JPH1027611A - Lithium-containing compound oxide for lithium ion secondary battery and its manufacture - Google Patents

Abstract

PROBLEM TO BE SOLVED: To restrict the decrease of electric capacity and improve cycle property by coprecipitating at least two types of hydroxide containing cobalt with nickel hydroxide in a reaction tank and additionally coprecipitating other hydroxide than cobalt therewith. SOLUTION: A reaction tank is used to supply nickel-cobalt-M salt water solution with the controlled concentration of salt, complexing agent to form complex salt with the water solution and alkali metal hydroxide in succession. Nickel-cobalt-M complex salt is produced and then decomposed with alkali metal hydroxide to precipitate nickel-cobalt-M hydroxide. The production and decomposition of the complex salt circulated in the tank are repeated to overflow and pick up the nickel-cobalt-M hydroxide. At this time, the concentration of salt in the reaction tank is kept at 50-200mS/cm, pH is at 11.0-13.0±0.05 and a temperature is at 20-80±0.5 deg.C. In this way, initial capacity is increased and the decrease of electric capacity with the repetition of charge and discharge is restricted.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a lithium-containing composite oxide used as a positive electrode active material of a non-aqueous solvent lithium ion secondary battery and a method for producing the same.

[0002]

2. Description of the Related Art In recent years, with the spread of small portable devices, batteries used for them have been required to have small size, light weight and high capacity. Lithium-ion secondary batteries are examples of batteries that meet these requirements. Inexpensive nickel hydroxide is used as a raw material for lithium nickel oxide, which is used as a positive electrode active material for lithium ion secondary batteries, but lithium ion secondary batteries using this raw material have poor cycle characteristics and are being improved. That is being considered. That is, it is required that nickel hydroxide has good crystallinity and is produced more stably.

However, it has been difficult to obtain nickel hydroxide having the above-mentioned characteristics in the conventional method for producing nickel hydroxide. In the conventional production method, nickel hydroxide was obtained in which the half-width of the (101) plane peak in X-ray diffraction was controlled by controlling the crystallinity by adjusting the pH.

When the nickel hydroxide obtained by the above-mentioned production method is used as a positive electrode active material of a lithium secondary battery,
The characteristics of the battery were poor, that is, the charge and discharge were repeated, so that the electric capacity was significantly reduced and the cycle characteristics were inferior.

[0005]

From the above, it is desired to improve nickel hydroxide and its production method. That is, when nickel carbonate was used as the material of the Li-ion secondary battery (Japanese Patent Publication No. 1-294364), it was difficult to obtain any powder characteristics, but the nickel hydroxide obtained in the present invention was used. This has made it possible to obtain a lithium-containing composite oxide having arbitrary powder characteristics.

In addition, it has been difficult to control and further improve crystals by adjusting pH in conventional nickel hydroxide and its production method. SUMMARY OF THE INVENTION The present invention has been made to solve such a problem, and it is an object of the present invention to suppress battery deterioration caused by repeated charge and discharge when a battery is configured.

[0007]

In order to solve this problem, the present invention is to co-precipitate two or more hydroxides with nickel hydroxide, which is a positive electrode active material of a lithium ion secondary battery. By limiting one type of to cobalt,
The polarization characteristics of the lithium-containing composite oxide active material were improved, and a hydroxide other than nickel and cobalt was coprecipitated to stabilize the lattice. In order to obtain the composite element coprecipitated hydroxide, the salt concentration in the nickel salt aqueous solution used as a raw material was controlled.

When the composite element coprecipitated hydroxide obtained by this method is used as a positive electrode active material for a lithium ion secondary battery, its battery characteristics are improved. That is, according to the present invention, the initial capacity is increased as compared with the case of using cobalt-nickel hydroxide, which is a two-element coprecipitated hydroxide, and cycle deterioration due to repetition of charge / discharge is suppressed. It will be a battery.

[0009]

BEST MODE FOR CARRYING OUT THE INVENTION In the three-element coprecipitated hydroxide of the present invention, the numerical limits of each physical property are based on the following reasons.

(1) Regarding the amount of co-precipitated cobalt-M: When y + z <0.1, cycle deterioration due to repeated charge / discharge is large. When y + z> 0.3, the particle shape does not take on a spherical shape, and the particle size distribution width is widened.

(2) The mechanism of precipitation of solid crystals from the aqueous solution state is that the aqueous solution shifts to a quasi-saturated state, a saturated state, and a supersaturated state, and crystals are precipitated. In this mechanism, if the absolute value of the concentration gradient of the aqueous solution is large,
The precipitated solid crystals are mostly fine particles. In order to grow particles, it is necessary to perform the above mechanism as slowly and smoothly as possible. That is, it is necessary to reduce the concentration gradient near the saturation state. However, the solubility curve of nickel hydroxide changes significantly with pH. That is, the concentration gradient of nickel with respect to pH in an aqueous solution is as follows:
Very large. Therefore, only the production of fine particles can be expected by the usual method.

In the method of the present invention for producing cobalt-nickel-M hydroxide, which is a three-element coprecipitated nickel hydroxide, since nickel is used as a complex salt, the concentration gradient of nickel with respect to pH in an aqueous solution becomes small, and Growth is promoted.

In order to maintain the state of the above mechanism, a complexing agent and an alkali metal hydroxide corresponding to the required nickel are always required, so that the reaction process is continuous. When nickel sulfate-cobalt-M (where M = Ca, nickel nitrate-cobalt-Ca) is used as the cobalt-nickel-M salt aqueous solution and ammonium sulfate as an ammonium ion donor is used as the complexing agent, the reaction vessel Is as shown in the following formulas (I) and (II).

Ni _1-x Co _y M _z SO ₄ + (NH ₄ ) ₂ SO ₄ → (NH ₄ ) ₂ Ni _1-x Co _y M _z (SO ₄ ) ₂ ... (I) (NH 4) ₂ Ni _1-x Co _y M _z (SO ₄ ) ₂ + 2NaOH → Ni _1-x Co _y M _z (OH) ₂ + (NH ₄ ) ₂ SO ₄ + Na ₂ SO ₄・ ・ ・ (II)

The product of formula (I), (NH ₄ ) ₂ Ni _1-x Co
_y M _z (SO ₄ ) ₂ has low solubility. Therefore, when the reactions of the above formulas (I) and (II) are carried out in separate tanks, it is necessary to lower the concentration of the product supplied to the subsequent tank, resulting in poor productivity. However, in the present invention, since the reactions of the above formulas (I) and (II) are carried out in one reaction vessel, it is not necessary to reduce the concentration of the above product to be supplied to the next step, and the productivity is improved. I do.

When ammonium sulfate is used, a neutral salt effect can be expected, so that nickel hydroxide has a higher density. As the ammonium ion supplier, ammonium chloride, ammonium carbonate, ammonium fluoride, or the like is used in addition to ammonium sulfate.

In the present invention, the salt concentration of the aqueous nickel salt solution is adjusted to 100 to 300 mS / cm, and the pH in the reaction tank is adjusted to 11.0 to 13.
Keep the temperature within ± 0.05 of the predetermined value within the range of 0 and keep the temperature at 2
By maintaining the predetermined value in the range of 0 to 80 ° C. within a range of ± 0.5 ° C., a composite element coprecipitated hydroxide having better characteristics can be obtained. An inorganic salt (sodium sulfate, sodium chloride) was used to adjust the salt concentration. These numerical limits are based on the following reasons.

(3) Regarding salt concentration: If it is less than 50 mS / cm, crystal growth is suppressed, and only low density ones can be obtained. -If it is larger than 200 mS / cm, the nickel salt aqueous solution tends to crystallize, so that it cannot be supplied stably. -When the value is in the range of ± 10 of the predetermined value, the dispersion of the crystal is reduced.

(4) Regarding pH: If the pH is less than 11.0, crystal growth is accelerated and crystals become too large. -If it is larger than 13.0, crystal growth is suppressed and only low density ones can be obtained. -When the value is in the range of ± 0.05 of the predetermined value, the dispersion of the crystal is reduced.

(5) Regarding temperature; If the temperature is lower than 20 ° C., Na ₂ SO ₄ crystals are likely to precipitate,
High concentration cannot be maintained.・ If the temperature is higher than 80 ° C, adjustment with a pH meter becomes difficult. When the temperature is within the range of ± 0.5 ° C. of the predetermined value, the dispersion of crystals is reduced.

[0021]

EXAMPLES Examples of the present invention will be specifically described below.

[0022]

Example 1 An aqueous solution of a mixture of nickel sulfate, cobalt sulfate, and aluminum sulfate was used as an aqueous solution of a nickel salt containing a cobalt salt and an aluminum salt, and an aqueous solution of ammonium sulfate as an ammonium ion donor was used as a complexing agent. Sodium hydroxide aqueous solution,
Each was used and performed as follows.

That is, a 2.0 mol / l nickel sulfate aqueous solution having a salt concentration adjusted to 100 mS / cm and containing 0.6 mol / l cobalt sulfate and 0.3 mol / l aluminum sulfate was placed in a reactor.
0 ml / min, and 6 mol / l ammonium sulfate aqueous solution
ml / min. On the other hand, a 10 mol / l sodium hydroxide aqueous solution was introduced so that the pH in the reaction tank was automatically maintained at 12.5. The temperature in the reaction vessel was maintained at 45 ° C., and was constantly stirred by a stirrer. The generated nickel hydroxide was taken out of the overflow tube by overflowing, and was washed with water, dehydrated, and dried. Thus, 3 of Example 1
An elemental coprecipitated hydroxide was obtained.

[0024]

Example 2 A 2.0 mol / l nickel sulfate aqueous solution containing 0.15 mol / l cobalt sulfate and 0.07 mol / l aluminum sulfate was prepared.
300 ml / min, 6 mol / l aqueous solution of ammonium sulfate
The same three-element coprecipitated hydroxide of Example 2 was obtained in the same manner as in Example 1 except that 50 ml / min was continuously charged at the same time.

[0025]

Example 3 A 2.0 mol / l nickel sulfate aqueous solution containing 0.5 mol / l cobalt sulfate and 0.13 mol / l magnesium sulfate was prepared.
300 ml / min, 6 mol / l aqueous solution of ammonium sulfate
The three-element coprecipitated hydroxide of Example 3 was obtained in the same manner as in Example 1, except that the mixture was continuously charged at 50 ml / min simultaneously.

[0026]

Example 4 A 2.0 mol / l nickel nitrate aqueous solution containing 0.5 mol / l cobalt nitrate and 0.13 mol / l calcium nitrate was added to 30
0 ml / min, and 6 mol / l ammonium nitrate aqueous solution
ml / min was continuously charged at the same time, and the others were carried out in the same manner as in Example 1 to obtain a three-element coprecipitated hydroxide of Example 4.

[0027]

Example 5 A 2.0 mol / l nickel sulfate aqueous solution containing 0.5 mol / l cobalt sulfate and 0.13 mol / l titanium sulfate was added to 300 ml /
min, and a 6 mol / l aqueous solution of ammonium sulfate at 150 ml / m
in, and were continuously charged at the same time, and otherwise performed in the same manner as in Example 1 to obtain a three-element coprecipitated hydroxide of Example 5.

[0028]

EXAMPLE 6 A 2.0 mol / l nickel sulfate aqueous solution containing 0.5 mol / l cobalt sulfate and 0.13 mol / l vanadium sulfate was added to 30
0 ml / min, and 6 mol / l ammonium sulfate aqueous solution
ml / min was continuously charged at the same time, and the others were carried out in the same manner as in Example 1 to obtain a three-element coprecipitated hydroxide of Example 6.

[0029]

Example 7 A 2.0 mol / l nickel sulfate aqueous solution containing 0.5 mol / l cobalt sulfate and 0.13 mol / l chromium sulfate was added to 300 ml /
min, and a 6 mol / l aqueous solution of ammonium sulfate at 150 ml / m
in, and they were continuously charged at the same time, and the others were carried out in the same manner as in Example 1 to obtain a three-element coprecipitated hydroxide of Example 7.

[0030]

Example 8 A 2.0 mol / l nickel sulfate aqueous solution containing 0.5 mol / l cobalt sulfate and 0.13 mol / l manganese sulfate was treated with 300 m
l / min, 6 mol / l ammonium sulfate aqueous solution 150 ml
/ min at the same time and continuously, and the others were carried out in the same manner as in Example 1 to obtain a three-element coprecipitated hydroxide of Example 8.

[0031]

Example 9 0.5 mol / l cobalt sulfate, 6.5 × 10−2 mol / l
2.0 mol / l nickel sulfate aqueous solution containing ferric sulfate
0 ml / min, and 6 mol / l ammonium sulfate aqueous solution
ml / min was continuously charged at the same time, and the others were carried out in the same manner as in Example 1 to obtain a three-element coprecipitated hydroxide of Example 9.

[0032]

Example 10 A 2.0 mol / l nickel nitrate aqueous solution containing 0.25 mol / l cobalt nitrate, 0.13 mol / l magnesium nitrate and calcium nitrate was 300 ml / min, and a 6 mol / l ammonium nitrate aqueous solution was 150 ml / min. , At the same time,
The other conditions were the same as in Example 1 to obtain the four-element coprecipitated hydroxide of Example 10.

[0033]

Comparative Example 1 A 2.0 mol / l aqueous solution of nickel sulfate containing 0.5 mol / l of cobalt sulfate was continuously and simultaneously supplied with 300 ml / min, and an aqueous solution of 6 mol / l of ammonium sulfate at 150 ml / min.
Otherwise in the same manner as in Example 1, the two-element coprecipitated hydroxide of Comparative Example 1 was obtained.

[0034]

Comparative Example 2 8.0 × 10−2 mol / l cobalt sulfate, 2.0 × 10−
300 mol / min of a 2.0 mol / l aqueous solution of nickel sulfate containing 2 mol / l of aluminum sulfate, and 150 ml / min of an aqueous solution of 6 mol / l of ammonium sulfate simultaneously and continuously, and in the same manner as in Example 1, The three-element coprecipitated hydroxide of Comparative Example 2 was obtained.

[0035]

Comparative Example 3 5.0 × 10 −2 mol / l cobalt sulfate, 0.45 mol / l
300 ml / min of a 2.0 mol / l aqueous solution of nickel sulfate containing 1 l of aluminum sulfate, and 150 ml / min of an aqueous solution of 6 mol / l of ammonium sulfate at the same time.
Was carried out in the same manner as in the above to obtain a two-element coprecipitated hydroxide of Comparative Example 3.

[0036]

Comparative Example 4 A 2.0 mol / l nickel sulfate aqueous solution containing 0.3 mol / l cobalt sulfate and 1.0 mol / l aluminum sulfate was added to 30
0 ml / min, and 6 mol / l ammonium sulfate aqueous solution
ml / min was continuously charged at the same time, and the other steps were carried out in the same manner as in Example 1 to obtain a two-element coprecipitated hydroxide of Comparative Example 4.

[0037]

Comparative Example 5 5.0 × 10−2 mol / l cobalt sulfate, 0.45 mol / l
1 mol of 2.0 mol / l nickel sulfate aqueous solution containing magnesium sulfate at 300 ml / min, and 6 mol / l ammonium sulfate aqueous solution at 150 ml / min, continuously and simultaneously.
In the same manner as in the above, a three-element coprecipitated hydroxide of Comparative Example 5 was obtained.

Table 1 shows the raw material liquids of the composite element coprecipitated hydroxide obtained in Examples 1 to 7 and Comparative Examples 1 to 4 and the component compositions of the obtained powder.

[0039]

[Table 1]

Battery Evaluation In order to demonstrate the effectiveness of the composite element coprecipitated hydroxide as a material for a positive electrode active material of a Li-ion battery, and to clarify improvements over the conventional nickel hydroxide, the following was carried out. Then, lithium-containing composite oxides were synthesized from the composite element coprecipitated hydroxides of Examples 1 to 10 and Comparative Examples 1 to 5, and the battery characteristics were evaluated.

Test Example (Synthesis of lithium-containing composite oxide) Lithium hydroxide-1
The hydrate and the Al-Co-Ni coprecipitated nickel hydroxide of Example 1 (Li:
(Ni + Co + Al)) = 1.03: 1.00 mixed in a molar ratio, in oxygen, 650
After heating at 4 ° C for 4 hours, the reaction was carried out in oxygen at 750 ° C for 10 hours. Li (Ni _0.70 Co _0.20 Al _0.10 ) O ₂ (aluminum-cobalt
-Nickel) lithium was synthesized.

(Production of Battery) The positive electrode was prepared by mixing the aluminum-cobalt-lithium nickelate obtained as described above, acetylene black as a conductive agent, and polytetrafluoroethylene as a binder in a weight ratio of 50:50. After mixing at 40:10 to obtain a positive electrode mixture, this positive electrode mixture was molded under pressure, and the diameter was adjusted.
It was cut out into a disk having a thickness of 16 mm and a thickness of 0.3 mm.

The negative electrode was manufactured by cutting a thin metal lithium film into a disk shape having a diameter of 16 mm. The reference electrode was made by winding a piece of lithium foil around the tip of a nickel wire. The electrolyte was prepared by mixing equal volumes of propylene carbonate and 1.2-dimethoxyethane and dissolving LiClO ₄ at a rate of 1 mol / l.

Using the positive electrode, the negative electrode, the reference electrode, and the nonaqueous electrolyte prepared as described above, an evaluation battery shown in FIG. 1 was assembled. This battery is a three-electrode battery. In FIG. 1, 1 is a positive electrode, 2 is a negative electrode, 3 is a separator, 4 is a non-aqueous electrolyte, 5 is a reference electrode, 6 is a cell body, 7 is a positive electrode holder, and 8 is a negative electrode holder. The nonaqueous electrolyte 4 is filled in a space surrounded by the cell body 6 and the holders 7 and 8. Positive electrode 1
Is placed on the titanium mesh 11 fixed to the side of the positive electrode holder 7 by spot welding, and is further sandwiched by the titanium mesh 21. As the separator 3, a microporous porous membrane made of polypropylene having ion permeability is used. The separator 3 is impregnated with a non-aqueous electrolyte.

(Charge / Discharge Cycle Test) A charge / discharge cycle test was performed using the prepared batteries. The charge and discharge cycle is
The battery was charged to 4.2 V at 1/36 CmA and discharged to 3.0 V at 1/24 CmA, and this was repeated. In order to focus on the positive electrode active material, the potential of the positive electrode and the reference electrode was measured as the battery potential in the battery for evaluation.

The tri-element coprecipitated hydroxide of Example 2 was treated in the same manner as the tri-element co-precipitated hydroxide of Example 1 to obtain Li (Ni _0.90 Co _0.07 A
l _0.03 ) O ₂ (aluminum-cobalt-nickel) lithium was synthesized, and after a battery was prepared, a charge / discharge cycle test was performed.

The three-element coprecipitated hydroxide of Example 3 was treated in the same manner as in the three-element coprecipitated hydroxide of Li (Ni _0.75 Co _0.20 M
g _0.05 ) Lithium O ₂ (magnesium-cobalt-nickel) ate was synthesized, and after a battery was prepared, a charge / discharge cycle test was performed.

The tri-element coprecipitated hydroxide of Example 4 was treated in the same manner as the tri-element co-precipitated hydroxide of Example 1 to obtain Li (Ni _0.75 Co _0.20 C
a _0.05 ) Lithium O ₂ (calcium-cobalt-nickel) ate was synthesized, and after a battery was prepared, a charge / discharge cycle test was performed.

The tri-element coprecipitated hydroxide of Example 5 was treated in the same manner as the tri-element co-precipitated hydroxide of Example 1 to obtain Li (Ni _0.75 Co _0.20 T
i _0.05 ) Lithium O ₂ (titanium-cobalt-nickel) ate was synthesized, and a battery was prepared and subjected to a charge / discharge cycle test.

The triprecipitated hydroxide of Example 6 was treated in the same manner as the triprecipitated hydroxide of Example 1 to obtain Li (Ni _0.75 Co _0.20 V
_0.05 ) Lithium O ₂ (vanadium-cobalt-nickel) ate was synthesized, and after a battery was prepared, a charge / discharge cycle test was performed.

The ternary coprecipitated hydroxide of Example 7 was treated in the same manner as the ternary coprecipitated hydroxide of Example 1 to obtain Li (Ni _0.75 Co _0.20 C
r _0.05 ) Lithium O ₂ (chromium-cobalt-nickel) oxide was synthesized, and after a battery was prepared, a charge / discharge cycle test was performed.

The ternary coprecipitated hydroxide of Example 8 was treated in the same manner as the ternary coprecipitated hydroxide of Example 1 to obtain Li (Ni _0.75 Co _0.20 M
n _0.05 ) O ₂ (manganese-cobalt-nickel) lithium was synthesized, and after a battery was prepared, a charge / discharge cycle test was performed.

The ternary coprecipitated hydroxide of Example 9 was treated in the same manner as in the ternary coprecipitated hydroxide of Example 1 to obtain Li (Ni _0.75 Co _0.20 F
e _0.05 ) Lithium O ₂ (iron-cobalt-nickel) oxide was synthesized, and a battery was prepared and subjected to a charge / discharge cycle test.

The four-element coprecipitated hydroxide of Example 10 was treated in the same manner as the three-element coprecipitated hydroxide of Example 1 to obtain Li (Ni _0.80 Co
_0.10 Ca _0.05 Mg _0.05 ) O ₂ (magnesium-calcium-cobalt-nickel) lithium is synthesized, and after battery fabrication,
A charge / discharge cycle test was performed.

With respect to the two-element coprecipitated hydroxide of Comparative Example 1, Li (Ni _0.80 Co _0.20 )
Lithium O ₂ (cobalt-nickel) oxide was synthesized, and after a battery was prepared, a charge / discharge cycle test was performed.

The tri-element coprecipitated hydroxide of Comparative Example 2 was subjected to Li (Ni _0.95 Co _0.04 A
l _0.01 ) O ₂ (aluminum-cobalt-nickel) lithium was synthesized, and after a battery was prepared, a charge / discharge cycle test was performed.

The three-element coprecipitated hydroxide of Comparative Example 3 was treated in the same manner as the three-element coprecipitated hydroxide of Example 1 to obtain Li (Ni _0.80 Co _0.02 A
l _0.18 ) Lithium O ₂ (aluminum-cobalt-nickel) oxide was synthesized, and after a battery was prepared, a charge / discharge cycle test was performed.

The tri-element coprecipitated hydroxide of Comparative Example 4 was treated in the same manner as in Example 1 to form a Li (Ni _0.60 Co _0.10 A
l _0.30 ) O ₂ (aluminum-cobalt-nickel) lithium was synthesized, and after a battery was prepared, a charge / discharge cycle test was performed.

The tri-element coprecipitated hydroxide of Comparative Example 5 was subjected to Li (Ni _0.80 Co
Lithium _0.02 Mg _0.15 ) O ₂ (magnesium-cobalt-nickel) was synthesized, and a battery was prepared and subjected to a charge / discharge cycle test.

Tables 2 and 3 show the results of the charge / discharge cycle test of the lithium-containing composite oxides of Examples 1 to 10 and Comparative Examples 1 to 5.
Shown in

[0061]

[Table 2]

[0062]

[Table 3]

[0063]

As described above, according to the composite element coprecipitated hydroxide of the present invention, an increase in the initial capacity is observed as compared with the binary element coprecipitated hydroxide, and a decrease in the electric capacity due to repetition of charging and discharging is observed. In other words, the cycle characteristics can be sufficiently improved.

In addition, according to the method for producing a three-element coprecipitated hydroxide of the present invention, the crystal growth can be progressed slowly by repeating the formation and decomposition of the nickel complex salt. Co-precipitated nickel hydroxide can be obtained.

In the above method, if the salt concentration of the nickel salt aqueous solution containing the cobalt-M salt is maintained, the crystal growth can proceed more slowly, that is, the control of the powder characteristics becomes easy, A three-element coprecipitated hydroxide having better characteristics can be obtained.

In the above method, the pH in the reaction tank is adjusted
If the temperature is maintained in the range of ± 0.5 ° C. of the predetermined value in the range of 20 to 80 ° C., the three elements having better characteristics are maintained in the range of ± 0.05 of the predetermined value in the range of 11.0 to 13.0. A coprecipitated hydroxide can be obtained.

[Brief description of the drawings]

FIG. 1 is a diagram showing an evaluation battery including a positive electrode, a negative electrode, a reference electrode, and a non-aqueous electrolyte.

[Explanation of symbols]

 1: Positive electrode 2: Negative electrode 3: Separator 4: Non-aqueous electrolyte 5: Reference electrode

Claims (4)

[Claims] [Claim 1] The general formula LiNi _1-x Co _y M _z O ₂ (0.1
≤ x ≤ 0.3, 0.05 ≤ y ≤ 0.28, 0.02 ≤ z ≤ 0.25, x = y + z, M is at least one of Mg, Al, Ca, Ti, V, Cr, Mn, Fe) A lithium-containing composite oxide for a lithium ion secondary battery represented by the formula: 2. The general formula LiNi _1-x Co _y M _z O ₂ (provided that 0.1
≤ x ≤ 0.3, 0.05 ≤ y ≤ 0.28, 0.02 ≤ z ≤ 0.25, x = y + z, M is at least one of Mg, Al, Ca, Ti, V, Cr, Mn, Fe) A method for producing a lithium-containing composite oxide represented by the formula, using a reaction vessel, a salt concentration adjusted nickel-cobalt-M salt aqueous solution, a complexing agent that forms a complex salt with the aqueous solution, and an alkali Each metal hydroxide is continuously supplied to produce a nickel-cobalt-M complex salt, and then the complex salt is decomposed by an alkali metal hydroxide to precipitate nickel-cobalt-M hydroxide,
The formation and decomposition of the above complex salt are repeated while circulating in the tank, and the nickel-cobalt-M hydroxide obtained by overflowing and taking out the nickel-cobalt-M hydroxide has a substantially spherical particle shape. Or further sintering it to make nickel-cobalt-M
2. The method for producing a lithium-containing composite oxide according to claim 1, wherein a lithium salt is mixed with the oxide and then calcined. 3. The lithium-containing composition according to claim 2, wherein the complexing agent is an ammonium ion donor, hydrazine, ethylenediaminetetraacetic acid, nitritotriacetic acid, uracildiacetate, dimethylglyoxime, dithizone, oxine, acetylacetone, or glycine. A method for producing a composite oxide. 4. A salt concentration of 50 to 200 mS / cm and a pH in the reaction vessel
The lithium-containing composite oxide according to claim 2, wherein the temperature is maintained within a range of ± 0.5 ° C of a predetermined value within a range of 20 to 80 ° C, and the temperature is maintained within a range of ± 0.05 of a predetermined value within a range of 11.0 to 13.0. Manufacturing method.