JP2011153067A - Method for producing composite metal hydroxide and lithium composite metal oxide, and nonaqueous electrolyte secondary battery - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for producing a composite metal hydroxide, capable of suppressing generation of a side product; and to provide a lithium composite metal oxide obtained by using the composite metal hydroxide as a raw material and capable of upgrading battery performance, especially high-output characteristics. <P>SOLUTION: The composite metal hydroxide is produced by contacting an aqueous solution including Ni, Mn and Fe with an alkali to obtain a coprecipitate slurry, then by subjecting the coprecipitate slurry to solid-liquid separation to make a wet cake, and by determining the keeping time until the drying of the wet cake to be 48 hr or less. The content of manganese oxide (Mn<SB>3</SB>O<SB>4</SB>) being a by-product and included in the composite metal hydroxide is lower than the conventional content. A non-aqueous electrolyte secondary battery is obtained by using, as a cathode active material, the lithium composite metal oxide obtained by mixing and burning the composite metal hydroxide with a lithium compound. The secondary battery exhibits high power output at a high electric current rate. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a method for producing a composite metal hydroxide and a lithium composite metal oxide, and a non-aqueous electrolyte secondary battery. Specifically, a composite metal hydroxide containing Ni, Mn, and Fe, a method for producing a lithium composite metal oxide using the composite metal hydroxide as a raw material, and a positive electrode having the lithium composite metal oxide as a positive electrode active material The present invention relates to a nonaqueous electrolyte secondary battery provided.

  Lithium composite metal oxide is used as a positive electrode active material in nonaqueous electrolyte secondary batteries such as lithium secondary batteries. Lithium secondary batteries have already been put into practical use as power sources for mobile phones, notebook computers, etc., and are also being applied to medium and large applications such as automobile applications and power storage applications.

  As a conventional method for producing a lithium composite metal oxide, as disclosed in Patent Document 1, a coprecipitate slurry formed by contacting an aqueous solution containing Mn, Ni and Fe with an alkali is subjected to solid-liquid separation. Thus, there is known a method of preparing a wet cake and drying the wet cake to obtain a dry product composed of a composite metal hydroxide, and firing the mixture of the dry product and the lithium compound.

International Publication No. 09/041722 Pamphlet

By the way, when manufacturing lithium composite metal oxide industrially, the coprecipitate slurry is often subjected to solid-liquid separation to prepare a wet cake and then stored for a long period of time. In that case, there was a problem that manganese oxide (Mn ₃ O ₄ ) was by-produced in the composite metal hydroxide. When a mixed metal hydroxide containing a by-product manganese oxide (Mn ₃ O ₄ ) and a lithium compound are mixed and fired, the product lithium mixed metal oxide has a non-uniform composition. Even if this was used for the positive electrode active material, sufficient battery performance could not be obtained.
Under such circumstances, the object of the present invention is to suppress the formation of by-products in the method for producing a composite metal hydroxide containing Mn, Ni and Fe that can be used as a precursor of a lithium composite metal oxide. An object of the present invention is to provide a method for producing a composite metal hydroxide, and a lithium composite oxide that can improve battery performance, particularly high output characteristics, as a positive electrode active material using the composite metal hydroxide as a raw material.

As a result of intensive studies to solve the above-mentioned problems, the inventors of the present invention generated Mn ₃ O ₄ as described above when the wet cake was stored when the Mn component in the composite metal hydroxide was in the wet cake. It was found that elution into water was the main cause. As a result of studying wet cake storage conditions, the inventors have found that the following inventions meet the above object, and have reached the present invention.

That is, the present invention relates to the following inventions.
<1> After an aqueous solution containing Ni, Mn and Fe is contacted with an alkali to obtain a coprecipitate slurry, the coprecipitate slurry is solid-liquid separated to prepare a wet cake. In the method for producing a composite metal hydroxide by drying, a method for producing a composite metal hydroxide, wherein the storage time from the preparation of the wet cake to the drying of the wet cake is 48 hours or less.
<2> The method for producing a composite metal hydroxide according to <1>, wherein the moisture content of the wet cake after solid-liquid separation is 60% by weight or less.
<3> A method for producing a lithium composite metal oxide, comprising mixing a composite metal hydroxide obtained by the production method according to <1> or <2> and a predetermined amount of a lithium compound and firing the mixture. .
<4> A lithium composite metal oxide obtained by the production method according to <3>.
<5> A nonaqueous electrolyte secondary battery comprising a positive electrode having a positive electrode active material for a nonaqueous electrolyte secondary battery, the main component of which is the lithium composite metal oxide according to <4>.

  According to the present invention, it is possible to produce a composite metal hydroxide with a small amount of by-products, and to stably produce a lithium composite oxide with improved battery performance, particularly high output characteristics, of the positive electrode material. it can. The non-aqueous electrolyte secondary battery using the manufactured lithium composite oxide as the positive electrode active material exhibits high output at a high current rate.

It is an explanatory view of a method of determining the intensity I _B of the diffraction peak B in the powder X-ray diffraction pattern. It is a powder X-ray diffraction pattern of the dried product (P ₁ ~P ₄₎ in Example. It is a powder X-ray diffraction pattern of the powder (B ₁ ~B ₄₎ in Example.

In the present invention, an aqueous solution containing Ni, Mn and Fe is contacted with an alkali to obtain a coprecipitate slurry, and then the coprecipitate slurry is solid-liquid separated to prepare a wet cake. In the method for producing a composite metal hydroxide by drying, a method for producing a composite metal hydroxide having a storage time of 48 hours or less after the preparation of the wet cake until the wet cake is dried (hereinafter, It is referred to as “the manufacturing method of the present invention”).
In the production method of the present invention, the step of obtaining a coprecipitate slurry by bringing an aqueous solution containing Ni, Mn and Fe into contact with an alkali is referred to as “step (1)”, and the coprecipitate slurry is subjected to solid-liquid separation. The step of producing a composite metal hydroxide by producing a wet cake and drying the wet cake is referred to as “step (2)”.

  In the step (1), the aqueous solution containing Ni, Mn, and Fe includes, for example, a simple metal element, an oxide, a hydroxide, an oxyhydroxide, and a carbonate as each raw material containing Ni, Mn, and Fe. , Sulfates, nitrates, acetates, halides, ammonium salts, oxalates, alkoxides, and the like that can be dissolved in water to form an aqueous solution can be suitably used. When the simple substance or the compound is difficult to dissolve in water, an aqueous solution containing each of the elements dissolved in an aqueous solution containing hydrochloric acid, sulfuric acid, nitric acid, acetic acid or the like can be used. Among these, an aqueous solution obtained by using each chloride and dissolving Ni chloride, Mn chloride and Fe chloride in water is preferable. The Fe chloride is preferably a divalent Fe chloride.

In step (1), examples of the alkali include LiOH (lithium hydroxide), NaOH (sodium hydroxide), KOH (potassium hydroxide), Li ₂ CO ₃ (lithium carbonate), Na ₂ CO ₃ (sodium carbonate), K One or more anhydrides selected from the group consisting of ₂ CO ₃ (potassium carbonate) and (NH ₄ ) ₂ CO ₃ (ammonium carbonate) and / or the one or more hydrates may be mentioned, In 1), it is preferable to use an aqueous solution of the alkali.
Aqueous ammonia can also be mentioned as an alkaline aqueous solution. The density | concentration of the alkali in aqueous alkali solution is about 0.5-10M normally, Preferably it is about 1-8M. From the viewpoint of production cost, it is preferable to use NaOH, KOH anhydride and / or hydrate as the alkali to be used. Two or more of the alkalis described above may be used in combination.

  The water used as the solvent for the aqueous solution containing Ni, Mn and Fe and the aqueous alkaline solution is preferably pure water and / or ion-exchanged water. In addition, an organic solvent other than water, such as alcohol, a pH adjuster, or the like may be included as long as the effects of the present invention are not impaired.

In the step (1), an aqueous solution containing Ni, Mn and Fe is brought into contact with an alkali to obtain a coprecipitate slurry containing Ni, Mn and Fe.
In the present invention, the “coprecipitate slurry” is a slurry mainly composed of a coprecipitate composed of a composite metal hydroxide containing Mn, Ni, and Fe and water, and is prepared as a coprecipitate. The raw material remaining in the process, a by-product salt (for example, KCl) additive, an organic solvent, or the like may be included.
As a contact method in the step (1), a method of adding and mixing an alkaline aqueous solution to an aqueous solution containing Ni, Mn and Fe, a method of adding and mixing an aqueous solution containing Ni, Mn and Fe to the alkaline aqueous solution A method of adding an aqueous solution containing Ni, Mn, Fe and an aqueous alkaline solution to water and mixing them can be mentioned. In mixing these, it is preferable to involve stirring. Of the above contact methods, the method of adding an aqueous solution containing Ni, Mn and Fe to an alkaline aqueous solution and mixing it can be preferably used because it is easy to maintain the pH within a certain range. In this case, as the aqueous solution containing Ni, Mn and Fe is added to and mixed with the alkaline aqueous solution, the pH of the mixed solution tends to decrease, but this pH is 9 or more, preferably 10 or more. It is preferable to add an aqueous solution containing Ni, Mn and Fe while adjusting so as to be. Further, when one or both of an aqueous solution containing Ni, Mn, and Fe and an alkaline aqueous solution are kept in contact at a temperature of 40 ° C. to 80 ° C., a coprecipitate having a more uniform composition is obtained. This is preferable.

  In the sense of obtaining a non-aqueous electrolyte secondary battery with higher capacity, in the aqueous solution containing Ni, Mn and Fe in step (1), the amount (mol) of Mn with respect to the total amount (mol) of Ni, Mn and Fe is changed. It is preferable to be 0.1 or more and 0.7 or less.

  Further, in the sense of obtaining a non-aqueous electrolyte secondary battery with higher capacity, in an aqueous solution containing Ni, Mn and Fe, the amount (mol) of Fe with respect to the total amount (mol) of Ni, Mn and Fe is set to 0.01. It is preferable to set it to 0.5 or less.

In the step (2), the coprecipitate slurry is subjected to solid-liquid separation to prepare a wet cake, and the wet cake is dried to obtain a dried composite metal hydroxide containing Mn, Ni, and Fe. (Hereafter, it may be described simply as “dried product”).
“Wet cake” is a slurry obtained by dehydrating the coprecipitate slurry by solid-liquid separation. In addition to the composite metal hydroxide as a solid content, the remaining moisture, raw material, by-product salt, added An agent or an organic solvent that cannot be completely removed may be included.

One of the features of the present invention is that the storage time until the wet cake is dried after the solid-liquid separation of the coprecipitate slurry is set to 48 hours or less. Generation of Mn ₃ O ₄ is suppressed. In particular, in order to enhance the effect of the present invention, the storage time is preferably 36 hours or less, more preferably 24 hours or less. On the other hand, if it exceeds 48 hours, there is a problem that a large amount of by-product Mn ₃ O ₄ is generated.
In addition, the storage temperature of the wet cake obtained by solid-liquid separation of the coprecipitate slurry is usually 10 to 50 ° C., preferably 20 to 30 ° C. The storage atmosphere is preferably an inert gas such as N ₂ or Ar, but may be a general atmosphere. Further, the storage container is preferably a container having high airtightness.

In order to suppress the generation of more Mn ₃ O ₄ is the water content of the wet cake is preferably at most 60 wt%, more preferably 30 wt% or less.
By doing so, suppressing the elution of Mn components to moisture in the wet cake, it is possible to suppress the generation of turn Mn ₃ O _4.
The moisture content M of the wet cake can be obtained by the following equation, where W _{1 is} the weight of the wet cake before drying and W ₂ is the weight of the wet cake after drying.

Moisture content M = (W ₁ −W ₂ ) / W ₁ × 100

The weight change of the wet cake may be a value obtained by directly measuring the weight of the wet cake itself, or may be a value obtained by collecting a part of the wet cake as a sample and using an infrared moisture meter.

  In step (2), the solid-liquid separation method may be any method, and specific examples include methods such as filtration and centrifugation. Among these, filtration is preferably used from the viewpoint of operability.

  In the step (2), the wet cake obtained by solid-liquid separation can be washed. By washing, if the impurities such as alkali and Cl are excessively present in the wet cake obtained after the solid-liquid separation, this can be removed. In order to efficiently clean the wet cake, it is preferable to use water as the cleaning liquid. In addition, you may add water-soluble organic solvents, such as alcohol and acetone, to a washing | cleaning liquid as needed. Moreover, you may perform washing | cleaning twice or more, for example, after washing with water, it can also wash | clean again with the above water-soluble organic solvents. As management of washing, the pH of the filtrate is 8 to 11, preferably 9 to 10.

  Next, the wet cake is dried to obtain a dried product. Drying is usually performed by heat treatment, but may be performed by air drying, vacuum drying, or the like. As the drying atmosphere, air, oxygen, nitrogen, argon, or a mixed gas thereof can be used, but an air atmosphere is preferable. When drying is performed by heat treatment, it is usually performed at 50 to 300 ° C, and preferably about 100 to 200 ° C.

The BET specific surface area of the dried product obtained by the step (2) is usually about 10 m ² / g or more and 100 m ² / g or less. The BET specific surface area of the dried product can be adjusted by the drying temperature. The BET specific surface area of the dried product is preferably 20 m ² / g or more, and more preferably 30 m ² / g or more, in order to promote the reactivity during firing described later. Further, in the viewpoint of operability, BET specific surface area of the dried product is preferably 90m ² / g or less, and more preferably less 85 m ² / g. The dried product is usually composed of a mixture of primary particles having a particle diameter of 0.001 μm or more and 0.1 μm or less and secondary particles having a particle diameter of 1 μm or more and 100 μm or less formed by aggregation of the primary particles. The particle diameters of the primary particles and the secondary particles can be measured by observing with a scanning electron microscope (hereinafter sometimes referred to as SEM). The particle size of the secondary particles is preferably 1 μm or more and 50 μm or less, and more preferably 1 μm or more and 30 μm or less.

  The dried composite metal hydroxide containing Mn, Ni and Fe described above can be used as a raw material for a lithium composite metal oxide, as will be described later, and is obtained by mixing and baking with a lithium compound as a lithium source. The obtained lithium composite metal oxide is useful as a positive electrode active material of a non-aqueous electrolyte secondary battery capable of exhibiting higher output at a high current rate.

Further, this dried product has an intensity of diffraction peak A having a maximum intensity in a range of diffraction angle 2θ of 16 ° to 21 ° in a powder X-ray diffraction pattern obtained by powder X-ray diffraction measurement using CuKα as a radiation source. and I _a, that the diffraction angle 2θ peak intensity ratio of the intensity I _B of the intensity peak maximum diffraction B in the range of 35 ° or more 37 ° or less (I _B / I _a) is less than 0.4 More preferred.
In the X-ray diffraction pattern of the composite metal hydroxide containing Mn, Ni and Fe according to the present invention, a broad signal is observed in the range of 2θ from about 33 ° to 43 °. Therefore, the intensity I _B of the diffraction peak B in the range 2θ of 35 ° or more 37 ° or less is obtained by regarding the broad signal and background. Specifically, the contact point of inflection opposite ends of the diffraction peak B, as shown in FIG. 1, the intensity I _B of the diffraction peak B the distance to the tangent at the inflection point from the peak top.

  A mixture obtained by mixing the dried product obtained above and the lithium compound is fired to obtain a lithium composite metal oxide. Examples of the lithium compound include one or more anhydrides and / or one or more hydrates selected from the group consisting of lithium hydroxide, lithium chloride, lithium nitrate, and lithium carbonate. The mixing may be either dry mixing or wet mixing, but from the viewpoint of simplicity, dry mixing is preferable. Examples of the mixing device include stirring and mixing, a V-type mixer, a W-type mixer, a ribbon mixer, a drum mixer, a ball mill, and the like.

The holding temperature in the firing is an important factor in terms of adjusting the BET specific surface area of the lithium composite metal oxide. Usually, the higher the holding temperature, the smaller the BET specific surface area tends to be.
The BET specific surface area tends to increase as the holding temperature is lowered. The holding temperature is preferably in the range of 650 ° C. or higher and 900 ° C. or lower. The holding time at the holding temperature is usually 0.1 to 20 hours, preferably 0.5 to 8 hours. The rate of temperature rise to the holding temperature is usually 50 ° C. to 400 ° C./hour, and the rate of temperature drop from the holding temperature to room temperature is usually 10 ° C. to 400 ° C./hour. As the firing atmosphere, air, oxygen, nitrogen, argon, or a mixed gas thereof can be used, but an air atmosphere is preferable.

During the firing, the mixture may contain a reaction accelerator such as ammonium fluoride or boric acid. More specifically, as a reaction accelerator, chlorides such as NaCl, KCl and NH ₄ Cl, carbonates such as Na ₂ CO ₃ and K ₂ CO ₃ , fluorides such as LiF, NaF, KF and NH ₄ F , Boric acid, preferably the above chlorides, and more preferably KCl. When the mixture contains a reaction accelerator, it may be possible to improve the reactivity during firing of the mixture and adjust the BET specific surface area of the obtained lithium composite metal oxide. Usually, when the holding temperature of baking is the same, the BET specific surface area tends to decrease as the content of the reaction accelerator in the mixture increases. Two or more reaction accelerators can be used in combination. The reaction accelerator may be added and mixed when the dried product and the lithium compound are mixed. Further, the reaction accelerator may remain in the lithium composite metal oxide, or may be removed by washing, evaporation or the like.

  Further, after the firing, the obtained lithium composite metal oxide may be pulverized using a ball mill, a jet mill or the like. It may be possible to adjust the BET specific surface area of the lithium composite metal oxide by grinding. Moreover, you may repeat a grinding | pulverization and baking twice or more. Further, the lithium composite metal oxide can be washed or classified as necessary.

  The lithium composite metal oxide obtained by the production method of the present invention is a lithium composite metal oxide useful for a nonaqueous electrolyte secondary battery capable of exhibiting high output at a high current rate.

  The lithium composite metal oxide of the present invention is usually composed of primary particles having an average particle diameter of 0.05 μm or more and 1 μm or less, and an average of 0.1 μm or more and 100 μm or less formed by agglomeration of primary particles and primary particles. It consists of a mixture with secondary particles of particle size. The average particle diameter of primary particles and secondary particles can be measured by observing with SEM. In order to further enhance the effect of the present invention, the size of the secondary particles is preferably 0.1 μm or more and 50 μm or less, and more preferably 0.1 μm or more and 10 μm or less.

In order to further enhance the effects of the present invention, the lithium composite metal oxide of the present invention preferably has an α-NaFeO ₂ type crystal structure, that is, a crystal structure belonging to the R-3m space group. The crystal structure can be identified for a lithium composite metal oxide from a powder X-ray diffraction pattern obtained by powder X-ray diffraction measurement using CuKα as a radiation source.

Moreover, as a composition of Li in the lithium composite metal oxide of the present invention, the amount (mol) of Li is usually 0.5 or more and 1.5 or less with respect to the total amount (mol) of Ni, Mn and Fe. In order to further increase the capacity retention rate, it is preferably 0.95 or more and 1.5 or less, more preferably 1.0 or more and 1.4 or less. When expressed as the following formula (A), z is usually 0.5 or more and 1.5 or less, preferably 0.95 or more and 1.5 or less, more preferably 1.0 or more and 1.4 or less. is there.
Li _z (Ni _1-xy Mn _x Fe _y ) O ₂ (A)
(Here, 0 <x <1, 0 <y <1, 0 <x + y <1.)

  Further, a part of Li, Ni, Mn, and Fe in the lithium composite metal oxide of the present invention may be substituted with other elements within a range not impairing the effects of the present invention. Here, as other elements, B, Al, Ga, In, Si, Ge, Sn, Mg, Sc, Y, Zr, Hf, Nb, Ta, Cr, Mo, W, Tc, Ru, Rh, Ir, Examples of the element include Pd, Cu, Ag, and Zn.

  In addition, a compound different from the lithium composite metal oxide may be attached to the surface of the particles constituting the lithium composite metal oxide of the present invention as long as the effects of the present invention are not impaired. As the compound, a compound containing at least one element selected from the group consisting of B, Al, Ga, In, Si, Ge, Sn, Mg and a transition metal element, preferably B, Al, Mg, Ga, A compound containing one or more elements selected from the group consisting of In and Sn, more preferably an Al compound, and specific examples of the compound include oxides, hydroxides, and oxywater of the elements. Examples thereof include oxides, carbonates, nitrates, and organic acid salts, and oxides, hydroxides, and oxyhydroxides are preferable. Moreover, you may use these compounds in mixture. Among these compounds, a particularly preferred compound is alumina. Moreover, you may heat after adhesion.

  The positive electrode active material for a non-aqueous electrolyte secondary battery comprising the lithium composite metal oxide of the present invention is suitable for a non-aqueous electrolyte secondary battery. In the present invention, the positive electrode active material for a non-aqueous electrolyte secondary battery may be composed of the lithium composite metal oxide of the present invention as a main component.

  Using the positive electrode active material for nonaqueous electrolyte secondary batteries, for example, a positive electrode for nonaqueous electrolyte secondary batteries can be produced as follows.

  The positive electrode for a non-aqueous electrolyte secondary battery is manufactured by supporting a positive electrode mixture containing a positive electrode active material, a conductive material and a binder on a positive electrode current collector. A carbonaceous material can be used as the conductive material, and examples of the carbonaceous material include graphite powder, carbon black, acetylene black, and fibrous carbon material. Since carbon black and acetylene black are fine particles and have a large surface area, adding a small amount to the positive electrode mixture can increase the conductivity inside the positive electrode and improve the charge / discharge efficiency and rate characteristics. This decreases the binding property between the positive electrode mixture and the positive electrode current collector by the binder, and causes an increase in internal resistance. Usually, the ratio of the conductive material in the positive electrode mixture is 5 parts by weight or more and 20 parts by weight or less with respect to 100 parts by weight of the positive electrode active material. In the case where a fibrous carbon material such as graphitized carbon fiber or carbon nanotube is used as the conductive material, this ratio can be lowered.

  As the binder, a thermoplastic resin can be used. Specifically, polyvinylidene fluoride (hereinafter sometimes referred to as PVdF), polytetrafluoroethylene (hereinafter sometimes referred to as PTFE), and four fluorine. Fluoropolymers such as fluorinated ethylene / hexafluoropropylene / vinylidene fluoride copolymers, propylene hexafluoride / vinylidene fluoride copolymers, tetrafluoroethylene / perfluorovinyl ether copolymers, polyethylene, polypropylene, etc. Polyolefin resin and the like. Moreover, you may mix and use these 2 or more types. Further, by using a fluororesin and a polyolefin resin as a binder, the ratio of the fluororesin to the positive electrode mixture is 1 to 10% by weight, and the ratio of the polyolefin resin is 0.1 to 2% by weight, A positive electrode mixture excellent in binding property with the positive electrode current collector can be obtained.

  As the positive electrode current collector, Al, Ni, stainless steel or the like can be used, but Al is preferable in that it is easily processed into a thin film and is inexpensive. As a method of supporting the positive electrode mixture on the positive electrode current collector, there is a method of pressure molding, or a method of pasting using an organic solvent or the like, applying onto the positive electrode current collector, drying and pressing to fix the positive electrode current collector. Can be mentioned. In the case of forming a paste, a slurry composed of a positive electrode active material, a conductive material, a binder, and an organic solvent is prepared. Examples of the organic solvent include amine solvents such as N, N-dimethylaminopropylamine and diethylenetriamine, ether solvents such as tetrahydrofuran, ketone solvents such as methyl ethyl ketone, ester solvents such as methyl acetate, dimethylacetamide, N-methyl- Examples include amide solvents such as 2-pyrrolidone.

  Examples of the method for applying the positive electrode mixture to the positive electrode current collector include a slit die coating method, a screen coating method, a curtain coating method, a knife coating method, a gravure coating method, and an electrostatic spray method. By the method mentioned above, the positive electrode for nonaqueous electrolyte secondary batteries can be manufactured.

  Using the positive electrode for a non-aqueous electrolyte secondary battery, a non-aqueous electrolyte secondary battery can be manufactured as follows. That is, an electrode group obtained by laminating and winding the separator, the negative electrode, and the positive electrode is housed in a battery can and then impregnated with an electrolytic solution composed of an organic solvent containing an electrolyte. Can do.

  As the shape of the electrode group, for example, a shape in which the cross section when the electrode group is cut in a direction perpendicular to the winding axis is a circle, an ellipse, a rectangle, a rectangle with rounded corners, etc. Can be mentioned. In addition, examples of the shape of the battery include a paper shape, a coin shape, a cylindrical shape, and a square shape.

  The negative electrode only needs to be capable of doping and dedoping lithium ions at a lower potential than the positive electrode, and an electrode in which a negative electrode mixture containing a negative electrode material is supported on a negative electrode current collector, or an electrode made of a negative electrode material alone Can be mentioned. Examples of the negative electrode material include carbonaceous materials, chalcogen compounds (oxides, sulfides, and the like), nitrides, metals, and alloys that can be doped / undoped with lithium ions at a lower potential than the positive electrode. Moreover, you may use these negative electrode materials in mixture.

The negative electrode material is exemplified below. Specific examples of the carbonaceous material include graphite such as natural graphite and artificial graphite, coke, carbon black, pyrolytic carbon, carbon fiber, and fired organic polymer compound. As the oxide, specifically, an oxide of silicon represented by the formula SiO _x (where x is a positive real number) such as SiO ₂ and SiO, a formula TiO _x such as TiO ₂ and TiO (where x is x) Is a positive oxide of titanium, V ₂ O ₅ , VO _2, etc., and VO _x (where x is a positive real number), vanadium oxide, Fe ₃ O ₄ , Fe ₂ O ₃ , FeO and the like FeO _x (where x is a positive real number) Iron oxide, SnO ₂ , SnO and the like SnO _x (where x is a positive real number) Tin oxide, WO ₃ , WO _{2 and} other tungsten oxides represented by the general formula WO _x (where x is a positive real number), Li ₄ Ti ₅ O ₁₂ , LiVO ₂ (for example Li _1.1 V _0.9 O and the like containing mixed metal oxide for the ₂₎ and lithium such as titanium and / or vanadium Door can be. Specific examples of the sulfide include titanium sulfides represented by the formula TiS _x (where x is a positive real number) such as Ti ₂ S ₃ , TiS ₂ , and TiS, V ₃ S ₄ , VS _2, VS and other formulas VS _x (where x is a positive real number), vanadium sulfide, Fe ₃ S ₄ , FeS ₂ , FeS and other formulas FeS _x (where x is a positive real number) Iron sulfide, Mo ₂ S ₃ , MoS _{2 and the} like MoS _x (where x is a positive real number) molybdenum sulfide, SnS _2, SnS and other formula SnS _x (where x is Tin sulfide represented by positive real number), WS _{2 and} other formulas WS _x (where x is a positive real number), tungsten sulfide represented by SbS _x such as Sb ₂ S ₃ (where, x is antimony represented by a positive real _{number), Se 5 S 3, SeS} 2, SeS formula SeS _x (wherein such, Mention may be made of such sulfide selenium represented by a positive real number). Specific examples of the nitride include lithium-containing nitrides such as Li ₃ N, Li _3-x A _x N (where A is Ni and / or Co, and 0 <x <3). Can be mentioned. These carbonaceous materials, oxides, sulfides, and nitrides may be used in combination, and may be crystalline or amorphous. Further, these carbonaceous materials, oxides, sulfides and nitrides are mainly carried on the negative electrode current collector and used as electrodes.

Specific examples of the metal include lithium metal, silicon metal, and tin metal. Examples of the alloy include lithium alloys such as Li—Al, Li—Ni, and Li—Si, silicon alloys such as Si—Zn, Sn—Mn, Sn—Co, Sn—Ni, Sn—Cu, and Sn—La. In addition to tin alloys such as Cu ₂ Sb, La ₃ Ni ₂ Sn _{7 and the} like can also be mentioned. These metals and alloys are mainly used alone as electrodes (for example, used in a foil shape).

  Among the negative electrode materials, a carbonaceous material mainly composed of graphite such as natural graphite or artificial graphite is preferably used from the viewpoint of high potential flatness, low average discharge potential, and good cycleability. The shape of the carbonaceous material may be, for example, a flake shape such as natural graphite, a spherical shape such as mesocarbon microbeads, a fibrous shape such as graphitized carbon fiber, or an aggregate of fine powder.

  The negative electrode mixture may contain a binder as necessary. Examples of the binder include thermoplastic resins, and specific examples include PVdF, thermoplastic polyimide, carboxymethyl cellulose, polyethylene, and polypropylene.

  Examples of the negative electrode current collector include Cu, Ni, and stainless steel. Cu may be used because it is difficult to form an alloy with lithium and it is easy to process into a thin film. The method of supporting the negative electrode mixture on the negative electrode current collector is the same as in the case of the positive electrode. The method is a method of pressure molding, pasted using a solvent, etc., coated on the negative electrode current collector, dried, pressed and pressed. And the like.

  As the separator, for example, a material having a form such as a porous membrane, a nonwoven fabric, a woven fabric made of a polyolefin resin such as polyethylene and polypropylene, a fluororesin, a nitrogen-containing aromatic polymer, and the like can be used. Moreover, it is good also as a separator using 2 or more types of the said material, and the said material may be laminated | stacked. Examples of the separator include separators described in JP 2000-30686 A, JP 10-324758 A, and the like. The thickness of the separator is preferably about 5 to 200 μm, and preferably about 5 to 40 μm, as long as the mechanical strength is maintained because the volume energy density of the battery is increased and the internal resistance is reduced.

  The separator preferably has a porous film containing a thermoplastic resin. In a non-aqueous electrolyte secondary battery, normally, when an abnormal current flows in the battery due to a short circuit between the positive electrode and the negative electrode, the function of shutting down the current and preventing the excessive current from flowing (shut down) It is preferable to have. Here, the shutdown is performed by closing the micropores of the porous film in the separator when the normal use temperature is exceeded. After the shutdown, even if the temperature in the battery rises to a certain high temperature, it is preferable to maintain the shutdown state without breaking the film due to the temperature. Examples of such a separator include a laminated film in which a heat-resistant porous layer and a porous film are laminated. By using the film as a separator, the heat resistance of the secondary battery in the present invention can be further increased. . Here, the heat-resistant porous layer may be laminated on both surfaces of the porous film.

  Hereinafter, a laminated film in which the heat-resistant porous layer and the porous film are laminated will be described.

  In the laminated film, the heat resistant porous layer is a layer having higher heat resistance than the porous film, and the heat resistant porous layer may be formed of an inorganic powder or may contain a heat resistant resin. When the heat resistant porous layer contains a heat resistant resin, the heat resistant porous layer can be formed by an easy technique such as coating. Examples of the heat resistant resin include polyamide, polyimide, polyamideimide, polycarbonate, polyacetal, polysulfone, polyphenylene sulfide, polyetherketone, aromatic polyester, polyethersulfone, and polyetherimide, from the viewpoint of further improving heat resistance. , Polyamide, polyimide, polyamideimide, polyethersulfone, and polyetherimide are preferable, and polyamide, polyimide, and polyamideimide are more preferable. Even more preferred are nitrogen-containing aromatic polymers such as aromatic polyamides (para-oriented aromatic polyamides, meta-oriented aromatic polyamides), aromatic polyimides, aromatic polyamideimides, and particularly preferred are aromatic polyamides and production surfaces. Particularly preferred is para-oriented aromatic polyamide (hereinafter sometimes referred to as “para-aramid”). Further, examples of the heat resistant resin include poly-4-methylpentene-1 and cyclic olefin polymers. By using these heat resistant resins, the heat resistance of the laminated film, that is, the thermal film breaking temperature of the laminated film can be further increased. Among these heat-resistant resins, when using a nitrogen-containing aromatic polymer, because of the polarity in the molecule, compatibility with the electrolyte, that is, the liquid retention in the heat-resistant porous layer may be improved, The rate of impregnation of the electrolytic solution during the production of the nonaqueous electrolyte secondary battery is also high, and the charge / discharge capacity of the nonaqueous electrolyte secondary battery is further increased.

  The thermal film breaking temperature of such a laminated film depends on the type of heat-resistant resin, and is selected and used according to the use scene and purpose of use. More specifically, as the heat resistant resin, the cyclic olefin polymer is used at about 400 ° C. when the nitrogen-containing aromatic polymer is used, and at about 250 ° C. when poly-4-methylpentene-1 is used. When using, the thermal film breaking temperature can be controlled to about 300 ° C., respectively. In addition, when the heat resistant porous layer is made of an inorganic powder, the thermal film breaking temperature can be controlled to, for example, 500 ° C. or higher.

  The para-aramid is obtained by condensation polymerization of a para-oriented aromatic diamine and a para-oriented aromatic dicarboxylic acid halide, and the amide bond is in the para position of the aromatic ring or an oriented position equivalent thereto (for example, 4,4′- It consists essentially of repeating units bonded at opposite orientations, such as biphenylene, 1,5-naphthalene, 2,6-naphthalene, etc., oriented in the opposite direction coaxially or in parallel. Specifically, poly (paraphenylene terephthalamide), poly (parabenzamide), poly (4,4′-benzanilide terephthalamide), poly (paraphenylene-4,4′-biphenylenedicarboxylic acid amide), poly ( Para-aligned or para-oriented such as paraphenylene-2,6-naphthalenedicarboxylic acid amide), poly (2-chloro-paraphenylene terephthalamide), paraphenylene terephthalamide / 2,6-dichloroparaphenylene terephthalamide copolymer Examples include para-aramid having a structure according to the type.

  The aromatic polyimide is preferably a wholly aromatic polyimide produced by condensation polymerization of an aromatic dianhydride and a diamine. Specific examples of the dianhydride include pyromellitic dianhydride, 3,3 ′, 4,4′-diphenylsulfone tetracarboxylic dianhydride, 3,3 ′, 4,4′-benzophenone tetracarboxylic Examples thereof include acid dianhydride, 2,2′-bis (3,4-dicarboxyphenyl) hexafluoropropane, 3,3 ′, 4,4′-biphenyltetracarboxylic dianhydride, and the like. Specific examples of the diamine include oxydianiline, paraphenylenediamine, benzophenonediamine, 3,3′-methylenedianiline, 3,3′-diaminobenzophenone, 3,3′-diaminodiphenylsulfone, 1,5 '-Naphthalenediamine and the like. Moreover, a polyimide soluble in a solvent can be preferably used. An example of such a polyimide is a polycondensate polyimide of 3,3 ′, 4,4′-diphenylsulfonetetracarboxylic dianhydride and an aromatic diamine.

  As the above-mentioned aromatic polyamideimide, those obtained from condensation polymerization using aromatic dicarboxylic acid and aromatic diisocyanate, those obtained from condensation polymerization using aromatic diacid anhydride and aromatic diisocyanate Is mentioned. Specific examples of the aromatic dicarboxylic acid include isophthalic acid and terephthalic acid. Specific examples of the aromatic dianhydride include trimellitic anhydride. Specific examples of the aromatic diisocyanate include 4,4'-diphenylmethane diisocyanate, 2,4-tolylene diisocyanate, 2,6-tolylene diisocyanate, orthotolylane diisocyanate, m-xylene diisocyanate, and the like.

  In order to further enhance the ion permeability, the heat-resistant porous layer is preferably a thin heat-resistant porous layer having a thickness of 1 μm to 10 μm, more preferably 1 μm to 5 μm, particularly 1 μm to 4 μm. The heat-resistant porous layer has fine pores, and the size (diameter) of the pores is usually 3 μm or less, preferably 1 μm or less. Moreover, when a heat resistant porous layer contains a heat resistant resin, a heat resistant porous layer can also contain the below-mentioned filler.

  In the laminated film, the porous film preferably has fine pores and has a shutdown function. In this case, the porous film contains a thermoplastic resin. The size of the micropores in the porous film is usually 3 μm or less, preferably 1 μm or less. The porosity of the porous film is usually 30 to 80% by volume, preferably 40 to 70% by volume. In the nonaqueous electrolyte secondary battery, when the normal use temperature is exceeded, the porous film containing the thermoplastic resin can close the micropores by softening the thermoplastic resin constituting the porous film.

  What is necessary is just to select the thermoplastic resin which does not melt | dissolve in the electrolyte solution in a nonaqueous electrolyte secondary battery. Specific examples include polyolefin resins such as polyethylene and polypropylene, and thermoplastic polyurethane resins, and a mixture of two or more of these may be used. It is preferable to contain polyethylene in the sense of softening and shutting down at a lower temperature. Specific examples of the polyethylene include polyethylene such as low density polyethylene, high density polyethylene, and linear polyethylene, and ultra high molecular weight polyethylene having a molecular weight of 1,000,000 or more. In the sense of further increasing the puncture strength of the porous film, the thermoplastic resin constituting the film preferably contains at least ultrahigh molecular weight polyethylene. In addition, in terms of production of the porous film, the thermoplastic resin may preferably contain a wax made of polyolefin having a low molecular weight (weight average molecular weight of 10,000 or less).

  Moreover, the thickness of the porous film in a laminated | multilayer film is 3-30 micrometers normally, More preferably, it is 3-25 micrometers. In the present invention, the thickness of the laminated film is usually 40 μm or less, preferably 20 μm or less. Moreover, when the thickness of the heat resistant porous layer is A (μm) and the thickness of the porous film is B (μm), the value of A / B is preferably 0.1 or more and 1 or less.

  Moreover, when the heat resistant porous layer contains a heat resistant resin, the heat resistant porous layer may contain one or more fillers. The filler may be selected from organic powder, inorganic powder, or a mixture thereof as the material thereof. The particles constituting the filler preferably have an average particle size of 0.01 μm or more and 1 μm or less.

  Examples of the organic powder include styrene, vinyl ketone, acrylonitrile, methyl methacrylate, ethyl methacrylate, glycidyl methacrylate, glycidyl acrylate, and methyl acrylate, or a copolymer of two or more kinds, polytetrafluoroethylene, 4 fluorine. Examples include fluorine-containing resins such as fluorinated ethylene-6-propylene-propylene copolymer, tetrafluoroethylene-ethylene copolymer, and polyvinylidene fluoride; melamine resin; urea resin; polyolefin; and powders made of organic substances such as polymethacrylate. . The organic powder may be used alone or in combination of two or more. Among these organic powders, polytetrafluoroethylene powder is preferable from the viewpoint of chemical stability.

  Examples of the inorganic powder include powders made of inorganic substances such as metal oxides, metal nitrides, metal carbides, metal hydroxides, carbonates, sulfates, etc. Among these, they are made of inorganic substances having low conductivity. Powder is preferably used. Specific examples include powders made of alumina, silica, titanium dioxide, calcium carbonate, or the like. The inorganic powder may be used alone or in combination of two or more. Among these inorganic powders, alumina powder is preferable from the viewpoint of chemical stability. Here, it is more preferable that all of the particles constituting the filler are alumina particles, and it is even more preferable that all of the particles constituting the filler are alumina particles, and part or all of them are substantially spherical alumina particles. It is embodiment which is. Incidentally, when the heat-resistant porous layer is formed from an inorganic powder, the inorganic powder exemplified above may be used, and may be mixed with a binder as necessary.

  The filler content when the heat-resistant porous layer contains a heat-resistant resin depends on the specific gravity of the filler material. For example, when all of the particles constituting the filler are alumina particles, When the total weight is 100, the weight of the filler is usually 5 or more and 95 or less, preferably 20 or more and 95 or less, more preferably 30 or more and 90 or less. These ranges can be appropriately set depending on the specific gravity of the filler material.

  Examples of the shape of the filler include a substantially spherical shape, a plate shape, a columnar shape, a needle shape, a whisker shape, and a fibrous shape, and any particle can be used. It is preferable that Examples of the substantially spherical particles include particles having a particle aspect ratio (particle major axis / particle minor axis) in the range of 1 to 1.5. The aspect ratio of the particles can be measured by an electron micrograph.

  In the present invention, from the viewpoint of ion permeability, the separator preferably has an air permeability of 50 to 300 seconds / 100 cc, more preferably 50 to 200 seconds / 100 cc in terms of air permeability by the Gurley method. preferable. Moreover, the porosity of a separator is 30-80 volume% normally, Preferably it is 40-70 volume%. The separator may be a laminate of separators having different porosity.

In the secondary battery, the electrolytic solution is usually composed of an organic solvent containing an electrolyte. Examples of the electrolyte include LiClO ₄ , LiPF ₆ , LiAsF ₆ , LiSbF ₆ , LIBF ₄ , LiCF ₃ SO ₃ , LiN (SO ₂ CF ₃ ) ₂ , LiN (SO ₂ C ₂ F ₅ ) ₂ , LiN (SO ₂ CF ₃ ) (COCF ₃ ), Li (C ₄ F ₉ SO ₃ ), LiC (SO ₂ CF ₃ ) ₃ , Li ₂ B ₁₀ Cl ₁₀ , LiBOB (where BOB is bis (oxalato) borate). ), Lithium salts such as lower aliphatic carboxylic acid lithium salts and LiAlCl _4, and a mixture of two or more of these may be used. The lithium salt is usually selected from the group consisting of LiPF ₆ , LiAsF ₆ , LiSbF ₆ , LiBF ₄ , LiCF ₃ SO ₃ , LiN (SO ₂ CF ₃ ) ₂ and LiC (SO ₂ CF ₃ ) ₃ containing fluorine among these. Those containing at least one selected are used.

In the electrolytic solution, examples of the organic solvent include propylene carbonate, ethylene carbonate, dimethyl carbonate, diethyl carbonate, ethyl methyl carbonate, 4-trifluoromethyl-1,3-dioxolan-2-one, 1,2-di ( Carbonates such as methoxycarbonyloxy) ethane; 1,2-dimethoxyethane, 1,3-dimethoxypropane, pentafluoropropyl methyl ether, 2,2,3,3-tetrafluoropropyl difluoromethyl ether, tetrahydrofuran, 2-methyl Ethers such as tetrahydrofuran; esters such as methyl formate, methyl acetate and γ-butyrolactone; nitriles such as acetonitrile and butyronitrile; N, N-dimethylformamide, N, N-dimethylacetate Amides such as amides; Carbamates such as 3-methyl-2-oxazolidone; Sulfur-containing compounds such as sulfolane, dimethyl sulfoxide and 1,3-propane sultone, or those obtained by further introducing a fluorine substituent into the above organic solvent Usually, two or more of these are mixed and used. Among these, a mixed solvent containing carbonates is preferable, and a mixed solvent of cyclic carbonate and acyclic carbonate or cyclic carbonate and ether is more preferable. The mixed solvent of cyclic carbonate and non-cyclic carbonate has a wide operating temperature range, excellent load characteristics, and is hardly decomposable even when a graphite material such as natural graphite or artificial graphite is used as the negative electrode active material. In addition, a mixed solvent containing ethylene carbonate, dimethyl carbonate and ethyl methyl carbonate is preferable. Further, in view of particularly excellent safety improving effect is obtained, it is preferable to use an electrolytic solution containing an organic solvent having a lithium salt and a fluorine substituent containing fluorine such as LiPF _6. A mixed solvent containing ethers having fluorine substituents such as pentafluoropropyl methyl ether and 2,2,3,3-tetrafluoropropyl difluoromethyl ether and dimethyl carbonate has excellent high-current discharge characteristics, preferable.

A solid electrolyte may be used instead of the above electrolytic solution. As the solid electrolyte, for example, an organic polymer electrolyte such as a polyethylene oxide polymer compound, a polymer compound containing at least one of a polyorganosiloxane chain or a polyoxyalkylene chain can be used. Moreover, what is called a gel type which hold | maintained the nonaqueous electrolyte solution in the high molecular compound can also be used. The _{Li 2 S-SiS 2, Li} 2 S-GeS 2, Li 2 S-P 2 S 5, Li 2 S-B 2 S 3, Li 2 S-SiS 2 -Li 3 PO 4, Li 2 S-SiS _An inorganic solid electrolyte containing a sulfide such as _2- Li ₂ SO ₄ may be used. Using these solid electrolytes, safety may be further improved. In the nonaqueous electrolyte secondary battery of the present invention, when a solid electrolyte is used, the solid electrolyte may serve as a separator, and in that case, the separator may not be required.

  EXAMPLES Hereinafter, although an Example demonstrates this invention further in detail, unless the summary of this invention is changed, it is not limited to a following example.

Powder X-ray diffraction measurement and BET specific surface area measurement were performed under the following conditions, respectively.
<Powder X-ray diffraction measurement>
The powder X-ray diffraction measurement (XRD) was performed using Ultima IVASC-10 manufactured by Rigaku Corporation. The measurement is carried out by filling a powder sample on a dedicated substrate and using a CuKα radiation source with a voltage of 40 kV, a current of 40 mA, a sampling width of 0.02 °, a scanning speed of 4.0 ° / min, and a diffraction angle 2θ = 10 °. The powder X-ray diffraction pattern was obtained in a range of ˜90 °.
<BET specific surface area measurement>
1 g of the powder was dried at 150 ° C. for 15 minutes in a nitrogen atmosphere, and then measured using a Micrometrics Flowsorb II2300.

Example 1
In a polypropylene beaker, 71.00 g of potassium hydroxide was added to 930 ml of distilled water and dissolved by stirring to completely dissolve potassium hydroxide to prepare an aqueous potassium hydroxide solution (alkali aqueous solution). Also, in a glass beaker, in 150 ml of distilled water, 55.86 g of nickel chloride (II) hexahydrate, 47.50 g of manganese (II) chloride tetrahydrate and iron (II) chloride tetrahydrate 4. 97 g was added and dissolved by stirring to obtain a nickel-manganese-iron mixed aqueous solution. While stirring the potassium hydroxide aqueous solution, the nickel-manganese-iron mixed aqueous solution was added dropwise thereto, whereby a coprecipitate was generated to obtain a coprecipitate slurry. The pH at the end of the reaction was measured and found to be 13.
Next, the coprecipitate slurry was filtered under reduced pressure using a Nutsche, and water was added onto the wet cake. After washing with water until the filtrate had a pH of less than 10, solid-liquid separation was performed to collect the wet cake. The moisture content of the wet cake at this time was 50% by weight.
The wet cake was stored at room temperature for 6.5 hours in an air atmosphere and then dried at 120 ° C. for 8 hours to obtain a dried product P ₁ . As a result of composition analysis of the dried product P ₁ , the molar ratio of Ni: Mn: Fe was 0.47: 0.48: 0.05.
The result of the powder X-ray diffraction measurement of the dried product P ₁ is shown in FIG. In the powder X-ray diffraction pattern, a peak A derived from the composite metal hydroxide is detected in the range of 2θ of 16 ° to 21 °, and manganese in the vicinity of 36 ° in the range of 2θ of 35 ° to 37 °. Peak B derived from the oxide was detected. And intensity I _B of a peak B, the ratio of the intensity I _A of the peak A, I _B / I _A was 0.301. The results are also shown in Table 1.
40.00 g of the dried product (P ₁ ), 20.89 g of lithium carbonate and 5.54 g of potassium carbonate were dry-mixed using a ball mill to obtain a mixture. Next, the mixture was put into an alumina firing container, and fired by holding it at 870 ° C. for 6 hours in the air using an electric furnace, and cooled to room temperature to obtain a fired product. Then, the fired product was pulverized, washed with distilled water by decantation, after filtration, and dried 6 hours at 300 ° C., to obtain a powder B _1.
The BET specific surface area of the powder B ₁ was 8.8 m ² / g. The result of the powder X-ray diffraction measurement of the powder B ₁ is shown in FIG. The crystal structure of the powder B _{1 was} a crystal structure belonging to the R-3m space group.

(Example 2)
The method from solid-liquid separation of the coprecipitate slurry to recovery of the wet cake was obtained in the same manner as in Example 1. The water content at this time was 50% by weight.
Next, the wet cake was stored at room temperature for 48 hours in an air atmosphere and then dried at 120 ° C. for 8 hours to obtain a dried product P ₂ . The result of the powder X-ray diffraction measurement of the dried product P ₂ is shown in FIG. In the powder X-ray diffraction pattern, a peak A derived from the composite metal hydroxide is detected in the range of 2θ of 16 ° to 21 °, and manganese in the vicinity of 36 ° in the range of 2θ of 35 ° to 37 °. Peak B derived from the oxide was detected. And intensity I _B of a peak B, the ratio of the intensity I _A of the peak A, I _B / I _A was 0.341. The results are also shown in Table 1.
For method after obtaining the dried product P _2, performed in the same manner as in Example 1 to obtain a powder B _2. The BET specific surface area of the powder B ₂ was 10.0 m ² / g. The result of the powder X-ray diffraction measurement of the powder B ₂ is shown in FIG. The crystal structure of the powder B _{2 was} a crystal structure belonging to the R-3m space group.

(Comparative Example 1)
The method from solid-liquid separation of the coprecipitate slurry to recovery of the wet cake was obtained in the same manner as in Example 1. The water content at this time was 70% by weight.
Subsequently, the wet cake was stored at room temperature for 72 hours in an air atmosphere and then dried at 120 ° C. for 8 hours to obtain a dried product P ₃ . The result of the powder X-ray diffraction measurement of the dried product P ₃ is shown in FIG. In the powder X-ray diffraction pattern, a peak A derived from the composite metal hydroxide is detected in the range of 2θ of 16 ° to 21 °, and manganese in the vicinity of 36 ° in the range of 2θ of 35 ° to 37 °. Peak B derived from the oxide was detected. And intensity I _B of a peak B, the ratio of the intensity I _A of the peak A, I _B / I _A was 0.638. The results are also shown in Table 1.
For method after obtaining the dried product P _3, performed in the same manner as in Example 1 to obtain a powder B _3. BET specific surface area of the powder B ₃ is 7.7 m ² / g, shows the results of powder X-ray diffraction measurement of the powder B ₃ in FIG. The crystal structure of the powder B _{3 was} a crystal structure belonging to the R-3m space group.

(Comparative Example 2)
The method from solid-liquid separation of the coprecipitate slurry to recovery of the wet cake was obtained in the same manner as in Example 1. The water content at this time was 70% by weight.
Next, the wet cake was stored at room temperature for 168 hours in an air atmosphere and then dried at 120 ° C. for 8 hours to obtain a dried product P ₄ . The result of the powder X-ray diffraction measurement of the dried product P ₄ is shown in FIG. In the powder X-ray diffraction pattern, a peak A derived from the composite metal hydroxide is detected in the range of 2θ of 16 ° to 21 °, and manganese in the vicinity of 36 ° in the range of 2θ of 35 ° to 37 °. Peak B derived from the oxide was detected. And intensity I _B of a peak B, the ratio of the intensity I _A of the peak A, I _B / I _A was 0.472. The results are also shown in Table 1.
For method after obtaining the dried product P _4, performed in the same manner as in Example 1 to obtain a powder B _4. The BET specific surface area of the powder B ₄ is 8.1 m ² / g, and the result of the powder X-ray diffraction measurement of the powder B ₄ is shown in FIG. It was found that the crystal structure of the powder B _{4 was} a crystal structure belonging to the R-3m space group.

<Preparation of nonaqueous electrolyte secondary battery>
A coin-type non-aqueous electrolyte secondary battery using the produced powders B _{1 to} B ₄ as a positive electrode active material was produced, and a charge / discharge test was performed.
A mixture of a positive electrode active material (powder B _{1 to} B ₄ ) and a conductive material (a mixture of acetylene black and graphite at a ratio of 9: 1 (weight ratio)), PVdF N-methyl-2-pyrrolidone (hereinafter referred to as “binder”) NMP.) The solution is added to the composition of active material: conductive material: binder = 87: 10: 3 (weight ratio) and kneaded to obtain a paste, and the thickness is 40 μm to be a current collector. The paste was applied to an Al foil and vacuum dried at 150 ° C. for 8 hours to obtain a positive electrode.
To the obtained positive electrode, 30 of ethylene carbonate (hereinafter sometimes referred to as EC), dimethyl carbonate (hereinafter sometimes referred to as DMC) and ethyl methyl carbonate (hereinafter sometimes referred to as EMC) as electrolytes. : 35:35 (volume ratio) LiPF ₆ dissolved in a mixed solution at 1 mol / liter (hereinafter sometimes referred to as LiPF ₆ / EC + DMC + EMC), a laminated film as a separator, and a negative electrode A coin-type battery (R2032) was manufactured by combining metallic lithium.
Using the above coin-type battery, a charge / discharge test was performed under the conditions shown below while maintaining at 25 ° C. The results are shown in Table 1.

<Charge / discharge test>
Charging maximum voltage 4.3V, charging time 8 hours, charging current 0.275mA / cm ²
During discharge, the minimum discharge voltage was kept constant at 2.5 V, and the discharge current in each cycle was changed as follows to perform discharge. In addition, it means that a high output is shown, so that the discharge capacity by the discharge in each cycle is high.
First cycle discharge (0.2 C): discharge current 0.275 mA / cm ²
Second cycle discharge (5C): Discharge current 6.875 mA / cm ²
3rd cycle discharge (10 C): discharge current 13.75 mA / cm ²

  According to the production method of the present invention, a stable composite metal hydroxide containing no impurities can be produced, and a lithium composite oxide using the composite metal hydroxide as a raw material can be produced stably. . The non-aqueous electrolyte secondary battery using the manufactured lithium composite oxide as the positive electrode active material exhibits high output at a high current rate, and therefore is required for high output at a high current rate, that is, for automobiles and power tools. It is extremely useful for non-aqueous electrolyte secondary batteries for power tools such as.

Claims (5)

Contacting an aqueous solution containing Ni, Mn, and Fe with an alkali to obtain a coprecipitate slurry, solid-liquid separation of the coprecipitate slurry to produce a wet cake, and drying the wet cake In the method for producing a composite metal hydroxide,
A method for producing a composite metal hydroxide, wherein the storage time from the preparation of the wet cake to the drying of the wet cake is 48 hours or less.   The method for producing a composite metal hydroxide according to claim 1, wherein the moisture content of the wet cake is 60% by weight or less.   A method for producing a lithium composite metal oxide, comprising mixing a composite metal hydroxide obtained by the production method according to claim 1 or 2 and a predetermined amount of a lithium compound and firing the mixture.   A lithium composite metal oxide obtained by the production method according to claim 3.   A nonaqueous electrolyte secondary battery comprising a positive electrode having a positive electrode active material mainly composed of the lithium composite metal oxide according to claim 4.

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