JP6221310B2 - Trimanganese tetraoxide composition, method for producing the same, and use thereof - Google Patents

Description

  The present invention relates to a manganese oxide composition as a raw material for a lithium composite oxide, a method for producing the same, and a method for producing a lithium composite oxide using the same.

  Lithium complex oxides such as lithium manganese complex oxides and lithium nickel complex oxides are used as positive electrode materials for lithium secondary batteries. A composite lithium composite oxide has been reported as a positive electrode material for a lithium secondary battery with higher battery performance.

  As a positive electrode material using a composite oxide, a method of mixing lithium hydroxide, γ-MnOOH, cobalt trioxide and nickel hydroxide and firing the same has been reported (Patent Document 1).

  Also, a solution containing manganese, nickel and cobalt is precipitated by coexistence of a complexing agent to obtain cobalt manganese coprecipitated nickel hydroxide particles in which these elements are uniformly dispersed, and this is used as a raw material for the positive electrode material. Has been reported (Patent Document 2).

Japanese Patent Laid-Open No. 08-37007 Japanese Patent Laid-Open No. 2002-201028

  In the method for producing a positive electrode material that mixes lithium, manganese, nickel, and cobalt raw materials disclosed in Patent Document 1, it is difficult to uniformly mix the raw materials. Therefore, the obtained positive electrode material not only has not enough battery characteristics, but also has a lot of variations in the lot of positive electrode materials, and a positive electrode material having the same battery characteristics cannot be obtained stably.

  On the other hand, the cobalt manganese coprecipitated nickel hydroxide particles disclosed in Patent Document 2 have uniform elements as compared with those obtained by mixing various raw materials. However, in order to obtain uniform cobalt manganese coprecipitated nickel hydroxide particles, ammonia or hydrazine is required as a reducing agent, and production on an industrial scale has been difficult.

  An object of this invention is to provide the trimanganese tetroxide composition which provides the positive electrode material for lithium ion secondary batteries excellent in battery characteristics, especially charging / discharging cycling characteristics, and its simple manufacturing method.

  The present inventor has intensively studied in view of the above problems. As a result, a trimanganese tetroxide composition having a structure in which various metal compounds are deposited on trimanganese tetroxide particles is a lithium composite oxide for lithium secondary batteries having excellent battery characteristics, particularly charge / discharge cycle characteristics. Found to give.

  Furthermore, it has been found that such a trimanganese tetroxide composition is obtained by precipitating a metal oxide on trimanganese tetraoxide particles deposited under specific conditions.

  Hereinafter, the trimanganese tetraoxide composition of the present invention will be described.

  The trimanganese tetroxide composition of the present invention is trimanganese tetroxide having a metal compound on the surface. Thereby, the battery characteristics of the lithium manganese composite oxide obtained using the trimanganese tetraoxide composition of the present invention as a raw material, particularly the charge / discharge cycle characteristics are enhanced.

  The metal compound is present on the surface of the trimanganese tetraoxide particles. A specific form of existence is a so-called core-shell structure in which a metal compound is present on the surface of the trimanganese tetroxide particles.

  In the present invention, the “composition” means particles that are combined in the form of particles. Further, “complexed in the form of particles” means that at least one of the primary particles aggregates with the other particles to form secondary particles of the metal compound and manganese trioxide. . Therefore, the trimanganese tetroxide composition of the present invention is secondary particles, so-called composite particles, in which the metal compound particles and the trimanganese tetroxide particles are not separated even if they are dispersed in a solvent. Therefore, for example, a mixture obtained by physical mixing such as mixing trimanganese tetroxide particles and metal compound particles, and the trimanganese tetraoxide composition of the present invention, that is, the trimanganese tetraoxide composite of the present invention. Different from particles.

  Manganese tetroxide has a Hausmannite type crystal structure and belongs to the space group I41 / amd.

  Examples of the metal compound include oxides, hydroxides, and carbonates, and hydroxides are preferable.

  The metal of the metal compound is preferably a metal element other than manganese (Mn), more preferably manganese or lithium (Li), magnesium (Mg), aluminum (Al), silica (Si), calcium (Ca), titanium (Ti), vanadium (V), chromium (Cr), cobalt (Co), nickel (Ni), copper (Cu), zinc (Zn), gallium (Ga), germanium (Ge), zirconium It is preferably at least one selected from the group of (Zr), molybdenum (Mo), silver (Ag), indium (In), and tin (Sn), and at least two selected from the above group. More preferred. When the trimanganese tetroxide composition of the present invention contains these metal compounds, the battery characteristics of the lithium composite oxide obtained using the trimanganese tetroxide composition of the present invention as a raw material are easily improved.

  From the viewpoint of improving charge / discharge cycle characteristics and battery characteristics at high temperatures when a lithium composite oxide is produced, it is more preferably at least one of cobalt and nickel, and more preferably cobalt and nickel.

  When the metal compound is a composite metal compound composed of a plurality of metals, the ratio of each metal is arbitrary. For example, when the metal oxide is a nickel-cobalt composite metal compound, the molar ratio of nickel / cobalt can be 1/5 to 5/1, and further 4/5 to 6/5.

  In the trimanganese tetroxide composition of the present invention, the molar ratio of the trimanganese tetroxide to the metal in the metal compound is preferably a molar ratio of Mn / Me from 4/1 to 1/4 (Me: metal compound) Metal inside).

  The average particle diameter of the trimanganese tetraoxide composition of the present invention is preferably more than 5 μm, more preferably 10 μm or more. The upper limit of the average particle diameter can be arbitrarily set depending on the particle diameter of the finally intended lithium composite oxide. Examples of the upper limit of the average particle diameter include 20 μm or less.

  In the present invention, the average particle diameter is a particle diameter (so-called D50) that is 50% on a volume basis. When the particle size distribution of the composite particles is monodispersed, the mode particle size and the average particle size match. In this case, the mode particle size can be used as the average particle size.

The trimanganese tetraoxide composition of the present invention preferably has a BET specific surface area of more than 10 m ² / g, more preferably 15 m ² / g or more. When the BET specific surface area exceeds 10 m ² / g, the reactivity with the lithium compound tends to be improved.

  Hereinafter, the manufacturing method of the trimanganese tetraoxide composition of this invention is demonstrated.

  The trimanganese tetraoxide composition of the present invention comprises a crystallization step of crystallizing trimanganese tetraoxide from a manganese salt aqueous solution containing manganese ions without going through manganese hydroxide, and a metal compound is added to the trimanganese tetraoxide. It can be obtained by a method for producing a trimanganese tetroxide composition characterized by having a step of precipitation.

  In the step of crystallizing manganese trioxide from an aqueous manganese salt solution without passing through the manganese hydroxide, manganese tetraoxide is produced from the aqueous manganese salt solution without precipitating manganese hydroxide crystals in the alkaline region. .

  Therefore, the method for producing a trimanganese tetraoxide composition of the present invention comprises depositing manganese hydroxide in an alkaline region from an aqueous manganese salt solution and oxidizing the manganese hydroxide with an oxidizing agent without passing through the steps of oxidizing the manganese hydroxide. A process for producing manganese.

  The method for producing the trimanganese tetroxide composition of the present invention includes a mode in which no crystal phase of manganese hydroxide is formed at all in the crystallization step, and after microcrystals of the hydroxide are precipitated for a short time, Is converted to trimanganese tetroxide before growing into hexagonal plate-like crystals. That is, the method for producing a trimanganese tetraoxide composition of the present invention is characterized in that hexagonal plate-like manganese hydroxide crystals are not produced in the crystallization step. Since no manganese hydroxide crystals are formed, it is possible to obtain trimanganese tetraoxide having a high density.

  Whether or not a hexagonal plate-like manganese hydroxide crystal has occurred can be determined by observing the particle shape of the resulting manganese trioxide.

  In the production method of the present invention, the pH of the aqueous manganese salt solution or the pH of the slurry when crystallizing the trimanganese tetraoxide is preferably set to a pH at which manganese hydroxide is difficult to be generated, from weakly acidic to weakly alkaline. More preferably, the pH is set.

  Specifically, the pH is preferably 6 or more and 9 or less, and more preferably pH 6.5 or more and pH 8.5 or less. Further, it is more preferable that the central value of pH is within this range. By making the pH of the manganese salt aqueous solution or slurry within this range, it becomes difficult to produce manganese hydroxide.

  The pH of the aqueous manganese salt solution or slurry is preferably set to the above range during the crystallization step. It is preferable to reduce the variation in pH of the aqueous manganese salt solution or slurry during the crystallization process. Specifically, the pH is maintained in the range of the center value ± 0.5, more preferably in the range of the center value ± 0.3, and still more preferably in the range of the center value ± 0.1.

  In the production method of the present invention, in the crystallization step, the redox potential (hereinafter also simply referred to as “redox potential”) of the aqueous manganese salt solution with respect to the standard hydrogen electrode is preferably 0 mV or more and 300 mV or less, preferably 30 mV or more, More preferably, it is 150 mV or less. By making the oxidation-reduction potential of the manganese salt aqueous solution within this range, it becomes difficult to produce manganese hydroxide. Furthermore, when the oxidation-reduction potential of the manganese salt aqueous solution is set to 300 mV or less, γ-MnOOH having a needle-like particle form is hardly generated as a by-product, and the filling property of the resulting manganese trioxide is likely to be higher.

  It is preferable that the oxidation-reduction potential of the manganese salt aqueous solution or slurry in the crystallization step is within the above range during the crystallization step. It is preferable to reduce the variation in redox potential of the aqueous manganese salt solution or slurry during the crystallization process. Specifically, the oxidation-reduction potential is preferably maintained in the range of the central value ± 50 mV, more preferably the central value ± 30 mV, and still more preferably the central value ± 20 mV.

  In the crystallization step, crystallization is carried out with the pH, oxidation-reduction potential, or both in the above-mentioned range, and the variation range of pH, oxidation-reduction potential, or both is reduced, so that the quaternary oxidation with uniform particle size Manganese can be obtained. The thus obtained trimanganese tetraoxide has a high filling property, and easily reacts uniformly with the lithium compound.

  Manganese sources of manganese salt solution include manganese sulfate, chloride, nitrate, and acetate aqueous solutions, and manganese metals and oxides dissolved in various acid aqueous solutions such as sulfuric acid, hydrochloric acid, nitric acid, and acetic acid. Can be used.

  The manganese concentration in the manganese salt aqueous solution can be set arbitrarily. It can be exemplified that the manganese ion concentration is 1 mol / L or more. By setting the manganese ion concentration of the aqueous manganese salt solution to 1 mol / L or more, trimanganese tetraoxide can be obtained efficiently.

  When adjusting pH of manganese salt aqueous solution, it is preferable to use alkaline aqueous solution (henceforth, aqueous alkali solution). Although there is no restriction | limiting in the kind of alkaline aqueous solution, Aqueous solutions, such as sodium hydroxide and potassium hydroxide, can be illustrated.

  The concentration of the alkali metal or alkaline earth metal in the alkaline aqueous solution may be 1 mol / L or more.

  In the production method of the present invention, in the crystallization step, the temperature of the manganese salt aqueous solution is 60 ° C. or higher and 95 ° C. or lower, preferably 70 ° C. or higher and 80 ° C. or lower. By setting the temperature of the manganese salt aqueous solution at the time of crystallization within this range, the particle size of the trimanganese tetroxide composition is likely to be uniform.

  In the production method of the present invention, the reaction time is preferably long in the crystallization step. Thereby, not only the filling property of trimanganese tetroxide is improved, but also impurities tend to be lowered.

  In the production method of the present invention, it is preferable to perform crystallization using an oxidizing agent in the crystallization step. Examples of the oxidizing agent include gas oxidizing agents such as oxygen-containing gas, and liquid oxidizing agents such as hydrogen peroxide. From the viewpoint of simplifying operability, the oxidizing agent is preferably a gaseous oxidizing agent, more preferably an oxygen-containing gas, and even more preferably air. Further, it is more preferable to perform crystallization by blowing a gaseous oxidant into an aqueous manganese salt solution. Thereby, crystallization of trimanganese tetraoxide is likely to occur more uniformly.

  In the production method of the present invention, it is preferable to mix a manganese salt aqueous solution and an alkaline aqueous solution in the crystallization step.

  The mixing method of the manganese salt aqueous solution and the alkaline aqueous solution is not particularly limited as long as both can be uniformly mixed. Examples of the mixing method include a method in which an alkaline aqueous solution is added to a manganese salt aqueous solution and mixing, a method in which a manganese salt aqueous solution and an alkaline aqueous solution are added to a solvent such as pure water, and the like. From the viewpoint of sufficiently and uniformly reacting the manganese salt aqueous solution and the alkaline aqueous solution, the mixing method is preferably a method in which the manganese salt aqueous solution and the alkaline aqueous solution are added to a solvent and mixed.

  In the production method of the present invention, trimanganese tetraoxide is directly crystallized from an aqueous manganese salt solution. Therefore, there is no need to change the reaction atmosphere during the process. Therefore, trimanganese tetraoxide can be produced directly and continuously from the aqueous manganese salt solution. Furthermore, since trimanganese tetroxide is directly crystallized, the resulting trimanganese tetroxide tends to have a high density.

  In the production method of the present invention, it is preferable to perform crystallization without coexisting a complexing agent in the crystallization step. The complexing agent in this specification has the complexing ability similar to these besides ammonia, ammonium salt, hydrazine, and EDTA.

  These complexing agents affect the crystallization behavior of trimanganese tetraoxide. Therefore, manganese trioxide obtained in the presence of a complexing agent has powder properties such as packing property and particle size even if the manganese trioxide obtained without using a complexing agent has the same composition. Different.

  In the production method of the present invention, a metal compound is deposited on trimanganese tetraoxide obtained by the above method.

  Precipitation of the metal compound is preferably performed by mixing a slurry containing trimanganese tetraoxide, a metal salt aqueous solution, and an alkali aqueous solution.

  Examples of the aqueous metal salt solution include aqueous solutions of various metal sulfates, chlorides, nitrates, acetates, and the like. Moreover, what melt | dissolved various metals or its oxides in various acid aqueous solution, such as a sulfuric acid, hydrochloric acid, nitric acid, and an acetic acid, can be used conveniently.

  The metal of the metal salt aqueous solution is preferably a metal element other than manganese (Mn), and Mg, Al, Si, Ca, Ti, V, Cr, Co, Ni, Cu, Zn, Ga, Ge, Zr, Mo , Ag, In, and Sn are preferably at least one selected from the group of compounds. By containing these metal compounds, the battery characteristics of the lithium composite oxide using the obtained trimanganese tetroxide composition as a raw material can be easily improved.

  From the viewpoint of improving charge / discharge cycle characteristics and battery characteristics at high temperatures when a lithium composite oxide is produced, the metal of the metal salt aqueous solution is more preferably at least one of cobalt and nickel, and is cobalt and nickel. It is preferable.

  The concentration of the metal salt aqueous solution is preferably 1 mol / L or more as the metal ion concentration from the viewpoint of productivity.

  Examples of the alkaline aqueous solution include aqueous solutions of sodium hydroxide, potassium hydroxide, ammonia and the like. For simplicity, the aqueous alkali solution is preferably an aqueous sodium hydroxide solution. Moreover, the concentration of the aqueous alkali solution can be exemplified by 1 mol / L or more as the hydroxide concentration.

  In the production method of the present invention, a metal compound is deposited on trimanganese tetraoxide by mixing a slurry containing trimanganese tetraoxide, a metal salt aqueous solution, and an alkali aqueous solution.

  In order to increase the filling property of the metal compound composition, the mixing temperature is preferably 40 ° C. or higher, and more preferably 60 ° C. or higher. The reaction time is preferably 1 hour or longer.

  The pH for precipitating the metal compound on trimanganese tetraoxide is arbitrary, and examples include pH of 7.5 or more and 10 or less.

  The method for producing a lithium composite oxide of the present invention includes a mixing step of mixing the above-described metal compound composition and at least one of lithium and a lithium compound, and a heating step of heat treatment.

  Any lithium compound may be used. Examples of the lithium compound include lithium hydroxide, lithium oxide, lithium carbonate, lithium iodide, lithium nitrate, lithium oxalate, and alkyl lithium. Examples of preferable lithium compounds include lithium hydroxide, lithium oxide, and lithium carbonate.

  The metal compound composition of the present invention can be used as a raw material for a lithium composite oxide that is a positive electrode active material for a lithium ion secondary battery. Since no complexing agent, reducing agent, atmosphere control or the like is required when producing this lithium composite oxide, the lithium composite oxide can be produced by a simple method.

XRD diagram of the nickel-cobalt hydroxide-containing trimanganese tetraoxide composition of Example 1 Particle size distribution of nickel-cobalt hydroxide-containing trimanganese tetroxide composition of Example 1 XRD diagram of the trimanganese tetraoxide of Example 1 XRD diagram of the lithium composite oxide of Example 1 XRD diagram of lithium composite oxide of Comparative Example 2

  EXAMPLES Hereinafter, although an Example demonstrates this invention further in detail, this invention is not limited by these Examples.

(Measurement of chemical composition)
The chemical composition was measured using ICP emission analysis.

(Identification of crystal phase)
The crystal phase was evaluated using a general X-ray diffractometer (MXP-3 manufactured by Mac Science). A CuKα ray (λ = 1.5405 mm) is used as the radiation source, the measurement mode is step scan, the scan condition is 0.04 ° per second, the measurement time is 3 seconds, and the measurement range is 2 ° to 5 ° to 100 ° Measured with

(Particle size distribution measurement)
The particle size distribution of the trimanganese tetroxide and the trimanganese tetroxide composition used as raw materials was measured as follows. 0.5 g of the sample was put into 50 mL of aqueous ammonia and ultrasonically irradiated for 10 seconds to obtain a dispersion slurry. A predetermined amount of the dispersed slurry was put into Microtrac HRA (manufactured by HONEWELL), and volume distribution was measured by a laser diffraction method. From the obtained volume distribution, the volume particle size was determined, the particle size distribution was evaluated, the mode particle size was determined, and this was taken as the average particle size.

(Battery performance evaluation)
The battery characteristic test as a positive electrode of lithium composite oxide was conducted.

A mixture of lithium composite oxide, polytetrafluoroethylene as a conductive agent, and acetylene black (trade name: TAB-2) is mixed at a weight ratio of 4: 1 and meshed at a pressure of 1 ton / cm ² (SUS316). Made into a pellet and dried under reduced pressure at 150 ° C. to produce a positive electrode for a battery. Electrolysis in which lithium hexafluorophosphate was dissolved in a mixed solvent of ethylene carbonate and diethyl carbonate at a concentration of 1 mol / dm ^{3 in} the obtained positive electrode for a battery, a negative electrode comprising a metal lithium foil (thickness 0.2 mm), and A battery was constructed using the liquid. Using the battery, the battery voltage was charged and discharged at a constant current between 4.3 V and 2.5 V at room temperature. The discharge capacity at the first charge and discharge 10 times was evaluated.

Example 1
[Production of complex oxides]
Manganese sulfate (manufactured by Wako Pure Chemicals, reagent special grade) was dissolved in pure water to obtain a raw material solution containing 2 mol / L manganese sulfate.

  The obtained raw material solution was added to 80 ° C. pure water, thereby obtaining a reaction slurry in which manganese oxide was crystallized. In addition, the raw material solution was added by blowing air so that the oxidation-reduction potential of the reaction slurry was 100 mV, and adding a 2 mol / L sodium hydroxide aqueous solution so that the pH of the reaction slurry was constant at 8.0. I went there. After the addition of the raw material solution, the reaction slurry was stirred for 1 hour.

  After stirring, a part of the reaction slurry was collected and filtered, washed and dried to obtain manganese oxide. The obtained manganese oxide has a JCPDS pattern No. of the crystal phase corresponding to the spinel structure. It was a pattern equivalent to the X-ray diffraction pattern of 24-734, and x = 1.33 when the composition was expressed by MnOx. Thereby, it was found that the manganese oxide was trimanganese tetraoxide.

  Next, nickel sulfate (manufactured by Wako Pure Chemicals, reagent grade) and cobalt sulfate (manufactured by Wako Pure Chemicals, reagent special grade) are dissolved in pure water, and a composite raw material solution containing 2 mol / L nickel sulfate and 2 mol / L cobalt sulfate Was prepared. The Ni / Co molar ratio in the composite raw material solution was 1.

  A composition was obtained by adding 67.2 g of the composite raw material solution to the stirred reaction slurry containing the above-described trimanganese tetraoxide. The composite raw material solution was added while adding a 2 mol / L sodium hydroxide aqueous solution to the reaction slurry so that the pH of the reaction slurry was constant at 7.5.

  After the addition of the composite raw material solution, the reaction slurry was stirred for 1 hour, then the reaction slurry was filtered and washed, and the resulting composition was dried at 110 ° C. to obtain the trimanganese tetraoxide composition of Example 1. .

  The trimanganese tetroxide composition of Example 1 contains 21.1% by weight of Ni, 21.6% by weight of Co, and 20.4% by weight of Mn as metal elements, and the Ni / Co / Mn molar ratio = 1. 0.0 / 1.0 / 1.0.

  Further, in the trimanganese tetroxide composition, the crystal phase contained trimanganese tetroxide (Hausmannite, space group I41 / amd) and nickel cobalt composite hydroxide (layered structure, space group P -3 m 1). .

From these results, the trimanganese tetroxide composition of Example 1 is a nickel-cobalt hydroxide-containing trimanganese tetroxide composition comprising Ni _0.5 Co _0.5 (OH) ₂ and Mn ₃ O ₄ . I found out that Furthermore, the nickel-cobalt hydroxide-containing trimanganese tetroxide composition was found to be agglomerated particles in which primary particles of nickel-cobalt hydroxide were agglomerated on the trimanganese tetroxide particles.

  The evaluation results of the nickel-cobalt hydroxide-containing trimanganese tetraoxide composition of Example 1 are shown in Table 1, the XRD diagram is shown in FIG. 1, and the particle size distribution is shown in FIG. Moreover, the XRD figure of the trimanganese tetraoxide obtained in Example 1 is shown in FIG.

[Production of lithium composite oxide]
After mixing the obtained nickel-cobalt hydroxide-containing trimanganese tetraoxide composition and lithium carbonate having an average particle size of 0.3 μm so that the Li / (Ni + Co + Mn) molar ratio = 1.05, The lithium composite oxide was obtained by firing at 900 ° C. for 24 hours.

The obtained lithium composite oxide has a composition of Li _1.04 Ni _0.33 Co _0.33 Mn _0.34 O _2.0 and a single phase having a crystal phase of a layered rock salt structure (space group R-3m). Met.

  As a result of evaluating the battery characteristics of the obtained lithium composite oxide, the initial discharge capacity was 150.0 mAh / g, and the 10th discharge capacity was 148.5 mAh / g. The volume ratio of the first time and the 10th time was 99.0%.

  The evaluation results of the lithium composite oxide of Example 1 are shown in Table 2, and the XRD diagram is shown in FIG.

Comparative Example 1
Nickel sulfate (Wako Pure Chemical Industries, reagent special grade) and cobalt sulfate (Wako Pure Chemical Industries, reagent special grade) were dissolved in pure water to prepare a raw material solution containing 2 mol / L nickel sulfate and 2 mol / L cobalt sulfate. . The Ni / Co molar ratio in the raw material solution was 1.

  67.3 g of the obtained raw material solution was added to 80 ° C. pure water to precipitate a coprecipitation compound, thereby obtaining a reaction slurry. The raw material solution was added while adding a 2 mol / L sodium hydroxide aqueous solution to the pure water (reaction slurry) so that the pH of the pure water (reaction slurry) was 8.0. After the addition of the raw material solution, the reaction slurry was stirred for 1 hour.

After stirring, filtration, washing, and drying were performed to obtain a dry powder of the coprecipitated compound. The obtained dry powder has a composition of Ni / Co molar ratio = 1: 1, a crystal phase of a layered structure (space group P-31m), and represented by Ni _0.5 Co _0.5 (OH) _2. It was found to be a nickel cobalt composite hydroxide. As a result of SEM observation, it was found that the nickel-cobalt composite oxide has a plate-like form.

The obtained nickel cobalt composite hydroxide, Mn ₃ O ₄ powder (trade name: Brownox, manufactured by Tosoh Corporation) and lithium carbonate were mixed with Li / (Ni + Co) / Mn molar ratio = 1.05 / (0.33 + 0). .33) /0.34 and mixed in air at 900 ° C. for 24 hours to obtain a lithium composite oxide.

The obtained lithium composite oxide had a composition of Li _1.03 Ni _0.33 Co _0.33 Mn _0.34 O _X. In addition, the lithium composite oxide has a layered rock salt structure (space group R-3m) as a main phase and a mixture containing Li ₂ MnO ₃ (space group C2 / m) and NiO. I understood.

  As a result of evaluating the battery characteristics of the obtained lithium composite oxide, the initial discharge capacity was 126.0 mAh / g, and the 10th discharge capacity was 70.7 mAh / g. The volume ratio of the first time and the 10th time was 56.1%.

  The evaluation results of the lithium composite oxide of Comparative Example 1 are shown in Table 2, and the XRD diagram is shown in FIG.

Comparative Example 2
Nickel chloride (Wako Pure Chemicals, reagent special grade), cobalt chloride (Wako Pure Chemicals, reagent special grade), and manganese chloride (Wako Pure Chemicals, reagent special grade) are dissolved in pure water and 0.5 mol / L of chloride is dissolved. A raw material solution containing nickel, 0.5 mol / L cobalt chloride, and 0.5 mol / L manganese chloride was obtained.

  The obtained raw material solution was added to pure water at 60 ° C., thereby obtaining a reaction slurry in which a coprecipitated hydroxide was precipitated. The raw material solution was added while adding a 3 mol / L sodium hydroxide aqueous solution to the pure water (reaction slurry) so that the pH of the pure water (reaction slurry) was constant at 9.0.

  The obtained coprecipitate compound slurry was filtered, washed with pure water, and dried to obtain a coprecipitate compound of Comparative Example 2.

The obtained coprecipitated compound had a composition of Ni: Co: Mn molar ratio = 1: 1: 1, and the crystal phase had a layered structure. From these results, it was found that the coprecipitated compound was a nickel-cobalt-manganese composite hydroxide represented by Ni _1/3 Co _1/3 Mn _1/3 (OH) ₂ . The particle size distribution curve showed a sharp single peak, and the mode particle size was 13 μm. The tap density was 1.5 g / cc.

[Production of lithium composite oxide]
The obtained nickel-cobalt-manganese composite hydroxide and lithium carbonate were mixed so that the Li / (Ni + Co + Mn) molar ratio = 1.05 / 1, and calcined in the atmosphere at 900 ° C. for 12 hours to form a lithium composite. An oxide was obtained.

The obtained lithium composite oxide has a composition of Li _1.04 [Ni _0.33 Mn _0.34 Co _0.33 ] O ₂ , and its crystal structure is a single layered rock salt structure (space group R-3m). It was a phase.

  As a result of battery performance evaluation of the obtained lithium composite oxide, the initial discharge capacity was 150 mAh / g, and the 10th discharge capacity was 148.0 mAh / g. The volume ratio of the first time and the 10th time was 98.7%.

  The evaluation results of the lithium composite oxide of Comparative Example 2 are shown in Table 2, and the XRD diagram is shown in FIG.

  From the results of Examples and Comparative Examples, the lithium-based composite oxide obtained using the trimanganese tetraoxide composition of the present invention was compared with the lithium composite oxide obtained by solid-phase mixing or coprecipitation method. However, not only the initial discharge capacity was large, but also the charge / discharge cycle life was high.

Claims (6)

The metal compounds possess a surface, trimanganese tetraoxide and ratio of the metal in the metal compound (Mn / Me) in a molar ratio of 4/1 to 1/4: (Me metal in the metal compound), an average particle A trimanganese tetraoxide composition having a diameter exceeding 5 μm . The metal compound is at least one compound selected from the group consisting of Mg, Al, Si, Ca, Ti, V, Cr, Co, Ni, Cu, Zn, Ga, Ge, Zr, Mo, Ag, In, and Sn. The trimanganese tetraoxide composition according to claim 1. The trimanganese tetroxide composition according to claim 1 or 2, wherein the metal compound is at least one selected from the group consisting of nickel hydroxide, cobalt hydroxide and nickel-cobalt composite hydroxide. It is a manufacturing method of the trimanganese tetroxide composition as described in any one of Claims 1 thru | or 3 , Comprising: Manganese tetroxide is crystallized from the manganese salt aqueous solution containing a manganese ion without going through a manganese hydroxide. crystallization step of analysis, have a step of depositing a metal compound on the trimanganese tetraoxide, the pH of the water-soluble manganese salt solution and 0~300mV the redox potential for pH6~pH9 and standard hydrogen electrode potential, in a manganese salt solution A method for producing a trimanganese tetroxide composition characterized by crystallizing trimanganese tetroxide with a manganese ion concentration of 1 mol / L or more . The method for producing a trimanganese tetroxide composition according to claim 4, wherein an oxygen-containing gas is blown into the manganese salt aqueous solution. A method for producing a lithium composite oxide, comprising: a mixing step of mixing the trimanganese tetroxide composition according to any one of claims 1 to 3 and a lithium compound; and a heating step of heat treatment.

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