JPH1087327A - Composite metal hydroxide, method for producing the same, and raw material for positive electrode active material for lithium secondary battery - Google Patents

Abstract

(57) Abstract: At least two or more selected from metal elements of Ni, Co and Mn, and Mg, Ti, Fe, Cu,
A composite metal hydroxide comprising at least one or more selected from metal elements of Zn and Cr in a solid solution and / or coprecipitated state in a composite metal hydroxide, a method for producing the same, and a method for producing the same. Positive electrode active material for secondary batteries using this. The composite hydroxide of the present invention has a substantially spherical particle form, and is useful as a raw material for a positive electrode active material for a lithium secondary battery.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a composite metal hydroxide, a method for producing the same, and a raw material for a positive electrode active material for a lithium secondary battery.

[0002]

2. Description of the Related Art In recent years, portable electronic devices have become more portable.
With the rapid progress of cordless technology, lithium secondary batteries have been put to practical use as power supplies for small electronic devices. Mizushima et al. Reported in 1980 that this lithium secondary battery was useful as a positive electrode active material for lithium cobaltate secondary batteries [“Material Research Brain” vol. 115,
P.783-789 (1980)], research and development on lithium-based composite oxides have been actively promoted, and many proposals have been made so far.

They include, for example, Li _1-a NiO ₂ (where 0 ≦ a ≦ 1) (US Pat. No. 4,302,518), Li _b Ni _2-b O ₂ and LiNi _1-d Co _d O _2.
(However, 0.84 ≦ b ≦ 1.22, 0.09 ≦ b ≦ 1.
22, 0.99 ≦ d ≦ 0.5) (JP-A-2-40861)
Publication), LinNimCo _1-m O ₂ (JP _-A- 63-2
99056, JP-A-1-120765, JP-A-1-294364, JP-A-5-290890
JP, JP-A-6-275274, JP-A-7-1
No. 42056) is a composite oxide mainly composed of lithium and a transition metal. Among the above compounds, lithium cobalt oxide has been studied since the earliest because it is relatively easy to synthesize. However, the raw material cobalt (Co) is expensive and rarely used as a resource, and when charged with 0.7 electrons or more, the crystal becomes crystalline. However, there is a problem that the increase in capacity is not suitable because the deterioration of the properties and the decomposition of the electrolytic solution occur. On the other hand, LiNiO ₂ and LiMn ₂ O
₄ has the advantage of being inexpensive compared to lithium cobalt oxide, but has poor stability as an active material due to the susceptibility to defects in the crystal, and has a discharge capacity characteristic when incorporated into batteries. Has many problems in practicality because it is inferior to cobalt type.

[0004]

In order to solve these problems, a lithium composite metal salt in which a part of Ni or Mn is replaced by a transition metal such as Co has been studied from an economical and functional viewpoint. . However, as a method for producing usually cobalt acid-containing lithium nickelate, there is known a method in which Co and Ni oxide or hydroxide powders and raw materials of lithium hydroxide or lithium carbonate are dry-mixed and fired. However, in this method, defects are easily generated in the crystal, and therefore, an active material for a lithium secondary battery having preferable discharge capacity characteristics has not been obtained.

Accordingly, it is an object of the present invention to provide a composite metal hydroxide useful as a raw material of a lithium metal composite oxide used for a positive electrode of a lithium secondary battery or the like, and a method for producing the same.

[0006]

Under such circumstances, the present inventors have conducted intensive studies on binary or ternary compounds selected from metal elements of Ni, Co and Mn as raw materials for batteries. It was completed.

That is, the present invention relates to Ni, Co and Mn.
At least two or more selected from metal elements and Mg,
A composite metal water comprising at least one or more selected from metal elements of Ti, Fe, Cu, Zn and Cr in a solid solution and / or coprecipitated state in a composite metal hydroxide. An oxide is provided.

[0008] The present invention also relates to a method of forming a coating of at least two metal salts selected from the group consisting of Ni, Co and Mn with Mg, Ti and F.
e, in a mixed solution of at least one or two or more metal salts selected from Cu, Zn and Cr, in the presence of a chelating agent having a complexing power for metal ions, a precipitation generation reaction by alkali hydrolysis is continuously performed. And then aging the precipitated product.

Further, the present invention provides a raw material for a positive electrode active material for a lithium secondary battery, comprising the above-mentioned composite metal hydroxide as an active ingredient.

[0010]

BEST MODE FOR CARRYING OUT THE INVENTION The composite metal hydroxide of the present invention comprises N
i, at least 2 selected from metal elements of Co and Mn
The hydroxide contains at least one or more kinds selected from metal elements of Mg, Ti, Fe, Cu, Zn and Cr in a solid solution and / or coprecipitation state in the hydroxide. That is, the composite metal hydroxide contains Ni—Co, Ni—Mn and M
An n-Co two-component system or a Ni-Co-Mn three-component system is used as a basic composition, and Mg, Ti, Fe, Cu, Z
n and Cr (hereinafter, referred to as “Mg or the like”) at least one or two or more metal element substances are in solid solution and / or
Or, they are co-precipitated.

The crystal particles formed in the solid solution and / or coprecipitation state include a binary or ternary composite metal hydroxide of Ni, Co and Mn metal elements serving as a skeleton and Mg added thereto. Are not simply mixed particles such as metal hydroxides.For example, as a result of the coprecipitation reaction at the time of formation, in the Ni-Co system, the atoms at the lattice points of the Ni crystal phase are atoms such as Co and Mg. Crystal grains in a partially substituted state, Ni
In the case of -Co-Mn-based, it refers to crystal particles in which a predetermined amount thereof and a hydrated oxide such as Mg are uniformly coprecipitated or occluded during generation.

The mixing ratio of Ni, Co and Mn is not particularly limited, and the amount of hydroxides such as Mg contained in these binary or ternary composite hydroxides depends on the type of the basic composition, Types of Mg and their chemical and physical properties,
Depending on the purpose of use, etc., in the composite hydroxide, 0.1 ~
It is preferably 10% by weight, particularly preferably 1 to 5% by weight.

[0013] The composite metal hydroxide of the present invention is characterized in that the crystal particles thereof do not form a solid solution, coprecipitate or occlude with the above metal,
It can be confirmed by powder X-ray diffraction. That is,
In this case, single hydroxide peaks of these metals are observed. However, the composite hydroxide of the present invention has very few such single hydroxides, and these peaks are hardly found in powder X-ray diffraction. not exist.

The composite metal hydroxide of the present invention has an average particle diameter determined by a laser method, which is not particularly limited, but is 0.1 to 50 μm, preferably 1 to 30 μm, and more preferably 5 to 20 μm. Range.

The composite metal hydroxide of the present invention has the above-mentioned characteristics, and a mixture obtained by mixing a lithium salt with the composite hydroxide and firing the mixture is used as a positive electrode active material for a lithium secondary battery. When used, it is particularly useful as an active material raw material because it has excellent discharge characteristics and characteristics having a discharge retention ratio, which have not been seen before.

The composite metal hydroxide of the present invention comprises Ni, Co
And at least two metal salts selected from Mn and Mn
g in the presence of a chelating agent having a complexing power for the metal ion in a mixture with at least one or two or more metal salts selected from And then aging the precipitated product.

The nickel salt used in the present invention includes:
Although not particularly limited, examples thereof include easily water-soluble mineral salts such as nickel sulfate, nickel nitrate, and nickel chloride. Further, the cobalt salt is not particularly limited, and examples thereof include cobalt sulfate, cobalt nitrate, and cobalt chloride. Examples of the manganese salt include manganese sulfate, manganese nitrate, and manganese chloride.

Further, Mg, Ti, Cr, Fe,
The salts of Cu and Zn are not particularly limited as long as they are soluble in water, and include nitrates, sulfates, and hydrochlorides. In particular, nickel, cobalt and manganese salts
It is preferably used at about 0.5 to 3.5 mol / L, and the magnesium salt or the like is preferably used at about 0.05 to 0.4 mol / L.

Examples of the chelating agent having a complexing power to these metal ions include hydrazine, triethanolamine, glycine, alanine, asparagine, iminodiacetic acid, glutamic acid, ethylenediamine, and the like.
Aminocarboxylic acids such as ethylenediaminetetraacetic acid or salts thereof; acetic acid, lactic acid, oxalic acid, malonic acid, malic acid,
Oxycarboxylic acids such as tartaric acid, citric acid, salicylic acid and thioglycolic acid or salts thereof and ammonia. The term "ammonia" refers to an ion supplier, and examples thereof include an aqueous solution of an ammonium salt such as ammonium nitrate, ammonium sulfate, and ammonium chloride, aqueous ammonia, and ammonia gas, and preferably aqueous ammonia.

The above-mentioned chelating agents such as aminocarboxylic acid, oxycarboxylic acid and ammonia may be used alone or in combination of two or more.
0.1 to 1 mol of salt, Co salt, Mn salt, Mg salt and the like.
A range of 2 to 4.0 moles is preferred. The method of compounding the chelating agent is not particularly limited, and it may be used alone, or may be added by mixing a predetermined ratio of an aqueous Ni salt solution and an aqueous solution of Co salt in advance. If it is less than 0.2 mol, the grain growth is not sufficient, and if it exceeds 0.4 mol, it is not preferable from the economical point of view.

Examples of the alkali used for the alkali hydrolysis include aqueous solutions of caustic alkali such as sodium hydroxide and potassium hydroxide. Of these, sodium hydroxide is preferred. The addition amount of the alkali is Ni salt, Co
1.1 to 1.1 mol per 1 mol of a salt, Mn salt, Mg salt, etc.
3.0 mol. If less than 1.1 moles, unreacted N
It is not preferable since i-salt and Mn salt are formed, which is not preferable.
If it exceeds 300, many ungrown particles with insufficient particle growth are generated, which is not preferable.

The reaction operation is not particularly limited. For example, the pH of the continuously added reaction solution is adjusted to 9-1.
A method in which the reaction is carried out by keeping the solution at a constant value in the range of 2 for at least 3 hours. At this time, the reaction solution may be subjected to an aging reaction in the next container once overflowed.

As another method, the volume of the reaction solution is controlled to a constant value except for the reaction medium solution without overflowing the reaction system solution containing the reaction product by continuously adding the reaction solution. This is a method of reacting while reacting. According to this method, the Ni-Mn composite hydroxide particles formed in the reaction vessel grow and increase continuously, so that stirring of the reaction system becomes gradually difficult. It is preferable to terminate the reaction.

The reaction conditions are preferably set so that the slurry concentration of the reaction system is at least 70 g / L or more. If the concentration is lower than this, particle growth becomes extremely slow, which is not preferable.

Each reaction solution to be added may be continuously added at once, or may be a multi-stage system in which the reaction solutions are divided and dropped in multiple stages.

The reaction temperature is usually 10 to 100 ° C., preferably 20 to 80 ° C., and the reaction time is about 1 to 72 hours.

[0027]

The composite metal hydroxide of the present invention has a substantially spherical particle form and is useful as a raw material for a positive electrode active material for a lithium secondary battery.

[0028]

Next, the present invention will be described in detail with reference to examples, but this is merely an example and does not limit the present invention.

Example 1 A 1 L beaker was previously filled with 200 ml of water, and 1.6 ml of water was added thereto.
mol / L CoS of NiSO ₄ · 6H ₂ O and 0.2mol / L of
O ₄ · mixture 1 of 7H ₂ O and 0.2 mol / L ZnSO ₄ of
200 ml, 800 ml of a 6 mol / L NaOH solution and 400 ml of a 14.8 mol / L ammonia solution as a complexing agent were added dropwise, and the mixture was kept at 50 ° C. while adjusting the pH to 11, and stirred and aged for 9 hours. During this time, the amount of liquid in the system was controlled by the overflow method, and a certain amount of the reaction liquid was discharged. Next, the crystals after the filtration were subjected to repulping washing, and the washing effect was confirmed by a conductivity meter. This crystal is a eutectic formed in a solid solution and / or coprecipitation state of Ni, Co and Zn, and has a composition of Ni: C
The molar ratio of o: Zn was 8: 1: 1. When this crystal was measured by a laser method, the average particle diameter was 12 μm.
Met.

[0030] Example 2 previously stretched to 200ml of water 1L beaker, MnSO of CoSO ₄ · 7H ₂ O and 0.3 mol / L of 1.6mol / L ₄ · 5
Mixed solution 12 of H ₂ O and 0.1 mol / L Ti (SO ₄ ) ₂
00 ml, 800 ml of a 6 mol / L NaOH solution and 400 ml of a 14.8 mol / L ammonia solution as a complexing agent were added dropwise, and the temperature was maintained at 50 ° C. while adjusting the pH to 11,
The mixture was stirred and aged for 9 hours. During this time, the amount of liquid in the system was controlled by the over method, and a certain amount of the reaction liquid was discharged. Next, the crystals after the filtration were subjected to repulping washing, and the washing effect was confirmed by a conductivity meter. This crystal was a eutectic obtained in a solid solution and / or coprecipitation state of Co, Mn and Ti, and the composition was such that the molar ratio of Co: Mn: Ti was 0.8: 0.15: 0.05. . When this crystal was measured by a laser method, the average particle diameter was 7 μm.
m.

Example 3 A 1 L beaker was previously filled with 200 ml of water, and 1.0 mol / L
NiSO ₄ .6H ₂ O and 0.9 mol / L CoSO _4.
1200m mixture of 7H ₂ O and 0.1mol / L MgSO ₄
1, 800 ml of a 6 mol / L NaOH solution and 400 ml of a 14.8 mol / L ammonia solution as a complexing agent were added dropwise, and the mixture was kept at 50 ° C. while adjusting the pH to 11, and aged for 9 hours with stirring. During this time, the amount of liquid in the system was controlled by the over method, and a certain amount of the reaction liquid was discharged. Next, the crystals after the filtration were subjected to repulping washing, and the washing effect was confirmed by a conductivity meter.
This crystal was a eutectic obtained in a solid solution and / or coprecipitation state of Ni, Co and Mg, and the composition was such that the molar ratio of Ni: Co: Mg was 0.5: 0.45: 0.05. . When this crystal was measured by a laser method, the average particle size was 10 μm.
Met.

[0032] Example 4 pre-tension the 200ml of water 1L beaker, CoSO ₄ · 7 of MnSO ₄ · 5H ₂ O and 0.9 mol / L of 1.0 mol / L
Mixture 1 between H ₂ O and _{0.1mol / L FeSO 4 · 7H 2} O of
200 ml, 800 ml of a 6 mol / L NaOH solution and 400 ml of a 14.8 mol / L ammonia solution as a complexing agent were added dropwise, and the mixture was kept at 50 ° C. while adjusting the pH to 11, and stirred and aged for 9 hours. During this time, the amount of liquid in the system was controlled by the over method, and a certain amount of the reaction liquid was discharged. Next, the crystals after the filtration were subjected to repulping washing, and the washing effect was confirmed by a conductivity meter. This crystal is a eutectic of Mn, Co and Fe, and has a composition of Mn: Co: Fe having a molar ratio of 0.5: 0.45: 0.
05. When this crystal was measured by a laser method, the average particle size was 10 μm.

Example 5 A 1 L beaker was previously filled with 200 ml of water and 1.4 mol / L.
NiSO ₄ .6H ₂ O and 0.2 mol / L CoSO _4.
7H ₂ O and 0.2 mol / L MnSO ₄ .5H ₂ O and 0.2
1200 ml of a mixed solution of ZnSO ₄ at mol / L, N at 6 mol / L
800 ml of an aOH solution and 400 ml of a 1 mol / L glycine solution as a complexing agent were added dropwise, and the mixture was kept at 70 ° C. while adjusting the pH to 10 and stirred and aged for 9 hours. During this time, the amount of liquid in the system was controlled by the overflow method, and a certain amount of the reaction liquid was discharged. Next, the crystals after the filtration were subjected to repulping washing, and the washing effect was confirmed by a conductivity meter. This crystal is Ni,
A eutectic obtained in a solid solution and / or coprecipitation state with Co, Mg, and Zn. The composition is such that the molar ratio of Ni: Co: Mn: Zn is 0.7: 0.1: 0.1: 0. It was one. The average particle size obtained by measurement by a laser method was 11 μm.

Claims (6)

[Claims] At least two kinds selected from metal elements of Ni, Co and Mn, and Mg, Ti, Fe, Cu,
A composite metal hydroxide comprising at least one or more selected from metal elements of Zn and Cr in a solid solution and / or coprecipitation state in the composite metal hydroxide. 2. The composite metal hydroxide according to claim 1, wherein the average particle diameter determined by a laser method is in the range of 0.1 to 50 μm. 3. At least two or more metal salts selected from Ni, Co and Mn, and Mg, Ti, Fe, Cu, Zn
And a precipitation reaction by alkali hydrolysis in a mixture of at least one or two or more metal salts selected from Cr and Cr in the presence of a chelating agent having a complexing power for the metal ions. And then aging the precipitated product. 4. The method for producing a composite metal hydroxide according to claim 3, wherein the continuous reaction is performed in a multistage manner. 5. The chelating agent is at least one selected from aminocarboxylic acids, oxycarboxylic acids and ammonia.
The method for producing a composite metal hydroxide according to claim 3 or 4, wherein the method is a kind or two or more kinds. 6. A raw material for a positive electrode active material for a lithium secondary battery, comprising the composite metal hydroxide according to claim 1 as an active ingredient.