Nickel-containing hydroxide, positive electrode active material using nickel-containing hydroxide as precursor, and method for producing nickel-containing hydroxide

Abstract

The present invention provides a nickel-containing hydroxide and a method for producing the nickel-containing hydroxide, which can provide a positive electrode active material having excellent initial charge-discharge efficiency. The present invention provides a nickel-containing hydroxide, which is a precursor of a positive electrode active material for a non-aqueous electrolyte secondary battery, and is made up of secondary particles formed by agglomeration of a plurality of primary particles, the primary particles having an average area of ​​0.035 μm 2 The nickel-containing hydroxide is as described above.

Description

[Technical Field]

[0001] The present invention relates to a nickel-containing hydroxide, a positive electrode active material using the nickel-containing hydroxide as a precursor, and a method for producing the nickel-containing hydroxide, and in particular to a nickel-containing hydroxide and a method for producing the nickel-containing hydroxide that can provide a positive electrode active material having excellent initial charge-discharge efficiency. [Background technology]

[0002] In recent years, in order to reduce environmental impact, secondary batteries have been used in a wide range of fields, such as portable devices such as mobile phones and portable personal computers, and vehicles that use or combine electricity as a power source. Examples of secondary batteries include secondary batteries using non-aqueous electrolytes, such as lithium-ion secondary batteries. Secondary batteries using non-aqueous electrolytes, such as lithium-ion secondary batteries, are suitable for miniaturization and weight reduction, and have properties such as high utilization rate and high cycle characteristics.

[0003] In order to improve the battery characteristics of lithium ion secondary batteries, high battery capacity and high output characteristics are required. As a precursor of a positive electrode active material for non-aqueous electrolyte secondary batteries that can obtain high battery capacity and high output characteristics, a compound represented by the general formula (1): Ni x Mn y M z (OH) 2+αPatent Document 1 has proposed a nickel-manganese composite hydroxide represented by the formula (1): (in the formula (1), M is at least one additive element selected from Co, Ti, V, Cr, Zr, Nb, Mo, Hf, Ta, Fe, and W; x is 0.1≦x≦0.8, y is 0.1≦y≦0.6, z is 0≦z≦0.8, and satisfies x+y+z=1.0; and α is 0≦α≦0.4), and the nickel-manganese composite hydroxide is composed of secondary particles formed by aggregation of a plurality of primary particles, wherein the primary particles have an aspect ratio of 3 or more, and at least some of the primary particles are arranged radially in a direction from the center toward the periphery of the secondary particles, and the secondary particles have an I(101) / I(001) ratio of the diffraction peak intensity I(101) of the 101 plane to the peak intensity I(001) of the 001 plane measured by X-ray diffraction measurement, of 0.15 or less.

[0004] Patent Document 1 describes that the particle structure of the positive electrode active material is significantly influenced by the particle structure and crystallinity of the composite hydroxide that serves as the precursor, and that by controlling the particle structure and crystallinity of the composite hydroxide, the characteristics of the positive electrode active material can be improved, thereby achieving high battery capacity and high output characteristics, and that the particle structure and crystallinity of the composite hydroxide can be controlled by specific crystallization conditions.

[0005] On the other hand, in portable devices such as mobile phones and portable personal computers, electric vehicles that use electricity as a power source, or hybrid vehicles that also use electricity as a power source, high initial charge-discharge efficiency is particularly required for the nonaqueous electrolyte secondary battery that serves as the power source. However, the precursor of the positive electrode active material in Patent Document 1 leaves room for improvement in the initial charge-discharge efficiency of the nonaqueous electrolyte secondary battery. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] International Publication No. 2018 / 020845 Summary of the Invention [Problem to be solved by the invention]

[0007] In view of the above circumstances, the present invention has an object to provide a nickel-containing hydroxide and a method for producing the nickel-containing hydroxide, which can provide a positive electrode active material having excellent initial charge-discharge efficiency. do. [Means for solving the problem]

[0008] The nickel-containing hydroxide of the present invention is a secondary particle formed by aggregation of a plurality of primary particles, and the average area of ​​the primary particles constituting the secondary particle is adjusted to fall within a predetermined range.

[0009] The gist of the configuration of the present invention is as follows. [1] A nickel-containing hydroxide, which is a precursor of a positive electrode active material for a non-aqueous electrolyte secondary battery, and is a secondary particle formed by agglomeration of a plurality of primary particles, The average area of ​​the primary particles is 0.035 μm 2 The nickel-containing hydroxide is as described above. [2] The average area of ​​the primary particles is 0.100 μm 2 The nickel-containing hydroxide according to [1] below. [3] The average area of ​​the primary particles is 0.039 μm 2 More than 0.080μm 2 The nickel-containing hydroxide according to [1] or [2] below. [4] The nickel-containing hydroxide according to any one of [1] to [3], wherein nickel (Ni) is contained in an amount of 80 mol % or more relative to the total amount of metals contained in the nickel-containing hydroxide. [5] The nickel-containing hydroxide according to [4], which is a composite hydroxide containing nickel (Ni) and at least one metal selected from the group consisting of cobalt (Co) and manganese (Mn). [6] The nickel-containing hydroxide according to [4], which is a composite hydroxide having a molar ratio of nickel (Ni):cobalt (Co):manganese (Mn):additive element M expressed as (1-xyz):x:y:z (0≦x≦0.15, 0≦y≦0.15, 0≦z≦0.05, where M represents one or more additive elements selected from the group consisting of Al, Fe, Ti, Mg, Ca, Sr, Ba, V, Nb, Cr, Mo, W, Ru, Cu, Zn, B, Ga, Si, Sn, P, Bi, and Zr). [7] A positive electrode active material for a non-aqueous electrolyte secondary battery, obtained by calcining the nickel-containing hydroxide according to any one of [1] to [6] with a lithium compound. [8] A method for producing a nickel-containing hydroxide, which is a precursor of a positive electrode active material for a non-aqueous electrolyte secondary battery and is a secondary particle formed by aggregating a plurality of primary particles, comprising: a reaction step of continuously supplying a metal-containing aqueous solution containing nickel, a complexing agent, and an alkaline aqueous solution to a reaction vessel to cause a crystallization reaction to obtain a nickel-containing hydroxide; a slurry withdrawing step of continuously withdrawing the slurry containing the nickel-containing hydroxide from the reaction tank; Including, A method for producing a nickel-containing hydroxide, wherein the flow rate of the metal-containing aqueous solution containing nickel supplied to the reaction tank in the reaction step is 0.25 m / sec or less. [9] The method for producing a nickel-containing hydroxide according to [8], wherein the flow rate of the metal-containing aqueous solution containing nickel supplied to the reaction tank in the reaction step is 0.01 m / sec or more.

[10] The method for producing a nickel-containing hydroxide according to [8] or [9], further comprising a solid-liquid separation step of washing the nickel-containing hydroxide obtained in the slurry extraction step with an alkaline aqueous solution and then separating it into solid and liquid.

[0010] In this specification, the term "average area of ​​primary particles" refers to an average area of ​​primary particles calculated from the areas of the 40 primary particles measured by a scanning electron microscope (SEM) at a magnification of 5000 times, which is obtained by obtaining an image of secondary particles of nickel-containing hydroxide particles through observation with a scanning electron microscope (SEM), selecting secondary particles from the obtained image, the particle diameter of which is a particle diameter at which the cumulative volume percentage is 50 volume % (D50) (±10%) as measured with a particle size distribution measuring device using a laser diffraction / scattering method, randomly selecting 40 primary particles from the surface portion of the selected secondary particles through a scanning electron microscope (SEM) image at a magnification of 20000 times, measuring the areas of the selected primary particles using the image processing software "ImageJ", and then calculating the average area of ​​the primary particles from the areas of the measured 40 primary particles. It means multiplication. [Effects of the Invention]

[0011] According to the nickel-containing hydroxide of the present invention, which is a precursor of the positive electrode active material of the non-aqueous electrolyte secondary battery, the average area of ​​the primary particles is 0.035 μm 2 As a result, a nonaqueous electrolyte secondary battery having excellent initial charge-discharge efficiency can be obtained.

[0012] According to the nickel-containing hydroxide of the present invention, the average area of ​​the primary particles is 0.035 μm 2 More than 0.100μm 2 By satisfying the following, a nonaqueous electrolyte secondary battery having excellent initial charge-discharge efficiency can be obtained.

[0013] According to the positive electrode active material of the present invention, the nickel-containing hydroxide of the present invention is calcined with a lithium compound, so that a nonaqueous electrolyte secondary battery having excellent initial charge-discharge efficiency can be obtained.

[0014] According to the method for producing a nickel-containing hydroxide of the present invention, the flow rate of the metal-containing aqueous solution containing nickel supplied to the reaction tank in the reaction step is 0.25 m / sec or less, so that the average area of ​​the primary particles of the nickel-containing hydroxide is 0.035 μm 2 As a result of the above adjustments, a non-aqueous electrolyte secondary battery having excellent initial charge-discharge efficiency can be obtained.

[0015] According to the method for producing a nickel-containing hydroxide of the present invention, the flow rate of the metal-containing aqueous solution containing nickel supplied to the reaction tank in the reaction step is 0.01 m / sec or more and 0.25 m / sec or less, so that the average area of ​​the primary particles of the nickel-containing hydroxide is 0.035 μm 2 As a result, a non-aqueous electrolyte secondary battery having even better initial charge-discharge efficiency can be obtained. DETAILED DESCRIPTION OF THE INVENTION

[0016] The nickel-containing hydroxide of the present invention, which is a precursor of the positive electrode active material of a non-aqueous electrolyte secondary battery, will be described in detail below. The nickel-containing hydroxide of the present invention is a secondary particle formed by aggregation of a plurality of primary particles. The particle shape of the nickel-containing hydroxide of the present invention is not particularly limited and may be a wide variety of shapes, such as a substantially spherical shape or a substantially elliptical shape.

[0017] The nickel-containing hydroxide of the present invention has a primary particle average area of ​​0.035 μm 2 From the above, it can be seen that the average area of ​​the primary particles constituting the nickel-containing hydroxide, which is the secondary particle, is 0.035 μm 2 That is, the secondary particles are formed by agglomeration of primary particles, and the average area of ​​the primary particles on the surface is controlled to 0.035 μm or more. 2 The nickel-containing hydroxide of the present invention is thus formed.

[0018] The nickel-containing hydroxide of the present invention has a primary particle average area of ​​0.035 μm 2 As described above, by using a positive electrode active material obtained from the nickel-containing hydroxide of the present invention in a non-aqueous electrolyte secondary battery, a non-aqueous electrolyte secondary battery having excellent initial charge-discharge efficiency can be obtained.

[0019] The average area of ​​the primary particles is 0.035 μm 2Although there is no particular limitation as long as it is equal to or greater than this, the lower limit of the average area of ​​the primary particles is 0.037 μm from the viewpoint of obtaining a nonaqueous electrolyte secondary battery having excellent initial charge / discharge efficiency. 2 More than 0.039 μm is preferable. 2 On the other hand, the upper limit of the average area of ​​the primary particles is preferably 0.100 μm from the viewpoint of obtaining a nonaqueous electrolyte secondary battery having excellent initial charge / discharge efficiency. 2 Preferably less than 0.090 μm 2 Less than 0.080 μm is more preferable. 2 The following is particularly preferred. The above lower and upper limits are arbitrary. The average area of ​​the primary particles of the nickel-containing hydroxide of the present invention can be, for example, 0.035 μm 2 More than 0.100μm 2 Preferably less than 0.037 μm 2 More than 0.090μm 2 Less than 0.039 μm is more preferable. 2 More than 0.080μm 2 The following are particularly preferred:

[0020] The particle diameter (D50) at a cumulative volume percentage of 50% by volume of the nickel-containing hydroxide of the present invention (hereinafter simply referred to as "D50") is not particularly limited, but the lower limit is preferably 5.0 μm or more, more preferably 7.0 μm or more, and particularly preferably 10.0 μm or more, from the viewpoint of improving the packing density of the positive electrode active material in the positive electrode. On the other hand, the upper limit of D50 of the nickel-containing hydroxide of the present invention is preferably 15.0 μm or less, more preferably 14.0 μm or less, and particularly preferably 13.0 μm or less, from the viewpoint of improving contact with the electrolyte. The above D50 refers to the particle diameter measured with a particle size distribution analyzer using a laser diffraction / scattering method. The above lower and upper limits can be combined arbitrarily. For example, the D50 of the nickel-containing hydroxide of the present invention is preferably 5.0 μm or more and 15.0 μm or less, more preferably 7.0 μm or more and 14.0 μm or less, and particularly preferably 10.0 μm or more and 13.0 μm or less.

[0021] The shape of the primary particles of the nickel-containing hydroxide of the present invention is not particularly limited, but examples thereof include spherical, elliptical, plate-like, and columnar shapes.

[0022] The composition of the nickel-containing hydroxide of the present invention is not particularly limited as long as it is a hydroxide containing nickel (Ni). The nickel content of the nickel-containing hydroxide of the present invention is not particularly limited, but the lower limit is preferably 80 mol% or more, and more preferably 82 mol% or more, based on the total amount of metals contained in the nickel-containing hydroxide, from the viewpoint of reducing raw material costs while obtaining a cathode active material with improved properties such as initial charge-discharge efficiency, high utilization rate, and high cycle characteristics. On the other hand, the upper limit of the nickel content of the nickel-containing hydroxide of the present invention can be 100 mol% or less, based on the total amount of metals contained. From the viewpoint of obtaining a cathode active material with improved properties such as initial charge-discharge efficiency, high utilization rate, and high cycle characteristics, the upper limit is preferably 95 mol% or less, and more preferably 90 mol% or less. The above upper and lower limits can be combined arbitrarily.

[0023] The nickel-containing hydroxide of the present invention may have a composition, for example, of a composite hydroxide containing nickel (Ni) and at least one metal selected from the group consisting of cobalt (Co) and manganese (Mn). Specific examples of the composition of the nickel-containing hydroxide of the present invention include composite hydroxides in which the molar ratio of nickel (Ni):cobalt (Co):manganese (Mn):additive element M is expressed as (1-xyz):x:y:z (0≦x≦0.15, 0≦y≦0.15, 0≦z≦0.05, where M represents one or more additive elements selected from the group consisting of Al, Fe, Ti, Mg, Ca, Sr, Ba, V, Nb, Cr, Mo, W, Ru, Cu, Zn, B, Ga, Si, Sn, P, Bi, and Zr).

[0024] The nickel-containing hydroxide of the present invention is preferably a composite hydroxide having a nickel content of 80 mol% or more relative to the total amount of metals contained in the nickel-containing hydroxide, and a molar ratio of nickel (Ni):cobalt (Co):manganese (Mn):additive element M expressed as (1-xyz):x:y:z (0≦x≦0.15, 0≦y≦0.15, 0≦z≦0.05, where M represents one or more additive elements selected from the group consisting of Al, Fe, Ti, Mg, Ca, Sr, Ba, V, Nb, Cr, Mo, W, Ru, Cu, Zn, B, Ga, Si, Sn, P, Bi, and Zr). Among these, from the viewpoint of obtaining a nonaqueous electrolyte secondary battery having excellent initial charge-discharge efficiency, x is preferably 0.05≦x≦0.14, and more preferably 0.07≦x≦0.13, and y is preferably 0.01≦y≦0.10, and more preferably 0.02≦y≦0.07. Preferably, z satisfies the condition 0≦z≦0.03, and particularly preferably 0≦z≦0.02.

[0025] Next, a method for producing a nickel-containing hydroxide, which is a precursor of a positive electrode active material for a non-aqueous electrolyte secondary battery and is composed of secondary particles formed by aggregation of a plurality of primary particles, will be described. The method for producing a nickel-containing hydroxide of the present invention includes a reaction step of continuously supplying a metal-containing aqueous solution containing nickel, a complexing agent, and an alkaline aqueous solution to a reaction vessel to cause a crystallization reaction to obtain a nickel-containing hydroxide, and a slurry withdrawal step of continuously withdrawing a slurry containing the nickel-containing hydroxide from the reaction vessel.

[0026] <Reaction step for obtaining nickel-containing hydroxide> The reaction process for obtaining a nickel-containing hydroxide is a crystallization process in which a metal-containing aqueous solution containing nickel, an alkaline aqueous solution, and a complexing agent are added to a reaction tank and mixed, and a coprecipitation reaction occurs in the reaction solution to obtain a nickel-containing hydroxide.

[0027] Specifically, by coprecipitation, a metal salt solution (hereinafter sometimes simply referred to as a "metal-containing aqueous solution") containing a nickel salt (e.g., sulfate) and optional components such as a cobalt salt (e.g., sulfate), a manganese salt (e.g., sulfate), and a salt of an additional element M (e.g., sulfate) is added to a reaction vessel, an alkaline aqueous solution, and a complexing agent are appropriately added, and a neutralization reaction is carried out in the reaction vessel to cause crystallization, thereby preparing a nickel-containing hydroxide and obtaining a slurry-like suspension containing the nickel-containing hydroxide. For example, water is used as the solvent for the suspension.

[0028] The complexing agent is not particularly limited as long as it can form a complex in an aqueous solution with nickel, the optional components cobalt and manganese, and the additional element M, and examples thereof include ammonium ion donors (ammonium sulfate, ammonium chloride, ammonium carbonate, ammonium fluoride, etc.), hydrazine, ethylenediaminetetraacetic acid, nitrilotriacetic acid, uracildiacetic acid, and glycine. The alkaline aqueous solution is not particularly limited as long as it adjusts the pH value of the aqueous solution during coprecipitation, and examples thereof include aqueous solutions of alkali metal hydroxides (e.g., sodium hydroxide and potassium hydroxide).

[0029] When the metal-containing aqueous solution, alkaline aqueous solution, and complexing agent are continuously supplied to a reaction vessel, nickel, the optional components cobalt and manganese, and the additional element M undergo a crystallization reaction to produce a nickel-containing hydroxide. During the crystallization reaction, the temperature in the reaction vessel is controlled, for example, within a range of 10°C to 80°C, preferably 20 to 70°C, and the pH value in the reaction vessel is controlled, based on a liquid temperature of 40°C, within a range of, for example, pH 9 to pH 13, preferably pH 10 to 12, while the substances in the reaction vessel are appropriately stirred. The reaction vessel may, for example, be a continuous type, in which the formed nickel-containing hydroxide is overflowed to separate it.

[0030] The reaction tank is also provided with a metal-containing aqueous solution supply pipe for supplying the metal-containing aqueous solution into the reaction tank, and the metal-containing aqueous solution is supplied from a reservoir in which the metal-containing aqueous solution is stored to the reaction tank via the metal-containing aqueous solution supply pipe. In addition to the metal-containing aqueous solution supply pipe, the reaction tank is also provided with an alkaline aqueous solution supply pipe for supplying the alkaline aqueous solution into the reaction tank and a complexing agent supply pipe for supplying the complexing agent into the reaction tank.

[0031] <Slurry extraction process> The slurry withdrawal step is a step in which the nickel-containing hydroxide produced in the continuous reaction vessel is allowed to overflow from the overflow pipe of the reaction vessel and is withdrawn as a slurry containing nickel-containing hydroxide.

[0032] <Solid-liquid separation process> If necessary, the slurry containing nickel-containing hydroxide obtained in the slurry extraction step may be The method may further include a solid-liquid separation step in which, after filtering the slurry, the nickel-containing hydroxide is washed with an alkaline aqueous solution and then separated into a solid phase and a liquid phase to obtain a solid phase containing the nickel-containing hydroxide. If necessary, the method may further include a step in which the solid phase containing the nickel-containing hydroxide is dried to obtain a nickel-containing hydroxide powder. If necessary, the solid phase may be washed with water or the like before drying.

[0033] In the method for producing a nickel-containing hydroxide of the present invention, in the reaction step, the flow rate of the metal-containing aqueous solution supplied to the reaction tank is controlled to 0.25 m / sec or less. By controlling the flow rate of the metal-containing aqueous solution supplied to the reaction tank to 0.25 m / sec or less, the average area of ​​the primary particles of the nickel-containing hydroxide can be reduced to 0.035 μm 2 As a result of the above adjustments, a non-aqueous electrolyte secondary battery having excellent initial charge-discharge efficiency can be obtained.

[0034] The flow rate (m / s) of the metal-containing aqueous solution supplied to the reaction vessel is calculated by the flow rate (m 3 / sec) / (cross-sectional area of ​​the outlet of the metal-containing aqueous solution supply pipe (m 2 Therefore, by adjusting the flow rate of the metal-containing aqueous solution flowing through the metal-containing aqueous solution supply pipe in accordance with the cross-sectional area of ​​the outlet of the metal-containing aqueous solution supply pipe, the flow rate of the metal-containing aqueous solution supplied to the reaction tank can be controlled to 0.25 m / sec or less.

[0035] The flow rate of the metal-containing aqueous solution flowing through the metal-containing aqueous solution supply pipe is not particularly limited, but is preferably 1.0×10 -7 m 3 / sec or more 2.0 x 10 -4 m 3 / sec or less is preferable, and 1.2 × 10 -7 m 3 / sec or more 1.0 x 10 -4 m 3 / sec or less is preferable, 1.5 x 10 -7 m 3 / sec or more 5.0 x 10 -5 m 3 The cross-sectional area of ​​the outlet of the metal-containing aqueous solution supply pipe is not particularly limited, but is preferably 1.0×10 -6 m 2 Over 1.0 x 10 -3 m 2 Less than 3.0 x 10 is preferable. -6 m 2 Over 5.0 x 10 -4 m 2 Less than 5.0 x 10 is preferable. -6 m 2 Over 3.0 x 10 -4 m 2 The following are particularly preferred:

[0036] The flow rate of the metal-containing aqueous solution is not particularly limited as long as it is 0.25 m / sec or less. 2 From the viewpoint of further adjustment, the speed is preferably 0.22 m / sec or less, more preferably 0.20 m / sec or less, and particularly preferably 0.18 m / sec or less.

[0037] In the reaction step, the flow rate of the metal-containing aqueous solution supplied to the reaction vessel is not particularly limited as long as it is 0.25 m / sec or less, but the lower limit is set to 0.035 μm when the average area of ​​the primary particles of the nickel-containing hydroxide is 0.035 μm. 2 Since the flow rate can be further adjusted, it is preferably 0.01 m / s or more, more preferably 0.015 m / s or more, and particularly preferably 0.02 m / s or more. The above upper and lower limits can be combined arbitrarily. For example, the flow rate of the metal-containing aqueous solution supplied to the reaction tank is preferably 0.01 m / s or more and 0.25 m / s or less, more preferably 0.01 m / s or more and 0.22 m / s or less, even more preferably 0.015 m / s or more and 0.20 m / s or less, and particularly preferably 0.02 m / s or more and 0.18 m / s or less.

[0038] The flow rate of the metal-containing aqueous solution supplied to the reaction vessel is 0.01 m / s or more and 0.25 m / s or less, so that the average area of ​​the primary particles of the nickel-containing hydroxide is 0.035 μm 2 The above can be further adjusted, and as a result, a nonaqueous electrolyte secondary battery having excellent initial charge-discharge efficiency can be obtained.

[0039] Next, a positive electrode active material for a non-aqueous electrolyte secondary battery using the nickel-containing hydroxide of the present invention as a precursor (hereinafter, sometimes simply referred to as the "positive electrode active material of the present invention") will be described. The positive electrode active material of the present invention is a material in which the nickel-containing hydroxide of the present invention, which is a precursor, is used in a lithium compound, for example. By calcining the nickel-containing hydroxide of the present invention with a lithium compound, a non-aqueous electrolyte secondary battery having excellent initial charge-discharge efficiency can be obtained.

[0040] The crystalline structure of the positive electrode active material of the present invention is a layered structure, and from the viewpoint of obtaining a secondary battery with a high discharge capacity, it is preferably a trigonal crystalline structure, a hexagonal crystalline structure, or a monoclinic crystalline structure. The positive electrode active material of the present invention can be used, for example, as a positive electrode active material for non-aqueous electrolyte secondary batteries such as lithium ion secondary batteries.

[0041] When producing the positive electrode active material of the present invention, a pretreatment step of converting a nickel-containing hydroxide into a nickel-containing oxide may be carried out as necessary, and the nickel-containing oxide may be used as a precursor. A method for preparing a nickel-containing oxide from a nickel-containing hydroxide includes an oxidation treatment of firing in an oxygen gas atmosphere at a temperature of 300°C to 800°C for 1 hour to 10 hours.

[0042] Next, a method for producing the positive electrode active material of the present invention will be described. For example, in the method for producing the positive electrode active material of the present invention, first, a lithium compound is added to a nickel-containing hydroxide (or nickel-containing oxide) to prepare a mixture of the nickel-containing hydroxide (or nickel-containing oxide) and the lithium compound. The lithium compound is not particularly limited as long as it is a compound containing lithium, and examples thereof include lithium carbonate and lithium hydroxide.

[0043] The mixing ratio of the lithium compound and the nickel-containing hydroxide (or nickel-containing oxide) may be, for example, such that the molar ratio of lithium in the lithium compound to the total amount of metals contained in the nickel-containing hydroxide (total amount of nickel and optional components cobalt, manganese, and additional element M) is in the range of 1.00 or more and 1.10 or less.

[0044] Next, the mixture is fired to produce a positive electrode active material. Examples of firing conditions include a firing temperature of 600°C to 1000°C, a temperature rise rate of 50°C / h to 300°C / h, and a firing time of 5 hours to 20 hours. The firing atmosphere is not particularly limited, but examples include air and oxygen. The firing furnace used for firing is not particularly limited, but examples include a stationary box furnace and a roller hearth continuous furnace.

[0045] Next, a positive electrode using the positive electrode active material of the present invention will be described. The positive electrode includes a positive electrode current collector and a positive electrode active material layer formed on the surface of the positive electrode current collector and using the positive electrode active material of the present invention. The positive electrode active material layer contains the positive electrode active material of the present invention, a binder, and, if necessary, a conductive additive. The conductive additive is not particularly limited as long as it can be used for non-aqueous electrolyte secondary batteries, and for example, a carbon-based material can be used. Examples of carbon-based materials include graphite powder, carbon black (e.g., acetylene black), and fibrous carbon materials. The binder is not particularly limited, but for example, a thermoplastic resin can be used. Examples of such thermoplastic resins include polyvinylidene fluoride (PVdF), butadiene rubber (BR), polyvinyl alcohol (PVA), carboxymethyl cellulose (CMC), polytetrafluoroethylene (PTFE), and the like, as well as combinations thereof. The positive electrode current collector is not particularly limited, but examples include conductive metal materials such as aluminum foil, nickel foil, and stainless steel.

[0046] In a method for producing a positive electrode, for example, a positive electrode active material, a conductive additive, and a binder are mixed to prepare a positive electrode active material slurry, which is then filled into a positive electrode current collector by a known filling method, dried, and then rolled and fixed by a press or the like.

[0047] A nonaqueous electrolyte secondary battery can be assembled by preparing a positive electrode using the positive electrode active material obtained as described above, a negative electrode, an electrolytic solution containing a predetermined electrolyte, and a separator by a known method.

[0048] The negative electrode may be an electrode in which a negative electrode active material layer using a negative electrode active material is supported on a negative electrode current collector, or an electrode made of a negative electrode active material alone. The negative electrode active material is not particularly limited as long as it is a commonly used material, and examples thereof include graphite such as natural graphite and artificial graphite, cokes, carbon black, pyrolytic carbons, carbon fiber, and organic polymer compound sintered bodies. The negative electrode current collector is not particularly limited, and examples thereof include metal materials such as copper foil, nickel foil, and stainless steel.

[0049] Furthermore, the negative electrode active material layer may further contain, as necessary, a conductive additive, a binder, etc. Examples of the conductive additive and binder include the same ones as those used in the positive electrode active material layer.

[0050] In a method for producing a negative electrode, for example, a negative electrode active material is mixed with, if necessary, a conductive additive and a binder, and water to prepare a negative electrode active material slurry, which is then filled into a negative electrode current collector by a known filling method, dried, and then rolled and fixed by a press or the like.

[0051] The electrolytes contained in non-aqueous electrolytes include LiClO4, LiPF6, LiAsF6, LiSbF6, LiBF4, LiCF3SO3, LiN(SO2CF3)2, LiN(SO2C2F5)2, LiN(SO2CF3)(COCF3), Li(C4F9SO3), LiC(SO2CF3)3, Li2B 10 Cl 10 Examples of the lithium salt include LiBOB (here, BOB is bis(oxalato)borate), LiFSI (here, FSI is bis(fluorosulfonyl)imide), lithium salts of lower aliphatic carboxylic acids, and lithium salts such as LiAlCl4. These may be used alone or in combination of two or more.

[0052] Examples of the dispersion medium for the electrolyte include carbonates such as propylene carbonate, ethylene carbonate, dimethyl carbonate, diethyl carbonate, ethyl methyl carbonate, 4-trifluoromethyl-1,3-dioxolan-2-one, and 1,2-di(methoxycarbonyloxy)ethane; 1,2-dimethoxyethane, 1,3-dimethoxypropane, pentafluoropropyl methyl ether, 2,2,3,3-tetrafluoropropyl difluoromethyl ether, tetrahydrofuran, and 2-methyltetrahydrofuran. Examples of suitable organic solvents include ethers such as methyl formate, methyl acetate, and γ-butyrolactone; nitriles such as acetonitrile and butyronitrile; amides such as N,N-dimethylformamide and N,N-dimethylacetamide; carbamates such as 3-methyl-2-oxazolidone; sulfur-containing compounds such as sulfolane, dimethyl sulfoxide, and 1,3-propane sultone; and organic solvents containing fluoro groups (organic solvents in which one or more hydrogen atoms have been replaced with fluorine atoms). These may be used alone or in combination of two or more.

[0053] Furthermore, instead of an electrolyte-containing electrolytic solution, a solid electrolyte may be used. Examples of solid electrolytes that can be used include organic polymer electrolytes such as polyethylene oxide polymer compounds, polymer compounds containing at least one of polyorganosiloxane chains or polyoxyalkylene chains, and the like. Also, so-called gel-type solid electrolytes, in which a non-aqueous electrolytic solution is held in a polymer compound, can be used. Examples of inorganic solid electrolytes that contain sulfides include Li2S-SiS2, Li2S-GeS2, Li2S-P2S5, Li2S-B2S3, Li2S-SiS2-Li3PO4, Li2S-SiS2-Li2SO4, and Li2S-GeS2-P2S5. These may be used alone or in combination of two or more. .

[0054] The separator is not particularly limited, but may be, for example, a material in the form of a porous film, nonwoven fabric, woven fabric, etc., made of a polyolefin resin such as polyethylene or polypropylene, a fluororesin, a nitrogen-containing aromatic polymer, etc. These may be used alone or in combination of two or more types. [Example]

[0055] Next, examples of the nickel-containing hydroxide of the present invention will be described, but the present invention is not limited to these examples as long as they do not depart from the spirit of the present invention.

[0056] Production of nickel-containing hydroxides in examples and comparative examples Preparation of nickel-containing hydroxide in Example 1 A metal-containing aqueous solution in which nickel sulfate, cobalt sulfate, and manganese sulfate were dissolved at a predetermined molar ratio of nickel:cobalt:manganese, an ammonium sulfate aqueous solution (complexing agent), and a sodium hydroxide aqueous solution were added dropwise to a reaction vessel having a predetermined volume, and the temperature in the reaction vessel was maintained at 70°C, and the pH in the reaction vessel was maintained at 10.5 based on a liquid temperature of 40°C, while the mixture was continuously stirred with a stirrer. The flow rate of the metal-containing aqueous solution added dropwise to the reaction vessel was adjusted to 0.06 m / sec. The produced hydroxide was allowed to overflow from the overflow pipe of the reaction vessel and extracted. The extracted hydroxide was subjected to treatments of washing with water, dehydration, and drying to obtain a nickel-containing hydroxide.

[0057] Preparation of nickel-containing hydroxide in Example 2 A metal-containing aqueous solution in which nickel sulfate, cobalt sulfate, and manganese sulfate were dissolved at a predetermined molar ratio of nickel:cobalt:manganese, an ammonium sulfate aqueous solution (complexing agent), and a sodium hydroxide aqueous solution were added dropwise to a reaction vessel having a predetermined volume, and the temperature in the reaction vessel was maintained at 70°C, and the pH in the reaction vessel was maintained at 11.2 based on a liquid temperature of 40°C, while the mixture was continuously stirred with a stirrer. The flow rate of the metal-containing aqueous solution added dropwise to the reaction vessel was adjusted to 0.16 m / sec. The subsequent steps were carried out in the same manner as in Example 1, and the nickel-containing hydroxide of Example 2 was obtained.

[0058] Preparation of nickel-containing hydroxide in Example 3 A metal-containing aqueous solution in which nickel sulfate, cobalt sulfate, and manganese sulfate were dissolved at a predetermined molar ratio of nickel:cobalt:manganese, an ammonium sulfate aqueous solution (complexing agent), and a sodium hydroxide aqueous solution were added dropwise to a reaction vessel having a predetermined volume, and the temperature in the reaction vessel was maintained at 70°C, and the pH in the reaction vessel was maintained at 11.4 based on a liquid temperature of 40°C, while the mixture was continuously stirred with a stirrer. The flow rate of the metal-containing aqueous solution added dropwise to the reaction vessel was adjusted to 0.02 m / sec. The subsequent steps were carried out in the same manner as in Example 1, and the nickel-containing hydroxide of Example 3 was obtained.

[0059] Preparation of nickel-containing hydroxide in Example 4 A metal-containing aqueous solution in which nickel sulfate, cobalt sulfate, and manganese sulfate were dissolved at a predetermined molar ratio of nickel:cobalt:manganese, an ammonium sulfate aqueous solution (complexing agent), and a sodium hydroxide aqueous solution were added dropwise to a reaction vessel having a predetermined volume, and the temperature in the reaction vessel was maintained at 70°C, and the pH in the reaction vessel was maintained at 11.3 based on a liquid temperature of 40°C, while the mixture was continuously stirred with a stirrer. The flow rate of the metal-containing aqueous solution added dropwise to the reaction vessel was adjusted to 0.07 m / sec. The subsequent steps were carried out in the same manner as in Example 1, and the nickel-containing hydroxide of Example 4 was obtained.

[0060] Preparation of nickel-containing hydroxide in Example 5 A metal-containing aqueous solution in which nickel sulfate, cobalt sulfate, and manganese sulfate are dissolved in a predetermined molar ratio of nickel:cobalt:manganese, an aqueous ammonium sulfate solution (complexing agent), and an aqueous sodium hydroxide solution are added dropwise to a reaction vessel having a predetermined volume, and the temperature in the reaction vessel is maintained at 70°C, and the pH in the reaction vessel is maintained at 11.3 based on a liquid temperature of 40°C, while the mixture is continuously stirred with a stirrer. The mixture was stirred. The flow rate of the metal-containing aqueous solution dropped into the reaction vessel was adjusted to 0.16 m / sec. The subsequent steps were carried out in the same manner as in Example 1, and the nickel-containing hydroxide of Example 5 was obtained.

[0061] Preparation of nickel-containing hydroxide of Comparative Example 1 A metal-containing aqueous solution in which nickel sulfate, cobalt sulfate, and manganese sulfate were dissolved at a predetermined molar ratio of nickel:cobalt:manganese, an ammonium sulfate aqueous solution (complexing agent), and a sodium hydroxide aqueous solution were added dropwise to a reaction vessel having a predetermined volume, and the temperature in the reaction vessel was maintained at 75°C, and the pH in the reaction vessel was maintained at 11.4 based on a liquid temperature of 40°C, while the mixture was continuously stirred with a stirrer. The flow rate of the metal-containing aqueous solution added dropwise to the reaction vessel was adjusted to 0.31 m / sec. The subsequent steps were carried out in the same manner as in Example 1, and a nickel-containing hydroxide of Comparative Example 1 was obtained.

[0062] The evaluation items for the physical properties of the nickel-containing hydroxides of the examples and comparative examples are as follows. (1) Composition analysis of nickel-containing hydroxides The composition analysis was carried out by dissolving the obtained nickel-containing hydroxide in hydrochloric acid and then using an inductively coupled plasma emission spectrometer (Optima8300DV, manufactured by PerkinElmer Japan Co., Ltd.).

[0063] (2) Average area of ​​primary particles of nickel-containing hydroxide For each of the nickel-containing hydroxide particles of the examples and comparative examples, secondary particle images were obtained by observation with a scanning electron microscope (SEM) at 5,000x magnification. From the obtained images, secondary particles with a particle diameter of 50 volume percent (D50) (±10%) were selected, as measured using a particle size distribution analyzer using a laser diffraction / scattering method. Next, for the selected secondary particles, 40 primary particles were randomly selected from the surface area of ​​the SEM image at 20,000x magnification, and the area of ​​each of the selected 40 primary particles was measured using the image processing software "ImageJ." The average area of ​​the primary particles was then calculated from the areas of the 40 measured primary particles.

[0064] The evaluation results of the physical properties of the nickel-containing hydroxides of the examples and comparative examples are shown in Table 1 below.

[0065] Production of positive electrode active materials using nickel-containing hydroxides of Examples and Comparative Examples as precursors Lithium hydroxide powder was added to and mixed with the nickel-containing hydroxides of the Examples and Comparative Examples so that the molar ratio of Li / (Ni+Co+Mn) was 1.05, to obtain a mixture of nickel-containing hydroxide and lithium hydroxide. The obtained mixture was subjected to a calcination treatment to obtain a lithium metal composite oxide, which was used as a positive electrode active material. The calcination conditions were an oxygen atmosphere, a temperature increase rate of 160°C / h, a calcination temperature of 750°C, and a calcination time of 5 hours.

[0066] Manufacturing of positive electrodes using positive electrode active materials A positive electrode was fabricated using the positive electrode active material obtained as described above, and a battery for evaluation was assembled using the fabricated positive electrode. Specifically, the positive electrode active material obtained, a conductive additive (acetylene black), and a binder (PVdF) were mixed in a weight ratio of 92:5:3, respectively, and the resulting mixture was applied to a positive electrode current collector (aluminum foil), dried, and pressed to adhere to the positive electrode current collector, thereby forming a positive electrode.

[0067] A lithium secondary battery was fabricated using the positive electrode obtained as described above, a negative electrode (metallic lithium), an electrolyte solution containing an electrolyte (LiPF6) (a mixed solution of ethylene carbonate: dimethyl carbonate: ethyl methyl carbonate in a volume ratio of 30:35:35), and a separator (made of polypropylene).

[0068] Evaluation items for lithium secondary batteries Initial charge / discharge efficiency An initial charge-discharge test was carried out using the prepared lithium secondary battery under the conditions shown below, and the ratio of the initial discharge capacity to the initial charge capacity expressed as a percentage was taken as the initial charge-discharge efficiency. <Charge / discharge test conditions> Test temperature: 25℃ Maximum charging voltage 4.3V, charging current 0.2CA, constant current constant voltage charging Minimum discharge voltage 2.5V, discharge current 0.2CA, constant current discharge When the initial charge-discharge efficiency was 83.0% or higher, the initial charge-discharge efficiency was evaluated as high.

[0069] The evaluation results of the lithium secondary batteries of the Examples and Comparative Examples are shown in Table 1 below.

[0070] [Table 1]

[0071] From Table 1, the average area of ​​the primary particles of nickel-containing hydroxide is 0.035 μm 2 In Examples 1 to 5, the initial charge-discharge efficiency was 83.0% or more, which was excellent. In Examples 1 to 5, the flow rate of the metal-containing aqueous solution dropped into the reaction vessel was adjusted to 0.25 m / sec or less. In Examples 1 to 3, the average area of ​​the primary particles of the nickel-containing hydroxide was 0.050 μm 2 In the above, an even better initial charge-discharge efficiency of 85.0% or more was obtained.

[0072] On the other hand, from Table 1, the average area of ​​the primary particles of nickel-containing hydroxide is 0.030 μm 2 In Comparative Example 1, the initial charge-discharge efficiency was 81.8%, and an excellent initial charge-discharge efficiency could not be obtained. In Comparative Example 1, the flow rate of the metal-containing aqueous solution dropped into the reaction tank was 0.31 m / sec, which was not adjusted to 0.25 m / sec or less. [Industrial Applicability]

[0073] When a positive electrode active material using the nickel-containing hydroxide of the present invention as a precursor is installed in a secondary battery, it can exhibit excellent initial charge-discharge efficiency, and therefore can be used in a wide range of secondary battery fields, such as portable devices and vehicles.

Claims

1. A nickel-containing hydroxide, which is a precursor of a positive electrode active material for a non-aqueous electrolyte secondary battery and is a secondary particle formed by aggregation of a plurality of primary particles, The average area of ​​the primary particles is 0.035 μm ２ The nickel-containing hydroxide is as described above.

2. The average area of ​​the primary particles is 0.100 μm ２ The nickel-containing hydroxide according to claim 1, wherein:

3. The average area of ​​the primary particles is 0.039 μm ２ 0.080 μm or more ２ The nickel-containing hydroxide according to claim 1 or 2, wherein:

4. 3. The nickel-containing hydroxide according to claim 1, wherein the nickel (Ni) is contained in an amount of 80 mol % or more based on the total amount of metals contained in the nickel-containing hydroxide.

5. The nickel-containing hydroxide according to claim 4, which is a composite hydroxide containing nickel (Ni) and at least one metal selected from the group consisting of cobalt (Co) and manganese (Mn).

6. The nickel-containing hydroxide according to claim 4, wherein the molar ratio of nickel (Ni): cobalt (Co): manganese (Mn): additional element M is (1-x-y-z): x:y:z (0≦x≦0.15, 0≦y≦0.15, 0≦z≦0.05, M is Al, Fe, Ti, Mg, Ca, Sr, Ba, V, Nb, Cr, Mo, W, Ru, Cu, Zn, B, Ga, Si, Sn, P, Bi, and Zr. It is a composite hydroxide represented by the formula: Zr=0.05, 0≦y≦0.15, 0≦z≦0.05, M is Al, Fe, Ti, Mg, Ca, Sr, Ba, V, Nb, Cr, Mo, W, Ru, Cu, Zn, B, Ga, Si, Sn, P, Bi, and Zr.

7. A positive electrode active material for a non-aqueous electrolyte secondary battery, comprising the nickel-containing hydroxide according to claim 1 or 2 calcined with a lithium compound.

8. A method for producing a nickel-containing hydroxide, which is a precursor of a positive electrode active material for a non-aqueous electrolyte secondary battery and is a secondary particle formed by aggregation of a plurality of primary particles, comprising: a reaction step of continuously supplying a metal-containing aqueous solution containing nickel, a complexing agent, and an alkaline aqueous solution to a reaction vessel to cause a crystallization reaction to obtain a nickel-containing hydroxide; a slurry withdrawing step of continuously withdrawing the slurry containing the nickel-containing hydroxide from the reaction tank; Including, The method for producing a nickel-containing hydroxide, wherein the flow rate of the metal-containing aqueous solution containing nickel supplied to the reaction tank in the reaction step is 0.25 m / sec or less.

9. 9. The method for producing a nickel-containing hydroxide according to claim 8, wherein the flow rate of the metal-containing aqueous solution containing nickel supplied to the reaction tank in the reaction step is 0.01 m / sec or more.

10. The method for producing a nickel-containing hydroxide according to claim 8 or 9, further comprising a solid-liquid separation step of washing the nickel-containing hydroxide obtained in the slurry extraction step with an alkaline aqueous solution and then separating the nickel-containing hydroxide into solid and liquid.

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