JP2017105690A - Nickel-manganese-titanium-based composite composition, manufacturing method therefor and application thereof - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a nickel-manganese-titanium-based composite composition stable in ambient air without generating segregation of a manganese component in general processes such as co-precipitation, washing and drying.SOLUTION: There is provided a nickel-manganese-titanium-based composite oxyhydroxide having a chemical composition represented by NiM1MnM2OOH, where M1 and M2 represent respectively one kind selected from Mg, Al, Ti, V, Cr, Fe, Co, Cu, Zn and Zr, 0≤x≤0.1, 0≤y≤0.25 and -0.025≤α≤0.025, and containing a nickel-manganese-based composite oxyhydroxide of which a crystal structure is a cadmium oxide type structure and titanium oxide, a manufacturing method thereof and an application thereof.SELECTED DRAWING: Figure 1

Description

  TECHNICAL FIELD The present invention relates to a nickel-manganese-titanium composite composition, a method for producing the same, and its use, and more specifically, nickel-manganese- suitable as a precursor of a lithium-nickel-manganese-titanium composite oxide. Titanium-based composite composition, lithium-nickel-manganese-titanium-based composite oxide obtained using the nickel-manganese-titanium-based composite composition, and lithium-nickel-manganese-titanium-based composite oxide as a positive electrode The present invention relates to a lithium secondary battery used as a battery.

  A spinel-type lithium-nickel-manganese composite oxide has attracted attention as a positive electrode active material for 5 V class lithium secondary batteries.

  However, when a current lithium ion secondary battery is configured using a lithium-nickel-manganese based composite oxide as a positive electrode, decomposition of the electrolyte at high voltage and elution of metal components of the positive electrode are problematic.

In Non-Patent Document 1 and Patent Document 1, in order to suppress electrolytic solution decomposition and elution of a positive electrode active material constituent element into an electrolytic solution during charge / discharge at a high voltage and prevent battery deterioration, Li [Ni _0.5 lithium was Ti introduced as _{Mn 1.5-x Ti x] O} 4 - nickel - manganese - titanium-based composite oxide is shown to be effective.

Patent Document 2 proposes a nickel-manganese-titanium compound that is a precursor of Li [Ni _0.5 Mn _1.5-x Ti _x ] O ₄ .

  On the other hand, in Patent Document 3, 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. It has been proposed to produce a composite metal hydroxide with a storage time of 48 hours or less until the wet cake is dried.

  In Non-Patent Document 2, a coprecipitate slurry is obtained by bringing an aqueous solution containing Ni and Mn into contact with an alkali, and then the coprecipitate slurry is solid-liquid separated and dried to obtain a composite metal hydroxide. Propose to manufacture.

Japanese Patent No. 4636934 JP-A-2015-845 JP 2011-153067 A

Kim et al, J.A. Powersources, 262 (2014), 62-71 F. Zhou et al. , Chem. Mater. 2010, 22, 1015-1021

The nickel-manganese-titanium precursor of Patent Document 2 is a composite of nickel-manganese composite hydroxide and titanium oxide, but manganese oxide (Mn ₃ O ₄ ) is by-produced. On the other hand, in the nickel-manganese-iron composite hydroxide of Patent Document 3, manganese oxide (Mn ₃ O ₄ ) is by-produced when the co-precipitate slurry is solid-liquid separated and the wet cake is stored for a long period of time. It points out the problem. In addition, when a composite hydroxide containing by-product Mn ₃ O ₄ and a lithium compound are mixed and baked, the product lithium composite metal oxide has a non-uniform composition and battery performance is insufficient. It mentions to become.

Moreover, in the nickel-manganese composite hydroxide of Non Patent Literature 2; Ni _x Mn _1-x (OH) ₂ , manganese oxide (Mn ₃ O ₄ ) is by-produced when the wet cake is dried with x ≦ 1/3. It shows that

  Thus, the nickel-manganese composite hydroxide having a relatively high manganese composition is unstable in the atmosphere, and there is a problem that the Mn component segregates despite the coprecipitate. Therefore, it goes without saying that when compounding with titanium oxide, a stable compound other than hydroxide is desirable.

  The present invention solves these problems and is a composite composition of a composite compound of nickel and manganese and a titanium oxide, which is stable in the atmosphere, and in a general process such as coprecipitation, washing and drying. Thus, it is possible to provide a nickel-manganese-titanium composite composition that does not cause segregation. Further, lithium-nickel-manganese-titanium composite oxide obtained using the nickel-manganese-titanium composite composition, and lithium using the lithium-nickel-manganese-titanium composite oxide as a positive electrode An object is to provide a secondary battery.

The present inventors diligently studied a precursor of a lithium-nickel-manganese-titanium composite oxide. As for the titanium raw material, a product obtained by neutralizing and crystallizing a water-soluble titanium salt such as titanyl sulfate as a raw material has high uniformity of the metal component. However, water-soluble titanium salts are significantly more expensive than titanium oxide. Therefore, it came to the idea of producing a chemically stable nickel-manganese-titanium composite composition by complexing titanium oxide, which is inexpensive, with a stable nickel and manganese component. As a result, if the oxyhydroxide is a similar structure of hydroxide as a nickel or manganese component complexed with titanium oxide, it is stable in the atmosphere even with a relatively high chemical composition of Mn, and stored for a long time. Further, it was found that manganese oxide (Mn ₃ O ₄ ) was not by-produced during drying, and further, a lithium-nickel-manganese-titanium composite oxide using the nickel-manganese-titanium composite composition of the present invention as a precursor As a result, the present inventors have found that a lithium secondary battery using as a positive electrode has high performance and completed the present invention. That is, according to the present invention, the chemical composition formula is Ni _{(0.25 + α) -x} M1 _x Mn _{(0.75-α) -y} M2 _y OOH (where M1 and M2 are Mg, Al, Ti, V, Cr, respectively). , Fe, Co, Cu, Zn, and Zr, and 0 ≦ x ≦ 0.1, 0 ≦ y ≦ 0.25, and −0.025 ≦ α ≦ 0.025). Nickel-manganese-based composite oxyhydroxide having a cadmium hydroxide type crystal structure and a titanium oxide, a nickel-manganese-titanium-based composite composition, its production method, and its use It is.

  Hereinafter, the present invention will be described in detail.

The nickel-manganese composite oxyhydroxide contained in the nickel-manganese-titanium composite composition of the present invention has a chemical composition formula of Ni _{(0.25 + α) -x} M1 _x Mn _{(0.75-α) -y.} M2 _y OOH (where M1 and M2 each represent one selected from Mg, Al, Ti, V, Cr, Fe, Co, Cu, Zn and Zr, and 0 ≦ x ≦ 0.1, 0 ≦ y ≦ 0.25 and −0.025 ≦ α ≦ 0.025). Different element substitution (M1, M2) can be expected to improve battery performance, in particular, charge / discharge cycle stability and suppress Mn elution. In order to maintain the degree of order of the Ni—Mn ordered arrangement in the spinel type sublattice and the battery capacity in the 5 V region, it is preferable that the amount of substitution of different elements for Ni is small. As specific chemical composition, for example, Ni _0.25 Mn _0.75 OOH, Ni _0.25 Mn _0.65 Ti _0.10 OOH, Ni _0.20 Fe _0.05 Mn _0.75 OOH, Ni _{0 .23} Mg _0.02 Mn _0.75 OOH, Ni _0.225 Mg _0.025 Mn _0.75 OOH, Ni _0.225 Co _0.05 Mn _0.725 OOH (Ni _0.225 Co _0.025 Mn _{0 .725} Co _0.025 OOH), Ni _0.23 Zn _0.02 Mn _{0.75, and the} like.

The nickel-manganese composite oxyhydroxide contained in the nickel-manganese-titanium composite composition of the present invention is an oxyhydroxide having a cadmium hydroxide type crystal structure. On the other hand, since the α-type nickel hydroxide structure has a relatively wide transition metal layer, it easily takes in anions that can be impurities such as SO ₄ . If it is a cadmium hydroxide type structure, an anion is not taken in between transition metal layers. The cadmium hydroxide structure is a crystal structure in which hydroxide ions are arranged at the positions of iodide ions of a hexagonal cadmium iodide structure. The hydroxide ions are arranged in a nearly hexagonal close-packed structure, and metal ions are located in the octahedral hexacoordinate gaps every other layer in the c-axis direction.

  Since the nickel-manganese composite oxyhydroxide contained in the nickel-manganese-titanium composite composition of the present invention has a theoretical average valence of trivalent, the average of Ni, Mn, M1 and M2 in the chemical composition formula The valence is preferably 2.8 to 3.1, and more preferably 2.9 to 3.0. Here, the average valence is determined by an iodometry method.

The nickel-manganese-titanium composite composition of the present invention contains titanium oxide. Here, the titanium oxide is titanium dioxide (TiO ₂ ), and the crystal form may be either anatase or rutile type. Further, the finer the particle size of titanium oxide, the better the dispersibility of the metal component, so the primary particle size is preferably 1 μm or less, more preferably 0.5 μm or less, and particularly preferably 0.15 μm or less. . Many exist as secondary agglomerated particles, but it is advantageous in terms of dispersibility that they are not agglomerated. The average particle size of the secondary aggregated particles is preferably 2 μm or less, more preferably 1 μm or less, and particularly preferably 0.5 μm or less. In addition, as the presence state of the aggregated particles, it is necessary that the titanium oxide particles are dispersed on both the surface and inside of the aggregated particles, that is, highly dispersed inside and outside the aggregated particles.

The tap density of the nickel-manganese-titanium composite composition of the present invention is preferably 1.0 g / cm ³ or more because the filling property of the positive electrode active material in the electrode affects the energy density. When the tap density is 1.0 g / cm ³ or more, the filling property of the lithium-nickel-manganese-titanium composite oxide obtained using the nickel-manganese-titanium composite composition of the present invention as a raw material tends to be high.

The specific surface area of the nickel-manganese-titanium composite composition of the present invention is preferably 70 m ² / g or less, and more preferably 50 m ² / g or less, in order to ensure fillability. In general, since the filling property and the specific surface area have a correlation, a powder having a high filling property is easily obtained with a low specific surface area.

  The average particle size of the nickel-manganese-titanium composite composition of the present invention is preferably 5 to 20 μm and more preferably 5 to 10 μm in order to adapt to the particle size at which an electrode can be easily formed. The average particle diameter is an average particle diameter of secondary particles in which primary particles are aggregated, that is, a so-called aggregated particle diameter.

  The particle distribution of the nickel-manganese-titanium composite composition of the present invention is a particle size distribution having a monodisperse, that is, monomodal distribution.

Manganese - - The nickel chemical composition of the titanium-based composite _{composition, (Ni (0.25 + α)} -x M1 x Mn (0.75-α) -y M2 y OOH) A - (TiO 2) B ( However, A + B = 1, M1 and M2 each represent one selected from Mg, Al, Ti, V, Cr, Fe, Co, Cu, Zn and Zr, and 0 ≦ x ≦ 0.1, 0 ≦ y ≦ 0.25 and −0.025 ≦ α ≦ 0.025). Here, B indicating the metal molar ratio of Ti is preferably 0.1 or less, more preferably 0.05 or less in terms of battery performance. In addition, as long as the effect is not inhibited about a chemical composition, you may contain alkali metals, alkaline-earth metals, such as Mg, Ca, Na, K, etc. separately from what is contained in a chemical composition formula, for example. Although the content is not particularly limited, 200 to 1000 ppm is preferable and 300 to 600 ppm is more preferable because battery performance is further improved.

  Next, a method for producing the nickel-manganese-titanium composite composition of the present invention will be described.

  The nickel-manganese-titanium composite composition of the present invention comprises at least one selected from nickel and manganese, or nickel, manganese, and Mg, Al, Ti, V, Cr, Fe, Co, Cu, Zn, and Zr. It can be produced by crystallization of a nickel-manganese-titanium composite composition by mixing an aqueous solution of metal salt, titanium oxide, an aqueous solution of caustic soda and an aerobic gas or aqueous hydrogen peroxide as an oxidizing agent at pH 8-10. .

  The metal salt aqueous solution contains at least nickel and manganese, and can further contain one or more metals selected from Mg, Al, Ti, V, Cr, Fe, Co, Cu, Zn, and Zr. Examples of the metal salt aqueous solution include nickel, manganese, an aqueous solution in which sulfates, chlorides, nitrates, acetates and the like containing other predetermined metals are dissolved, and nickel and inorganic acids such as sulfuric acid, hydrochloric acid, nitric acid, acetic acid. An aqueous solution in which manganese and other predetermined metals are dissolved can be used. An example of a preferable aqueous metal salt solution is an aqueous solution containing nickel sulfate and manganese sulfate.

  In addition, the ratio of nickel, manganese, and other predetermined metals in the metal salt aqueous solution should be the ratio of nickel, manganese, and other predetermined metals of the target nickel-manganese composite oxyhydroxide. Good. The proportions of nickel, manganese, and other predetermined metals in the aqueous metal salt solution are molar ratios of Ni + M1: Mn + M2 = 0.25 + α: 0.75-α, Ni: M1 = (0.25 + α) −x: x, Mn : M2 = (0.75−α) −y: y (where M1 and M2 each represent one selected from Mg, Al, Ti, V, Cr, Fe, Co, Cu, Zn and Zr, and 0 ≦ x ≦ 0.1, 0 ≦ y ≦ 0.25, and −0.025 ≦ α ≦ 0.025).

  Although the total concentration (metal concentration) of all metals such as nickel and manganese in the metal salt aqueous solution is arbitrary, since the metal concentration affects the productivity, 1.0 mol / L or more is preferable, and 2.0 mol / L The above is more preferable.

Titanium oxide is titanium dioxide (TiO ₂ ), which can be introduced as a suspension dispersed in water or directly as a powder. In order to improve the dispersibility of titanium oxide in the nickel-manganese-titanium composite composition, it is first necessary to improve the dispersibility / peptization properties of titanium oxide in the suspension. For this purpose, first, there is a method of adjusting pH by adding an acid or an alkali to water. In this case, an acid or an alkali agent that does not leave impurities in the crystallized nickel-manganese-titanium composite composition is desirable, and examples thereof include nitric acid and aqueous ammonia. As a second method, dispersion and peptization can be improved by adding a small amount of a surfactant. Further, as a third method, the dispersibility / peptization can be similarly increased by a pulverizer, an ultrasonic device, or the like, but often involves expensive equipment. Among these three methods, when evaluating the cost of chemicals and equipment and the dispersion / peptization effect, it was found that the method of adding a surfactant is highly cost-effective. From the above, it is preferable to add a surfactant to the titanium oxide suspension.

  Needless to say, a surfactant having a high dispersion / peptification effect is selected as the surfactant in the case of adding a surfactant to the titanium oxide suspension, but the crystallized nickel-manganese- Those in which no impurities remain in the titanium-based composite composition are preferred. In this respect, an ammonium polycarboxylate is most suitable as the surfactant species. Further, a sufficient amount of surfactant can be obtained with a small amount. A surfactant / titanium oxide weight ratio is 0.02 or less, preferably 0.01 or less, and more preferably 0.0075 or less.

  The caustic soda aqueous solution is an aqueous sodium hydroxide solution, and for example, an aqueous solution of solid sodium hydroxide or an aqueous solution of sodium hydroxide generated from salt electrolysis can be used.

  The oxidizing agent is aerobic gas or hydrogen peroxide solution. When the oxidizing agent is not an aerobic gas or hydrogen peroxide water (for example, sodium persulfate, sodium chlorate, etc.), the target oxyhydroxide cannot be obtained. Examples of the aerobic gas include air, oxygen and the like, but air is most preferable from an economic viewpoint. Gases such as air and oxygen are added by bubbling with a bubbler or the like. On the other hand, the hydrogen peroxide solution can be mixed similarly to the metal salt aqueous solution and the caustic soda aqueous solution. Examples of the concentration of the hydrogen peroxide solution include 3 to 30% by weight.

  The nickel-manganese-titanium composite composition of the present invention is crystallized by mixing an aqueous solution of metal salt, titanium oxide, aqueous solution of caustic soda, and oxygen gas or hydrogen peroxide water as an oxidizing agent at pH 8.5-10. When the pH exceeds 10, the nickel and manganese components become crystalline phases other than the cadmium hydroxide type structure and tend to be fine particles. Such fine particles have low filtration / cleaning efficiency, which significantly reduces production efficiency. On the other hand, when the pH is less than 8.5, a mixed phase of α-type oxyhydroxide and spinel-type oxide is formed, and the nickel-manganese-titanium composite composition is hardly crystallized. In order to enable production with high production efficiency, pH 9 to 10 is preferable.

  The mixing temperature when mixing the metal salt aqueous solution, titanium oxide, caustic soda aqueous solution and oxidant is not particularly limited, but the oxidation reaction of the metal salt aqueous solution is facilitated, and the nickel-manganese-titanium composite composition is more Since it becomes easy to crystallize, 50 degreeC or more is preferable, 60 degreeC or more is more preferable, and 80 degreeC or more is especially preferable.

  The pH may fluctuate due to mixing of the metal salt aqueous solution, titanium oxide, caustic soda aqueous solution, and oxidizing agent. In this case, the pH can be controlled by appropriately mixing an alkaline aqueous solution other than the caustic soda aqueous solution with the mixed aqueous solution. Mixing of the alkaline aqueous solution other than the caustic soda aqueous solution may be performed continuously or intermittently. Examples of the alkaline aqueous solution other than the caustic soda aqueous solution include aqueous solutions of alkali metals such as potassium hydroxide and lithium hydroxide. Moreover, the alkali concentration of aqueous alkali solution can illustrate 1 mol / L or more.

In the production of the nickel-manganese-titanium composite composition of the present invention, a complexing agent can be added. When a complexing agent is present, the solubility of nickel ions increases, the particle surface becomes smooth, and the sphericity is improved. As a result, there is an advantage that the tap density is improved. As the complexing agent, ammonia, an ammonium salt, and an amino acid are preferable. As the ammonia, for example, aqueous ammonia is exemplified, and as the ammonium salt, for example, ammonium sulfate, ammonium chloride, ammonium nitrate, ammonium carbonate, and the like are exemplified. Examples of amino acids include glycine and the like. The complexing agent is preferably fed together with metal ions. The concentration is preferably 0.1 to 2, more preferably 0.5 to 1, as the NH ₃ / transition metal molar ratio.

  Manufacture of the nickel-manganese-titanium composite composition of the present invention does not require atmospheric control, and can be performed in a normal air atmosphere.

  If a nickel-manganese-titanium composite composition is obtained, the production can be performed either batchwise or continuously. In the case of a batch type, the mixing time is arbitrary. For example, 3 to 48 hours can be mentioned, and further 6 to 24 hours can be mentioned. On the other hand, in the case of a continuous type, it is preferable that the average residence time in which the nickel-manganese-titanium composite composition stays in the reaction vessel is 1 to 30 hours, and more preferably 3 to 20 hours.

  In the method for producing a nickel-manganese-titanium composite composition of the present invention, filtration, washing and drying are performed after the nickel-manganese-titanium composite composition is crystallized.

  Filtration is a general solid-liquid separation operation and is not particularly limited.

  In the cleaning, impurities adhering to and adsorbing to the nickel-manganese-titanium composite composition are removed. Examples of the cleaning method include a method of adding a nickel-manganese-titanium composite composition to water (for example, pure water, tap water, river water, etc.) and cleaning the same.

  In the drying, the moisture of the nickel-manganese-titanium composite composition is removed. Examples of the drying method include drying the nickel-manganese-titanium composite composition at 110 to 150 ° C. for 2 to 15 hours.

In the method for producing a nickel-manganese-titanium composite composition of the present invention, the nickel-manganese-titanium composite composition after filtration, washing, and drying may be fired. The firing temperature is desirably higher than the exhaust gas temperature to be applied. Specifically, it is preferably 300 ° C. or higher, more preferably 450 ° C. or higher. On the other hand, since it can be prevented from being decomposed into monoclinic ZrO ₂ and Mn oxide, 900 ° C. or lower is preferable. Although there is no restriction | limiting in particular in baking time, It is not necessary to make it extremely long time, for example, 5 to 100 hours, Preferably 5 to 20 hours is mentioned. The firing atmosphere is not particularly limited, and examples thereof include an oxygen atmosphere such as air and a non-oxygen atmosphere such as nitrogen. However, it is preferable that the firing is performed in the air because it is simple. The firing method is not particularly limited, and various firing methods using a muffle furnace, a rotary kiln, a fluidized firing furnace, and the like can be used.

  In the method for producing a nickel-manganese-titanium composite composition of the present invention, pulverization may be performed after drying or sintering.

  In pulverization, a powder having an average particle size suitable for the application is used. If it becomes a desired average particle diameter, grinding | pulverization conditions are arbitrary, For example, grind | pulverizing by methods, such as wet grinding and dry grinding, can be illustrated.

  Since the nickel-manganese-titanium composite composition of the present invention has relatively high dispersibility of metal elements and high chemical stability, it can be used for the production of lithium-nickel-manganese-titanium composite oxides. .

  In the case of producing a lithium-nickel-manganese-titanium composite oxide using the nickel-manganese-titanium composite composition of the present invention as a raw material, the production method includes the following: nickel-manganese-titanium composite composition, lithium and lithium It is preferable to have a mixing step of mixing at least one of the compounds and a firing step.

  In the mixing step, any lithium compound can be used. Examples of the lithium compound include one or more selected from the group consisting of lithium hydroxide, lithium oxide, lithium carbonate, lithium iodide, lithium nitrate, lithium oxalate, and alkyl lithium. As a preferable lithium compound, any one or more selected from the group of lithium hydroxide, lithium oxide and lithium carbonate can be exemplified.

  In the firing step, the raw materials are mixed and then fired to produce a lithium-nickel-manganese-titanium composite oxide. Firing can be performed at any temperature of 500 to 1000 ° C. in various atmospheres such as air and oxygen.

  The lithium-nickel-manganese-titanium composite oxide thus obtained is used as a positive electrode active material for a lithium secondary battery.

  As the negative electrode active material used in the lithium secondary battery of the present invention, metallic lithium, lithium, or a material capable of occluding and releasing lithium ions can be used. Examples include lithium metal, lithium / aluminum alloy, lithium / tin alloy, lithium / lead alloy, and carbon materials that can electrochemically insert and desorb lithium ions, and electrochemically insert lithium ions. A carbon material that can be detached is particularly suitable from the viewpoint of safety and battery characteristics.

  The electrolyte used in the lithium secondary battery of the present invention is not particularly limited. For example, a lithium salt dissolved in an organic solvent such as carbonates, sulfolanes, lactones, ether condyles, or a lithium ion conductive solid An electrolyte can be used.

  Although there is no restriction | limiting in particular as a separator used with the lithium secondary battery of this invention, For example, the microporous film made from polyethylene, a polypropylene, etc. can be used.

  As an example of the configuration of the lithium secondary battery as described above, a molded product obtained by molding a mixture with a conductive agent into a pellet and then drying under reduced pressure at 100 to 200 ° C. is used as a battery positive electrode. And those using an electrolytic solution in which lithium hexafluorophosphate is dissolved in a mixed solvent of ethylene carbonate and diethyl carbonate.

The nickel-manganese-titanium composite composition of the present invention is stable in the air, and manganese oxide (Mn ₃ O ₄ ) is not by-produced during long-term storage or drying. Thus, it can be said that it is a chemically stable precursor with high dispersibility of a metal element in which low-cost titanium oxide is appropriately dispersed. A lithium secondary battery using a lithium-nickel-manganese-titanium composite oxide having the nickel-manganese-titanium composite composition of the present invention as a precursor as a positive electrode has high performance.

2 is a SEM image of the nickel-manganese-titanium-aluminum composite composition of Example 1. FIG. 3 is a SEM image of the nickel-manganese-titanium composite composition of Example 2. FIG. 4 is a SEM image of the nickel-manganese-titanium composite composition of Example 3. FIG. 2 is an XRD pattern of a nickel-manganese-titanium-aluminum composite composition of Example 1. FIG. 2 is an XRD pattern of a nickel-manganese-titanium composite composition of Example 2. FIG. 3 is an XRD pattern of a nickel-manganese-titanium composite composition of Example 3. FIG. It is the SEM image of the cross section of the nickel-manganese-titanium-type composite composition of Example 1, and the EDS element mapping image of Ni, Mn, Ti, and Al. It is a STEM image of the cross section of the nickel-manganese-titanium composite composition of Example 2, and an EDS element mapping image of Ni, Mn, and Ti.

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

<Measurement of chemical composition>
The composition analysis of the obtained nickel-manganese-titanium composite composition was performed by inductively coupled plasma emission spectrometry (ICP method). That is, the measurement solution was prepared by putting the obtained nickel-manganese-titanium composite composition and sulfuric acid into an autoclave and performing pressure acid decomposition. The composition of the obtained nickel-manganese-titanium composite composition was analyzed by measuring the obtained measurement solution using a general inductively coupled plasma optical emission analyzer (trade name: OPTIMA 3000 DV, manufactured by PERKIN ELMER). .

<Measurement of metal valence>
The average valence of metals such as nickel and manganese was measured by iodometry. After 0.3 g of the obtained nickel-manganese-titanium composite composition and 3.0 g of potassium iodide were dissolved in 50 ml of 7N-hydrochloric acid solution, 200 ml of 1N-NaOH solution was added for neutralization. 0.1N-sodium thiosulfate aqueous solution was dripped with respect to the neutralized sample liquid, and average valence was computed from the dripping amount. A starch solution was used as an indicator.

<Powder X-ray diffraction measurement>
Using a general X-ray diffractometer (trade name: MXP-3, manufactured by MacScience), powder X-ray diffraction measurement of the sample was performed. 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 in range.

<Identification of crystal phase>
In the XRD pattern obtained by the XRD measurement under the above conditions, it has a sharp peak at 2θ = 19.0 ± 0.5 °, 36.9 ± 1.5 °, 48.0 ± 3.5 °, A cadmium hydroxide structure was considered to have a broad XRD peak at 62.0 ± 5.0 ° and 65.0 ± 5.0 °. The peak shape other than the lowest angle is broad because of stacking faults. Titanium dioxide has a sharp main peak at 2θ = 27.0 ± 2.0 ° in the XRD pattern.

<Measurement of particle size distribution and average particle size>
0.5 g of the obtained nickel-manganese-titanium composite composition was put into 50 mL of 0.1N ammonia water, and subjected to ultrasonic irradiation for 10 seconds to obtain a dispersion slurry. The dispersed slurry was put into a particle size distribution measuring apparatus (trade name: Microtrac HRA, manufactured by HONEWELL), and volume distribution was measured by a laser diffraction method. The particle size distribution and average particle size (μm) were determined from the obtained volume distribution.

<Measurement of tap density>
2 g of the obtained nickel-manganese-titanium composite composition was filled into a 10 mL glass graduated cylinder and tapped 200 times. The tap density (g / cm ³ ) was calculated from the weight and the volume after tapping.

<Measurement of specific surface area>
Using a flow-type specific surface area automatic measuring apparatus (trade name: Flowsorb 3-2305, manufactured by Micrometrics), 1.0 g of the obtained nickel-manganese-titanium composite composition was pretreated in a nitrogen stream at 150 ° C. for 1 hour. Then, after measuring the adsorption / desorption area by the BET one-point method, the specific surface area (m ² / g) was determined by dividing by the weight.

<Evaluation of element distribution in particles>
The obtained nickel-manganese-titanium composite composition was embedded in a resin and then cut by ion milling, and SEM observation of the particle cross section and element mapping by EDS were performed. A scanning electron microscope (trade name: JSM-7600F, manufactured by JEOL) was used for SEM observation, and an EDS detector (trade name: NSS312E, manufactured by Thermo Fisher Scientific) was used for EDS.

  STEM-EDS mapping was also performed. The nickel-manganese-titanium composite composition was pulverized in a mortar, then ultrasonically dispersed in acetone, and dried on a microgrid as a measurement sample. A transmission electron microscope (trade name: JEM-2100F, manufactured by JEOL) was used for STEM, and an EDS detector (trade name: JED-2300T, manufactured by JEOL) was used for EDS.

<Battery performance evaluation>
A battery characteristic test as a positive electrode of a lithium-nickel-manganese-titanium composite oxide was performed.

A lithium-nickel-manganese-titanium composite oxide, a mixture of polytetrafluoroethylene and acetylene black (trade name: TAB-2) as a conductive agent are mixed at a weight ratio of 4: 1, and 1 ton / cm. After forming into a pellet shape on a mesh (made of SUS316) at a pressure of ² , it was dried under reduced pressure at 150 ° C. to produce a battery positive electrode. 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 lithium secondary battery was constructed using the liquid. Using the lithium secondary battery, the battery voltage was charged and discharged at a constant current for 30 cycles at room temperature between 4.9V and 3.0V. The current density during charge / discharge was 0.4 mA / cm ² .

Example 1
Nickel sulfate, manganese sulfate, and aluminum sulfate were dissolved in pure water to form a metal salt aqueous solution having a Ni: Mn: Al molar ratio = 0.505: 1.474: 0.021 (total of all metals in the metal salt aqueous solution). The concentration was 2.0 mol / L).

  On the other hand, a titanium oxide suspension was prepared by dissolving titanium dioxide (trade name: A120, manufactured by Sakai Chemical Industry) and an ammonium polyacrylate surfactant (San Nopco, SN Dispersant 5020) in pure water. The weight fraction of titanium dioxide in the suspension was 2.5%, and the surfactant / titanium dioxide weight ratio was 0.6%.

  Further, 200 g of pure water was put into a reaction vessel having an internal volume of 1 L, and then this was heated to 70 ° C. and maintained.

  The metal salt aqueous solution containing nickel, manganese, and aluminum was added to the reaction vessel at a supply rate of 1.04 g / min and a titanium oxide suspension at 0.20 g / min, respectively. Further, air was bubbled into the reaction vessel at a supply rate of 1 L / min as an oxidant. A nickel-manganese-titanium-aluminum composite composition is mixed by intermittently adding a 20 wt% sodium hydroxide aqueous solution (caustic soda aqueous solution) so that the pH becomes 9.25 when supplying the raw material liquid and air. The product crystallized to obtain a slurry. The obtained slurry was filtered and washed, and then the washed wet cake was air-dried in the air for 1 week, and then dried at 115 ° C. for 5 hours to obtain a nickel-manganese-titanium-aluminum composite composition.

  The XRD pattern of the obtained nickel-manganese-titanium-aluminum composite composition had a sharp peak at 2θ = 19.0 °, and a broad peak was observed after 2θ = 40 °. In addition, a sharp peak that was relatively weak at 2θ = 25.4 ° but could be attributed to rutile titanium dioxide appeared. Therefore, the crystal structure was a mixed phase of a cadmium hydroxide structure having a stacking fault and a rutile type titanium oxide.

  The measurement results of the nickel-manganese-titanium-aluminum composite composition are shown in Table 1. From Table 1, it can be seen that the tap density is relatively high.

  Nickel sulfate and manganese sulfate were dissolved in pure water to obtain a metal salt aqueous solution having a Ni: Mn molar ratio = 0.521: 1.479 (the total concentration of all metals in the metal salt aqueous solution was 2.0 mol / L).

  Further, a titanium oxide suspension was prepared by dispersing titanium dioxide (trade name: A120, manufactured by Sakai Chemical Industry) in pure water. The weight fraction of titanium dioxide in the suspension was 2.5%.

  Next, after adding 200 g of pure water to a reaction vessel having an internal volume of 1 L, the temperature was raised to 70 ° C. and maintained.

  The metal salt aqueous solution containing nickel and manganese was added to the reaction vessel at a supply rate of 1.04 g / min and a titanium oxide suspension at 0.27 g / min, respectively. Further, air was bubbled into the reaction vessel at a supply rate of 1 L / min as an oxidant. When supplying the raw material liquid and air, the nickel-manganese-titanium composite composition is mixed by intermittently adding a 20 wt% sodium hydroxide aqueous solution (caustic soda aqueous solution) so that the pH becomes 9.25. Crystallization gave a slurry. The obtained slurry was filtered and washed, and then the washed wet cake was air-dried in the air for 1 week, and then dried at 115 ° C. for 5 hours to obtain a nickel-manganese-titanium composite composition.

  The XRD pattern of the obtained nickel-manganese composite oxyhydroxide had a sharp peak at 2θ = 19.0 ° and a broad peak after 2θ = 40 °. In addition, a sharp peak that was relatively weak at 2θ = 25.4 ° but could be attributed to rutile titanium dioxide appeared. Therefore, the crystal structure was a mixed phase of a cadmium hydroxide structure having a stacking fault and a rutile type titanium oxide.

  The measurement results of the nickel-manganese-titanium composite composition are shown in Table 1. From Table 1, it can be seen that the tap density is relatively high.

Example 3
A slurry was obtained in the same manner as in Example 2 except that a 0.25 mol / L glycine solution was added to one of the raw material liquids and added at 0.35 g / min. The obtained slurry was filtered, washed, and dried to obtain a nickel-manganese-titanium composite composition.

  The XRD pattern of the obtained nickel-manganese composite oxyhydroxide had a sharp peak at 2θ = 19.0 ° and a broad peak after 2θ = 40 °. In addition, a sharp peak that was relatively weak at 2θ = 25.4 ° but could be attributed to rutile titanium dioxide appeared. Therefore, the crystal structure was a mixed phase of a cadmium hydroxide structure having a stacking fault and a rutile type titanium oxide.

  The measurement results of the nickel-manganese-titanium composite composition are shown in Table 1. From Table 1, it can be seen that the tap density is relatively high.

Example 4
The nickel-manganese-titanium-aluminum composite composition obtained in Example 1 and lithium carbonate were mixed, fired at 900 ° C. for 10 hours in an air stream, and then fired at 700 ° C. for 48 hours. -A nickel-manganese-titanium-aluminum composite oxide was synthesized. From the results of chemical composition analysis, the composition formula could be expressed as Li _1.00 Ni _0.48 Mn _1.44 Ti _0.06 Al _0.02 O ₄ . Further, from the XRD pattern, all diffraction peaks can be attributed to a cubic spinel structure, and a minute superlattice peak was also confirmed. Furthermore, when the structure was refined by the Rietveld method and the lattice constant was determined, it was 8.180 mm (space group Fd3-m).

  The battery performance of the lithium-nickel-manganese-titanium-aluminum composite oxide was evaluated. The measurement results are shown in Table 2. Since the initial discharge capacity is 129 mAh / g, the discharge capacity ratio of the discharge capacities of the first and 30th cycles (the discharge capacity of the 30th cycle / the discharge capacity of the 1st cycle) is 98.6%. The performance was found to be good.

Example 5
The nickel-manganese-titanium composite composition obtained in Example 2 and lithium carbonate were mixed, fired at 900 ° C. for 10 hours in an air stream, and then fired at 700 ° C. for 48 hours. -Manganese-titanium composite oxide was synthesized. From the results of chemical composition analysis, the composition formula could be expressed as Li _1.00 Ni _0.50 Mn _1.41 Ti _0.09 O ₄ . Further, from the XRD pattern, all diffraction peaks can be attributed to a cubic spinel structure, and a minute superlattice peak was also confirmed. Furthermore, when the structure was refined by the Rietveld method and the lattice constant was determined, it was 8.187Å (space group Fd3-m).

  The battery performance of the lithium-nickel-manganese-titanium composite oxide was evaluated. The measurement results are shown in Table 2. Since the initial discharge capacity was 128 mAh / g and the discharge capacity ratio was 98.8%, it was found that the charge / discharge cycle performance was good.

Comparative Example Nickel sulfate and manganese sulfate were dissolved in pure water to form a metal salt aqueous solution having a Ni: Mn molar ratio = 0.521: 1.479 (the total concentration of all metals in the metal salt aqueous solution was 2.0 mol / L). ).

  Next, after adding 200 g of pure water to a reaction vessel having an internal volume of 1 L, the temperature was raised to 70 ° C. and maintained.

  The metal salt aqueous solution containing nickel and manganese was added to the reaction vessel at a supply rate of 1.04 g / min. Further, air was bubbled into the reaction vessel at a supply rate of 1 L / min as an oxidant. When supplying the raw material liquid and air, the nickel-manganese composite composition is crystallized by mixing by intermittently adding a 20 wt% sodium hydroxide aqueous solution (caustic soda aqueous solution) so that the pH becomes 9.25. To obtain a slurry. The obtained slurry was filtered and washed, then the washed wet cake was air-dried in the air for 1 week, and then dried at 115 ° C. for 5 hours to obtain a nickel-manganese composite composition.

  The XRD pattern of the obtained nickel-manganese composite oxyhydroxide had a sharp peak at 2θ = 19.0 ° and a broad peak after 2θ = 40 °. Therefore, the crystal structure was a cadmium hydroxide structure having a stacking fault.

The nickel-manganese composite composition, lithium carbonate, and titanium dioxide (trade name: A120, manufactured by Sakai Chemical Industry Co., Ltd.) are mixed, fired at 900 ° C. for 10 hours in an air stream, and then fired at 700 ° C. for 48 hours. Thus, a lithium-nickel-manganese-titanium composite oxide was synthesized. From the results of chemical composition analysis, the composition formula could be expressed as Li _1.00 Ni _0.50 Mn _1.42 Ti _0.08 O ₄ . Further, from the XRD pattern, all diffraction peaks can be attributed to a cubic spinel structure, and a minute superlattice peak was also confirmed. Furthermore, when the structure was refined by the Rietveld method and the lattice constant was determined, it was 8.176 mm (space group Fd3-m).

  The battery performance of the lithium-nickel-manganese-titanium composite oxide was evaluated. The measurement results are shown in Table 2. Since the initial discharge capacity is 129 mAh / g and the discharge capacity ratio is 95.4%, it is clear that the charge / discharge cycle performance is lower than those in Examples 4 and 5.

  The nickel-manganese-titanium composite composition of the present invention can be used as a precursor of a lithium-nickel-manganese-titanium composite oxide used for a positive electrode active material of a lithium secondary battery. A high-performance lithium secondary battery using a nickel-manganese-titanium composite oxide as a positive electrode for a battery can be configured.

Claims (11)

Chemical composition formula is Ni _{(0.25 + α) -x} M1 _x Mn _{(0.75-α) -y} M2 _y OOH (where M1 and M2 are Mg, Al, Ti, V, Cr, Fe, Co, Cu, respectively) , Zn and Zr, and 0 ≦ x ≦ 0.1, 0 ≦ y ≦ 0.25, and −0.025 ≦ α ≦ 0.025). A nickel-manganese-titanium composite composition comprising a nickel-manganese composite oxyhydroxide having a cadmium hydroxide type structure and titanium oxide. The nickel-manganese-titanium composite composition according to claim 1, wherein the average valences of Ni, Mn, M1, and M2 are 2.8 to 3.1. The nickel-manganese-titanium composite composition according to claim 1 or 2, wherein the average particle size is 5 to 20 µm. The nickel-manganese-titanium composite composition according to any one of claims 1 to 3, wherein the primary particle diameter of titanium oxide is less than 1 µm. The metal salt aqueous solution containing nickel and manganese, titanium oxide, caustic soda aqueous solution and aerobic gas or hydrogen peroxide solution as an oxidizing agent are mixed at pH 8 to 10, respectively. A method for producing a nickel-manganese-titanium composite composition as described in 1. above. The method for producing a nickel-manganese-titanium composite composition according to claim 5, wherein the titanium oxide suspension contains a surfactant. The method for producing a nickel-manganese-titanium composite composition according to claim 6, wherein the surfactant is ammonium polycarboxylate. The method for producing a nickel-manganese-titanium composite composition according to any one of claims 5 to 7, further comprising adding a complexing agent. The method for producing a nickel-manganese-titanium composite composition according to claim 8, wherein the complexing agent is at least one selected from ammonia, ammonium salts and amino acids. A method for producing a lithium-nickel-manganese-titanium composite oxide, comprising mixing the aggregated particles according to any one of claims 1 to 4 and a lithium compound, followed by heat treatment. A lithium secondary battery comprising, as a positive electrode active material, a lithium-nickel-manganese-titanium composite oxide obtained by the method for producing a lithium-nickel-manganese-titanium composite oxide according to claim 10. .

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