, P, Si, Ge, Group 1 element, Group 2 element, Group 3 element, and halogen element in the periodic table, and a is 0 A number of 2 or more and 2 or less, t is a number of 1 or more and 6 or less, and u is a number of 0.5 or less.

Of the general formula (1), compounds of the following general formula (2) are more preferable.
SnM ² _b O _t S _u general formula (2)
In the formula, M ² represents two or more elements selected from Al, B, P, Ge, Group 1 elements, Group 2 elements, Group 3 elements, and halogen elements in the periodic table, and b is 0.2. The number is 2 or less, t is 1 or more and 6 or less, and u is 0.5 or less.

Of the general formula (1), compounds of the following general formula (3) are more preferable.
^{_{SnM 3 c M 4 d O t}} S u general formula (3)
In the formula, M ³ represents at least two of Al, B, P, Si, and Ge, and M ⁴ represents at least one of Group 1 element, Group 2 element, Group 3 element, and halogen element of the periodic table. , C is a number of 0.2 or more and 2 or less, d is a number of 0.01 or more and 1 or less, 0.2 <c + d <2, t is a number of 1 or more and 6 or less, and u is 0.5 or less. Represents a number.

M ³ and M ⁴ are elements for making the compound of the general formula (3) amorphous as a whole, M ³ is an element that can be made amorphous, and 2 of Al, B, P, Si, Ge It is preferable to use a combination of more than one species. M ⁴ is an element that can be amorphously modified, and is a group 1 element, group 2 element, group 3 element, or halogen element in the periodic table, and K, Na, Cs, Mg, Ca, Ba, Y and F are preferred.

  As the amorphous composite compound, any of a firing method and a solution method can be adopted, but a firing method is more preferable. In the firing method, it is preferable to obtain an amorphous composite compound by thoroughly mixing oxides or compounds of the elements described in the general formula (1) and then firing.

As firing conditions, the temperature rise rate is preferably 5 ° C. or more and 200 ° C. or less per minute, the firing temperature is preferably 500 ° C. or more and 1500 ° C. or less, and the firing time is 1 hour. It is preferable that it is 100 hours or less. Further, the rate of temperature decrease is preferably 2 ° C. or more and 10 ⁷ ° C. or less per minute.

  The rate of temperature rise is the average rate of temperature rise from “50% of the firing temperature (expressed in ° C)” to “80% of the firing temperature (expressed in ° C)”. ) 80% ”) to“ 50% of the firing temperature (expressed in degrees Celsius) ”.

  The temperature lowering may be cooled in a firing furnace, or taken out of the firing furnace and cooled, for example, in water. Also, super quenching methods such as gun method, Hammer-Anvil method, slap method, gas atomization method, plasma spray method, centrifugal quenching method, meltdrag method and the like described on page 217 of ceramics processing (Gihodo Publishing 1987) can be used. Moreover, you may cool using the single roller method and the double roller method of New Glass Handbook (Maruzen 1991) p.172. In the case of a material that melts during firing, the fired product may be continuously taken out while supplying raw materials during firing. In the case of a material that melts during firing, it is preferable to stir the melt.

  The firing gas atmosphere is preferably an atmosphere having an oxygen content of 5% by volume or less, and more preferably an inert gas atmosphere. Examples of the inert gas include nitrogen, argon, helium, krypton, and xenon. The most preferred inert gas is pure argon.

  The average particle size of the compound of the negative electrode material is preferably 0.1 to 60 μm. To obtain a predetermined particle size, a well-known pulverizer or classifier is used. For example, a mortar, a ball mill, a sand mill, a vibrating ball mill, a satellite ball mill, a planetary ball mill, a swirling air flow type jet mill, a sieve, or the like is used. When pulverizing, wet pulverization in the presence of water or an organic solvent such as methanol can be performed as necessary. In order to obtain a desired particle size, classification is preferably performed. The classification method is not particularly limited, and a sieve, an air classifier, or the like can be used as necessary. Classification can be used both dry and wet.

Examples of the negative electrode material are shown below, but are not limited thereto. SnAl _0.1 B _0.3 P _0.4 K _0.2 O _2.7 , SnAl _0.1 B _0.3 P _0.4 Na _0.2 O _2.7 , SnAl _0.1 B _0.3 P _0.4 Rb _0.2 O _2.7 , SnAl _0.1 B _0.3 P _0.4 Cs _0.2 O _2.7 , SnAl _0.1 B _0.5 P _0.5 Mg _0.1 F _0.2 O _3.15 , SnAl _0.1 B _0.5 P _0.5 Ba _0.08 F _0.08 O _3.19 , SnAl _0.2 B _0.4 P _0.4 O _2.9 , SnAl _0.3 B _0.5 P _0.2 O _2.7 , SnAl _0.3 B _0.7 O _2.5 , SnB _0.2 P _0.6 Ba _0.08 F _0.08 O _2.84 , SnB _0.4 P _0.4 Ba _0.1 F _0.1 O _2.65 , SnB _0.5 P _0.5 O ₃ , SnB _0.5 P _0.5 Mg _0.1 O _3.1 , SnB _0.5 P _0.5 Mg _0.1 F _0.2 O ₃ , SnB _0.5 P _0.5 Li _0.1 Mg _0.1 F _0.2 O _3.05 , SnB _0.5 P _0.5 K _0.1 Mg _0.1 F _0.2 O _3.05 , SnB _0.5 P _0.5 K _0.05 Mg _0.05 F _0.1 O _3.03 , SnB _0.5 P _0.5 K _0.05 Mg _0.1 F _0.2 O _3.03 , SnB _0.5 P _0.5 Cs _0.1 Mg _{0.1 0.2 O 3.05, SnB 0.5 P 0.5} Cs 0.05 Mg 0.05 F 0.1 O 3.03, SnB 0.5 P 0.5 Mg 0.1 F 0.1 O 3.05, SnB 0.5 P 0.5 Mg 0.1 F 0.2 O 3, SnB 0.5 P 0.5 Mg 0.1 F 0.06 O 3.07, SnB _0.5 P _0.5 Mg _0.1 F _0.14 O _3.03 , SnPBa _0.08 O _3.58 , SnPK _0.1 O _3.55 , SnP _0.05 Mg _0.05 O _3.58 , SnPCs _0.1 O _3.55 , SnPBa _0.08 F _0.08 O _3.54 , SnPK _0.1 Mg _0.1 F _0.2 O _3.55 , SnP _0.05 Mg _0.05 F _0.1 O _3.53 , SnPCs _0.1 Mg _0.1 F _0.2 O _3.55 , SnPCs _0.05 Mg _0.05 F _0.1 O _3.53 , Sn _1.1 B _0.2 P _0.6 Ba _0.08 F _0.08 O _2.94 , Sn _1.1 B _0.2 P _0.6 Li _0.1 K _0.1 Ba _0.1 F _0.1 O _3.05 , Sn _1.1 B _0.4 P _0.4 Ba _0.08 O _2.74 , Sn _1.1 PCs _0.05 O _3.63 , Sn _1.1 PK _0.05 O _3.63 , Sn _1.2 Al _0.1 B _0.3 P _0.4 Cs _0.2 O _2.9 , Sn _1.2 B _0.2 P _0.6 Ba _0.08 O _3.08 , Sn _1.2 B _0.2 P _0.6 Ba _0.08 F _0.08 O _3.04 , Sn _1.2 B _0.2 P _0.6 Mg _0.04 Ba _0.04 O _3.08 , Sn _1.2 B _0.3 P _0.5 Ba _0.08 O _2.98 , Sn _1.3 Al _0.1 B _0.3 P _0.4 Na _0.2 O ₃ , Sn _1.3 B _0.4 P _0.4 Ca _0.2 O _3.1 , Sn _1.3 B _0.4 P _0.4 Ba _0.2 O _3.1 , Sn _1.4 PK _0.2 O ₄ , Sn _1.4 Ba _0.1 PK _0.2 O _4.15 , Sn _1.4 Ba _0.2 PK _0.2 O _4.3 , Sn _1.4 Ba _0.2 PK _0.2 Ba _0.1 F _0.2 O _4.3 , Sn _1.4 PK _0.3 O _4.05 , Sn _1.5 PK _0.2 O _4.1 , Sn _1.5 PK _0.1 O _4.05 , Sn _1.5 PCs _0.05 O _4.03 , Sn _1.5 PCs _0.05 Mg _0.1 F _0.2 O _4.03 , Sn ₂ P ₂ O ₇ , SnSi _0.5 Al _0.1 B _0.2 P _0.1 Ca _0.4 O _3.1 , SnSi _0.4 Al _0.2 B _0.4 O _2.7 , SnSi _0.5 Al _0.2 B _0.1 P _0.1 Mg _0.1 O _2.8 , SnSi _0.6 Al _0.2 B _0.2 O _2.8 , SnSi _0.5 Al _0.3 B _0.4 P _0.2 O _3.55 , SnSi _0.5 Al _0.3 B _0.4 P _0.5 O _4.30 , SnSi _0.6 Al _0.1 B _0.1 P _0.3 O _3.25 , SnSi _0.6 Al _0.1 B _0.1 P _0.1 Ba _0.2 O _2.95 , SnSi _0.6 Al _0.1 B _0.1 P _0.1 Ca _0.2 O _2.95 , SnSi _0.6 Al _0.1 B _0.2 Mg _0.2 O _2.85 , SnSi _0.6 Al _0.1 B _0.3 P _0.1 O _3.05 , SnSi _0.6 Al _0.2 Mg _0.2 O _2.7 , SnSi _0.6 Al _0.2 Ca _0.2 O _2.7 , SnSi _0.6 Al _0.2 P _0.2 O ₃ , SnSi _0.36 B _0.2 P _0.2 O ₃ , SnSi _0.8 Al _0.2 O _2.9 , SnSi _0.8 Al _0.3 B _0.2 P _0.2 O _3.85 , SnSi _0.8 B _0.2 O _2.9 , SnSi _0.8 Ba _0.2 O _{2.8, SnSi 0.8 Mg 0.2 O 2.8} , SnSi 0.8 Ca 0.2 O 2.8, SnSi 0.8 P 0.2 O 3.1, Sn 0.9 Mn 0.3 B 0.4 P 0.4 Ca 0.1 Rb 0.1 O 2.95, Sn 0.9 Fe 0.3 B 0.4 _{0.4 Ca 0.1 Rb 0.1 O 2.95,} Sn 0.8 Pb 0.2 Ca 0.1 P 0.9 O 3.35, Sn 0.3 Ge 0.7 Ba 0.1 P 0.9 O 3.35, Sn 0.9 Mn 0.1 Mg 0.1 P 0.9 O 3.35, Sn 0.2 Mn 0.8 Mg 0.1 P 0.9 O _{3.35, Sn 0.7 Pb 0.3 Ca 0.1} P 0.9 O 3.35, Sn 0.2 Ge 0.8 Ba 0.1 P 0.9 O 3.35. SnAl _0.3 B _0.5 P _0.2 O _2.7 S _0.01 , SnAl _0.2 B _0.4 P _0.4 O _2.85 S _0.05 , SnB _0.2 P _0.5 K _0.1 Mg _0.1 Ge _0.1 O _2.7 S _0.1
The chemical formula of the compound obtained by firing can be calculated from an inductively coupled plasma (ICP) emission spectroscopic analysis method as a measurement method and a weight difference between powders before and after firing as a simple method.

  Various elements can be included in the negative electrode material. For example, it may contain a dopant of a lanthanoid metal (Hf, Ta, W, Re, Os, Ir, Pt, Au, Hg) or various compounds that increase electron conductivity (for example, Sn, In, Nb compounds). . The amount of the compound to be added is preferably 0 to 5 mol%.

The surface of the oxide positive electrode active material or negative electrode material can be coated with an oxide having a chemical formula different from that of the positive electrode active material or negative electrode material used. The surface oxide is preferably an oxide containing a compound that dissolves both acidic and alkaline. Furthermore, a metal oxide with high electron conductivity is preferable. For example, PbO ₂ , Fe ₂ O ₃ , SnO ₂ , In ₂ O ₂ , ZnO or the like or a dopant (for example, a metal having a different valence in the oxide, a halogen element, or the like) is preferably included in these oxides. . Particularly preferred are SiO ₂ , SnO ₂ , Fe ₂ O ₃ , ZnO, and PbO ₂ . The amount of the metal oxide used for these surface treatments is preferably 0.1 to 10% by weight, particularly preferably 0.2 to 5% by weight, and preferably 0.3 to 3% per positive electrode active material / negative electrode material. Weight percent is most preferred.

  In addition, the surface of the positive electrode active material or the negative electrode material can be modified. For example, the surface of the metal oxide may be treated with an esterifying agent, treated with a chelating agent, treated with a conductive polymer, polyethylene oxide, or the like.

  The positive electrode active material may be a transition metal oxide capable of reversibly inserting and releasing lithium ions, but a lithium-containing transition metal oxide is particularly preferable. Preferred lithium-containing transition metal oxide positive electrode active materials include oxides containing lithium-containing Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Mo, and W. Alkali metals other than lithium (elements IA and IIA in the periodic table) and / or Al, Ga, In, Ge, Sn, Pb, Sb, Bi, Si, P, B, etc. may be mixed. . The mixing amount is preferably 0 to 30 mol% with respect to the transition metal.

  More preferable lithium-containing transition metal oxide positive electrode active material is a lithium compound / transition metal compound (where the transition metal is at least one selected from Ti, V, Cr, Mn, Fe, Co, Ni, Mo, W) It is preferable to mix and synthesize so that the total molar ratio of the seeds is 0.3 to 2.2.

  A particularly preferable lithium-containing transition metal oxide positive electrode active material is a total mole of lithium compound / transition metal compound (wherein the transition metal is at least one selected from V, Cr, Mn, Fe, Co, and Ni). It is preferable to mix and synthesize so that the ratio is 0.3 to 2.2.

A particularly preferable lithium-containing transition metal oxide positive electrode active material is Li _x QO _y (where Q is mainly a transition metal containing at least one of Co, Mn, Ni, V, and Fe, x = 0.02 to 1). .2, y = 1.4-3). As Q, in addition to the transition metal, Al, Ga, In, Ge, Sn, Pb, Sb, Bi, Si, P, B, or the like may be mixed. The mixing amount is preferably 0 to 30 mol% with respect to the transition metal.

More preferable lithium-containing metal oxide positive electrode active materials include Li _x CoO ₂ , Li _x NiO ₂ , Li _x MnO ₂ , Li _x Co _a Ni _1-a O ₂ , Li _z Co _b V _1-b O _z , _{Li x Co b Fe 1-b} O 2, Li x Mn 2 O 4, Li x Mn c Co 2-c O 4, Li x Mn c Ni 2-c O 4, Li x Mn c V 2-c O z _{, Li x Mn c Fe 2-} c O 4, Li x Co b B 1-b O 2, Li x Co b Si 1-b O 2, a mixture of Li _x Mn ₂ O ₄ and MnO _2, Li _2x MnO ₃ And MnO ₂ mixture, Li _x MnO ₄ , Li _2x MnO ₃ and MnO ₂ mixture (where x = 0.02-1.2, a = 0.1-0.9, b = 0.8-0 .98, c = 1.6 to 1.96, z = 2.01 to 5).

More preferable lithium-containing metal oxide positive electrode active materials include Li _x CoO ₂ , Li _x NiO ₂ , Li _x MnO ₂ , Li _x Co _a Ni _1-a O ₂ , Li _x Co _b V _1-b O _z , _{Li x Co b Fe 1-b} O 2, Li x Mn 2 O 4, Li x Mn c Co 2-c O 4, Li x Mn c Ni 2-c O 4, Li x Mn c V 2-c O 4 Li _x Mn _c Fe _{2 -c} O ₄ (where x = 0.02 to 1.2, a = 0.1 to 0.9, b = 0.8 to 0.98, c = 1.6 to 1.96, z = 2.01 to 2.3).

The most preferable lithium-containing transition metal oxide positive electrode active materials include Li _x CoO ₂ , Li _x NiO ₂ , Li _x MnO ₂ , Li _x Co _a Ni _1-a O ₂ , Li _x Mn ₂ O ₄ , Li _x Co. _b V _1-b O _z (where x = 0.02 to 1.2, a = 0.1 to 0.9, b = 0.9 to 0.98, z = 2.02 to 2.3) Is mentioned. Here, said x value is a value before the start of charging / discharging, and it increases / decreases by charging / discharging.

  The positive electrode active material can be synthesized by a method in which a lithium compound and a transition metal compound are mixed and fired, or by a solution reaction, and the firing method is particularly preferable. The baking temperature may be a temperature at which a part of the mixed compound is decomposed and melted, and is preferably 250 to 2000 ° C, and particularly preferably 350 to 1500 ° C. In firing, it is preferably calcined at 250 to 900 ° C. The firing time is preferably 1 to 72 hours, more preferably 2 to 20 hours. The raw material mixing method may be dry or wet. Moreover, you may anneal at 200 to 900 degreeC after baking.

  The firing gas atmosphere is not particularly limited and can be either an oxidizing atmosphere or a reducing atmosphere. For example, in the air or a gas whose oxygen concentration is adjusted to an arbitrary ratio, hydrogen, carbon monoxide, nitrogen, argon, helium, krypton, xenon, carbon dioxide, or the like can be given.

  In synthesizing the positive electrode active material, a method of chemically inserting lithium ions into the transition metal oxide is preferably a method of synthesizing lithium metal, a lithium alloy, or butyl lithium by reacting with the transition metal oxide.

Although the average particle size of a positive electrode active material is not specifically limited, 0.1-50 micrometers is preferable. Although it does not specifically limit as a specific surface area, 0.01-50 m < ² > / g is preferable by BET method. The pH of the supernatant when 5 g of the positive electrode active material is dissolved in 100 ml of distilled water is preferably 7 or more and 12 or less.

  To obtain a predetermined particle size, a well-known pulverizer or classifier is used. For example, a mortar, a ball mill, a vibration ball mill, a vibration mill, a satellite ball mill, a planetary ball mill, a swirling air flow type jet mill, a sieve, or the like is used.

The positive electrode active material obtained by firing may be used after being washed with water, an acidic aqueous solution, an alkaline aqueous solution, or an organic solvent.
The combination of the negative electrode material and the positive electrode active material is preferably a compound represented by the above general formula (1), Li _x CoO ₂ , Li _x NiO ₂ , Li _x Co _a Ni _1-a O ₂ , or Li _x MnO _2. , Li _x Mn ₂ O ₄ , or Li _x Co _b V _1-b O ₂ (where x = 0.02 to 1.2, a = 0.1 to 0.9, b = 0.9 to 0. 98, z = 2.02 to 2.3), and a non-aqueous secondary battery having high discharge voltage, high capacity and excellent charge / discharge cycle characteristics can be obtained.

  A conductive agent, a binder, a filler, or the like can be added to the electrode mixture. The conductive agent may be anything as long as it is an electron conductive material that does not cause a chemical change in the constructed battery. Usually, natural graphite (such as scaly graphite, scaly graphite, earthy graphite), artificial graphite, carbon black, acetylene black, ketjen black, carbon fiber or metal (copper, nickel, aluminum, silver, etc.) powder, metal fiber or A conductive material such as a polyphenylene derivative may be included as one type or a mixture thereof. The combined use of graphite and acetylene black is particularly preferred. The addition amount is preferably 1 to 50% by weight, particularly preferably 2 to 30% by weight. In the case of carbon or graphite, 2 to 15% by weight is preferable.

  The binder is usually starch, polyvinyl alcohol, carboxymethyl cellulose, hydroxypropyl cellulose, regenerated cellulose, diacetyl cellulose, polyvinyl chloride, polyvinyl pyrrolidone, tetrafluoroethylene, polyvinylidene fluoride, polyethylene, polypropylene, ethylene-propylene-di. Enter polymers (EPDM), sulfonated EPDM, styrene butadiene rubber, polybutadiene, fluoro rubber, polyethylene oxide and other polysaccharides, thermoplastic resins, rubber elastic polymers, and the like are used as one kind or a mixture thereof. Moreover, when using the compound containing a functional group which reacts with lithium like a polysaccharide, it is preferable to add the compound like an isocyanate group and to deactivate the functional group, for example. The amount of the binder added is preferably 1 to 50% by weight, and particularly preferably 2 to 30% by weight.

  Any filler can be used as long as it is a fibrous material that does not cause a chemical change in the constructed battery. Usually, olefin polymers such as polypropylene and polyethylene, fibers such as glass and carbon are used. Although the addition amount of a filler is not specifically limited, 0 to 30 weight% is preferable.

  When the negative electrode material is used in a non-aqueous secondary battery system, a water-dispersed mixture paste containing a compound is applied and dried on a current collector. The pH of the aqueous dispersion mixture paste is preferably 5 or more and less than 10, and more preferably 6 or more and less than 9. In addition, it is preferable that the temperature of the water-dispersed paste is kept at 5 ° C. or higher and lower than 80 ° C., and is applied onto the current collector within 7 days after the paste is prepared.

  As the separator 3 shown in FIG. 1, a material having a large ion permeability, a predetermined mechanical strength, and an insulating microporous or gap is used. Furthermore, in order to improve safety, it is necessary to have a function of blocking the current by closing the gaps at 80 ° C. or higher to increase resistance. The closing temperature of these gaps is 90 ° C. or higher and 180 ° C. or lower, more preferably 110 ° C. or higher and 170 ° C. or lower.

  The method of creating the gap varies depending on the material, but any known method may be used. In the case of a porous film, the shape of the hole is usually circular or elliptical, and the size is 0.05 μm to 30 μm, preferably 0.1 μm to 20 μm. Furthermore, it may be a rod-like or irregular-shaped hole as in the case of making by a stretching method or a phase separation method. In the case of cloth, the gap is a gap between fibers and depends on how to make a woven or non-woven fabric. The proportion of these gaps, that is, the porosity, is 20% to 90%, preferably 35% to 80%.

  The separator has a film thickness of 5 μm or more and 100 μm or less, more preferably 10 μm or more and 80 μm or less, such as a microporous film, a woven fabric, or a nonwoven fabric. The separator preferably contains at least 20% by weight of an ethylene component, and particularly preferably contains 30% or more. Examples of components other than ethylene include propylene, butene, hexene, ethylene fluoride, vinyl chloride, vinyl acetate, and acetalized vinyl alcohol, with propylene and ethylene fluoride being particularly preferred.

  The microporous film is preferably made of polyethylene, ethylene-propylene copolymer or ethylene-butene copolymer. Further, those prepared by mixing and dissolving polyethylene and polypropylene, or polyethylene and polytetrafluoroethylene are also preferred.

  Nonwoven fabrics and woven fabrics have a thread diameter of 0.1 μm to 5 μm, polyethylene, ethylene-propylene copolymer, ethylene-butene 1 copolymer, ethylene-methylbutene copolymer, ethylene-methylpentene copolymer, polypropylene Those made of polytetrafluoroethylene fiber are preferred.

  These separators may be a single material or a composite material. In particular, a composite of two or more types of microporous films with different pore sizes, porosity and pore closing temperature, etc., microporous films and nonwoven fabrics, microporous films and woven fabrics, and nonwoven fabrics and papers. That is particularly preferred.

  The positive and negative electrode current collectors may be anything as long as they are electronic conductors that do not cause a chemical change in the constructed battery. For example, a material obtained by treating the surface of aluminum or stainless steel with carbon, nickel, titanium, or silver in addition to stainless steel, nickel, aluminum, titanium, carbon, or the like as a material is used for the positive electrode. In particular, aluminum or an aluminum alloy is preferable.

  For the negative electrode, in addition to stainless steel, nickel, copper, titanium, aluminum, carbon, etc., the surface of copper or stainless steel treated with carbon, nickel, titanium or silver, Al-Cd alloy, etc. are used. It is done. In particular, copper or a copper alloy is preferable.

  The surface of these materials may be oxidized. Further, it is desirable to make the current collector surface uneven by surface treatment. As the shape, a film, a sheet, a net, a punched product, a lath body, a porous body, a foamed body, a molded body of a fiber group, and the like are used in addition to the foil. The thickness is not particularly limited, but a thickness of 1 to 500 μm is used.

  The battery shape can be applied to any of coins, buttons, sheets, cylinders, flats, corners, and the like. When the shape of the battery is a coin or button, the positive electrode active material or the negative electrode material mixture is mainly used after being compressed into a pellet shape. The thickness and diameter of the pellet are determined by the size of the battery. Moreover, when the shape of the battery is a sheet, cylinder, or corner, the positive electrode active material or the negative electrode material mixture is mainly used after being applied (coated), dried and compressed on the current collector. As a coating method, a general method can be used.

  Examples thereof include a reverse roll method, a direct roll method, a blade method, a knife method, an extrusion method, a curtain method, a gravure method, a bar method, a dip method, and a squeeze method. Of these, the blade method, knife method and extrusion method are preferred. The application is preferably performed at a speed of 0.1 to 100 m / min. Under the present circumstances, the surface state of a favorable coating layer can be obtained by selecting the said application | coating method according to the solution physical property and dryness of a mixture. The application may be performed one side at a time or simultaneously on both sides. The application may be continuous, intermittent, or striped. Although the thickness, length, and width of the coating layer are determined by the size of the battery, the thickness of the coating layer on one side is particularly preferably 1 to 2000 μm in a compressed state after drying.

As a method for drying or dehydrating pellets and sheets, a generally adopted method can be used. In particular, it is preferable to use hot air, vacuum, infrared rays, far-infrared rays, electron beams and low-temperature air alone or in combination. The temperature is preferably in the range of 80 to 350 ° C, particularly preferably in the range of 100 to 250 ° C. The water content is preferably 2000 ppm or less for the entire battery, and preferably 500 ppm or less for each of the positive electrode mixture, the negative electrode mixture, and the electrolyte in terms of cycleability. As a pressing method for pellets and sheets, a generally adopted method can be used, and a die pressing method and a calendar pressing method are particularly preferable. Although a press pressure is not specifically limited, 0.2-3 t / cm < ² > is preferable. The press speed of the calendar press method is preferably 0.1 to 50 m / min, and the press temperature is preferably room temperature to 200 ° C. The ratio of the width of the negative electrode sheet to the positive electrode sheet is preferably 0.9 to 1.1, particularly preferably 0.95 to 1.0. The content ratio of the positive electrode active material and the negative electrode material varies depending on the compound type and the mixture formulation, and thus cannot be limited, but can be set to an optimal value from the viewpoint of capacity, cycle performance, and safety.

  As shown in FIG. 1, after overlapping the mixture sheets 1 and 2 with the separator 3, the sheets 1 and 2 are rolled or folded and inserted into the can 4. After electrically connecting 2, an electrolytic solution is injected and a battery can is formed using a sealing plate. At this time, the safety valve 7 can be used as a sealing plate. In addition to the safety valve 7, various conventionally known safety elements may be provided. For example, a fuse, bimetal, PTC element, or the like is used as the overcurrent prevention element. In addition to the safety valve, as a countermeasure against the increase in internal pressure of the battery can, a method of cutting the battery can, a method of cracking the gasket, a method of cracking the sealing plate, or a method of cutting the lead plate can be used. Further, the charger may be provided with a protection circuit incorporating measures against overcharge and overdischarge, or may be connected independently.

In addition, as a measure against overcharging, a method of cutting off current by increasing the battery internal pressure can be provided. At this time, a compound for increasing the internal pressure can be contained in the mixture or the electrolyte. Examples of compounds used to increase the internal _{pressure, Li 2 CO 3, LiHCO 3} , Na 2 CO 3, NaHCO 3, CaCO 3, MgCO and carbonates, such as ₃ can be cited.

  For the can and lead plate, a metal or alloy having electrical conductivity can be used. For example, metals such as iron, nickel, titanium, chromium, molybdenum, copper, and aluminum, or alloys thereof are used. As a method for welding the cap, the can, the sheet, and the lead plate, a known method (eg, direct current or alternating current electric welding, laser welding, ultrasonic welding) can be used. As the sealing agent for sealing, a conventionally known compound or mixture such as asphalt can be used.

  Applications of non-aqueous secondary batteries are not particularly limited. For example, when installed in electronic devices, color notebook computers, monochrome notebook computers, pen input computers, pocket (palmtop) computers, notebook word processors, pocket word processors, electronic Book player, mobile phone, cordless phone, pager, handy terminal, mobile fax, mobile copy, mobile printer, headphone stereo, video movie, LCD TV, handy cleaner, portable CD, minidisc, electric shaver, electronic translator, Car phones, transceivers, power tools, electronic notebooks, calculators, memory cards, tape recorders, radios, backup power supplies, memory cards, etc. Others for consumer use include automobiles, electric vehicles, motors, lighting equipment, toys, game equipment, road conditioners, irons, watches, strobes, cameras, medical equipment (such as pacemakers, hearing aids, shoulder grinders). Furthermore, it can be used for various military use and space use. Moreover, it can also combine with a solar cell.

The preferred combination of the members constituting the non-aqueous secondary battery is preferably a combination of the above-mentioned chemical materials and preferred battery components. In particular, as the positive electrode active material, Li _x CoO ₂ , Li _x NiO ₂ , Li _It contains at least one compound selected from _x MnO ₂ and Li _x MnO ₄ (where x = 0.02 to 1.2), and also contains acetylene black as a conductive agent.

The positive electrode current collector is made of stainless steel or aluminum and has a shape such as a net, sheet, foil, or lath. As a negative electrode material, lithium metal, lithium alloy (Li—Al), carbonaceous compound, oxide (LiCoVO ₄ , SnO ₂ , SnO, SiO, GeO ₂ , GeO, SnSiO ₃ , SnSi _0.3 Al _0.1 B _0.2 P _0.3 O _3.2 ), Sulfide (TiS ₂ , SnS ₂ , SnS, GeS ₂ , GeS) and the like are preferably used. The negative electrode current collector is made of stainless steel or copper and has a shape such as a net, sheet, foil, or lath. In the mixture used together with the positive electrode active material or the negative electrode material, a carbon material such as acetylene black or graphite may be mixed as an electron conductive agent. As the binder, fluorine-containing thermoplastic compounds such as polyvinylidene fluoride and polyfluoroethylene, polymers containing acrylic acid, elastomers such as styrene butadiene rubber and ethylene propylene terpolymer can be used alone or in combination. In addition, the electrolyte includes ethylene carbonate, and a combination of cyclic and non-cyclic carbonates such as diethyl carbonate and dimethyl carbonate or ester compounds such as ethyl acetate, and the supporting electrolyte includes LiPF ₆ , and further includes LiBF ₄ , LiCF ₃ SO It is preferable to use a mixture of lithium salts such as ₃ . Further, as the separator, polypropylene or polyethylene alone or a combination thereof is preferable. The form of the battery may be any of a cylinder, a flat shape, and a square shape. It is preferable that the battery is provided with means (eg, an internal pressure relief type safety valve, a current cutoff type safety valve, a separator that increases resistance at high temperatures) that can ensure safety against malfunction.

Hereinafter, the present invention will be described in more detail with specific examples. However, the present invention is not limited to the examples unless it exceeds the gist of the invention.
Example-1 86 parts by weight of SnB _0.2 P _0.5 K _0.1 Mg _0.1 Ge _0.1 O _2.8 (average particle size 7.5 μm) as a negative electrode material and 3 parts by weight of acetylene black and 6 parts by weight of graphite as a conductive agent were mixed. Further, 4 parts by weight of polyvinylidene fluoride and 1 part by weight of carboxymethyl cellulose were added as binders and kneaded using water as a medium to obtain a negative electrode mixture slurry. The slurry was coated on both sides of a 10 μm thick copper foil using an extrusion coater and dried to obtain a negative electrode mixture sheet.

  Next, 79 parts by weight of α-alumina, 18 parts by weight of graphite, and 3 parts by weight of carboxymethyl cellulose were added with water as a medium and kneaded to obtain an auxiliary layer slurry. The slurry was coated on the negative electrode mixture sheet, dried, and then compression molded by a calender press to prepare a strip-shaped negative electrode sheet precursor having a thickness of 98 μm, a width of 55 mm, and a length of 520 mm.

After spot-welding a nickel lead plate to this negative electrode sheet precursor, it was dehydrated and dried at 230 ° C. for 30 minutes in air having a dew point of −40 ° C. or lower.
12 sheets of lithium foil (purity 99.5%) each having a thickness of 40 μm cut to 20 mm × 55 mm were bonded to both sides of the sheet. The pressure bonding was performed while transferring the lithium foil to a 300 mm diameter polyethylene roller and simultaneously applying a pressure of 5 kg / cm ^{2 to} both sides of the sheet. At this time, the coverage of the negative electrode sheet with lithium foil was 40%.

87 parts by weight of LiCoO ₂ as a positive electrode active material, 3 parts by weight of acetylene black and 6 parts by weight of graphite as a conductive agent are mixed, and 3 parts by weight of Nipo1820B (manufactured by Nippon Zeon) and 1 part by weight of carboxymethylcellulose as a binder. And kneaded with water as a medium to obtain a positive electrode mixture slurry.

  The slurry was applied to both sides of an aluminum foil having a thickness of 20 μm using an extrusion type coater, dried, and then compression-molded by a calendar press machine, and a strip-like positive electrode sheet having a thickness of 260 μm, a width of 53 mm, and a length of 445 mm ( 1) was created. After welding an aluminum lead plate to the end of the positive electrode sheet, it was dehydrated and dried at 230 ° C. for 30 minutes in dry air having a dew point of −40 ° C. or lower.

  As shown in FIG. 1, a heat-treated positive electrode sheet (1), a microporous polyethylene / polypropylene film separator (3), a negative electrode sheet (2) and a separator (3) are laminated in this order, and this is spirally formed. I wound it.

This wound body was stored in a nickel-plated iron-bottomed cylindrical battery can (4) that also served as a negative electrode terminal.
Furthermore, a 2 to 8 weight ratio mixed solution of ethylene carbonate and diethyl carbonate was used as an electrolyte solution solvent. To the above solvent, 1 mol / liter of LiPF ₆ was added as a supporting salt, and chain hydrocarbons were added in the types and amounts shown in [Table 1]. The electrolyte was injected into the battery can (4) while keeping the battery can temperature at room temperature. A battery lid (5) having a positive electrode terminal was caulked through a gasket (6) to produce a cylindrical battery having a height of 65 mm and an outer diameter of 18 mm. The positive electrode terminal (5) was connected to the positive electrode sheet (1) and the battery can (4) was previously connected to the negative electrode sheet by a lead terminal. (7) is a safety valve.

After caulking, the mixture was aged at 0 ° C. for 2 hours and then at 25 ° C. for 15 hours, and then charged at 25 ° C. at a constant voltage of 0.4 mA / cm ² to 3.1 V, and further stored at 50 ° C. for 2 weeks. The open circuit voltage of this battery after 3 days of aging was 2.58V.

After storage, the battery was charged at 1 mA / cm ² to 4.1 V, and then discharged at 1 mA / cm ² to 2.8 V. After discharge capacity was charged to 4.1V in this after 1mA / cm ^2, it was determined to discharge at 0.5mA / cm ² to 2.8V. Further, a cycle test of 4.1-2.8 V was performed at 2.5 mA / cm ² , and the capacity retention rate at the 500th cycle was measured. The results are shown in Table 1.

  The batteries 1 to 8 and 10 to 12 are obtained by adding chain hydrocarbons to the electrolytic solution, and the battery 9 is one in which chain hydrocarbons are not added to the electrolytic solution. Each of the batteries 1 to 6, 8, and 10 to 12 includes any one of n-dodecane, n-decane, n-tetradecane, n-octane, and n-hexane in an electrolyte solution. No. 7 is obtained by adding two kinds of n-dodecane and n-decane to the electrolytic solution at a weight ratio of 1: 1.

  The batteries 1 to 8 and 10 to 12 to which chain hydrocarbons are added have a higher capacity maintenance rate than the battery 9 to which chain hydrocarbons are not added. When at least one kind of chain hydrocarbon is included in the electrolytic solution, the capacity retention rate of the battery is increased, and good results are obtained.

  The battery 12 to which n-hexane is added has a lower capacity retention rate than the batteries 1 to 8, 10 and 11 to which other chain hydrocarbons are added. The chain hydrocarbon to be added is a hydrocarbon having 7 or more carbon atoms (for example, n-dodecane, n-decane, n-tetradecane, n-octane) rather than a hydrocarbon having 6 or less carbon atoms (for example, n-hexane). ) Is preferable. Since a mixture of two types of chain hydrocarbons may be added as in the battery 7, the chain hydrocarbon to be added is one or a plurality of arbitrary mixtures selected from carbon atoms having 7 to 25 carbon atoms. It is preferable that The chain hydrocarbon is a straight chain or branched heptane, octane, nonane, decane, undecane, dodecane, tridecane, tetradecane, pentadecane, hexadecane, heptadecane, octadecane, nonadecane, or eicosane. An arbitrary mixture of plural kinds is preferable. If a compound having a carbon number equal to or greater than Eicosan is used, it is difficult to form a uniform electrolyte.

  Batteries 1 to 4 and 9 to 11 differ in the amount of n-dodecane added to the electrolyte. FIG. 2 is a graph showing the relationship between the capacity retention ratio and the discharge capacity with respect to the n-dodecane content. Batteries 9 and 10 having an n-dodecane content of 0.008 [wt%] or less are not preferable because they have a lower capacity retention rate than the batteries 1 to 4 having a content of 0.05 [wt%] or more. Further, the battery 11 having an n-dodecane content of 3.2 wt% or more preferably has a smaller discharge capacity than the batteries 1 to 4, 9, and 10 having a content of 2.0 wt% or less. Absent. In order to increase the discharge capacity and improve the cycle characteristics, the chain hydrocarbon content in the electrolyte is preferably 0.01 to 3% by weight.

It is a longitudinal cross-sectional view of a general cylindrical battery. It is a graph which shows the relationship between the capacity | capacitance maintenance factor with respect to content of the chain type hydrocarbon in electrolyte solution, and discharge capacity.

Explanation of symbols

1 Positive electrode 2 Negative electrode 3 Separator 4 Battery can 5 Battery lid 6 Gasket 7 Safety valve

Claims (4)

A positive electrode sheet having a layer mainly composed of a lithium-containing metal oxide, a carbonaceous compound having a graphite structure selected from natural graphite and artificial graphite, and / or a non-mainly composed mainly of tin represented by the following general formula (1) In a non-aqueous secondary battery having a negative electrode sheet having a mixture layer mainly composed of a negative electrode material made of a crystalline composite compound , a non-aqueous electrolyte containing a lithium salt, and a separator,
The non-aqueous electrolyte contains a combination of at least one cyclic carbonate selected from propylene carbonate, ethylene carbonate and butylene carbonate, and at least one non-cyclic carbonate selected from dimethyl carbonate and diethyl carbonate , and at least n-dodecane is non-aqueous. A non-aqueous secondary battery comprising 0.01 to 3% by weight with respect to the electrolytic solution.
SnM ¹ _a O _t S u _... the general formula (1)
(In the formula, M ¹ represents two or more elements selected from Al, B, P, Si, Ge, Group 1 element, Group 2 element, Group 3 element, and halogen element in the periodic table; Is a number of 0.2 or more and 2 or less, t is a number of 1 or more and 6 or less, and u is a number of 0.5 or less.) 0 The non-aqueous electrolyte further comprises a chain hydrocarbon having 8 to 16 carbon atoms (excluding n- dodecane), a chain hydrocarbon having 8 to 16 carbon atoms (including n- dodecane) in total. The non-aqueous secondary battery according to claim 1, comprising 0.1 to 3% by weight . 3. The non-aqueous secondary battery according to claim 1, wherein the non-aqueous electrolyte contains both or one of LiBF ₄ and LiPF _{6. 4} . The content of the C8-16 chain hydrocarbon (including n-dodecane) in the non-aqueous electrolyte is 0.02 to 2% by weight. The non-aqueous secondary battery in any one.

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