JP6221309B2 - Metal compound composition and method for producing the same - Google Patents

Description

  The present invention relates to a metal compound composition that is a raw material for a lithium composite oxide that is a positive electrode active material of a lithium secondary battery.

  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 metal compound 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, it has been found that a composition having a structure in which manganese oxide is deposited on metal compound particles is suitable as a raw material for obtaining a lithium manganese composite oxide having a high charge / discharge cycle life. Furthermore, it has been found that such a metal chemical composition can be easily produced by crystallizing trimanganese tetraoxide under specific conditions.

  Hereinafter, the metal compound composition of the present invention will be described.

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

  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 metal compound composition of the present invention is a so-called composite particle, which is a secondary particle in which the metal compound particle and the trimanganese tetroxide particle are not separated even when dispersed in a solvent. Therefore, for example, a mixture obtained by physical mixing such as mixing trimanganese tetroxide particles and metal compound particles is different from the metal compound composition of the present invention, that is, the metal compound composite particles of the present invention. .

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

  The metal of the metal compound particles is a metal element other than manganese (Mn), more preferably manganese and 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 (Zr) ), Molybdenum (Mo), silver (Ag), indium (In), and tin (Sn), preferably at least one compound selected from the group consisting of at least two compounds selected from the above group. It is preferable. By containing 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 particles are particles of a composite metal compound composed of a plurality of metals, the ratio of each metal is arbitrary. For example, when the metal oxide particles are nickel-cobalt composite metal compound particles, the molar ratio of nickel / cobalt may be 1/5 to 5/1, and further 4/5 to 6/5.

  The metal compound composition of the present invention has trimanganese tetraoxide on its surface. Here, trimanganese tetraoxide has a Hausmannite type crystal structure, and is attributed to the space group I41 / amd.

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

  In the metal compound composition of the present invention, one of the existence forms of trimanganese tetroxide is a so-called core-shell structure constituted by the presence of trimanganese tetroxide on the surface of a single metal compound particle. In such a presence form, by using a porous metal compound, trimanganese tetraoxide can be dispersed into the pores of the metal oxide particles. Therefore, the metal oxide particles contained in the metal compound composition of the present invention are preferably porous.

  The metal compound composition of the present invention preferably has an average particle diameter of more than 5 μm, more preferably 10 μm or more. Thereby, trimanganese tetraoxide is easily dispersed on the metal compound particles. 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 metal compound 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 metal compound composition of this invention is demonstrated.

  The trimanganese tetraoxide composition of the present invention passes through manganese hydroxide from a manganese salt aqueous solution (hereinafter referred to as “particle-containing manganese salt aqueous solution”) containing metal compound particles and manganese ions having an average particle diameter of more than 5 μm. Without being produced by a production method having a crystallization step of crystallizing trimanganese tetraoxide.

  In the above-described step, that is, the step of crystallizing manganese tetroxide from the aqueous manganese salt solution without passing through the manganese hydroxide, manganese hydroxide crystals are precipitated in the alkaline region from the aqueous manganese salt solution. Without making it, a metal compound composition is produced by crystallizing trimanganese tetraoxide on the metal compound particles.

  Therefore, the method for producing a metal compound composition of the present invention comprises depositing a manganese hydroxide in an alkaline region from a particle-containing manganese salt aqueous solution and oxidizing the manganese hydroxide with an oxidizing agent without passing through the steps of oxidizing the manganese hydroxide. Manufacturing things.

  In addition, in the method for producing the metal compound composition of the present invention, the crystal phase of manganese hydroxide is not generated at all in the crystallization step, and after the microcrystals of the hydroxide are precipitated for a short time, The embodiment includes conversion to trimanganese tetraoxide before growing into a plate-like crystal. That is, the method for producing a metal compound composition of the present invention is characterized in that hexagonal plate-like manganese hydroxide crystals are not produced in the crystallization step.

  Whether or not hexagonal plate-like manganese hydroxide crystals have occurred depends on the difference in the particle shape of the obtained metal compound particles and the particle shape of the metal compound composition, that is, the amount of manganese trioxide on the metal compound particles. This can be determined by observing the particle shape.

  In the production method of the present invention, the pH of the particle-containing manganese salt aqueous solution or the pH of the slurry when crystallizing trimanganese tetraoxide is preferably set to a pH at which manganese hydroxide is difficult to be generated. It is more preferable to set it to pH up to.

  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 particle-containing manganese salt aqueous solution or slurry within this range, it becomes difficult to produce manganese hydroxide.

  The pH of the particle-containing manganese salt aqueous solution or slurry is preferably in the above range during the crystallization step. It is preferable to reduce the variation in pH of the particle-containing manganese salt aqueous solution or slurry during the crystallization step. 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 oxidation-reduction potential (hereinafter also simply referred to as “oxidation-reduction potential”) with respect to the standard hydrogen electrode of the aqueous manganese salt solution containing particles when crystallizing trimanganese tetraoxide is 0 mV or more. 300 mV or less, more preferably 30 mV or more and 150 mV or less. By making the oxidation-reduction potential of the particle-containing manganese salt aqueous solution within this range, it becomes difficult to produce manganese hydroxide. Furthermore, by setting the oxidation-reduction potential of the aqueous manganese salt solution containing particles 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 trimanganese tetraoxide composition is higher. Prone.

  The oxidation-reduction potential of the particle-containing manganese salt aqueous solution or slurry in the crystallization step is preferably in the above range during the crystallization step. It is preferable to reduce the variation in oxidation-reduction potential of the particle-containing manganese salt aqueous solution or slurry during the crystallization step. 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 a uniform particle size is achieved. A manganese composition can be obtained. The metal compound composition obtained in this way has a high filling property and easily reacts uniformly with the lithium compound.

  The particle-containing manganese salt aqueous solution contains manganese ions. Particle-containing manganese salt aqueous solution is an aqueous solution of manganese sulfate, chloride, nitrate and acetate, or manganese metal or oxide dissolved in various acid aqueous solutions such as sulfuric acid, hydrochloric acid, nitric acid and acetic acid Etc. can be used.

  The concentration in the particle-containing manganese salt aqueous solution can be set arbitrarily, but the manganese ion concentration can be exemplified as 1 mol / L or more. By setting the manganese ion concentration of the particle-containing manganese salt aqueous solution to 1 mol / L or more, a metal compound composition in which trimanganese tetraoxide is uniformly dispersed on the metal compound particles can be efficiently obtained.

  The particle-containing manganese salt aqueous solution contains metal compound particles in addition to manganese ions.

  The metal compound particles preferably have an average particle diameter of more than 5 μm and 10 μm or more. When the average particle size is 5 μm or less, the manganese trioxide becomes a single particle in a state in which a plurality of metal compound particles are taken in when the manganese trioxide crystallizes. Therefore, not only the composition of the obtained metal compound composition is not uniform, but also the density of the metal compound composition is lowered. The upper limit of the average particle diameter of the metal compound particles can be arbitrarily selected depending on the particle diameter of the target metal compound composition. For example, the upper limit of the average particle diameter can be 20 μm or less.

The metal compound particles preferably have a BET specific surface area of 10 m ² / g or more, and more preferably 15 m ² / g or more. When the BET specific surface area is 10 m ² / g or more, trimanganese tetraoxide is easily deposited on the metal compound particles.

  From the viewpoint of facilitating the precipitation and precipitation of trimanganese tetraoxide on the metal compound particles, the metal compound particles are preferably porous. For example, examples of the porous metal compound particles include secondary particles in which plate crystals are aggregated.

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

  The metal of the metal compound particles is preferably a metal element other than manganese (Mn), more preferably other than Mn and Li, Mg, Al, Si, Ca, Ti, V, Cr, Co, Ni, More preferably, it is at least one selected from the group of compounds of Cu, Zn, Ga, Ge, Zr, Mo, Ag, In, and Sn. By containing these metal compounds, the battery characteristics of the lithium manganese composite oxide obtained using the trimanganese tetraoxide 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 manganese 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 particles are a composite metal compound composed of a plurality of metals, the ratio of each metal is arbitrary. For example, when the metal oxide particles are 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.

  As the metal compound particles used in the production method of the present invention, any particles can be used as long as they have the above physical properties.

  Particularly preferred metal compound particles include metal hydroxide particles obtained by precipitation from metal salt aqueous solutions containing various metal ions.

  Precipitation of the metal hydroxide particles can be performed by adding an aqueous alkali solution to the aqueous metal salt solution.

  Examples of the aqueous metal salt solution include aqueous solutions such as sulfates, chlorides, nitrates and acetates, and metals and metal oxides dissolved in various acid aqueous solutions such as sulfuric acid, hydrochloric acid, nitric acid and acetic acid. . Moreover, as aqueous alkali solution, aqueous solution, such as sodium hydroxide, potassium hydroxide, ammonia, can be illustrated.

  The conditions for the precipitation of the metal hydroxide include a temperature of 40 ° C. or higher and a pH of 7.5 to 10 in an arbitrary atmosphere such as an air atmosphere or a nitrogen atmosphere. Furthermore, from the viewpoint of increasing the filling properties of the metal hydroxide particles, the reaction time is preferably 1 hour or longer.

  In the production method of the present invention, it is preferable to use an alkaline aqueous solution (hereinafter referred to as an alkaline aqueous solution) when adjusting the pH of the particle-containing manganese salt aqueous solution in the crystallization step. 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 particle-containing manganese salt aqueous solution may be 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 particle-containing manganese salt aqueous solution at the time of crystallization within this range, a metal compound composition can be obtained without agglomeration of metal compound part particles. Therefore, the particle diameter of the metal compound composition tends to be uniform.

  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. Furthermore, it is more preferable to crystallize the gaseous oxidant by blowing it into the particle-containing manganese salt aqueous 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 the aqueous manganese salt solution and the aqueous alkali solution in the crystallization step.

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

  In the production method of the present invention, trimanganese tetraoxide is directly crystallized on individual metal compound particles from a particle-containing manganese salt aqueous solution. Therefore, there is no need to change the reaction atmosphere during the process. Therefore, the metal compound composition can be produced directly and continuously from the particle-containing manganese salt aqueous solution.

  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, the metal compound composition obtained in the presence of the complexing agent has powder physical properties such as filling property and particle size even if the metal compound composition obtained without using the complexing agent has the same composition. Different.

  The method for producing a metal compound composition of the present invention may include a firing step in which the obtained metal compound composition is fired to convert manganese trioxide to manganese trioxide.

  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.

  Furthermore, the production method of the present invention does not require a complexing agent, a reducing agent, an atmosphere control, and the like, and can produce a metal compound composition by a simpler method compared to conventional raw materials for lithium composite oxides. .

3 is a particle size distribution of the trimanganese tetraoxide-containing nickel-cobalt composite hydroxide of Example 1. FIG. X-ray powder diffraction pattern of trimanganese tetraoxide-containing nickel-cobalt composite hydroxide of Example 1 SEM observation result of nickel-cobalt composite hydroxide containing trimanganese tetraoxide of Example 1 (scale in the figure is 1 μm) SEM observation result of nickel-cobalt composite hydroxide obtained in Example 1 (scale in the figure is 1 μm) Powder X-ray diffraction pattern of lithium composite oxide of Example 1

  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 of the sample was measured using ICP emission analysis.

(Identification of crystal phase)
The crystal phases of the transition metal composite hydroxide, the metal compound, and the lithium manganese dissimilar metal composite oxide were 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 metal compound and metal compound 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.

(Tap density measurement)
A transition metal composite hydroxide or 2 g of lithium manganese dissimilar metal composite oxide was filled in a 10 ml glass graduated cylinder and manually tapped 200 times. The tap density was calculated from the weight and the volume after tapping.

(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 composite metal compounds]
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. Thereby, 99.9% of nickel and cobalt in the raw material solution were precipitated as a coprecipitation compound.

A part of the reaction slurry was collected, filtered, washed and dried 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. Further, as a result of SEM observation, it was found that the composite oxide formed particles by aggregation of plate-like particles.

  On the other hand, a composite coprecipitate was obtained by adding 32.8 g of a 2 mol / L aqueous manganese sulfate solution to the reaction slurry containing nickel cobalt composite hydroxide after stirring. The addition of the manganese sulfate aqueous solution is performed by blowing oxygen gas into the reaction slurry so that the oxidation-reduction potential in the reaction slurry is 100 ± 20 mV, and 2 mol / wt so that the pH of the reaction slurry is constant at 7.0. L was added while adding an aqueous sodium hydroxide solution to the reaction slurry.

  After the addition of the manganese sulfate solution, the reaction slurry is stirred for 1 hour, and then the reaction slurry is filtered and washed, and the resulting composite coprecipitate is dried at 110 ° C. to obtain the composite metal compound composition of Example 1. Obtained.

  The composite metal compound composition of Example 1 contains 21.1% by weight of Ni, 21.2% by weight of Co, and 20.3% by weight of Mn as metal elements, and the Ni / Co / Mn molar ratio = 1. It was 0 / 1.0 / 1.0.

  Furthermore, the crystal phase of the composite metal compound composition is a mixed phase of manganese trioxide (Hausmannite, space group I41 / amd) and nickel cobalt composite hydroxide (layered structure, space group P -3 m 1). I found out.

Furthermore, as a result of SEM observation, amorphous particles were confirmed on the plate-like nickel-cobalt composite hydroxide. From these results, the composite metal compound of Example 1 is a trimanganese tetraoxide-containing nickel-cobalt composite hydroxide in which Mn ₃ O ₄ is deposited on Ni _0.5 Co _0.5 (OH) _2. Was confirmed. Further, in the nickel-cobalt composite hydroxide containing trimanganese tetraoxide, agglomeration of trimanganese tetraoxide with a primary particle diameter of 1 μm or less aggregated on the surface of the secondary particles of the plate-like nickel-cobalt composite hydroxide. It turned out to be a particle.

  The evaluation results of the trimanganese tetraoxide-containing nickel cobalt composite hydroxide of Example 1 are shown in Table 1, the particle size distribution is shown in FIG. 1, the XRD diagram is shown in FIG. 2, and the SEM observation result is shown in FIG.

  Moreover, the SEM observation result of the nickel cobalt composite hydroxide obtained in Example 1 is shown in FIG.

[Production of lithium composite oxide]
The obtained tribasic manganese tetraoxide-containing nickel cobalt composite hydroxide and lithium carbonate having an average particle size of 0.3 μm were mixed so that the Li / (Ni + Co + Mn) molar ratio = 1.05, and then 900 ° C. in the atmosphere. And calcined for 24 hours to obtain a lithium composite oxide.

The obtained lithium composite oxide has a composition of Li _1.03 Ni _0.33 Co _0.33 Mn _0.34 O _2.0 and a single phase having a layered rock-salt structure (space group R-3m). The tap density was 2.0 g / cm ³ .

  As a result of evaluating the battery characteristics of the obtained lithium composite oxide, the initial discharge capacity was 158.5 mAh / g, and the 10th discharge capacity was 156.9 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
Mn ₃ O ₄ powder (trade name: Brownox, manufactured by Tosoh Corporation), nickel-cobalt composite hydroxide obtained in Example 1, and lithium carbonate, Li / (Ni + Co) / Mn molar ratio = 1. It mixed so that it might become 05 / (0.33 + 0.33) /0.34, and it baked at 900 degreeC in air | atmosphere for 24 hours, and obtained lithium complex 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 had a layered rock salt structure (space group R-3m), but was a mixture containing Li ₂ MnO ₃ (space group C2 / m) and NiO.

  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.

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 average particle size was 8.5 μm.

  The evaluation results of the nickel-cobalt-manganese composite hydroxide of Comparative Example 2 are shown in Table 1.

[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 had a composition of Li _1.04 [Ni _0.33 Mn _0.34 Co _0.33 ] O ₂ . The lithium composite oxide was found to have a layered rock salt structure (space group R-3m) in the crystal phase. The particle size distribution was wide and the tap density was 2.84 g / cm ³ .

  As a result of battery performance evaluation of the obtained lithium composite oxide, the initial discharge capacity was 150.0 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.

  From the results of Examples and Comparative Examples, the lithium-based composite oxide obtained using the metal compound composition of the present invention was compared with the lithium-based composite oxide obtained by dry mixing or coprecipitation method. The charge / discharge cycle life was also high. Furthermore, the lithium composite oxide of the example had a larger initial discharge capacity than the lithium composite oxide of comparative example 2. Thereby, it turned out that the lithium composite oxide obtained by using the metallized compound composition of the present invention increases not only the charge / discharge cycle life but also the discharge capacity.

Claims (6)

Have a trimanganese tetraoxide the surface, forty-three ratio of the metal in the manganese oxide and the metal compound (Mn / Me) are in a molar ratio of 4/1 to 1/4: (Me metal in the metal compound) metal Compound composition. The metal compound composition according to claim 1, wherein the metal compound is a compound containing at least one of nickel and cobalt. The metal compound composition according to claim 1 or 2, wherein the metal compound is a hydroxide. The metal compound composition according to any one of claims 1 to 3, wherein an average particle diameter exceeds 5 µm. A method for producing a metal compound composition according to any one of claims 1 to 4, wherein the metal compound particles having an average particle diameter exceeding 5 µm and a manganese salt aqueous solution containing manganese ions are passed through a manganese hydroxide. production of trimanganese tetraoxide have a crystallization step to crystallize the metal compound composition to crystallize the trimanganese tetraoxide manganese ion concentration manganese salt in an aqueous solution containing manganese ions as above 1 mol / L without Method. A method for producing a lithium composite oxide, comprising: a mixing step of mixing the metal compound composition according to any one of claims 1 to 4 and a lithium compound; and a heating step of heat treatment.

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