JPH10134811A - Manufacture of positive electrode material for lithium cell - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a manufacturing method of the positive electrode material for a lithium cell, which can prevent its cell characteristics from being degraded because of repeated discharging/discharging, and is excellent in durability (cyclic characteristics). SOLUTION: In a case that nickel acid lithium is manufacture, to which the third constituent other than nickel and lithium is added, water solution where water soluble nickel compounds and water soluble compounds of the aforesaid third constituent are mixed, it prepared so as to be reacted with the water solution of alkaline compounds, and the copresipitates of the third constituent with nickel are thereby deposited, the aforesaid coprecipitates are dried so as to be sintered into powder, and the powder of lithium compounds is added to, and mixed with the aforesaid powder so as to be sintered in the range of 600 to 850 deg.C in oxygen environment. As the third constituent, its ion radius shall be 0.6 to 1.5 timed as large as the ion radius 0.56Å of nickel, and practically, Al, Co, Fe, Mn, Mg and the like are desirable.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION Devices that use a battery as a power source, such as tape recorders, mobile phones, and radios, include:
There is a demand for a battery that is small / light, has a large capacity, and can be used repeatedly after being charged many times. At present, a lithium battery meets the demand, and lithium nickel oxide is used as a positive electrode material of the lithium battery.

[0002]

2. Description of the Related Art As a positive electrode material of a lithium battery, lithium cobalt oxide has been put to practical use, but it is expensive and the effective charge is only about 50% of the theoretical amount. There is a need for a positive electrode material. Lithium nickelate has been listed as the most promising candidate as a positive electrode material that is inexpensive and has a large effective storage capacity. However, lithium nickelate has a large decrease in battery characteristics due to repeated charge / discharge.
There is a problem that durability (cycle characteristics) is inferior. No. 3 to improve the durability of lithium nickelate
Attempts have been made to provide various characteristics by adding components, but mere mixing produces only the properties of a mixture, and requires some means of addition.

[0003]

SUMMARY OF THE INVENTION An object of the present invention is to provide a method for producing a lithium battery positive electrode material which is excellent in durability (cycle characteristics) with little deterioration in battery characteristics due to repeated charge / discharge.

[0004]

According to the present invention, there is provided a method for producing a positive electrode material for a lithium battery, wherein a lithium nickel oxide to which a third component other than nickel and lithium is added is produced as a positive electrode material for a lithium battery. And preparing a mixed aqueous solution of a third component and a water-soluble compound to be added, and reacting the mixed aqueous solution with an aqueous solution of an alkali compound to form a coprecipitate of nickel and the third component. Alternatively, a lithium compound powder is added to and mixed with the calcined powder, and the mixture is heated to 600 to 850 ° C. in an oxygen atmosphere.
Firing at a temperature in the range of

[0005]

BEST MODE FOR CARRYING OUT THE INVENTION Cobalt (Co), manganese (Mn), iron (Fe) are used as third components added for the purpose of improving the durability and other properties of lithium nickelate used as a battery cathode material. , Magnesium (Mg), aluminum (Al), or a combination thereof. Conventionally, these third component raw materials,
For example, powders of a cobalt raw material, a nickel raw material, and a lithium raw material are pulverized and mixed well, and then mixed in an oxygen atmosphere at 600
Although firing is performed at a temperature in the range of ~ 850 ° C, only LiNiO ₂ (lithium nickelate) and LiCoO ₂ are obtained.
It is merely a mixture of each of (lithium cobaltate) and not a homogeneous compound (see Comparative Example 2). In the present invention, first, a mixed aqueous solution of a water-soluble nickel compound and a water-soluble compound of the third component is prepared, and this is reacted with an aqueous solution of an alkali compound to form a coprecipitate of nickel and the third component. A powder of a lithium compound is added to a powder obtained by drying the coprecipitate or a powder obtained by further firing, and firing is performed at a temperature in a range of 600 to 850 ° C. in an oxygen atmosphere.

[0006] The method of the present invention can be applied to any third component other than the above, but in order to be uniformly present in the crystal structure of lithium nickelate, the third component can be an ion. It is desirable that the radius be in the range of 0.8 to 1.5 times, preferably 0.9 to 1.3 times, the ionic radius of Ni of 0.56 °. Table 1 shows such third components and their respective ionic radii.

[0007]

[Table 1]

As the water-soluble nickel compound and the water-soluble compound of the third component, respective nitrates, sulfates or hydrochlorides are suitable. The concentration of the mixed aqueous solution of the nickel compound and the third component is preferably in the range of 0.15 to 1.5 mol / L (liter). Suitable alkali compounds are hydroxides or carbonates of sodium, potassium or ammonia. When sodium or potassium is used, it is necessary to filter and wash the coprecipitate to remove the sodium salt or potassium salt. When ammonia is used, nickel forms complex ions when it forms a precipitate with an aqueous solution, and escapes into the wastewater when partially dissolving and filtering the coprecipitate. It is necessary to devise such measures as drying all at once. However, there is an advantage that washing for removing sodium and potassium salts is unnecessary. The concentration of the aqueous solution of the alkali compound is also 0.15 to 1.
A range of 5 mol / L is preferred. Ni and the third component (M)
Ratio Ni: M is 0.5 to 0.95: 0.5 to 0.05.
Is appropriate.

The method of the precipitation reaction by the reaction of a mixed aqueous solution of a nickel compound and a third component compound (aqueous metal salt solution) with an aqueous solution of an alkali compound is as follows: (1) A method of pouring an aqueous alkali solution into an aqueous metal salt solution And (2) a method of pouring an aqueous solution of a metal salt into an aqueous alkali solution, and (3) a method of simultaneously pouring and mixing both aqueous solutions.
pH range where precipitation of i occurs and p where precipitation of the third component occurs
In the method (1), there is a difference between Ni and the third region.
The component (2) or (3) is preferred because the component and the component may not precipitate at the same time. The coprecipitate of Ni and the third component may be pulverized to fine particles by a wet pulverizer if necessary, and then dried and granulated by a spray drier to adjust the particle size.

[0010] The thus obtained coprecipitate of nickel and the third component is converted into a dried powder or a further calcined powder,
Add lithium compound powder and add 600
By calcining at a temperature in the range of ８850 ° C., lithium nickelate having the third component in the crystal structure is obtained. The ratio of the sum of Ni and the third component M to Li (Ni +
M): Li is suitably in the range of 1: 1.0 ± 0.05.

It has been reported that the presence of the third component in the crystal structure of lithium nickelate can be confirmed by X-ray. The improvement in durability can be determined from the results of the charge / discharge test. It is said that the inflection point of the charge / discharge characteristic curve corresponds to the change in the crystal structure.Thus, it is considered that a material with a small inflection point and a smooth voltage change has a gradual change in the crystal structure and high durability. Can be

Hereinafter, the present invention will be described specifically with reference to examples, but the present invention is not limited to the following examples.

[0013]

Comparative Example 1 (LiNiO ₂ ) Nickel hydroxide [Ni (OH) ₂ : 95% purity] was pulverized with a wet pulverizer using water as a solvent, and the average particle size was about 1 μm.
Particles. The slurry of the particles was dried and granulated with a spray drier to obtain particles having an average particle size of about 13 μm.
69.5 g (0.71 mol) of nickel hydroxide adjusted for particle size and 30.5 g (0.71 mol) of 98% pure lithium hydroxide
Mol) (Ni: Li atomic ratio = 1: 1) was well pulverized and mixed in a mortar. This was baked at 700 ° C. for 10 hours under flowing oxygen. The result of X-ray diffraction measurement of this sample is shown in FIG. From this chart, it was confirmed that lithium nickelate with sufficiently grown crystals was synthesized. This sample, acetylene black and PTFE (polytetrafluoroethylene) powder were mixed in a weight ratio of 75: 20: 5, and kneaded in a mortar for 5 minutes. 0.1mm sheet, 16mmφ
Then, it was vacuum-dried at 110 ° C. to obtain a positive electrode material for testing (lithium nickel oxide alone). The positive electrode material thus obtained, a nonwoven fabric (made of polypropylene), a separator (made of polypropylene, product name: Celgard), a thickness of 0.2
mm metal lithium foil was laminated in a button-type battery cell. As an electrolyte, a mixed solvent of propylene carbonate and dimethoxyethane at a volume ratio of 1: 1 in which 1 mol / l of LiClO ₄ was dissolved was used. A battery was prepared with such a configuration, and a charge / discharge test was performed. Charge / discharge condition is 0.5 at constant current
The measurement was performed at a current density of mA / cm ² , and the charging potential was controlled to 4.3 V and the discharge voltage was controlled to 3.0 V. The discharge curve at this time is shown in FIG. Plateaus were observed at two places, V1 and V2, where dislocation of the crystal structure occurred,
It is generally said that repetition of dislocations causes crystal structure destruction, resulting in a reduction in capacity. Table 3 shows the cycle characteristics. The initial performance is as high as 200 mAh / g, but the charge and discharge are repeated, so that
It decreased to 5 mAh / g.

[0014]

Comparative Example 2 59.0 g (0.605 mol) of the same nickel hydroxide used in the comparative example, 10.5 g (0.107 mol) of 94.6% pure cobalt hydroxide, and lithium hydroxide 30 0.5 g (0.712 mol) (Ni + Co: L
i atomic ratio = 0.85 + 0.15: 1) was pulverized and mixed well in a mortar. This was baked at 700 ° C. for 10 hours under flowing oxygen. FIG. 2 shows an X-ray diffraction measurement result of this sample.
LiNiO ₂ (lithium nickelate) and LiCoO ₂
(Lithium cobaltate), two types of peaks were observed,
It turns out that it is only a mere mixture of each and not a homogeneous compound. A symbol indicates a peak attributed to LiCoO ₂ . A coin battery was prepared for this sample in the same manner as in Comparative Example 1, and charge / discharge measurement was performed under the same measurement conditions. The initial capacity is 160 mAh / g, 96 m for the 30th time
Ah / g, inferior in initial performance and cycle characteristics.

[0015]

Example 1 494.2 g (1.7 mol) of nickel nitrate
And 89.1 g (0.3 mol) of 98% cobalt nitrate were dissolved in water to obtain a mixed solution (solution A) of 2 L of nickel nitrate and cobalt nitrate. 318.0 g of sodium carbonate
(3.0 mol) was dissolved in water to prepare a 1.8 L sodium carbonate solution (solution B). Solution A and Solution B were simultaneously poured into 1 L of hot water at 80 ° C. over a period of 80 minutes at a constant rate to cause a reaction. At this time, the temperature was maintained at 80 ° C., and a good stirring state was maintained. After completion of the pouring, this state was further maintained for 60 minutes to perform aging. The precipitate thus obtained was filtered, washed with water and dried at 120 ° C. for 16 hours to obtain a coprecipitate of a basic carbonate of nickel and cobalt. The precipitate was pulverized with a wet pulverizer using water as a solvent to obtain a granular slurry having an average particle size of about 1 μm. The slurry was dried and granulated with a spray dryer to obtain granules having an average particle size of about 13 μm. The powder having an average particle size of about 13 μm was heated to 400 ° C. in an air stream, and maintained at this temperature for about 2 hours until generation of carbon dioxide gas was no longer observed, to obtain an oxide. The composition of the oxide is Ni6
3.1 Wt. %, Co 11.2 Wt. %Met. 100.0 g of this oxide powder (Ni + Co = 1.26 mol)
And 98% pure lithium hydroxide 54.1 g (1.26 mol) (Ni + Co: Li atomic ratio = 0.85 + 0.15:
1 = 1: 1) was crushed and mixed well in a mortar. This is baked at 700 ° C. for 10 hours under flowing oxygen to form LiCo _0.15 Ni.
_0.85 O ₂ was obtained.

[0016]

Example 2 552.4 g (1.9 mol) of nickel nitrate
And a 2 L aqueous solution in which 29.7 g (0.1 mol) of 98% cobalt nitrate was dissolved as solution A, and the mixing ratio of the oxide powder and lithium hydroxide was (Ni + Co: Li atomic ratio = 0.95 + 0). 0.05: 1 = 1: 1) except that LiCo _0.05 Ni _0.95 O ₂ was synthesized in the same manner as in Example 1.

[0017]

Example 3 407.0 g (1.4 mol) of nickel nitrate
And a 2 L aqueous solution in which 178.0 g (0.6 mol) of 98% cobalt nitrate was dissolved as solution A, and the mixing ratio between the oxide powder and lithium hydroxide was (Ni + Co: Li atomic ratio = 0.70 + 0 .30: 1 = 1: 1), except that LiCo _0.30 Ni _0.70 O ₂ was synthesized in the same manner as in Example 1.

[0018]

Embodiment 4 494.2 g (1.7 mol) of nickel nitrate
And a 2 L aqueous solution in which 86.1 g (0.3 mol) of manganese nitrate and manganese nitrate were dissolved, and the mixing ratio of the oxide powder and lithium hydroxide was (Ni + Mn: Li atomic ratio = 0.8
LiMn _0.15 Ni _0.85 O ₂ was synthesized in the same manner as in Example 1 except that 5 + 0.15: 1 = 1: 1).

[0019]

Embodiment 5 552.4 g (1.9 mol) of nickel nitrate
And a 2 L aqueous solution in which 28.7 g (0.1 mol) of manganese nitrate were dissolved, and the mixture ratio of the oxide powder and lithium hydroxide was set to (Ni + Mn: Li atomic ratio = 0.9).
LiMn _0.05 Ni _0.95 O ₂ was synthesized in the same manner as in Example 1 except that 5 + 0.05: 1 = 1: 1).

[0020]

EXAMPLE 6 Nickel nitrate 94.2 g (1.7 mol) and ferric nitrate _{[Fe (NO 3) 3 ·} 9H 2 O] 121.
A 2 L aqueous solution in which 2 g (0.3 mol) was dissolved was used as solution A, and the mixing ratio of oxide powder and lithium hydroxide was changed to (N
i + Fe: Li atomic ratio = 0.85 + 0.15: 1 = 1: 1:
1) LiFe _0.15 N in the same manner as in Example 1 except that
i _0.85 O ₂ was synthesized.

[0021]

Example 7 552.4 g (1.9 mol) of nickel nitrate
And 40.4 g of ferric nitrate (0.1 mol) dissolved therein
The L aqueous solution was used as the A liquid, and the mixing ratio of the oxide powder and lithium hydroxide was set to (Ni + Fe: Li atomic ratio = 0.95
LiFe _0.05 Ni _0.95 O ₂ was synthesized in the same manner as in Example 1 except that +0.05: 1 = 1: 1).

[0022]

Example 8 523.3 g (1.8 mol) of nickel nitrate
And 51.8 g of 99% magnesium nitrate (0.2 mol)
Example 2 except that a 2 L aqueous solution in which A was dissolved was used as solution A, and the mixing ratio of the oxide powder and lithium hydroxide was (Ni + Mg: Li atomic ratio = 0.90 + 0.10: 1 = 1: 1). LiMg _0.10 Ni _0.90 O ₂ was synthesized in the same manner as in Example 1.

[0023]

Example 9 564.0 g (1.94 mol) of nickel nitrate and 15.5 g (0.06 mol) of 99% magnesium nitrate
Mol) was used as solution A, and the mixing ratio between the oxide powder and lithium hydroxide was (Ni + Mg: L
LiMg _0.03 Ni _0.97 O ₂ was synthesized in the same manner as in Example 1 except that the i atomic ratio was 0.97 + 0.03: 1 = 1: 1).

[0024]

Example 10 494.2 g (1.7 mol) of nickel nitrate was dissolved in water to prepare a 2 L nickel nitrate solution. 28.5 g of sodium aluminate (Al content 28.4%)
(0.3 mol of Al) and 318.0 g of sodium carbonate
(3.0 mol) was dissolved in water to prepare 1.8 L of a mixed solution (solution C) of sodium aluminate and sodium carbonate. 80
The nickel nitrate solution and the C solution were simultaneously poured into 1 L of hot water at 80 ° C. at a constant rate over 80 minutes to cause a reaction. At this time, the temperature was maintained at 80 ° C. and a good stirring state was maintained. After pouring,
Further, this state was maintained for 30 minutes to ripen. The precipitate thus obtained was filtered, washed with water, and dried at 120 ° C. for 1 hour.
After drying for 6 hours, a coprecipitate of a basic carbonate of nickel and aluminum was obtained. This dried precipitate is wet-milled,
Pulverization was performed using water as a solvent to obtain a granular slurry having an average particle size of about 1 μm. The slurry was dried and granulated with a spray dryer to obtain granules having an average particle size of about 13 μm. The temperature of the granules was increased to 400 ° C. in a stream of air, and the temperature was maintained at this temperature for about 2 hours until generation of carbon dioxide gas was no longer observed. The composition of the oxide was Ni 62.6 Wt%, Al
4.3 Wt%. 100.0 g of this oxide powder
(Ni + Al = 1.23 mol) and 52.5 g of 98% pure lithium hydroxide 52.5 g (1.23 mol) of lithium hydroxide (Ni + Al: Li atomic ratio = 0.85 + 0.15:
1 = 1: 1) was crushed and mixed well in a mortar. This is calcined at 700 ° C. for 10 hours under flowing oxygen to obtain LiAl _0.15 Ni
_0.85 O ₂ was obtained.

[0025]

Example 11 Sodium aluminate (Al content: 28.4)
%) 9.5 g (Al 0.1 mol) and sodium carbonate 3
180 g (3.0 mol) of a 1.8 L aqueous solution dissolved
And the mixture ratio of the oxide powder and lithium hydroxide was (Ni + Al: Li atomic ratio = 0.95 + 0.05:
1 = 1: 1), except that LiAl _0.05 Ni _0.95 O ₂ was synthesized in the same manner as in Example 10.

[0026]

[Measurement result 1] (X-ray diffraction measurement) Example 1, Example 4, Example 6, Example 8, Example 10
Fig. 1 shows the X-ray diffraction pattern of the sample synthesized in step 1.
D, F, E, C, and B of FIG. Thus, LiNiO ₂
No peak other than the peak attributed to the crystal structure of was observed, and it was confirmed that the added third component was uniformly dissolved without disturbing the basic crystal structure of LiNiO ₂ .

Further, Example 1 (LiCo _0.15 Ni _0.85 O
₂ ) and a sample of Example 10 (LiAl _0.15 Ni _0.85 O ₂ ) were refined in crystal structure by the Rietveld method, and the lattice constant was determined. Thus, the lattice constant of LiCo _0.15 Ni _0.85 O ₂ is LiNiO ₂
It was confirmed that the lattice constant was changed. In other words, cobalt or aluminum is definitely LiNiO
_It can be seen that the solid solution is in the crystal structure of ₂ .

[0028]

[Table 2]

[0029]

[Measurement Result 2] (Evaluation of battery performance) Comparative Example 1 for the samples synthesized in Examples 1 to 11
A coin battery was prepared in the same manner as described above, and charge / discharge measurement was performed under the same measurement conditions. LiCo _0.15 Ni synthesized in Example 2
The discharge curve of _0.85 O ₂ is shown in FIG.
FIG. 5 shows a discharge curve of iAl _0.15 Ni _0.85 O ₂ . Thus, the two plateaus observed in FIG. 3 of Comparative Example 1 disappeared, that is, the crystal transition disappeared, and improvement in cycle characteristics was expected. Table 3 shows the discharge capacity at the first cycle (mAh / g) and the discharge capacity at the 30th cycle as actual cycle characteristics. As described above, by adding cobalt, manganese, iron, magnesium, or aluminum as the third component by the coprecipitation method, a positive electrode material with significantly improved cycle characteristics could be obtained.

Table 4 shows the molecular formula, molecular weight and purity of the raw materials (reagents) used in the examples and comparative examples.

[0031]

[Table 3]

[0032]

[Table 4]

According to the present invention, it is possible to obtain a lithium battery positive electrode material which is excellent in durability (cycle characteristics) with little deterioration in battery characteristics due to repeated charge / discharge.

[Brief description of the drawings]

FIG. 1 shows Comparative Example 1 (A), Example 1 (D), and Example 4.
(F), Example 6 (E), Example 8 (C), Example 10
It is a figure which shows the X-ray diffraction pattern about the sample synthesize | combined in (B).

FIG. 2 is a view showing an X-ray diffraction pattern of a sample synthesized in Comparative Example 2.

FIG. 3 is a diagram showing a discharge curve of a lithium battery using a positive electrode material sample synthesized in Comparative Example 1.

FIG. 4 shows a positive electrode material sample (LiCo) synthesized in Example 2.
Is a diagram showing discharge curves of lithium batteries using _0.15 Ni _0.85 O _2).

FIG. 5 shows a positive electrode material sample (LiA) synthesized in Example 10.
l is a diagram showing discharge curves of lithium batteries using _0.15 Ni _0.85 O _2).

 ────────────────────────────────────────────────── ─── Continuing on the front page (72) Inventor Susumu Yokono 1-26 Takiya Honcho Niigata Niigata Pref. Inside the Central Research Laboratories (72) Inventor Takayuki Fujita 1-26 Takiya Honmachi Niigata Niigata Pref. Central Research Laboratory (72) Inventor Masami Sakaguchi 1-26 Takitani Honmachi, Niitsu City, Niigata Prefecture JGC Chemicals Central Research Laboratory

Claims (7)

[Claims] When producing a lithium nickel oxide to which a third component other than nickel and lithium is added as a lithium battery cathode material, a mixed aqueous solution of a water-soluble nickel compound and a water-soluble compound of the third component to be added is prepared. And
This is reacted with an aqueous solution of an alkali compound to form a coprecipitate of nickel and a third component, and the coprecipitate is dried or further calcined, and a lithium compound powder is added and mixed. And baking at a temperature in the range of 600 to 850 ° C. in an oxygen atmosphere. 2. An aqueous alkaline compound solution having a concentration of 0.15 to 1.5 mol / L (liter) has a concentration of 0.15
The method for producing a positive electrode material for a lithium battery according to claim 1, wherein a coprecipitate is obtained by pouring a mixed aqueous solution of a nickel compound and the third component at up to 1.5 mol / L. 3. An aqueous solution of an alkali compound having a concentration of 0.15 to 1.5 mol / L, and an aqueous solution of an alkali compound having a concentration of 0.15 to 1.5 mol / L.
The method for producing a lithium battery cathode material according to claim 1, wherein a mixed aqueous solution of the nickel compound of L and the third component is simultaneously poured and mixed to obtain a coprecipitate. 4. The lithium battery positive electrode according to claim 1, wherein the ionic radius of the third component is 0.8 to 1.5 times the ionic radius of nickel of 0.56 °. The method of material production. 5. The method according to claim 1, wherein the third component is Al, Co, Fe, Mn,
The method for producing a lithium battery positive electrode material according to claim 4, wherein the material is at least one of Mg. 6. The composition according to claim 1, wherein the ratio of Ni to the third component M is Ni: M = 0.
5 to 0.95: in the range of 0.5 to 0.05, the ratio of the sum of Ni and the third component M to Li (Ni + M): Li is 1: 1.
The method for producing a positive electrode material for a lithium battery according to claim 4, wherein the range is 0 ± 0.05. 7. A coprecipitate of Ni and a third component is pulverized by a wet pulverizer, and then dried and granulated by a spray drier.
The method for producing a positive electrode material for a lithium battery according to claim 1, wherein the particle size is adjusted.