JPH06168721A - Manufacture of lithium secondary battery and positive electrode active material - Google Patents

Abstract

PURPOSE:To provide a manufacturing method for a lithium secondary battery, positive electrode active material, and a positive electrode of a high capacity, a high energy, and a long cyclic life. CONSTITUTION:A battery is formed of a negative electrode active material 101, a separator 107, a positive electrode active material 103 to/from lithium ions can be moved by charge/discharge, electrolyte 104 as ion conductive material, a collecting electrode 100, and a battery case 108 at least. A main component material of the positive electrode active material is a compound of one sort or more of transition metal and group 6A element having a structure of a collected body selected among amorphous material, microcrystals, mixture of amorphous materialand microcrystals, and mixture of amorphous material, microcrystals, and polycrystals of a crystal grain size of 500Angstrom or less. The compound of the transition metal and group 6A element comprises transition metal, its salt, organic compound, hydroxide, etc., which are regulated by use of solution reaction, gas phase reaction, dissolving, and quenching.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a lithium secondary battery in which lithium ions enter and leave the positive electrode active material by charging and discharging. In particular, the present invention relates to a high-capacity lithium secondary battery having excellent charge / discharge repeating characteristics.

[0002]

2. Description of the Related Art Recently, it is expected that global warming will occur due to the greenhouse effect caused by an increase in CO ₂ , and it will become difficult to construct a new thermal power plant. It has been devised to carry out so-called load leveling, in which the load is leveled by accumulating in the secondary battery installed in. In addition, the development of high energy density secondary batteries for electric vehicles that do not emit air pollutants is desired, and they are highly efficient as power sources for portable devices such as book-type personal computers, word processors, video cameras, and mobile phones. The demand for the development of secondary batteries is ever increasing.

As the above high performance secondary battery, a rocking chair type lithium ion battery in which lithium ion is introduced into an intercalation compound as a positive electrode active material and carbon as a negative electrode active material has been developed and partially put into practical use. It's starting. However, the lithium ion battery has not achieved the high energy density which is the original feature of the lithium battery in which metallic lithium is used as the negative electrode active material. Furthermore, development of a lithium storage battery with high capacity, high energy, and long cycle life is desired.

[0004]

SUMMARY OF THE INVENTION It is an object of the present invention to solve the above-mentioned conventional drawbacks and to provide a lithium battery of high capacity, high energy and long cycle life.

[0005]

As a result of intensive studies to solve the above-mentioned conventional drawbacks, the present inventor has found that one or more kinds of transition metals having a crystal grain size of 500 angstroms or less. It has been found that high capacity, high energy, and long cycle life can be achieved by adopting a compound of a group 6A element and a group 6A element as a positive electrode active material of a lithium secondary battery.

The present invention provides a lithium secondary material formed at least from a battery case, a negative electrode active material, a separator, a positive electrode active material capable of allowing lithium ions to move in and out by charging and discharging, an electrolyte as an ion conductor, a current collecting electrode. In a battery, the main constituent material of the positive electrode active material is a crystal grain size of 5
A lithium secondary battery, which is a compound of one or more kinds of transition metals and a Group 6A element having a thickness of 00 angstroms or less.

Further, the main constituent material of the positive electrode active material is
It has an aggregate structure selected from amorphous, microcrystalline, a mixture of amorphous and microcrystalline, and a mixture of amorphous, microcrystalline and polycrystalline. Amorphous, microcrystalline, a mixture of amorphous and microcrystalline, a mixture of amorphous, microcrystalline and polycrystalline, with a crystal grain size of 500 angstroms or less, more preferably 200 angstroms or less. ，
By adopting the compound of the transition metal having the structure of the aggregate selected from the group 6A element as the positive electrode active material of the lithium secondary battery, 1) the reaction area of the positive electrode active material can be increased, so The electrochemical reaction of can be made smoother, and the charge capacity can be improved. 2) It is possible to suppress the strain generated in the positive electrode active material due to the movement of lithium ions during charging and discharging, and to extend the cycle life. , Etc. can be obtained.

The specific surface area of the positive electrode active material containing a compound of the above transition metal and a 6A group element as a main constituent is preferably 50 m ² / g or more before being formed as a positive electrode,
It is more preferably 100 m ² / g or more. Furthermore, by adopting a compound of a transition metal and a 6A group element containing a hydrogen element, the charge / discharge cycle characteristics can be improved.

By subjecting the positive electrode active material to lipophilic treatment with an organometallic compound, the solid-liquid reaction between the electrolytic solution and the positive electrode active material can be made smoother during charging and discharging.
Specific examples of the compound of a transition metal and a 6A group element include nickel oxide, cobalt oxide, titanium oxide, iron oxide, vanadium oxide, manganese oxide, molybdenum oxide, chromium oxide, metal oxides such as tungsten oxide, or molybdenum sulfide. , A metal sulfide such as iron sulfide and titanium sulfide, a hydroxide such as iron oxyhydroxide, or a complex of the above compounds.

Further, by using metallic lithium whose surface is coated with a film that permeates lithium ions, as a negative electrode active material of the secondary battery, a lithium secondary battery having a long life and a high energy density can be obtained. The present invention also provides a method for producing a positive electrode active material for a lithium secondary battery, which comprises a transition metal itself, a transition metal salt, a transition metal organometallic compound, a transition metal hydride, a transition metal hydride, and a transition metal carbonyl. Using one or more materials selected from compounds and transition metal oxides as raw materials, solution reaction, gas phase reaction, melting and quenching,
The size of the crystal grain is 500 using the reaction selected from
Å or less, more preferably 200 Å or less, amorphous, microcrystalline, mixed amorphous and microcrystalline, mixed amorphous, microcrystalline and polycrystalline,
A method for producing a positive electrode active material, which comprises at least a step of forming a compound of a transition metal and a 6A group element having a structure of an aggregate selected from.

The present invention particularly uses one or more reactions selected from a reaction of a salt of a transition metal with an alkali, a hydrolysis reaction of an organic transition metal compound, a reaction of a transition metal with an alkali, and a transition reaction. After the metal hydroxide is prepared, the transition metal salt or the organic transition metal compound is decomposed in the dehydration reaction or in the gas phase, or the decomposition product or the transition of the transition metal salt or the organic transition metal compound is generated. A metal selected from a 6A group element and a 6A group element compound by reacting a metal group vapor with a 6A group element or a 6A group element compound or by melting one or more kinds of materials selected from transition metals and transition metal compounds. After reacting with one or more kinds of materials, it is rapidly cooled to have a crystal grain size of 500 angstroms or less, amorphous or microcrystalline, or a mixture of amorphous and microcrystalline, or non-crystalline. Quality and microcrystalline and polycrystalline mixed-although the aggregate structure of a manufacturing method for forming a positive electrode active material is a compound of a transition metal and the group 6A element.

Transition Metal Element The transition metal element of the positive electrode active material of the present invention is an element having a partial d-shell or f-shell, such as Sc, Y, lanthanoid, actinide, Ti, Zr, Hf, V, Nb, T
a, Cr, Mo, W, Wn, Tc, Re, Fe, Ru,
Os, Co, Rh, Ir, Ni, Pd, Pt, Cu, A
g and Au are used. Mainly, Ti of the first transition series metal,
V, Cr, Mn, Fe, Co, Ni, Cu are used.
As a raw material for producing an actual compound of a transition metal and a 6A group element, the above transition metal, a salt of the transition metal, an oxide of the transition metal, a hydroxide of the transition metal, or the like is used.

Group 6A Element As the group 6A element of the positive electrode active material of the present invention, O, S, S
e, Te, Po are used. Mainly O and S are used. In addition to the above elements, sulfur, selenium, and selenium can be used as raw materials for producing a compound of an actual transition metal and a Group 6A element.
Compounds of tellurium and polonium such as hydrides, halides, halogenated oxides and oxides can be used.

Addition Element By adding an element other than the transition metal, the strain of the positive electrode active material caused by the entry and exit of lithium ions can be relaxed. As a method of adding, lithium, magnesium, sodium, potassium, aluminum, zinc, calcium, barium, lead, indium, boron, silicon, tin, phosphorus, arsenic, antimony, bismuth, A method of adding a salt or hydroxide or an organometallic compound of one or more elements selected from chlorine and fluorine is effective. The atomic ratio of the additive element to the transition metal element is preferably 1 or less.

(Method for Producing Compound of Transition Metal and Group 6A Element) The method for producing the compound of transition metal and group 6A element of the present invention is roughly classified into a solution of a transition metal salt or an organic transition metal compound solution. From the above, a method of preparing via a hydroxide, a method of melting and rapidly cooling a transition metal or a transition metal compound, and a method of reacting a transition metal compound in a gas phase are suitable.

As a specific example of preparing a transition metal oxide from a hydroxide, there is a method of preparing a powder by firing or drying the hydroxide in air or in an oxygen atmosphere. As a specific example of preparing the transition sulfide from the hydroxide, there is a method of preparing the powder by firing the hydroxide in a hydrogen reducing atmosphere mixed with hydrogen sulfide. As a method of preparing a transition metal oxide by a quenching method, a transition metal compound such as a transition metal or a transition metal oxide is melted, and then oxygen gas mixed with an inert gas is sprayed on a rotating disk to obtain a powder. There is a method of preparing.

As a method for preparing a transition metal oxide by a gas phase reaction, a salt of a transition metal is oxidized or hydrolyzed, a transition metal metal vapor is reacted with a 6A group element or a 6A group element compound, or an organic compound is used. Decomposing transition metal compounds,
There is a method of preparing powder. The preparation temperature in each of the above various preparation methods except the quenching method is preferably 400 ° C. or lower, and more preferably 300 ° C. or lower.

The liquid phase reaction method, the gas phase reaction method, and the melt quenching method will be described below. [Liquid phase reaction] As a method for preparing the hydroxide of the main reaction in the method for producing a solution from a solution via a hydroxide, the following methods can be mentioned. Method for Preparing Hydroxide As a method for preparing a transition metal hydroxide, it is appropriate to use a reaction such as a reaction between a salt of a transition metal and an alcal, a hydrolysis reaction of an organic transition metal compound, a reaction between a transition metal and an alkali. Is. The preparation temperature is preferably 150 ° C or lower, more preferably 100 ° C or lower.

Reaction of Transition Metal Salt with Alkali It is prepared by reacting an aqueous solution of a transition metal salt with an alkali to precipitate as a transition metal hydroxide. At this time, when two or more kinds of transition metal salts are mixed and used, a composite transition metal hydroxide is obtained. Typical examples of the transition metal salt include carbonate, nitrate, halide, sulfate, sulfamate, acetate, oxalate, citrate, tartrate, formate and ammonium salt.

As the alkali, lithium hydroxide, sodium hydroxide, potassium hydroxide, ammonium hydroxide and the like can be used, and also urea, thiourea and the like which generate a hydroxide ion by heating to raise the pH. Can be used. It is preferable to finely precipitate the hydroxide precipitation particles by adding a small amount of an organic acid, an inorganic acid, various amines, or an organic solvent such as alcohol while reacting the aqueous solution of the transition metal salt with an alkali. .

It is also possible to further miniaturize the precipitated particles by applying ultrasonic vibration during precipitation.
This can increase the specific surface area. Hydrolysis Reaction of Organic Transition Metal Compounds Transition metal hydroxides can also be prepared by hydrolyzing transition metal alkoxides, acetylacetonates, octylates, naphthenates, and other organometallic compounds. .

The specific hydrolysis reaction of alkoxide is as follows.
Add transition metal alkoxide to water, alcohol or ethanol.
Dissolve it in nolamine, etc., and add inorganic acid such as hydrochloric acid or acetic acid.
Add organic acid such as ammonium hydroxide or amine
In addition, as the transition metal alkoxide, Mn (OC
₂H_Five)₂, Mn (OC₃H₇)₂, Mn (OC_FourH₉)
₂, Ni (OC₂H_Five)₂, Ni (OC₃H₇)₂, Ni
(OC_FourH₉)₂, Co (OC₂H_Five)₂, Co (OC₃
H₇)₂, Co (OC_FourH₉)₂, Ti (OC
₂H_Five)₂, Ti (OC₃H₇)₂, Ti (OC_FourH₉)
₂, Fe (OC₂H_Five)₂, Fe (OC₃H₇)₂, Fe
(OC_FourH₉)₂, Cu (OC₂H_Five)₂, Cu (OC₃
H₇)₂, Cu (OC_FourH₉)₂, VO (OCH₃)₃ ，
VO (OC₂H_Five)₃, VO (OC₃H₇)₃, VO (O
C_FourH₉)₃, Y (OC_FourH₉)₃,, etc. can be used.

As a transition metal acetylacetonate
Is Cu (C_FiveH₇O₂)₂, Co (C _FiveH₇O₂)
₂(H₂O)₂, Co (C_FiveH₇O₂)₃, Ni (C_Five
H₇O₂)₂(H₂O)₂, Mn (C_FiveH₇O₂)₂(H₂
O)₂, Cr (C_FiveH₇O₂)₃, VO (C_FiveH₇O₂)
₂, Fe (C_FiveH₇O₂)₃, Ti (OC_FourH₉)₂(C
_FiveH₇O)₂, La (C_FiveH₇O₂)₃, Y (C_FiveH₇O
₂)₃, Zr (C_FiveH₇O₂)_FourTransition metal octylates
As for Cu (C₇H₁₅COO)₂, Ni (C₇H_{1 Five}
COO)₂, Fe (C₇H₁₅COO)₃, Mn (C₇H₁₅
COO)₂, Co (C₇H₁₅COO)₂, Zr (C₇H₁₅
COO)_Four, Y (C₇H₁₅COO)₃, La (C₇H₁₅
COO)₃Examples of the transition metal naphthenate include C_nH
_2n-2O₂Naphthenic salt of naphthenic acid represented by the general formula
Cobaltate, Copper naphthenate, Manganese naphthenate, Na
Iron naphthenate, nickel naphthenate, vanadiu naphthenate
, Yttrium naphthenate, lanthanum naphthenate, a
As rucor, methyl alcohol, ethyl alcohol
, Isopropyl alcohol, ethylene glycol,
Ropylene glycol, etc. are used.

Dehydration reaction From the transition metal hydroxide prepared by the solution reaction described above,
In order to obtain the transition metal oxide by dehydration, is it necessary to immerse the transition metal hydroxide in an organic solvent such as alcohol or acetone that mixes with water to sufficiently replace the water content, and then vacuum dry at a temperature of 100 ° C. or higher? Alternatively, it is preferable to use a method of dehydration by heating with microwaves. If the drying temperature is too high, crystallization will proceed and hydroxyl groups will decrease, so a temperature of 400 ° C. or lower is more preferable. The microwave frequency is preferably a frequency that is easily absorbed by water.

Further, in order to improve the specific surface area, a method of dehydrating by freeze-drying can also be used. Hydrogen treatment A method of mixing hydrogen gas in a dry atmosphere to heat-treat a transition metal hydroxide or drying the transition metal hydroxide or a hydrogen plasma treatment of the transition metal hydroxide is used. As a method of generating hydrogen plasma, a method of discharging hydrogen gas or exciting decomposition of hydrogen gas with a laser can be adopted.

Introduction of Group 6A element other than oxygen A method of treating the transition metal hydroxide or the transition metal oxide with hydrogen sulfide or hydrogen selenide, or mixing the group 6A element compound when preparing the transition metal hydroxide. Is used. [Gas phase reaction method] As a method for preparing a compound of a transition metal and a 6A group element by a gas phase reaction, a transition metal salt or an organic transition metal compound in a gaseous state, or a transition metal metal vapor, and a 6A group element are used. Alternatively, there is a method in which a powder is prepared by reacting with a 6A group element compound in a gas phase. It is also possible to prepare a compound of a transition metal and a 6A group element by decomposing a gasified transition metal salt or organic transition metal compound containing a 6A group element in the gas phase.

When the transition metal salt or organic transition metal compound is a solid, it is heated to vapor, or heated to a liquid and then bubbled with a carrier gas to be introduced into a reaction vessel, or a solvent. A method of bubbling a carrier gas into a solution dissolved therein and introducing it into a reaction vessel can also be adopted. When the transition metal salt or the organic transition metal compound is a liquid, it is possible to employ a method of heating it into vapor or bubbling a carrier gas and introducing it into the reaction vessel.

Halides such as chlorides are mainly used as salts of transition metals, and carbonates, nitrates, sulfates, sulfamate, acetate, oxalate, citrate, tartrate, formate are used. , Ammonium salts and the like can also be used. Specific examples of the chloride include VOCl ₃ , MnCl
₂ , MoCl ₅ , TiCl ₄ , NiCl ₂ , CoCl,
₂ , FeCl ₃ , WCl ₆ , YCl ₃ , ZrCl ₄ , and the like.

As the raw material of the 6A group element, gaseous 6
A group A element, a hydride of a group 6A element, a halide of a group 6A element, or the like can be used. Further, by mixing hydrogen gas in the above gas phase reaction, it is possible to prepare a compound of a transition metal and a Group 6A element containing a hydrogen element. As a method used for the gas phase reaction, a thermal CVD (Chemical Vapor Dep) is used.
position), plasma CVD, laser CVD,
A filament method, a reactive sputtering method, an electron beam method, etc. are preferable.

Thermal CVD is plasma CVD by heating.
Is by discharge, laser CVD is by thermal energy or light energy of laser, filament method is by heating filament such as tungsten, reactive sputtering method is by sputtering in a reactive gas atmosphere, electron beam method is by electron beam heating. , And each gas phase reaction. In the reactive sputtering method and the electron beam method, it is desirable that the raw material is a solid.

[Quenching Method] A shock wave generated by helium gas mixed with oxygen or hydrogen sulfide is generated by breaking the Mylar film, sprayed on the high-frequency molten transition metal or transition metal compound, and the blown compound powder is cooled on the slide below. Gun method of hitting a steel plate to rapidly cool it, method of atomizing molten metal by an inert gas jet mixed with oxygen or hydrogen sulfide, 6A group element such as oxygen or 6A group element compound such as hydrogen sulfide Atomization method of spraying a molten metal of a transition metal or a transition metal compound in a rotating disc in an atmosphere to form a powder,
Etc. can be used. Further, elemental hydrogen can be introduced into the product by mixing hydrogen gas into the inert gas.

The quenching rate at this time is preferably 10 ¹ to 10 ⁸ K, more preferably 10 ² to 10 ⁸ . A crucible furnace, an induction furnace, an arc furnace, an electron beam furnace, or the like can be used as the type of the melting heating furnace. As an example of directly reacting a transition metal with an alkali, there is a method of reacting a metal such as vanadium with molten alkali to prepare an oxide.

(Conductor Nucleus) By mixing a conductor powder when preparing a compound of a transition metal and a 6A group element, and using the conductor powder as a nucleus to grow a compound of a transition metal with a 6A group element, It is possible to increase the collection rate, facilitate the entry and exit of lithium ions, and improve the battery capacity.

As the material of the conductor powder, carbon, titanium,
Carbon and metals such as nickel, cobalt, iron, chromium, manganese, vanadium, platinum, palladium, copper, silver, gold, zinc, tin, indium, lead, tungsten and molybdenum can be used. Preferably, at least one of carbon, titanium, nickel, cobalt, iron, chromium, manganese, vanadium and platinum is used.

As the shape of the conductor powder, a mixture of one or more kinds of conductor powder selected from spherical, flaky, needle-like, and fibrous is used. This allows the transition metal and 6A
The compound powder with the group element also has a mixed shape such as a spherical shape, a flake shape, a needle shape, or a fibrous shape, which improves the efficiency of electron transfer between the positive electrode active materials and improves charge / discharge characteristics.

As the particle diameter of the conductor powder, the value measured by an electron microscope is preferably in the range of 10 Å to 100 μm, more preferably in the range of 10 Å to 10 μm. (Pulverization of Positive Electrode Active Material) The positive electrode active material prepared by the above-mentioned method needs to be pulverized to a proper particle size, if necessary, especially when the obtained positive electrode active material is lumpy. .

For the pulverization, a pulverization method selected from a compression crusher, a shear crusher, an impact crusher, a roll mill, a roller mill, a high speed rotation mill, a ball mill, a medium stirring mill, a jet mill, a mortar, a stamp mill, etc. is appropriately combined. It is good to do it. (Conductor coating) The powder of the compound of the transition metal and Group 6A element prepared by the above method is chemically plated (electroless plating),
The conductor thin film is coated by a method such as vapor deposition. By this treatment, current collection efficiency can be increased, lithium ions can easily enter and leave, and battery capacity can be improved.

As the material of the conductor thin film, carbon, titanium, nickel, cobalt, iron, chromium, manganese, vanadium, platinum, palladium, copper, silver, gold, zinc, tin,
Carbon and metals such as indium, lead, tungsten and molybdenum can be used, preferably carbon, titanium, nickel, cobalt, iron, chromium, manganese, vanadium,
Use one or more of the platinum materials.

Chemical plating is a method of reducing metal ions with a reducing agent such as formaldehyde to deposit a metal film. Vapor deposition is carried out by generating a metal vapor with an electron beam or a laser, coating by sputtering a carbon or metal target, or discharging a hydrocarbon, an organic solvent or an organic metal compound, laser, heat, etc. A method of disassembling and coating can be used. A carbon film can be formed by the decomposition of hydrocarbons and organic solvents, and a metal film can be formed by the decomposition of organometallic compounds.

The thickness of the conductor film is preferably in the range of 50 angstrom to 1 micron. (Lipophilic treatment agent) Lipophilic treatment of the positive electrode active material prepared by the above-described method improves the leak property with the non-aqueous electrolyte to facilitate the entry and exit of lithium ions into and from the positive electrode active material. You can

As a method for subjecting the positive electrode active material to lipophilic treatment, the positive electrode active material is molded before or after molding.
The organometallic compound is immersed in a solution of an organic solvent, dried and treated. As the organometallic compound used for the lipophilic treatment, it is preferable to use an organometallic compound such as a silane coupling agent or an organic titanate. When diluted and used, the concentration of dilution is suitably 0.05 to 2% by weight with respect to the solvent.

Specific examples of the silane coupling agent include:
Vinyltrimethoxysilane, vinylethoxysilane, N
-(2-aminoethyl) 3-aminopropylmethyldimethoxysilane, N- (2-aminoethyl) 3-aminopropyltrimethoxysilane, 3-aminopropyltriethoxysilane, 3-glycidoxypropyltrimethoxysilane, 3 -Glycidoxypropylmethyldimethoxysilane, 2- (3,4-epoxycyclohexyl) ethyltrimethoxysilane, 3-chloropropylmethyldimethoxysilane, 3-chloropropyltrimethoxysilane,
3-methacryloxytrimethoxysilane, 3-mercaptotrimethoxysisilane, N- [2- (vinylpentylamino) ethyl] -3-aminopropyltrimethoxysilane, and the like.

Specific examples of the organic titanate include tetra-i-propoxy titanium, tetra-n-ptoxy titanium, tetrakis (2-ethylhexyloxy) titanium,
Tetrastearyloxytitanium, di-i-proxy bis (acetylacetonate) titanium, dihydroxy bis (lactato) titanium, titanium-i-propoxyoctylene glycol, titanium stearate, propanedioxytitanium bis (ethylacetoacetate) , Propanedioxytitanium (acetylacetonate) (ethylacetoacetate), oxotitanium bis (monoammonium oxalate), tri-n-butoxytitanium monostearate, various titanium polymers, and the like.

(Analysis of Compound of Transition Metal and Group 6A Element) Measurement of Crystal Grain Size The crystal grain size is determined by the following Scherrer's value from the half-value width of the X-ray diffraction curve peak and the diffraction angle. A judgment was made using a formula. t = 0.9λ / _B cos θ _B (Scherrer's formula) t: size of crystal grain λ: wavelength of X-ray beam B: peak half width θ _B : diffraction angle transition metal used in the secondary battery of the present invention And the size of the crystal grain of the positive electrode active material, which is a compound of the 6A group element, is
The value calculated using the error formula is preferably 500 angstroms or less on average, and more preferably 200 angstroms or less.

Observation of Crystal Structure The crystal structure of the compound of the transition metal and Group 6A element prepared by the method of the present invention is the waveform of the radial distribution function by X-ray diffraction,
Diffraction pattern of reflection high-energy electron diffraction (RHEED), X
It can be observed by the waveform of the line diffraction curve. The radial distribution function is obtained by Fourier transforming the measured X-ray or neutron beam scattering intensity. The radial distribution function is expressed as a function of the existence probability of atoms or the distance of deviation from the average number density with respect to any atom, and in the case of amorphous a continuous gentle peak curve is obtained. In the crystal, a sharp discontinuous peak is obtained.

From RHEED, a halo pattern is observed in the case of amorphous, a ring pattern in the case of fine crystal, and a spot pattern in the case of polycrystal. From the scattering angle and the scattering intensity obtained by the X-ray small angle scattering method, a non-uniform density fluctuation peculiar to amorphous is also observed. Further, by differential thermal analysis, with temperature rise, endothermic or exothermic heat due to structural relaxation or structural change due to crystallization is observed, and endothermic heat due to dehydration is observed if there is a hydroxyl group.

By using the above method,
The structure of the compound of the transition metal and Group 6A element prepared by the production method of the present invention was analyzed, and the structure of amorphous, microcrystalline, or polycrystalline was confirmed. Analysis of Hydrogen Element A compound of a transition metal containing a hydrogen element and a 6A group element can be analyzed by SIMS (Secondary Ion Mass).
The elemental hydrogen was qualitatively analyzed by Spectrometry).

(Preparation of Positive Electrode) The positive electrode is formed together with the current collector by mixing the powder of the compound of the transition metal and the Group 6A element prepared by the above-mentioned method with the binder and, in some cases, the conductor powder. To produce. The forming step is preferably performed in dry air from which water is sufficiently removed, and more preferably in an inert gas atmosphere.

The role of the conductor powder is to assist electron conduction and facilitate current collection because the active material, which is a compound of a transition metal and a 6A group element, has almost no electron conductivity.
As the conductor powder, various carbon agents such as acetylene black, Ketjen black, graphite powder, nickel,
Metal materials such as titanium, copper and stainless steel can be used. The mixing weight ratio of the conductor powder to the positive electrode active material is preferably 1 or less.

The binder has a role of adhering the positive electrode active material powders to each other and preventing cracks from occurring in the charge / discharge cycle and dropping from the current collector. As the material for the binder, one or more kinds of resins selected from fluororesins, polyethylene, polypropylene, and silicone resins, which are stable in organic solvents, can be used. It is preferable to use a liquid or a solution, or a resin having a low melting point, as the above resin, to remove the solvent and crosslink the resin in the manufacturing process of the positive electrode, thereby reducing the content of the binder in the positive electrode. Therefore, the capacity of the battery can be improved. Specific examples of the resin that is liquid or soluble in a solvent include a fluororesin and a silicone resin having an ether bond. In particular, when a fluororesin having an ether bond is used, it can be dissolved in a solvent and used at a low concentration, so that the content in the positive electrode can be reduced as much as possible and the porosity can be increased, and it is very stable after crosslinking. Thus, the effect of charging / discharging cycle characteristics is also good.

After forming the positive electrode, it may be dehydrated by microwave heating and then dehydrated by a vacuum dryer.
The mixing ratio of the binder to the positive electrode active material is preferably 0.1 or less. (Lithium Battery) The basic structure of a lithium secondary battery using the positive electrode active material manufactured by the above method is at least a negative electrode, a separator, a negative electrode active material, an electrolyte, and a current collector. FIG. 1 shows a basic configuration diagram of the lithium secondary battery of the present invention. In FIG. 1, 100 is a negative electrode current collector, 101 is a negative electrode active material (lithium), 102 is a positive electrode current collector, 103
Is a positive electrode active material, 104 is an electrolyte, 105 is a negative electrode terminal, 1
Reference numeral 06 is a positive electrode terminal, 107 is a separator, and 108 is a battery case. In the discharge reaction, lithium ions in the electrolyte 104 enter between the layers of the positive electrode active material 103, and at the same time, are dissolved as lithium ions from the lithium negative electrode 101 into the electrolyte 104. On the other hand, in the charging reaction, the electrolyte 10
The lithium ions in No. 4 are deposited on the negative electrode 101 as lithium metal, and at the same time, the lithium between the layers of the positive electrode active material 103 is dissolved in the electrolyte 104.

Actual battery shapes include flat type, cylindrical type, rectangular type and sheet type batteries. In the spiral cylinder type, the electrode area can be increased by wrapping the separator between the negative electrode and the positive electrode,
A large current can flow during charging and discharging. Further, in the rectangular parallelepiped type, it is possible to effectively use the storage space of the device that stores the secondary battery. As for the structure, there are structures such as a single layer type and a multilayer type.

FIG. 2 and FIG. 3 are examples of schematic cross-sectional views of a single-layer flat type battery and a spiral structure cylindrical battery, respectively. 2 and 3, 200 and 300 are negative electrode current collectors, 201 and 301 are negative electrode active materials, 203 and 303 are positive electrode active materials, 205 and 305 are negative electrode terminals (negative electrode caps), 206 and 306 are positive electrode cans, 207 and 307 are electrolyte and separator, 210 and 310 are insulating packing,
311 is an insulating plate. As an example of assembling the battery of FIGS. 2 and 3, after the separators 207 and 307 are sandwiched between the negative electrode active materials 201 and 301 and the molded positive electrode active materials 203 and 303, and the electrolyte is injected into the positive electrode cans 206 and 306, Negative electrode cap 205, 305 and insulating packing 2
A battery is manufactured by incorporating 10, 310 and caulking.

The preparation of the battery material and the assembly of the battery are preferably carried out in dry air from which water has been sufficiently removed or in dry inert gas. Negative Electrode Active Material The negative electrode active material 101 (201, 301) is composed of at least one kind of material selected from lithium metal, lithium alloy, and carbon. As a lithium alloy, a lithium alloy containing one or more elements selected from magnesium, aluminum, potassium, sodium, calcium, zinc, and lead is required to obtain a high energy density battery. Is preferably used.

When lithium metal is used as the negative electrode active material, it is particularly preferable to coat the surface of the lithium metal with an insulating film, a semiconductor film, or a conductive film having a material and a film thickness capable of transmitting lithium ions. The thickness of the film formed on the lithium surface is preferably in the range of 10 Å to 100 μm, more preferably in the range of 50 Å to 10 μm. The optimum film thickness of the coating varies depending on the density or porosity of the coating and the type of electrolyte used. The film thickness of the film can be adjusted by changing the concentration of the film forming main material in the coating liquid.

Electrolyte Electrolyte 104 (207, 307) is a solid, a solution in which a supporting electrolyte is dissolved in a non-aqueous solvent, or a solid-liquid coexisting state in which a polymer that absorbs the solvent of the electrolytic solution and swells is immobilized. The one in the state selected from is used. Generally, an electrolyte solution of a non-aqueous solvent having high ionic conductivity is used.

The higher the conductivity of the electrolyte, the better
Conductivity of 1 x 10 at 25 ° C^-3S / cm or less
Desirable to be above 5 × 10^-3S / cm or more
And are more preferable. As the electrolyte solvent, acetonite
Lil: CH₃CN, benzonitrile: C₆H_FiveCN,
Ropylene Carbonate: PC, Ethylene Carbonate:
EC, dimethylformamide: DMF, tetrahydrof
Orchid: THF, nitrobenzene: C ₆H_FiveNO₂, Jiku
Loroethane, diethoxyethane, chlorobenzene, γ-
Butyrolactone, dioxolane, sulfolane, nitrome
Tan, dimethyl sulfide, dimethyl sulphoxide,
Dimethoxyethane, methyl formate, 3-methyl-2-oxy
Dazolidinone, 2-methyltetrahydrofuran, dioxide
Sulfur, Phoslyl chloride, Thionyl chloride, Sulfur chloride
Etc., and mixtures of these can be used.

The solvent may be dehydrated with activated alumina, molecular sieves, phosphorus pentoxide, calcium chloride or the like, or depending on the solvent, it may be distilled in an inert gas in the presence of an alkali metal to remove impurities and dehydrate. Is good. Supporting electrolyte, H ₂ SO _4, HCl, acids such as HNO _3, lithium ion (Li ⁺⁾ and Lewis acid ion (BF ₄ ^-,
PF ^{6 _{-, AsF 6 -, ClO 4}} - salt consisting of), and use of these mixed salts. In addition to the above supporting electrolyte, a salt of a cation such as sodium ion, potassium ion, tetraalkylammonium ion and Lewis acid ion can be used. It is desirable that the salt be heated under reduced pressure to be sufficiently dehydrated and deoxidized. Gelation is preferable in order to prevent leakage of the electrolytic solution. As the gelling agent, it is desirable to use a polymer that absorbs the solvent of the electrolytic solution and swells, and a polymer such as polyethylene oxide, polyvinyl alcohol or polyacrylamide is used.

As the current collectors 101, 102, 200 and 300, fibrous, porous or mesh carbon, stainless steel, titanium, nickel, copper, platinum, gold and the like are used. Separator The separators 107, 207 and 307 have a role of preventing a short circuit between the negative electrode and the positive electrode. It may also have a role of holding the electrolytic solution. Since the separator has pores through which lithium ions can move, and is required to be insoluble and stable in an electrolytic solution, a non-woven fabric such as glass, polypropylene, polyethylene, fluororesin or polyamide, or a material having a micropore structure is used.

As materials for the positive electrode cans 206 and 306 and the negative electrode caps 205 and 305 of the actual battery, stainless steel, particularly titanium clad stainless steel, copper clad stainless steel, nickel plated copper plate and the like are used. Insulating packing As materials for the insulating packings 201 and 310, fluororesin, polyamide resin, polysulfone resin and various rubbers can be used. As a sealing method, besides caulking using a gasket such as an insulating packing as shown in FIGS. 2 and 3, a glass sealing tube, an adhesive, welding, soldering, or the like is used.

Various organic resin materials and ceramics are used as the material of the insulating plate of FIG. Outer can (battery case ) In FIGS. 2 and 3, the positive electrode cans 206 and 306 also serve as a battery case. As the material of the battery case, metal such as zinc, plastic such as polypropylene, other than stainless steel, Alternatively, a composite material of metal or glass fiber and plastic can be used.

Although not shown in FIGS. 2 and 3, a safety valve is generally provided as a safety measure when the internal pressure of the battery increases.

[0063]

EXAMPLES The present invention will be described in detail below based on examples. The present invention is not limited to these examples. (Preparation of Positive Electrode Active Material) Examples of methods for preparing the positive electrode active material of the present invention are shown in Preparation Methods 1 to 10 and comparative preparation methods 1 to 9 are shown as examples of conventional preparation methods.

(Preparation Method 1) Lithium-manganese oxide was prepared by the following method. After dissolving manganese nitrate in water, nickel ultrafine powder ENP-005 made by Sumitomo Metal Co., Ltd. is suspended in an aqueous solution of manganese nitrate, and then an aqueous solution of lithium hydroxide is added to the solution while applying ultrasonic vibration of 20 kHz at 20.
A precipitate was formed by dropping until H8 or more. Ethyl alcohol was added, the supernatant of the solution containing the precipitate was decanted off, and ethyl alcohol washing and decantation were repeated. After dipping in a 0.1% methyl alcohol solution of silane coupling agent Sila Ace S210 (vinyl methoxysilane) manufactured by Chisso, the solvent was removed by a centrifugal separator. The obtained precipitate was dried at 120 ° C and then dried at 200 ° C in a vacuum drier to prepare manganese oxide fine powder.

The size of the crystal grain was determined from the half width of the peak of the X-ray analysis curve derived from manganese oxide and the diffraction angle using the following Scherrer's equation. Crystal grain size is 6
It was 0 angstrom. A ring pattern close to a halo pattern was obtained from the RHEED pattern.

As the radial distribution function by X-ray, a continuous gentle peak curve was obtained. Further, from the scattering angle and the scattering intensity by the X-ray small angle scattering method, nonuniform density fluctuation is observed. From the scattering angle and the scattering intensity obtained by the X-ray small angle scattering method, non-uniform density fluctuations were observed. The specific surface area was measured by the BET method, and the specific surface area was 123 m ² / g.

(Preparation Method 2) Panadium oxide was prepared by the following method. Panadium pentoxide was gradually added to and dissolved in an aqueous solution of lithium hydroxide. While applying ultrasonic vibration, the aqueous solution was sprayed into liquid nitrogen and frozen, and then -20
The temperature was raised to ° C, the pressure was reduced, and the product was dehydrated and dried by freeze drying. The obtained fine powder was dried at 150 ° C. and further dried at 250 ° C. in a vacuum drier to prepare a vanadium oxide fine powder. 0.1 of tetra-iso-propoxy titanium
After immersing in a isopropyl alcohol solution, the solvent was removed by a centrifuge. The obtained precipitate was dried at 120 ° C. and then vacuum dried at 200 ° C. to prepare manganese oxide fine powder.

The size of the crystal grains was tried to be determined from the full width at half maximum of the peak of the X-ray diffraction curve and the diffraction angle using the Scherrer's formula, but the diffraction curve was broad, and therefore the calculation was possible. There wasn't. A halo pattern was obtained from RHEED. For the radial distribution function by X-ray, a continuous gentle peak curve was obtained.

Further, from the scattering angle and the scattering intensity by the X-ray small angle scattering method, nonuniform density fluctuations were observed. BET
The specific surface area measured by the method was 105 m ² / g. (Preparation Method 3) Lithium-nickel oxide was prepared by the following method.

Nickel acetate was added to acetic acid-ethyl alcohol-
After dissolving in a water mixed solvent, while applying ultrasonic vibration of 20 kHz, an ethyl alcohol solution of alkoxide ethoxylithium is added dropwise and mixed, and heated to 80 ° C. to cause a hydrolysis reaction to proceed to form a sol. did. The supernatant of the solution containing the sol-like precipitate was decanted off, washed with ethyl alcohol, the decantation was repeated, and the solvent was removed by a centrifuge. The obtained precipitate was dried at 150 ° C., immersed in an electroless nickel plating solution Ni-701 manufactured by Kojundo Chemical Laboratory, and heated to 70 ° C. for nickel plating coating, followed by washing with water and decantation. Repeatedly, then washed with ethyl alcohol, repeated decantation, and desolvated with a centrifuge. Vacuum drying was carried out at 230 ° C. to prepare nickel oxide fine powder.

From the half width of the peak of the X-ray diffraction curve and the diffraction angle, an attempt was made to determine the size of the crystal grain by using the following Scherrer's formula, but the diffraction curve derived from the oxide was broad. I couldn't calculate because it was there. From RHEED,
A ring pattern that was probably derived from nickel plating was obtained. The one before nickel plating had a halo pattern.

As for the radial distribution function by X-ray before nickel plating, a continuous and gentle peak curve was obtained.
Further, from the scattering angle and the scattering intensity by the X-ray small angle scattering method, nonuniform density fluctuation is observed. From the scattering angle and the scattering intensity obtained by the X-ray small angle scattering method, non-uniform density fluctuations were observed. The specific surface area measured by the BET method is 210 m ² /
It was g.

(Preparation Method 4) Lithium-nickel-cobalt oxide was prepared by the following method. After nickel nitrate and cobalt nitrate were dissolved in water, an aqueous solution of lithium hydroxide was added dropwise to the aqueous solution of nickel nitrate and cobalt nitrate while ultrasonically oscillating at 20 kHz until a pH of 8 or higher was reached to form a precipitate. . Add ethyl alcohol,
The supernatant of the solution containing the precipitate was decanted off, and the washing with ethyl alcohol and decantation were repeated, and the solvent was removed by a centrifuge. The precipitate obtained is 120
After drying at 0 ° C., vacuum drying was performed at 200 ° C. to prepare nickel cobalt oxide fine powder.

The size of the crystal grain was determined from the half width of the peak of the X-ray diffraction curve and the diffraction angle by using the following Scherrer's equation. The crystal grain size was 140 Å. A ring pattern similar to a halo pattern was obtained from RHEED. The radial distribution function by X-ray is
A continuous, gentle peak curve was obtained.

Further, from the scattering angle and the scattering angle by the X-ray small angle scattering method, nonuniform density fluctuation is observed. From the scattering angle and the scattering intensity obtained by the X-ray small angle scattering method, non-uniform density fluctuations were observed. The specific surface area measured by the BET method is
It was 160 m ² / g. (Preparation Method 5) Panadium-molybdenum oxide was prepared by the following method.

Vanadyl sulfate and molybdenum sulfate were added to water and suspended, and acetic acid was gradually added and dissolved. Next, while applying ultrasonic vibration of 20 kHz to the solution of vanadium oxide and acetic acid, an aqueous solution of lithium hydroxide was added dropwise until the pH became 8 or more to form a precipitate. Ethyl alcohol was added, and the supernatant of the solution containing the precipitate was decanted off, washed with ethyl alcohol, the decantation was repeated, and the solvent was removed by a centrifuge. The precipitate obtained is dried at 120 ° C. and then vacuum dried at 200 ° C.
A vanadium oxide fine powder was prepared.

The size of the crystal grain was determined from the half width of the peak of the X-ray diffraction curve and the diffraction angle using the following Scherrer's equation. The crystal grain size was 80 Å. From RHEED, a ring pattern close to a halo pattern was obtained. For the radial distribution function by X-ray, a continuous gentle peak curve was obtained.

Further, from the scattering angle and the scattering intensity by the X-ray small angle scattering method, nonuniform density fluctuations are observed. From the scattering angle and the scattering intensity obtained by the X-ray small angle scattering method, non-uniform density fluctuations were observed. The specific surface area measured by the BET method is
It was 100 m ² / g. (Preparation Method 6) Vanadium-molybdenum oxide was prepared by the following method.

Vanadium oxide and molybdenum oxide were mixed at 7: 3.
After mixing at a ratio of 1, the mixture is heated to 800 ° C. and melt-mixed to form a molten metal, and the molten metal is dispersed by a jet of a gas in which 20% oxygen and 2% hydrogen are mixed in argon gas, and the cooled rotating metal disk is Vanadium oxide-molybdenum oxide fine powder was prepared by spraying at high speed. The size of the crystal grain was determined from the half width of the peak of the X-ray diffraction curve and the diffraction angle using the following Scherrer's equation. Crystal grain size is 1
It was 10 angstroms.

From RHEED, a weakly strong ring pattern was obtained. For the radial distribution function by X-ray, a continuous gentle peak curve was obtained. In addition, nonuniform density fluctuations are observed from the scattering angle and scattering intensity measured by the X-ray promoted scattering method. From the scattering angle and the scattering intensity obtained by the X-ray small angle scattering method, non-uniform density fluctuations were observed.

The specific surface area measured by the BET method is 60 m ^2.
/ G. (Preparation Method 7) Titanium sulfide was prepared by the following method. Hydrogen gas 50 was placed in the reaction chamber of the plasma CVD apparatus that had been degassed in vacuum.
Flow at 0 sccm, maintain pressure at 10 Torr, 1
A discharge was generated at a high frequency of 3.56 MHz. Next, 200 sccm of hexane solution of tetrabutoxytitanium was bubbled with helium gas as clear gas, and 200 sccm from the nozzle was blown into the reaction chamber of the plasma CVD apparatus. At the same time, 250 sccm of hydrogen sulfide was introduced to cause a gas phase reaction and a collector. Titanium sulfide derivative was collected in.

The size of the crystal grain was determined from the half width of the peak of the X-ray diffraction curve and the diffraction angle using the following Scherrer's equation. The crystal grain size was 200 Å. From RHEED, a weak intensity ring pattern was obtained. For the radial distribution function by X-ray, a continuous gentle peak curve was obtained.

Further, from the scattering angle and the scattering intensity by the X-ray small angle scattering method, nonuniform density fluctuation is observed. From the scattering angle and the scattering intensity obtained by the X-ray small angle scattering method, non-uniform density fluctuations were observed. The specific surface area measured by the BET method is
It was 175 m ² / g. (Preparation Method 8) Lithium-iron-cobalt oxide was prepared by the following method.

In a 5 mol / l aqueous solution of lithium hydroxide,
Cobalt chloride 0.5 mol / l, ferric chloride 1 mol /
1: 1 mixed solution was stirred while bubbling argon gas and gradually added. 100 ℃ reaction vessel
Aged in. After aging, pour into a large amount of water-cooled water,
The washing solution was washed with water-cooled water by decantation until the pH became 8, dried under vacuum at 200 ° C., and pulverized with a ball mill under an argon atmosphere.

The size of the crystal grain was determined from the half width of the peak of the X-ray diffraction curve and the diffraction angle using the Scherrer's formula below. The crystal grain size was 150 Å. From RHEED, a weak intensity ring pattern was obtained. For the radial distribution function by X-ray, a continuous gentle peak curve was obtained.

Further, from the scattering angle and the scattering intensity obtained by the X-ray small angle scattering method, nonuniform density fluctuations are observed. From the scattering angle and the scattering intensity obtained by the X-ray small angle scattering method, non-uniform density fluctuations were observed. The specific surface area measured by the BET method is
It was 210 m ² / g. (Preparation Method 9) Magnesium-containing manganese-vanadium oxide was prepared by the following method.

Vanadium pentoxide 300 to 2 liters of hydrochloric acid
Manganese nitrate, magnesium chloride, and urea were added to an aqueous solution in which g was dissolved, heated at 95 to 98 ° C. for 10 minutes to generate ammonia, and an aqueous lithium hydroxide solution was added dropwise to adjust the pH to 7 to form a precipitate. After repeating decantation and washing with water, the product was washed with ethyl alcohol and dried with a spray dryer. Furthermore, it vacuum-dried at 200 degreeC.

The size of the crystal grain was determined from the half width of the peak of the X-ray diffraction curve and the diffraction angle using the following Scherrer's equation. The crystal grain size was 90 Å. A ring pattern similar to a halo pattern was obtained from RHEED. For the radial distribution function by X-ray, a continuous gentle peak curve was obtained.

Further, from the scattering angle and the scattering intensity obtained by the X-ray small angle scattering method, nonuniform density fluctuations are observed. From the scattering angle and the scattering intensity obtained by the X-ray small angle scattering method, non-uniform density fluctuations were observed. The specific surface area measured by the BET method is
It was 80 m ² / g. (Preparation method 10) Lithium-copper-cobalt oxide was prepared by the following method. After adding oxalic acid to the aqueous solution of copper sulfate and cobalt nitrate dissolved in water, ultrasonic vibration was added, and the aqueous lithium hydroxide solution was added dropwise until the pH reached 7, forming a precipitate, washing with water and decantation. After repeating, an aqueous lithium hydroxide solution was added, ultrasonic vibration was added, ethyl alcohol was added, and then decantation and washing with ethyl alcohol were repeated, followed by drying with a spray dryer. Furthermore, it vacuum-dried at 200 degreeC.

The size of the crystal grain was determined from the half width of the peak of the X-ray diffraction curve and the diffraction angle using the following Scherrer's equation. The crystal grain size was 160 Å. From RHEED, a weak intensity ring pattern was obtained. For the radial distribution function by X-ray, a continuous gentle peak curve was obtained.

Further, from the scattering angle and the scattering intensity by the X-ray small angle scattering method, nonuniform density fluctuations are observed. From the scattering angle and the scattering intensity obtained by the X-ray small angle scattering method, non-uniform density fluctuations were observed. The specific surface area measured by the BET method is
It was 50 m ² / g. [Other Analysis] It was confirmed by SIMS analysis that all the positive electrode active materials prepared by the methods of Preparation Examples 1 to 10 contained hydrogen and lithium. The presence of hydroxyl groups was also confirmed from the dehydration peaks of TG (thermogravimetric measurement), DTA (differential thermal analysis), and DSC (differential scanning calorimetry) and FTIR (Fourier transform infrared) absorption spectrum.

(Comparative Preparation Method 1) Lithium-manganese oxide was prepared by the following method. Mitsui Kinzoku's electrolytic manganese dioxide powder and lithium carbonate were mixed at a ratio of 1: 0.4 and then heated at 800 ° C. to prepare a lithium manganese oxide. From the half width of the peak of the X-ray diffraction curve and the diffraction angle, the size of the obtained crystal grains was 600 angstroms or more, using the following Scherrer's equation.

From RHEED, a ring pattern with which a spot pattern could be confirmed was obtained. For the radial distribution function by X-ray, a curve of discontinuous peaks was obtained. The specific surface area was measured by the BET method and the specific surface area was 40 m ² / g. (Comparative Preparation Method 2) Vanadium pentoxide was prepared by the following method.

The Wako Pure Chemicals Reagent was vacuum dried at 400 ° C. From the full width at half maximum of the X-ray diffraction curve and the diffraction angle, Sch
Using the error formula, the size of the obtained crystal grains is 8
It was 00 angstrom. From RHEED, a ring pattern with which a spot pattern could be confirmed was obtained.

As the radial distribution function by X-ray, a curve of discontinuous peaks was obtained. The specific surface area measured by the BET method was 4 m ² / g. (Comparative Preparation Method 3) Lithium-nickel oxide was prepared by the following method. Lithium carbonate and nickel nitrate were mixed at an equimolar ratio of 1: 1 and then heated at 800 ° C. to obtain lithium-
A nickel oxide was prepared.

The size of the crystal grains obtained by using the Scherrer's formula from the half width of the peak of the X-ray diffraction curve and the diffraction angle was 2000 angstroms or more. RHE
From the ED, a ring pattern in which a spot pattern could be confirmed was obtained. For the radial distribution function by X-ray, a curve of discontinuous peaks was obtained.

The specific surface area measured by the BET method is 50 m ²
/ G. (Comparative Preparation Method 4) Lithium-nickel-cobalt oxide was prepared by the following method. Lithium carbonate, nickel carbonate and cobalt carbonate were mixed at a molar ratio of 10: 3: 7 and then thermally decomposed at 900 ° C. for 20 hours to prepare a nickel-cobalt oxide.

The size of the crystal grain obtained by using the Scherrer's formula from the half width of the peak of the X-ray diffraction curve and the diffraction angle was 1100 angstroms or more. RHE
From the ED, a ring pattern in which a spot pattern could be confirmed was obtained. For the radial distribution function by X-ray, a curve of discontinuous peaks was obtained.

The specific surface area measured by the BET method is 40 m ²
/ G. (Comparative Preparation Method 5) Vanadium-molybdenum oxide was prepared by the following method. Vanadium oxide and molybdenum oxide are mixed at a ratio of 7: 3, heated to 800 ° C. in a platinum crucible and melt-mixed, and then cooled to form lumpy vanadium oxide and molybdenum oxide, which are crushed by a roller mill and vanadium oxide A fine powder of molybdenum oxide was prepared.

The size of the crystal grain obtained by using the Scherrer's formula from the half width of the peak of the X-ray diffraction curve and the diffraction angle was 700 angstroms or more. RHEE
From D, a ring pattern in which a spot pattern can be confirmed was obtained. For the radial distribution function by X-ray, a curve of discontinuous peaks was obtained.

The specific surface area measured by the BET method is 10 m ^2.
/ G. (Comparative Preparation Method 6) Titanium sulfide was prepared by the following method.
High purity chemical laboratory reagent titanium disulfide powder was vacuum dried at 400 ° C. The size of the crystal grain obtained by using the Scherrer's formula from the half width of the peak of the X-ray diffraction curve and the diffraction angle was 900 angstroms or more.

From RHEED, a ring pattern with which a spot pattern could be confirmed was obtained. For the radial distribution function by X-ray, a curve of discontinuous peaks was obtained. BET
The specific surface area measured by the method was 50 m ² / g. (Comparative Preparation Method 7) Lithium-iron-cobalt oxide was prepared by the following method.

Lithium carbonate, ferrous acetate and cobalt carbonate were mixed in an equimolar ratio and then pyrolyzed in air at 600 ° C.,
An iron cobalt oxide was prepared. Then, it was crushed with a ball mill to obtain a fine powder. The size of the crystal grain obtained by using Scherrer's formula from the half width of the peak of the X-ray diffraction curve and the diffraction angle was 1000 angstroms or more.

From RHEED, a ring pattern with which a spot pattern could be confirmed was obtained. For the radial distribution function by X-ray, a curve of discontinuous peaks was obtained. BET
The specific surface area measured by the method was 40 m ² / g. (Comparative Preparation Method 8) Magnesium-added manganese-vanadium oxide was prepared by the following method.

Manganese dioxide, vanadium pentoxide and magnesium hydroxide were mixed at a molar ratio of 10: 10: 1, and then thermally decomposed in air at 700 ° C. to prepare a magnesium-added manganese-vanadium oxide. Then, it was crushed with a ball mill to obtain a fine powder. The size of the crystal grain obtained by using the Scherrer's equation from the half width of the peak of the X-ray diffraction curve and the diffraction angle was 1300 angstroms or more.

From RHEED, a ring pattern with which a spot pattern could be confirmed was obtained. For the radial distribution function by X-ray, a curve of discontinuous peaks was obtained. BET
The specific surface area measured by the method was 27 m ² / g. (Comparative Preparation Method 9) Lithium-copper-cobalt oxide was prepared by the following method.

Lithium carbonate, cobalt carbonate and copper carbonate were mixed in an equimolar ratio, and then thermally decomposed in air at 600 ° C.,
Prepared. Then, it was crushed with a ball mill to obtain a fine powder. From the full width at half maximum of the X-ray diffraction curve and the diffraction angle, Sch
The size of the crystal grain obtained by using the error formula is 1
It was 100 angstroms or more. From RHEED, a ring pattern with which a spot pattern could be confirmed was obtained.

As the radial distribution function by X-ray, a curve of discontinuous peaks was obtained. The specific surface area measured by the BET method was 10 m ² / g. [Analyzer] Analysis of the positive electrode active materials prepared by the methods of Preparations 1 to 10 and Comparative Examples 1 to 9 was performed using the following apparatus. The X-ray diffraction measurement was performed using MXP3VA manufactured by Mac Science.

RHEED measurement was carried out by JEM-1 of JEOL Ltd.
Performed using 00SX. The specific surface area was measured by the BET method using GEMIN12300 manufactured by Micromeritics. From the comparative analysis results of the compounds of the transition metal and the Group 6A element by the method of Preparation Example and Comparative Preparation Example, the compound of Preparation Example has a smaller crystal grain size than that of Comparative Preparation Example and has an amorphous or microcrystalline structure. It turned out to have.

[Preparation of Lithium Secondary Battery] A lithium secondary battery was prepared using the positive electrode active material prepared by the above preparation method. (Example 1) Using the positive electrode active material prepared by the above-mentioned preparation method 1, a battery having a schematic sectional structure shown in FIG.

First, in a dry argon gas atmosphere, a titanium mesh current collector 200 was pressure-bonded to a lithium metal foil as a negative electrode active material 201 from the back side, and a dilute solution of Lumiflon fluororesin paint manufactured by Asahi Glass Co., Ltd. was used to obtain a lithium surface. Was coated with a fluororesin thin film to prepare a negative electrode. The lithium-manganese oxide positive electrode active material prepared in Preparation Method 1 was mixed with acetylene black powder and a xylene solution of fluororesin paint Lumiflon manufactured by Asahi Glass Co., Ltd., applied on a titanium mesh, and cured at 80 ° C. Heat the positive electrode 2
03 was formed.

As the electrolytic solution 207, 1M (mol / l) of lithium tetrafluoroborate salt was used in a liquid medium of an equal amount of propylene carbonate (PC) and dimethoxyethane (DME).
What was melt | dissolved was used. As the separator 207, a polypropylene nonwoven fabric sandwiched with polypropylene micropore separators was used.

For assembly, the separator 207 is sandwiched between the negative electrode 201 and the positive electrode 203, inserted into the positive electrode can 206 made of a titanium clad stainless material, the electrolytic solution is injected, and then the negative electrode cap 205 made of a titanium clad stainless material is formed. A lithium secondary battery was produced by sealing with an insulating packing 210 of fluororubber. (Example 2) Using vanadium oxide prepared by the above-mentioned preparation method 2 as a positive electrode active material, a battery having a schematic sectional structure shown in FIG. 2 was produced.

First, in a dry argon gas atmosphere, a nickel mesh current collector was pressure-bonded to the lithium metal foil from the back surface side to prepare a negative electrode. To the vanadium oxide positive electrode active material prepared in Preparation Method 2, acetylene black powder and NOF powder fluororesin coating material Super Konak F were mixed, a small amount of xylene was added, and the mixture was applied to a nickel mesh.
It was cured at 0 ° C. to form a positive electrode.

Thereafter, the battery shown in FIG. 2 was assembled in the same manner as in Example 1. (Example 3) Using the positive electrode active material prepared by the above-mentioned preparation method 3, a battery having a schematic sectional structure shown in Fig. 2 having a simple structure and assembly was assembled. First, in a dry argon gas atmosphere, a nickel mesh current collector was pressure-bonded to the lithium metal foil from the back surface side to produce a negative electrode.

Acetylene black powder and tetrafluoroethylene polymer powder were mixed with the lithium-nickel oxide positive electrode active material prepared in Preparation Method 3, and the resulting mixture was thermocompression-bonded to a nickel mesh to form the positive electrode 203. Thereafter, the battery shown in FIG. 2 was assembled in the same manner as in Example 1. (Example 4) Using the lithium-nickel-cobalt oxide prepared by the above-mentioned preparation method 4 as the positive electrode active material, the battery shown in FIG. 2 was produced in the same procedure as in Example 3.

Example 5 Using the vanadium-molybdenum oxide prepared by the above-mentioned preparation method 5 as the positive electrode active material,
The battery shown in FIG. 2 was manufactured in the same procedure as in Example 3. (Example 6) Vanadium-prepared by the above-mentioned preparation method 6
Using molybdenum oxide as the positive electrode active material, the battery shown in FIG. 2 was produced in the same procedure as in Example 3.

Example 7 Using the titanium sulfide prepared by the above-mentioned preparation method 7 as the positive electrode active material, the battery shown in FIG. (Example 8) Using the lithium-iron-cobalt oxide prepared by the above-mentioned preparation method 8 as the positive electrode active material, the battery shown in FIG. 2 was produced in the same procedure as in Example 3.

Example 9 Using the magnesium-added manganese-vanadium oxide prepared by the above-mentioned preparation method 9 as the positive electrode active material, the battery shown in FIG. 2 was produced in the same procedure as in Example 3. (Example 10) Using the lithium-copper-cobalt oxide prepared by the above-mentioned preparation method 10 as the positive electrode active material, the battery shown in FIG. 2 was produced in the same procedure as in Example 3.

Comparative Example 1 Using the positive electrode active material prepared by the above-mentioned comparative preparation method 1, a battery having a schematic sectional structure shown in FIG. First, in a dry argon gas atmosphere, a titanium metal current collector 200 was pressure-bonded to the lithium metal foil from the back surface side to produce a negative electrode.

A positive electrode 203 was formed by mixing acetylene black powder and tetrafluoroethylene polymer powder with the lithium-manganese oxide positive electrode active material prepared in Comparative Preparation Method 1, followed by thermocompression molding on a titanium mesh. Hereinafter, a lithium secondary battery was produced in the same procedure as in Example 1. (Comparative Example 2) Using the vanadium oxide prepared by the above-mentioned comparative preparation method 2 as the positive electrode active material, the battery shown in FIG.

Comparative Example 3 Using the lithium-nickel oxide prepared in Comparative Preparation Method 3 described above as the positive electrode active material,
The battery shown in FIG. 2 was manufactured in the same procedure as in Example 3. (Comparative Example 4) Using the lithium-nickel-cobalt oxide prepared by the above-mentioned comparative preparation method 4 as the positive electrode active material, the battery shown in FIG. 2 was produced in the same procedure as in Example 3.

Comparative Example 5 Using the vanadium-molybdenum oxide prepared in Comparative Preparation Method 5 described above as the positive electrode active material, the battery shown in FIG. 2 was prepared in the same procedure as in Example 3. (Comparative Example 6) Using the titanium sulfide prepared in Comparative Preparation Method 6 described above as the positive electrode active material, the battery shown in FIG.
It was made in the same procedure as.

Comparative Example 7 Using the lithium-iron-cobalt oxide prepared by the above-mentioned comparative preparation method 7 as the positive electrode active material, the battery shown in FIG. 2 was prepared in the same procedure as in Example 3. . (Comparative Example 8) Using the magnesium-added manganese-vanadium oxide prepared by the above-mentioned comparative preparation method 8 as the positive electrode active material, the battery shown in FIG. 2 was produced in the same procedure as in Example 3.

Comparative Example 9 Using the lithium-copper-cobalt oxide prepared by the above-mentioned comparative preparation method 9 as the positive electrode active material, the battery shown in FIG. 2 was prepared in the same procedure as in Example 3. . [Performance Evaluation of Lithium Secondary Battery] The lithium secondary batteries produced in Examples and Comparative Examples were subjected to a charge / discharge cycle test under the following conditions, and the performance was evaluated in comparison with the batteries of Comparative Examples.

The condition of the cycle test is 0.2 C (capacity /
Charge / discharge of 0.2 times the time), break time of 30 minutes,
The cutoff voltage was 1.0 V. Hokuto Denko HJ-101M6 was used for the battery charging / discharging device. In addition,
The charge / discharge test was started from discharge, the battery capacity was the third discharge amount, and the cycle life was the number of cycles below 60% of the battery capacity.

The results of evaluation of the lithium battery prepared by using the positive electrode active material prepared by the method of the present invention and the positive electrode active material prepared by the comparative example preparation method, that is, the battery capacity and the cycle life performance of Examples and Comparative Examples are shown. The performance of the battery of the comparative example is shown in Table 1 as 1.0. As described above, from Table 1, comparison of Examples 1 to 10 and Comparative Examples 1 to 9 revealed that the use of the present invention increases the capacity of the battery and extends the cycle life.

[0128]

[Table 1]

[0129]

By using the compound of a transition metal having a small crystal grain size and a Group 6A element prepared by the preparation method of the present invention as the positive electrode active material of the lithium secondary battery of the present invention,
It becomes possible to manufacture a lithium secondary battery with high capacity and high energy density. At the same time, the charge / discharge cycle life can be extended.

[Brief description of drawings]

FIG. 1 is a basic configuration diagram of a lithium secondary battery of the present invention.

FIG. 2 is an example of a schematic cross-sectional view of a flat battery to which the present invention is applied.

FIG. 3 is an example of a schematic sectional view of a cylindrical battery to which the present invention is applied.

[Explanation of symbols]

 100, 200, 300 negative electrode current collector, 101, 201, 301 negative electrode active material, 102 positive electrode current collector, 103, 203, 303 positive electrode active material, 104 electrolytic solution, 105, 205, 305 negative electrode terminal, 106, 206, 306 positive electrode terminal, 107 separator, 207, 307 electrolyte and separator, 108 battery case, 210, 310 insulating packing, 311 insulating plate.

Claims (45)

[Claims] 1. A lithium secondary battery comprising at least a negative electrode active material, a separator, a positive electrode active material capable of allowing lithium ions to move in and out by charging and discharging, an electrolyte that is a conductor of ions, a current collecting electrode, and a battery case. In, the main constituent material of the positive electrode active material has a crystal grain size of 500
One or more transition metals below Angstrom and 6
A lithium secondary battery, which is a compound with a Group A element. 2. The main constituent material of the positive electrode active material is selected from amorphous, microcrystalline, a mixture of amorphous and microcrystalline, and a mixture of amorphous, microcrystalline and polycrystalline. The lithium secondary battery according to claim 1, wherein the lithium secondary battery is an assembly. 3. The lithium secondary battery according to claim 1, wherein the positive electrode active material contains a hydrogen element. 4. The lithium secondary battery according to claim 3, wherein the positive electrode active material has a hydroxyl group. 5. The positive electrode active material is lithium, carbon, magnesium, sodium, potassium, nitrogen, aluminum, calcium, barium, lead, indium, boron,
The lithium secondary battery according to any one of claims 1 to 4, comprising one or more kinds of elements selected from silicon, tin, phosphorus, arsenic, antimony, bismuth, fluorine and chlorine. . 6. The lithium secondary battery according to claim 1, wherein the 6A group element of the main constituent elements of the positive electrode active material is oxygen. 7. The lithium secondary battery according to claim 1, wherein the 6A group element of the main constituent elements of the positive electrode active material is sulfur. 8. The lithium secondary battery according to claim 1, wherein the positive electrode active material is coated with an electric conductor. 9. A conductive powder serving as a core is mixed with the transition metal and 6A.
The lithium secondary battery according to claim 1, wherein a positive electrode active material coated with a compound with a group element is used. 10. A positive electrode formed by mixing a positive electrode active material with one or more kinds of materials selected from a carbon material, a resin material, and a metal material. The lithium secondary battery according to Item 1. 11. The lithium secondary battery according to claim 1, wherein the positive electrode active material is subjected to lipophilic treatment. 12. The lithium secondary battery according to claim 11, wherein the lipophilic treatment of the positive electrode active material is a treatment with an organometallic compound. 13. The lithium secondary battery according to claim 10, wherein one or more kinds of resins selected from fluororesins, polyethylene, polypropylene, and silicone resins are used as the resin material. 14. The lithium secondary battery according to claim 13, wherein the resin material is a liquid or a solution, or a resin having a low melting point. 15. The lithium secondary battery according to claim 14, wherein the resin is a fluororesin having an ether bond. 16. The lithium secondary battery according to claim 1, wherein the negative electrode active material is composed of at least one kind of material selected from lithium metal, lithium alloy, and carbon. 17. The surface of a negative electrode active material of a lithium battery,
The lithium secondary battery according to claim 1, which is coated with a film that is permeable to lithium ions. 18. The lithium secondary battery according to claim 1, wherein the electrolyte is composed of at least an alkali metal compound. 19. The lithium secondary battery according to claim 1, wherein the electrolyte is in a state selected from a solid state, a solution state dissolved in a non-aqueous solvent, and a solid-liquid coexisting state. Next battery. 20. A method for producing a positive electrode active material for a lithium secondary battery, which utilizes a reaction selected from a solution reaction, a gas phase reaction, melting and quenching, and a transition having a crystal grain size of 500 angstroms or less. A method for producing a positive electrode active material, which comprises at least a step of forming a compound of a metal and a 6A group element. 21. A compound of a transition metal and a Group 6A element,
21. The positive electrode active material according to claim 20, which is an aggregate selected from amorphous, microcrystalline, a mixture of amorphous and microcrystalline, and a mixture of amorphous, microcrystalline and polycrystalline. Method. 22. A transition metal itself, a salt of a transition metal, as a raw material of a transition metal element of a compound of a transition metal and a Group 6A element,
Use one or more materials selected from organometallic compounds of transition metals, transition metal hydroxides, hydrides of transition metals, carbonyl compounds of transition metals, transition metal oxides,
22. The method for producing a positive electrode active material according to claim 20, comprising a compound of a transition metal and a Group 6A element. 23. One or more kinds of materials selected from the group 6A element itself, water, alcohols, hydroxides, hydrides and halides as the raw material of the group 6A transition metal compound of the compound of the group 6A element of the transition metal. Material used, transition metal and 6A
21. It is composed of a compound with a group element.
23. The method for producing a positive electrode active material according to any one of items 22 to 22. 24. The method for producing a positive electrode active material according to claim 20, wherein the Group 6A element is oxygen. 25. The method for producing a positive electrode active material according to claim 20, wherein the 6A group element is sulfur. 26. The positive electrode active material according to claim 20, further comprising a step of reacting hydrogen in the step of forming a compound of a transition metal and a 6A group element. Production method. 27. The solution reaction in the method for producing a positive electrode active material includes the reaction between a salt of a transition metal and an alkali, the hydrolysis reaction of an organic transition metal compound, the reaction between a transition metal and an alkali,
21. The positive electrode active material according to claim 20, comprising a compound of a transition metal and a Group 6A element, which has at least a step of forming a hydroxide of a transition metal using one or more kinds of reactions selected from Manufacturing method. 28. The gas phase reaction in the method for producing a positive electrode active material comprises a transition metal salt or an organic transition metal compound or a transition metal metal vapor in a gas phase, and a 6A group element or a 6A group element compound. To react with each other in the gas phase or to decompose a gasified transition metal salt or organic transition metal compound containing the group 6A element in the gas phase to prepare a compound of the transition metal and the group 6A element. 21. The method for producing a positive electrode active material according to claim 20, further comprising at least a step. 29. The melting and quenching reaction in the method for producing a positive electrode active material melts one or more kinds of materials selected from transition metals and transition metal compounds, and one kind selected from 6A group elements and 6A group element compounds. After reacting with the above materials,
21. The method for producing a positive electrode active material according to claim 20, comprising a compound of a transition metal and a Group 6A element, which has at least a quenching step. 30. The method for producing a positive electrode active material according to claim 20, wherein the positive electrode active material comprises a compound of a transition metal and a Group 6A element, which has at least a step of applying ultrasonic vibration. 1. A method for producing a positive electrode active material. 31. The transition metal salt is a nitrate, a carbonate, a sulfate, a halide, a phosphate, a borate, an organic acid salt,
23. The method for producing a positive electrode active material according to claim 22, wherein the positive electrode active material is one or more kinds of salts selected from ammonium salts. 32. The positive electrode active material according to claim 22, wherein the organic transition metal compound is one or more kinds of salts selected from metal alkoxides, acetylacetonates, octylates, and naphthenates. Manufacturing method. 33. The method for producing a positive electrode active material according to claim 27, wherein an acid, an alkali, or an acid and an alkali are added in the hydrolysis reaction of the organic transition metal compound. 34. The method for producing a positive electrode active material according to claim 27, further comprising a dehydration reaction step. 35. The method for producing a positive electrode active material according to claim 27, comprising a step of reacting hydrogen sulfide. 36. A solid transition metal salt or organic transition metal compound is heated to vapor, or heated to a liquid, and then a carrier gas is bubbled and introduced into a reaction vessel, or in a solvent. 29. The method for producing a positive electrode active material according to claim 28, wherein the solution dissolved in is bubbled with a carrier gas and introduced into a reaction vessel to cause a gas phase reaction. 37. A liquid phase transition metal salt or organic transition metal compound is heated to form vapor, or a carrier gas is bubbled into the reaction vessel to cause a gas phase reaction. The method for producing a positive electrode active material according to claim 28. 38. The method for producing a positive electrode active material according to claim 29, wherein the quenching rate is 10 ¹ to 10 ⁸ K per second. 39. Lithium, carbon, magnesium, sodium, potassium, nitrogen, aluminum, calcium,
A compound of a transition metal and a Group 6A element having at least a step of adding one or more elements selected from barium, lead, indium, boron, silicon, tin, phosphorus, arsenic, antimony, bismuth, fluorine and chlorine. The method for producing a positive electrode active material according to any one of claims 20 to 38, which comprises: 40. As a raw material for the additive element of the positive electrode active material,
Added element itself, salt of added element, organic compound of added element,
The method for producing a positive electrode active material according to claim 39, wherein one or more kinds of materials selected from hydroxides of additional elements and hydrides of additional elements are used. 41. The method for producing a positive electrode active material according to claim 20, further comprising a step of mixing a conductor powder which serves as a nucleus of a compound of a transition metal and a 6A group element. Method. 42. The method for producing a positive electrode active material according to claim 20, further comprising a step of preparing a compound of a transition metal and a 6A group element and coating the compound with a conductor. Method. 43. A positive electrode active material prepared by the method according to any one of claims 20 to 42, comprising a fluororesin,
A method for producing a positive electrode, which is formed by mixing at least one resin selected from polyethylene, polypropylene, and silicone resins. 44. The method for producing a positive electrode according to claim 43, wherein the resin material is a liquid or a solution, or a resin having a low melting point. 45. The method for producing a positive electrode according to claim 43, wherein the resin material is a fluororesin having an ether bond.