KR20120098591A - Process for production of positive electrode material for lithium ion secondary battery - Google Patents

Abstract

Provided is a production method in which a lithium composite oxide having excellent charge / discharge cycle durability, low free alkali amount, high discharge capacity, high chargeability, and high volume capacity density is obtained.
General formula Li _a Ni _b Co _c Mn _d M _e O ₂ (M represents at least one element selected from the group consisting of transition metal elements other than Ni, Co and Mn, aluminum, tin, zinc and alkaline earth metals. The lithium composite oxide represented by 0.95 ≦ a ≦ 1.2, 0 ≦ b ≦ 1, 0 ≦ c ≦ 1, 0 ≦ d ≦ 0.6, 0 ≦ e ≦ 0.2, a + b + c + d + e = 2), and the concentration of zirconium is 5? A method for producing a positive electrode material for a lithium ion secondary battery, comprising contacting an aqueous 1000 ppm zirconium solution and then separating the aqueous zirconium solution from the lithium composite oxide.

Description

The manufacturing method of the positive electrode material for lithium ion secondary batteries {PROCESS FOR PRODUCTION OF POSITIVE ELECTRODE MATERIAL FOR LITHIUM ION SECONDARY BATTERY}

This invention relates to the manufacturing method of the positive electrode material for lithium ion secondary batteries, the positive electrode using the positive electrode material obtained by the manufacturing method, and a lithium ion secondary battery.

In recent years, as portable devices and cordless devices have progressed, demands for nonaqueous electrolyte secondary batteries such as lithium ion secondary batteries having small size, light weight, and high energy density have increased. Typical positive electrode materials for nonaqueous electrolyte secondary batteries include LiCoO ₂ , LiNi _1/3 Co _1/3 Mn _1/3 O ₂ , LiNi _0.6 Co _0.2 Mn _0.2 O ₂ , LiNiO ₂ , LiNi _0.8 Co _0.2 O ₂ , LiMn ₂ O ₄ and composite oxides (such as lithium composite oxides in the present invention) may be known, such as lithium and transition metal elements such as LiMnO ₂ .

Among these, use of LiCoO ₂ as a positive electrode material, since the carbon, such as lithium alloy or graphite or carbon fibers lithium secondary battery using as a negative electrode (負極) is obtained with the high voltage of 4 V class, having a high energy density It is widely used as a battery.

In addition, since positive electrode materials such as LiNi _1/3 Co _1/3 Mn _1/3 O ₂ , LiNi _0.6 Co _0.2 Mn _0.2 O ₂ , LiNiO ₂ , and LiNi _0.8 Co _0.2 O ₂ have a low content of expensive Co, they are low in cost. It is expected as a material. Moreover, in these positive electrode materials, it is known that the charge / discharge capacity per unit weight increases so that content of Ni increases, and the battery with high energy density can be manufactured.

However, in any positive electrode material, the discharge capacity, the chargeability, the volume capacity density related to the discharge capacity per unit volume, the charge and discharge cycle durability related to the reduction of the discharge capacity by repeating charging and discharging, and the charging state were left for a long time. The storage characteristics relating to the amount of gas generated at the time and the amount of free alkali related to the coating properties on the coating state of the current collector at the time of electrode production were insufficient, and none of them were satisfied.

In order to solve such a problem, various studies have been made in the past. For example, the positive electrode material obtained by disperse | distributing a lithium nickel cobalt complex oxide in water, the positive electrode material obtained by filtering, after disperse | distributing a lithium nickel cobalt complex oxide to water, and adding phosphoric acid, and cobalt acid The positive electrode material obtained by filtering lithium after stirring in acidic aqueous solution containing sulfuric acid, nitric acid, or hydrochloric acid is proposed (refer patent document 1, patent document 2).

Further, particles of a lithium composite oxide such as a lithium manganese composite oxide having a spinel structure are dispersed in water or alcohol, followed by addition of an alkoxide of aluminum or zirconium, further addition of water to hydrolyze the alkoxide, followed by filtration. And the positive electrode material obtained by heating is proposed (refer patent document 3, patent document 4).

Further, the 2-propanol solution dissolving _{Zr (OC 3 H 7) 4} , by dispersing a lithium-nickel-manganese composite oxide, stirred, filtered, and then the positive electrode material obtained by the heat treatment at 500 ℃ has been proposed ( See Patent Document 5).

Moreover, the positive electrode material obtained by mixing and baking the aqueous solution which Zr melt | dissolved, and a lithium cobalt complex oxide is proposed (refer patent document 6).

Japanese Laid-Open Patent Publication 2000-090917 Japanese Unexamined Patent Publication No. 2003-123755 Japanese Laid-Open Patent Publication 2001-313034 Japanese Patent Publication No. 2003-500318 Japanese Laid-Open Patent Publication 2005-310744 International publication WO2007 / 052712

As mentioned above, although various examinations have been made conventionally, the lithium composite oxide which satisfy | fills all the characteristics, such as discharge capacity, chargeability, volume capacity density, charge / discharge cycle durability, and free alkali amount, is still not obtained.

For example, in the positive electrode materials described in Patent Literature 1 and Patent Literature 2, the alkali compound on the particle surface can be removed by washing the particle surface of the lithium composite oxide, and the decrease in the amount of free alkali is observed, but the particle surface is Because of contact with water or acid with high acidity, ions of lithium, nickel, cobalt or manganese elute from the particle surface of the positive electrode material, resulting in unstable crystal structure and extreme deterioration of charge / discharge cycle durability. It wasn't there.

Moreover, in the positive electrode material of patent document 3 and patent document 4, the solvent made to contact a lithium composite oxide is organic solvents, such as alcohol, and an organic solvent is comparatively difficult to dissolve alkali compound, and exists in the particle surface of a lithium composite oxide. Alkaline compounds cannot be removed. Therefore, when there is much free alkali amount and it uses as a positive electrode material of a battery, when processing with an electrode, the slurry which disperse | distributed the positive electrode material turns into a gel form, the positive electrode material peels off from an electrical power collector, or a coating property deteriorates. In addition, the storage characteristics were also poor, and as charging and discharging were repeated, gas was generated inside the battery, causing the battery to swell, and thus could not withstand practical use.

Moreover, about the positive electrode material obtained by disperse | distributing a lithium composite oxide in the organic solvent which dissolve | dissolved the alkoxide of a zirconium alkoxide of patent document 5, and filtering and heat-processing, the disperse | distributed solvent is an organic solvent to the particle surface of a lithium composite oxide. Since the existing alkali compound could not be removed, the amount of free alkali was large, the storage characteristic and coating property were bad, and it was not able to endure practical use.

In the positive electrode material described in Patent Literature 6, although the improvement of the charge / discharge cycle durability is seen, the decrease in the amount of free alkali is small and the amount of free alkali is large, and when used as the positive electrode material, the slurry in which the positive electrode material is dispersed is processed when used as a positive electrode material. It becomes a phase, the positive electrode material peels off from an electrical power collector, or a deterioration of coatability is seen. In addition, the storage characteristics were also poor, and as charging and discharging were repeated, gas was generated inside the battery, causing the battery to swell, and thus could not withstand practical use.

In general, when a positive electrode material having a large amount of free alkali is to be processed into an electrode from a slurry obtained by dispersing it in a solvent, the positive electrode material tends to be gelled, and the positive electrode material is peeled off from the current collector, resulting in poor coatability. In addition, when a positive electrode material having a large amount of free alkali is used as a positive electrode of a battery and stored for a long time in a charged state, or if charge and discharge are repeated for a long time, decomposition reaction of the electrolyte proceeds, resulting in gas generation such as carbon dioxide, while generating heat. And water were generated, leading to expansion and rupture of the battery, resulting in poor storage characteristics.

Therefore, this invention is excellent in charge / discharge cycle durability, is low in free alkali amount, contains the positive electrode material obtained by the manufacturing method of the positive electrode material which has high discharge capacity, high filling property, and high volume capacity density, and the manufacturing method. It is an object to provide a lithium ion secondary battery containing a positive electrode and the positive electrode material.

MEANS TO SOLVE THE PROBLEM As a result of continuing earnest research, the present inventors contacted a lithium composite oxide with the zirconium aqueous solution in a predetermined density | concentration range, and then uses the positive electrode material obtained by isolate | separating a lithium composite oxide from a zirconium aqueous solution, and solves the said subject. I found out what could be achieved.

This invention is based on the said novel knowledge, and makes the following a summary.

(1) General formula Li _a Ni _b Co _c Mn _d M _e O ₂ (wherein M is at least one member selected from the group consisting of transition metal elements other than Ni, Co and Mn, aluminum, tin, zinc and alkaline earth metals) The concentration of zirconium in the lithium composite oxide represented by 0.95 ≦ a ≦ 1.2, 0 ≦ b ≦ 1, 0 ≦ c ≦ 1, 0 ≦ d ≦ 0.6, 0 ≦ e ≦ 0.2, a + b + c + d + e = 2) 5? A method for producing a positive electrode material for a lithium ion secondary battery, comprising contacting an aqueous 1000 ppm zirconium solution and then separating the aqueous zirconium solution from the lithium composite oxide.

(2) The positive electrode material is further 50? The manufacturing method as described in said (1) heated at the temperature of 1000 degreeC.

(3) The aqueous zirconium solution is selected from the group consisting of ammonium zirconium carbonate, ammonium zirconium fluoride, zirconyl chloride, zirconyl nitrate, zirconyl carbonate, basic zirconium carbonate, potassium zirconium carbonate, and a water-soluble zirconium salt cheated with an organic acid. The manufacturing method as described in said (1) or (2) which is an aqueous solution which melt | dissolves at least 1 sort (s) of compound.

(4) pH of the said zirconium aqueous solution is 3? 12 (1) above? The manufacturing method in any one of (3).

(5) The said zirconium aqueous solution is 1-1 by mass ratio with respect to lithium composite oxide. (1) above, 20 times contacted The manufacturing method in any one of (4).

(6) The amount of zirconium contained in the positive electrode material is 10? 800 ppm, (1) above? The manufacturing method in any one of (5).

(7) Said (1) which is the amount of free alkali contained in the said positive electrode material 0.8 mol% or less? The manufacturing method in any one of (6).

(8) In the general formula, the lithium composite oxide is represented by 0.97 ≦ a ≦ 1.1, 0.2 ≦ b ≦ 0.8, 0.1 ≦ c ≦ 0.4, 0.1 ≦ d ≦ 0.4, and 0 ≦ e ≦ 0.1. One) ? The manufacturing method in any one of (7).

(9) above (1)? After mixing the positive electrode material obtained by the manufacturing method in any one of (8), the electrically conductive agent, a binder, and a solvent, and apply | coating the slurry obtained to a metal foil, it removes a solvent by heating and is obtained, It is a lithium ion secondary characterized by the above-mentioned. The manufacturing method of the battery positive electrode.

The manufacturing method of the lithium ion secondary battery characterized by inject | pouring electrolyte solution, after laminating | stacking a separator and a negative electrode in the positive electrode obtained by the manufacturing method of said (9), and storing in a battery case.

(11) A positive electrode containing a positive electrode material, a conductive agent and a binder, wherein the positive electrode material is the above (1)? It is a positive electrode material obtained by the method in any one of (8), The positive electrode for lithium ion secondary batteries characterized by the above-mentioned.

(12) A lithium ion secondary battery comprising a positive electrode, a negative electrode, and an electrolytic solution, wherein the positive electrode is a positive electrode according to the above (11).

According to the present invention, there is provided a production method in which a positive electrode material having a good charge / discharge cycle durability useful as a positive electrode of a lithium ion secondary battery, low free alkali amount, high discharge capacity, high chargeability, and high volume capacity density is obtained. . Moreover, the positive electrode for lithium ion secondary batteries and lithium ion secondary battery which have the outstanding battery performance using the positive electrode material obtained by the said manufacturing method are provided.

In addition, in this invention, the amount of alkali compound which exists in the particle surface of a positive electrode material or the grain boundary of particle | grains is evaluated by measuring the amount of free alkali. The positive electrode material obtained by the present invention has a low amount of this free alkali, prevents gelation of the slurry of the positive electrode material, improves coatability, and also suppresses generation of gas and water accompanying the decomposition reaction of the electrolyte solution, thereby expanding the battery, and the like. Can be prevented and the storage characteristic can be improved.

About how the positive electrode material obtained by this invention has the said outstanding characteristic, although the mechanism is not necessarily clear, it is estimated as follows.

In general, a lithium composite oxide is obtained by mixing a lithium source with a transition metal source containing nickel, cobalt, manganese, or the like, and baking the resulting raw material mixture. In this lithium composite oxide, there exist a lithium atom which exists away from the lattice point of a crystal lattice, and alkali compounds, such as a lithium compound in which reaction was insufficient and remained. When charging and discharging are repeated in a battery using a positive electrode material made of such a lithium composite oxide, the alkali compound is eluted from the surface of particles or grain boundaries of the particles in the electrolyte solution, and the composition of the positive electrode material is changed or the decomposition of the electrolyte solution is promoted. This causes deterioration of battery performance such as coatability and storage characteristics.

However, in order to remove the alkali compound, when the particle surface of the lithium composite oxide or the grain boundary of the particles is simply washed with water or an acidic aqueous solution, components such as lithium, nickel, cobalt, and manganese are removed from the particle surface of the lithium composite oxide. It becomes an ion and elutes, the crystal structure becomes unstable, and the charge / discharge cycle durability deteriorates.

On the other hand, according to the present invention, the alkali compound can be efficiently removed by bringing the particles of the lithium composite oxide into contact with an aqueous zirconium solution in a predetermined concentration range. Further, elution of lithium, nickel, cobalt, manganese and the like is suppressed, and even when eluted, zirconium is substituted at the site of the eluted atom, so that the charge and discharge cycle durability is not deteriorated. In addition, when the amount of alkali compounds present in the lithium composite oxide is reduced, coating property is improved because gelation of the slurry using the same is suppressed, and storage characteristics are considered to be improved since gas generated in the battery is reduced. do.

In this way, in the present invention, by contacting the lithium composite oxide with a zirconium aqueous solution having a predetermined concentration range, the favorable removal effect of the alkali compound in the lithium composite oxide and the effect of inhibiting the dissolution of the component in the lithium composite oxide work together to form a charge. It is thought to greatly improve the discharge cycle durability and to significantly reduce the amount of free alkali.

In addition, by contacting the compound of zirconium with the lithium composite oxide in an aqueous solution state, the excess zirconium compound is prevented from adhering to the particle surface of the lithium composite oxide, and the amount of zirconium derived from the zirconium aqueous solution contained on the particle surface of the positive electrode material is in an appropriate range. It is thought that the control can be controlled to improve the charge and discharge cycle durability without reducing the discharge capacity.

In the present invention, after the particles of the lithium composite oxide having a predetermined composition are contacted with an aqueous solution of zirconium at a predetermined concentration to remove the alkali compound present on the particle surface, the zirconium aqueous solution is separated from the lithium composite oxide, It consists of the process of obtaining the positive electrode material for lithium ion secondary batteries.

The lithium composite oxide used in the present invention is represented by the general formula Li _a Ni _b Co _c Mn _d M _e O ₂ . The definitions of a, b, c, d and e in the general formula are as described above, but among them, 0.97 ≦ a ≦ 1.1, 0.2 ≦ b ≦ 0.8, 0.1 ≦ c ≦ 0.4, and 0.1 ≦ d ≦ 0.4 , 0 ≦ e ≦ 0.1 is preferred, and 0.99 ≦ a ≦ 1.05, 0.4 ≦ b ≦ 0.7, 0.15 ≦ c ≦ 0.3, 0.15 ≦ d ≦ 0.3, and 0 ≦ e ≦ 0.05. In the case where importance is placed on the rate characteristic, 0.97 ≦ a ≦ 1.03, b = 0, 0.97 ≦ c ≦ 1, d = 0, 0 ≦ e ≦ 0.03 are preferred.

Further, from the viewpoint that a large capacity lithium ion secondary battery can be obtained at low cost, 1.05 ≦ a ≦ 1.2, 0.1 ≦ b ≦ 0.3, 0.05 ≦ c ≦ 0.20, 0.45 ≦ d ≦ 0.60, and 0 ≦ e ≦ 0.03 are preferable. Moreover, the lithium composite oxide used by this invention may improve the rate characteristic and safety of a battery by replacing a part of the oxygen atom with a fluorine atom. In this case, 0.001? It is preferable to replace 5 mol% with a fluorine atom, and it is 0.5? It is more preferable to substitute 3 mol% with a fluorine atom.

The solid phase method, the coprecipitation method, etc. can be used suitably for the manufacturing method of the lithium composite oxide used by this invention, It does not specifically limit. Specific examples of the nickel source, cobalt source, manganese source, and M element source include hydroxides, oxides, and oxyhydroxides of the respective elements. In addition, co-precipitation hydroxides, co-precipitation oxides, co-precipitation oxyhydroxides, etc., in which the elements of nickel, cobalt, manganese, and M elements are co-precipitated in any combination can be used. Moreover, although it does not specifically limit as a lithium source, At least 1 sort (s) chosen from the group which consists of lithium carbonate and lithium hydroxide is preferable, and lithium carbonate is especially preferable. The average particle diameter of the lithium source is 2? 25 μm is preferred. Moreover, water may be mixed as needed with respect to the mixture of the raw material containing a lithium source etc.

In the present invention, the molar ratio a / (b + c + d + e), which is a value obtained by dividing the molar amount of lithium in the lithium composite oxide by the sum of the molar amounts of Ni, Co, Mn, and M elements, is 0.95? It is preferably 1.20, and 0.97? 1.10 is more preferable, and 0.99? Particularly preferred is 1.05. In this case, growth of the particles of the lithium composite oxide is promoted, and more dense particles can be obtained.

Moreover, since a large capacity lithium ion secondary battery is obtained inexpensively, it is 0.45 <= d <0.60, and molar ratio a / (b + c + d + e) is 1.05? It is preferable that it is 1.20, and 1.10? 1.20 is more preferred. Specific examples of such a lithium composite oxide include Li _1.2 Ni _0.175 Co _0.10 Mn _0.525 O ₂ , Li _1.2 Ni _0.175 Co _0.05 Mn _0.575 O ₂ , Li _1.2 Ni _0.175 Co _0.10 Mn _0.525 O _1.98 F _0.02 , Li _1.17 (Ni _1/6 Co _1/6 Mn _4/6 ) _0.83 O ₂ , and the like.

In the present invention, the M element is at least one element selected from the group consisting of transition metal elements other than Ni, Co, and Mn, Al, Sn, Zn, and alkaline earth metals. The transition metal element means a transition metal of Group 4, Group 5, Group 6, Group 7, Group 9, Group 10, or Group 11 of the periodic table. Among them, at least one member selected from the group consisting of Al, Ti, Zr, Hf, Nb, Ta, Mg, Sn, and Zn is preferable. Particularly, in view of discharge capacity, safety, and charge / discharge cycle durability, the M element is more preferably at least one member selected from the group consisting of Al, Ti, Zr, Hf and Mg, and more preferably Al, Zr and Mg. Particular preference is given to at least one species selected from.

In the present invention, the average particle diameter of the particles of the lithium composite oxide is 8? 25 micrometers is preferable, and 10? 20 micrometers is more preferable. In addition, the specific surface area of a lithium composite oxide is measured by the BET method, and is 0.1? 1.5 m <2> / g is preferable and 0.15? 1.2 m <2> / g is more preferable, and 0.20? 1.0 m 2 / g is particularly preferred.

In the present invention, the zirconium aqueous solution means an aqueous solution in which a compound of zirconium is dissolved. The aqueous zirconium solution used in the present invention does not contain a suspension and a colloidal form, and at least the zirconium source is dissolved to the extent that the human eye cannot recognize it as a solid component. The zirconium concentration of the aqueous solution is preferably in the following range. The upper limit of zirconium concentration is 1000 ppm, 500 ppm is preferable, and 200 ppm is more preferable. Moreover, the minimum of zirconium concentration is 5 ppm, 20 ppm is preferable and 50 ppm is more preferable. When the zirconium concentration is in this range, the amount of free alkali contained in the obtained positive electrode material is low, and the charge and discharge cycle durability tends to be improved, which is preferable. On the other hand, when the concentration of the zirconium aqueous solution is higher than 1000 ppm, excess zirconium adheres to the lithium composite oxide, which is not preferable because the discharge capacity is reduced. Moreover, when the zirconium concentration is lower than 5 ppm, the element which forms the particle | grains of a lithium composite oxide elutes, and since charge / discharge cycle durability deteriorates, it is unpreferable. In addition, in this invention, the concentration ppm of zirconium is a mass reference | standard.

PH of aqueous zirconium solution is 3? 12 is preferable and 5? 11 is particularly preferred. Moreover, pH of the zirconium aqueous solution after isolate | separating from lithium complex oxide is 7? 13 is preferable, and 9? 12 is particularly preferred. When the pH of the zirconium aqueous solution is lower than the above range, the lithium composite oxide is exposed to an acidic environment, and Li, Ni, Co, Mn, and the like are eluted from the particles, and the charge / discharge cycle durability tends to be deteriorated. Moreover, when pH is higher than the said range, there exists a tendency for the alkali compound which exists in the particle | grain surface and grain boundary of a lithium composite oxide not fully removed, and a large amount of free alkali exists.

Water-soluble zirconium compounds are used for the zirconium source forming the zirconium aqueous solution, and among these, zirconium salts obtained by reacting an inorganic acid and / or an organic acid with a zirconium or zirconium-containing compound are preferable. The zirconium salt is at least selected from the group consisting of ammonium zirconium carbonate, ammonium zirconium fluoride, zirconyl chloride, zirconyl nitrate, zirconyl carbonate, basic zirconium carbonate, potassium zirconium carbonate, and a water-soluble zirconium salt chelated with an organic acid. 1 species is more preferable. The water-soluble zirconium salt chelate-formed with the organic acid chelates from an zirconium atom and an organic acid by reacting organic acids, such as saturated fatty acid, hydroxy acid, or unsaturated dicarboxylic acid, with zirconium. Moreover, as this organic acid, 1 type of organic acids selected from the group which consists of formic acid, acetic acid, propionic acid, citric acid, glycolic acid, hydroxybutyric acid, malic acid, tartaric acid, maleic acid, oxalic acid, malonic acid, succinic acid, and glyoxylic acid are mentioned. Among them, one type of organic acid selected from the group consisting of citric acid, malic acid, tartaric acid, maleic acid, oxalic acid, malonic acid, succinic acid and glyoxylic acid is more preferable, and citric acid, tartaric acid or glyoxylic acid are particularly preferable.

Among the above zirconium sources, at least one compound selected from the group consisting of zirconium ammonium carbonate, zirconium ammonium fluoride, and water-soluble zirconium salts chelated with citric acid, glyoxylic acid or tartaric acid is preferable. Further, at least one compound selected from the group consisting of zirconium carbonate ammonium, zirconium ammonium fluoride, and water-soluble zirconium salts chelated with citric acid or glyoxylic acid is more preferable, and group consisting of zirconium ammonium carbonate and ammonium zirconium fluoride At least one compound selected from more preferred. As the zirconium source, zirconium ammonium carbonate is particularly preferred because it is easy to handle and inexpensive, and furthermore, excellent in performance of the obtained positive electrode material. By using an aqueous zirconium solution in which these zirconium sources are dissolved, the alkali compound is removed from the surface of the lithium composite oxide, and the elution of elements such as lithium, nickel, cobalt, and manganese forming the lithium composite oxide from the particle surface can be suppressed. This can reduce the amount of free alkali.

In addition, when an organic solvent in which a zirconium source is dissolved in place of the zirconium aqueous solution is used, alkali compounds present on the particle surface of the lithium composite oxide cannot be removed, and the electrolyte is decomposed to swell the battery, resulting in deterioration of storage characteristics. In addition, when zr (OC ₃ H ₇ ) ₄ is used as the zirconium source and water is used as the solvent, the zirconium alkoxide is hydrolyzed to form a suspension or slurry, so that a large amount of zirconium compound is present on the particle surface of the lithium composite oxide. Microparticles | fine-particles will adhere, and a free alkali amount cannot be reduced and a discharge capacity will fall.

The method of bringing the particles of the lithium composite oxide into contact with the zirconium aqueous solution is not particularly limited. For example, the lithium composite oxide is added to the zirconium aqueous solution placed in a beaker or stainless steel bath and mixed using a stirring means such as a stirring blade. Or a method of circulating an aqueous solution with a pump to mix the powder of the zirconium aqueous solution and the lithium composite oxide. Moreover, you may use the method of spraying a zirconium aqueous solution to the lithium composite oxide put on the filter cloth, and sucking from under the filter cloth, and the filtration by a filter press. By making it contact by the said method, the alkali compound which exists in the particle surface of a lithium composite oxide can be removed efficiently. Moreover, although the conditions which make a lithium zirconium aqueous solution contact a lithium composite oxide are not specifically limited, The contact time is 10 second? 8 hours is preferred, 1 minute? 5 hours is more preferable, 5 minutes? 3 hours is particularly preferred. Moreover, the temperature at the time of contact is 5? 80 degreeC is preferable and 10? 60 degreeC is more preferable, and it is 20? 40 ° C. is particularly preferred. Moreover, the pressure at the time of contact is 0.5? 3 atmospheres are preferred, and most preferably atmospheric pressure.

Moreover, the ratio of the zirconium aqueous solution made to contact a lithium composite oxide is 1 to a mass ratio with respect to a lithium composite oxide. The range which becomes 20 times is preferable. The ratio of the zirconium aqueous solution brought into contact with a lithium composite oxide is 3 to 3 mass ratio especially. 10 times more preferable, and 4? 6 times is particularly preferred. When the ratio of this zirconium aqueous solution exists in the said range, a lithium composite oxide can be made to fully contact a zirconium aqueous solution, and an alkali compound can fully be removed. When the mixing ratio is larger than the above, the amount of the zirconium aqueous solution to be used increases, and the amount of waste water tends to increase.

In the present invention, after the contact between the lithium composite oxide and the zirconium aqueous solution, separation of the zirconium aqueous solution from the lithium composite oxide is performed. Separation of such a zirconium aqueous solution is performed in order to isolate | separate the free alkali component eluted from the lithium composite oxide to the zirconium aqueous solution from a lithium composite oxide. As a method of separating the zirconium aqueous solution from the lithium composite oxide, various methods can be adopted. For example, the method of a filter press, the method of centrifugation, the method of suction filtration, etc. are mentioned.

In this invention, although a positive electrode material is obtained by isolate | separating a zirconium aqueous solution from a lithium composite oxide, it is preferable to heat-process a positive electrode material next. 50 degreeC or more is preferable, as for heating temperature, 60 degreeC or more is more preferable, 400 degreeC or more is more preferable, 600 degreeC or more is especially preferable. Moreover, 1000 degrees C or less is preferable, 900 degrees C or less is more preferable, and 830 degrees C or less of heating temperature is especially preferable. If the lower limit of the heating temperature is lower than the above, water remaining in the positive electrode material after separating the zirconium aqueous solution cannot be completely removed, and there is a fear that the battery performance is lowered. On the other hand, when the upper limit of heating temperature is higher than the above, the particle | grains of a positive electrode material may sinter, and form coarse particle, and the fall of discharge capacity and a rate characteristic may fall. Although the method of heating is not specifically limited, It is preferable to implement in an oxygen containing atmosphere using a roller hearth kiln or a rotary kiln. Although heating time is not specifically limited, 1? 24 hours is preferred, and 2? 18 hours is more preferable, 3? 12 hours is particularly preferred.

Although the positive electrode material obtained by this invention has a low free alkali amount, 0.8 mol% or less is preferable with respect to the lithium complex oxide contained in a positive electrode material, and 0.7 mol% or less is more preferable. Moreover, since the contact time of a lithium composite oxide and a zirconium aqueous solution can be shortened, and the positive electrode material of this invention can be synthesize | combined efficiently, the minimum of free alkali amount is preferably 0.01 mol%, and if it is about this, it will be close to battery performance. Does not affect When the amount of free alkali is in the above range, when the slurry of the positive electrode material is coated on the current collector or the like during electrode production, the slurry does not tend to gel, so that the slurry can be easily and uniformly coated, and the coatability is improved. In addition, when the battery is charged and maintained for a long time or when the charge / discharge cycle is repeated, gas generation can be suppressed to prevent swelling of the battery, thereby improving storage characteristics.

The free alkali amount in this invention is a value which concerns on the quantity of the alkali compound which exists in the particle surface of a positive electrode material, and the grain boundary of a particle | grain. The amount of the free alkali was mixed in 1 g of the powder of the positive electrode material, and 50 g of water was stirred for 30 minutes, and the filtrate obtained by filtration and the filtrate obtained by adding 10 g of water to the filtrate three times. The alkali is diluted with dilute hydrochloric acid until the pH reaches 4.0, and the free alkali amount of the positive electrode material is determined from the amount of hydrochloric acid used for the titration.

Although a small amount of zirconium remains in the positive electrode material obtained by the present invention, the amount of zirconium derived from the zirconium aqueous solution remaining in the positive electrode material is 10? 800 ppm is preferable and 20? 600 ppm is more preferable and 50? 300 ppm is particularly preferred. When the amount of zirconium contained in the positive electrode material is in the above range, it is preferable because the positive electrode material excellent in charge / discharge cycle durability and a small amount of free alkali is obtained with good reproducibility. In addition, in this invention, the quantity of zirconium derived from the zirconium aqueous solution contained in this positive electrode material may be called zirconium residual amount (Zr residual amount). This zirconium residual amount can be measured by ICP (inductively coupled plasma) emission spectrometry. In addition, when zirconium is previously contained in the lithium composite oxide before contacting with a zirconium aqueous solution, the zirconium residual amount (Zr residual amount) is contained before contact with a zirconium aqueous solution from the amount of zirconium contained in the positive electrode material measured by ICP analysis. The value is obtained by subtracting the amount of zirconium.

The press density of the positive electrode material obtained by the present invention is 2.7? 3.6 g / cm <3> is preferable and 2.8? 3.4 g / cm 3 is more preferred. In addition, in this invention, a press density means the apparent press density when 5 g of powder of a positive electrode material is pressed at the pressure of 0.32 t / cm <2>. Moreover, the average particle diameter of the particle | grains of a positive electrode material is 8? 25 micrometers is preferable, and 10? 20 micrometers is more preferable. In addition, the specific surface area of a positive electrode material is measured by the BET method, and is 0.1? 1.5 m <2> / g is preferable and 0.15? 1.2 m <2> / g is more preferable, and 0.20? 1.0 m 2 / g is particularly preferred. In this invention, an average particle diameter means the cumulative 50% value of the volume particle size distribution obtained by the laser-scattering particle size distribution measuring apparatus (For example, Nikkiso company make Microtorak HRAX-100 etc.). In this invention, this average particle diameter may be called average particle diameter D50 or simply D50. In addition, D10 mentioned later means the cumulative 10% value, and D90 means the cumulative 90% value. Moreover, when the particle | grains of a positive electrode material consist of secondary particle, the average particle diameter of a secondary particle is shown, and when the particle | grains of a positive electrode material are primary particle, the average particle diameter of a primary particle is shown. In addition, the particle shape of a positive electrode material is influenced by the shape of the lithium composite oxide used for a raw material.

When manufacturing the positive electrode for lithium ion secondary batteries from the positive electrode material obtained by this invention, it forms by mixing carbonaceous materials, such as acetylene black, graphite, Ketjen black, and a binder with the powder of positive electrode material. As the binder, polyvinylidene fluoride, polytetrafluoroethylene, polyamide, carboxymethyl cellulose, acrylic resin and the like are preferably used. The powder, the conductive material and the binder of the positive electrode material obtained by the present invention are made into a slurry or a kneaded product using a solvent or a dispersion medium. This is supported on a positive electrode current collector such as aluminum foil or stainless steel foil by coating or the like to produce a positive electrode for a lithium ion secondary battery.

In the lithium ion secondary battery using the positive electrode material obtained by this invention, a porous polyethylene, the film of porous polypropylene, etc. are used as a separator. Moreover, although various solvent can be used as a solvent of the electrolyte solution of a battery, carbonate ester is especially preferable. Carbonic acid ester can use both a cyclic and a chain form. As cyclic carbonate, propylene carbonate, ethylene carbonate (EC), etc. are illustrated. Examples of the chain carbonate include dimethyl carbonate, diethyl carbonate (DEC), ethyl methyl carbonate (EMC), methyl propyl carbonate and methyl isopropyl carbonate.

In this invention, the said carbonate ester can be used individually or in mixture of 2 or more types. Moreover, you may mix and use with another solvent. Moreover, depending on the material of a negative electrode active material, when a chain carbonate ester and a cyclic carbonate are used together, discharge characteristic, cycling durability, and charging / discharging efficiency may be improved.

Moreover, in the lithium ion secondary battery using the positive electrode material obtained by this invention, a vinylidene fluoride-hexafluoropropylene copolymer (for example, Atochem Co., Ltd. make: brand name Kynar) or vinylidene fluoride perfluoropropyl vinyl A gel polymer electrolyte containing an ether copolymer may be used for the electrolyte. A solute which is added to the electrolyte solvent, or the polymer ^{_{electrolyte, ClO 4 -, CF 3 SO}} 3 -, BF 4 -, PF 6 -, AsF 6 -, SbF 6 -, CF 3 CO 2 -, (CF 3 SO 2 Any one or more types of lithium salts having anion) ₂ N ^- and the like are preferably used. The concentration of the lithium salt contained in the electrolyte solvent or the polymer electrolyte is 0.2? 2.0 mol / l (liter) is preferable and 0.5? 1.5 mol / l is especially preferable. In this concentration range, the ionic conductivity is large, and the electrical conductivity of the electrolyte is increased.

In the lithium ion secondary battery using the positive electrode material obtained by this invention, the material which can occlude and release lithium ion is used for a negative electrode active material. Although the material which forms this negative electrode active material is not specifically limited, For example, a lithium metal, a lithium alloy, a carbon material, oxide, a carbon compound, a silicon carbide compound, a silicon oxide compound mainly consisting of metals of group 14 or 15 of a periodic table, Titanium sulfide, a boron carbide compound, etc. are mentioned. As a carbon material, what thermally decomposed organic substance in various pyrolysis conditions, artificial graphite, natural graphite, soil graphite, expanded graphite, flaky graphite, etc. can be used. As the oxide, a compound mainly composed of tin oxide can be used. Copper foil, nickel foil, etc. are used as a negative electrode electrical power collector. Such a negative electrode is preferably manufactured by kneading the active material with an organic solvent to form a slurry and applying the slurry to a metal foil current collector to obtain a slurry.

There is no restriction | limiting in particular in the shape of the lithium battery using the positive electrode material obtained by this invention. Sheet shape, film shape, folding shape, wound bottomed cylindrical shape, button shape and the like are selected according to the use.

Example

Hereinafter, although an Example and a comparative example demonstrate this invention concretely, this invention is not limited to these Examples. Example 1 below? Example 5, Example 11? Example 13 and Example 15? Example 21 is an example, and Example 6? Examples 10 and 14 are comparative examples.

[Example 1]

In an aqueous solution in which nickel sulfate, cobalt sulfate, and manganese sulfate were dissolved such that the atomic ratio of nickel, cobalt, and manganese was Ni: Co: Mn = 6: 2: 2, so that the pH of the aqueous solution was 11.0 and the temperature was 50 ° C. The aqueous solution and the aqueous sodium hydroxide solution were continuously fed while stirring to precipitate a coprecipitate. The powder of the nickel cobalt manganese composite hydroxide was obtained by adjusting the liquid amount in a reaction system by the overflow system, filtering the copulation slurry which overflowed, washing with water, and then drying at 80 degreeC. The specific surface area of the powder of the composite hydroxide was 5.6 m 2 / g, and the average particle diameter D50 was 11.8 µm.

The lithium hydroxide powder was mixed with the obtained composite hydroxide powder, and calcined at 500 ° C. for 10 hours in an air atmosphere. The obtained fired product was mixed again, fired at 900 ° C for 24 hours, and pulverized to obtain a powder of a lithium composite oxide having a composition of Li _1.02 (Ni _0.6 Co _0.2 Mn _0.2 ) _0.98 O ₂ . The specific surface area of the powder of this lithium composite oxide was 0.29 m 2 / g, and the average particle diameter D50 was 14.0 µm. As a result of measuring the powder X-ray diffraction spectrum using the CuKα ray with respect to the powder, it was found that the powder had a similar structure to the rhombohedral system (R-3m). The Rigaku Corporation RINT 2100 type was used for the measurement. Moreover, about the said powder, when particle | grains were observed using the scanning electron microscope (henceforth SEM), it was the secondary particle which the many primary particle aggregated. Moreover, when the amount of zirconium contained in the said powder was measured using ICP, it was not detected.

Subsequently, water was added to 0.71 g of aqueous zirconium ammonium carbonate (Baycoat 20 manufactured by Nippon Light Metal Co., Ltd.) having a zirconium content of 14.1% by mass to prepare 1000 g, and an aqueous zirconium solution having a concentration of 100 ppm of zirconium was prepared. Further, the general formula of ammonium zirconium carbonate used is _{(NH 4) 2 [Zr (} CO 3) 2 (OH) 2]. The slurry liquid obtained by adding 200 g of the powders of the lithium composite oxide to 1000 g of the zirconium aqueous solution was stirred for 10 minutes. Subsequently, the obtained liquid was suction filtered using 5C filter paper, the liquid was isolate | separated, and the granular material was obtained. In addition, the operation of stirring and separation was performed at room temperature. PH of the zirconium aqueous solution was 9.0, and pH of the zirconium aqueous solution after separation was 11.8. This granular material was heated at 120 degreeC for 5 hours, and then it heated at 800 degreeC for 5 hours. The obtained granular material was passed through a sieve to obtain a powder of a positive electrode material. Stirring, separation, and heating were all performed in an atmospheric atmosphere. The average particle diameter of the positive electrode material was 15.3 μm, D10 was 8.1 μm, D90 was 33.6 μm, and the specific surface area was 0.25 m 2 / g.

0.02 mol / L hydrochloric acid was added to the filtrate obtained by mixing the powder obtained by mixing 1 g of the positive electrode material and 50 g of water, followed by stirring for 30 minutes. The aqueous solution was titrated until pH reached 4.0. The free alkali amount was 0.56 mol% when the free alkali amount of the positive electrode material was calculated | required from the amount of hydrochloric acid used for titration.

The particle | grains of the obtained positive electrode material were 2.73 g / cm <3> in press density, and the amount of zirconium contained in a particle | grain was 120 ppm. The amount of zirconium derived from the zirconium aqueous solution, ie, the zirconium residual amount (Zr residual amount), was 120 ppm.

The powder of the positive electrode material, acetylene black and polyvinylidene fluoride powder were mixed at a mass ratio of 90/5/5, N-methylpyrrolidone was added to prepare a slurry, and the doctor blade was added to an aluminum foil having a thickness of 20 µm. Single sided coating using The obtained aluminum sheet was dried, and roll press rolling was performed 3 times to produce a positive electrode sheet for a lithium battery.

Next, the positive electrode sheet is used for the positive electrode, a metal lithium foil having a thickness of 500 μm is used for the negative electrode, 20 μm of nickel foil is used for the negative electrode current collector, and porous polypropylene having a thickness of 25 μm is used for the separator. In addition, a simple stainless steel sealant was used for the electrolytic solution by using a LiPF ₆ / EC + DEC (1: 1) solution (meaning a mixed solution of volume ratio (1: 1) of EC and DEC having solute LiPF ₆ ) in an electrolyte solution. Cellular lithium batteries were assembled in an argon glove box.

The simple sealed cell lithium battery was charged with a maximum voltage of 4.3 V at a current of 170 kV with respect to 1 g of the positive electrode active material at 25 ° C, charged with a constant current of 170 kV for 3 hours (CCCV mode), and the battery voltage was at an upper limit voltage. After the charging was completed, the battery was charged at a constant voltage having an upper limit voltage (total charge time was 3 hours), and then discharged to 2.75 V at a current value of 85 mA to 1 g of the positive electrode active material, thereby increasing the initial discharge capacity. Obtained. In addition, the battery was repeatedly charged and discharged under the same conditions, and the charge and discharge cycle test was conducted 30 times. As a result, 25 ° C., 2.75? The initial discharge capacity of the positive electrode active material at 4.3 V was 167.4 mAh / g, and the capacity retention rate after 30 charge / discharge cycles was 94.5%.

[Example 2]

As the zirconium aqueous solution, a positive electrode material was synthesized in the same manner as in Example 1 except that a zirconium aqueous solution having a zirconium concentration of 500 ppm was used, and each characteristic was measured. The pH of the zirconium aqueous solution was 9.1, and the pH of the zirconium aqueous solution after separation was 10.8. As a result, the average particle diameter D50 of the obtained positive electrode material was 14.6 µm, D10 was 7.8 µm, D90 was 26.1 µm, the specific surface area was 0.28 m 2 / g, and the press density was 2.83 g / cm 3. In addition, the amount of free alkali of the obtained positive electrode material was 0.39 mol%, and the residual amount of zirconium was 320 ppm. The initial discharge capacity was 166.8 mAh / g, and the capacity retention rate after 30 charge / discharge cycles was 94.2%.

Example 3

As the zirconium aqueous solution, a positive electrode material was synthesized in the same manner as in Example 1 except that a zirconium aqueous solution having a zirconium concentration of 1000 ppm was used, and each characteristic was measured. The pH of the zirconium aqueous solution was 9.1, and the pH of the zirconium aqueous solution after separation was 10.1. As a result, the average particle diameter D50 of the obtained positive electrode material was 14.5 µm, D10 was 7.8 µm, D90 was 26.3 µm, the specific surface area was 0.28 m 2 / g, and the press density was 2.81 g / cm 3. The free alkali amount of this positive electrode material was 0.47 mol%, and the residual amount of zirconium was 670 ppm. The initial discharge capacity was 164.2 mAh / g, and the capacity retention rate was 95.4%.

Example 4

As the zirconium aqueous solution, a positive electrode material was synthesized in the same manner as in Example 1 except that a zirconium aqueous solution having a zirconium concentration of 20 ppm was used, and each characteristic was measured. PH of the zirconium aqueous solution was 8.9, and pH of the zirconium aqueous solution after separation was 11.9. As a result, the average particle diameter D50 of the obtained positive electrode material was 15.4 µm, D10 was 8.0 µm, D90 was 31.3 µm, the specific surface area was 0.29 m 2 / g, and the press density was 2.75 g / cm 3. The free alkali amount of this positive electrode material was 0.58 mol%, and the residual amount of zirconium was 22 ppm. The initial discharge capacity was 169.6 mAh / g, and the capacity retention rate was 94.2%.

Example 5

As the zirconium aqueous solution, a positive electrode material was synthesized in the same manner as in Example 1 except that a zirconium aqueous solution having a zirconium concentration of 5 ppm was used, and each characteristic was measured. PH of the zirconium aqueous solution was 8.9, and pH of the zirconium aqueous solution after separation was 11.9. As a result, the average particle diameter D50 of the obtained positive electrode material was 15.2 µm, D10 was 7.9 µm, D90 was 27.3 µm, the specific surface area was 0.29 m 2 / g, and the press density was 2.75 g / cm 3. The free alkali amount of this positive electrode material was 0.54 mol%, and the residual amount of zirconium was 10 ppm. The initial discharge capacity was 168.3 mAh / g, and the capacity retention rate was 89.1%.

Example 6

In Example 1, the positive electrode material was synthesize | combined similarly to Example 1 except not having contacted with the zirconium aqueous solution. That is, the lithium composite oxide which has the composition of Li _1.02 (Ni _0.6 Co _0.2 Mn _0.2 ) _0.98 O ₂ obtained in Example 1 was used as a positive electrode material as it was, and each characteristic was measured. The average particle diameter D50 of this positive electrode material was 14.0 µm, D10 was 7.6 µm, D90 was 28.5 µm, the specific surface area was 0.29 m 2 / g, and the press density was 2.79 g / cm 3. The free alkali amount of this positive electrode material was 1.27 mol%. As a result of coating the electrode by the same operation as in Example 1, it was confirmed that the coating property was poor, and that the positive electrode material was peeled off from the aluminum foil in a part of the electrode after coating, drying, and roller pressing. As a result of producing a battery using the electrode portion which did not come off, the initial discharge capacity was 167.7 mAh / g, and the capacity retention rate was 94.7%.

[Example 7]

A positive electrode material was synthesized in the same manner as in Example 1 except that pure water was used instead of the zirconium aqueous solution, and each characteristic was measured. The pH of water was 6.7 and the pH of water after separation was 12.1. As a result, the average particle diameter D50 of the obtained positive electrode material was 16.1 µm, D10 was 8.4 µm, D90 was 29.9 µm, the specific surface area was 0.22 m 2 / g, and the press density was 2.72 g / cm 3. The free alkali amount of this positive electrode material was 0.54 mol%. The initial discharge capacity was 167.3 mAh / g, and the capacity retention rate was 79.3%.

Example 8

As the zirconium aqueous solution, a positive electrode material was synthesized in the same manner as in Example 1 except that a zirconium aqueous solution having a zirconium concentration of 1 ppm was used to measure each characteristic. PH of the zirconium aqueous solution was 8.8, and pH of the zirconium aqueous solution after separation was 11.9. As a result, the average particle diameter D50 of the obtained positive electrode material was 14.6 µm, D10 was 8.0 µm, D90 was 26.0 µm, the specific surface area was 0.26 m 2 / g, and the press density was 2.86 g / cm 3. The free alkali amount of this positive electrode material was 0.53 mol%, the amount of zirconium contained in particle | grains could not be confirmed, and the residual amount of zirconium was less than 10 ppm. The initial discharge capacity was 166.5 mAh / g, and the capacity retention rate was 80.1%.

Example 9

As the zirconium aqueous solution, a positive electrode material was synthesized in the same manner as in Example 1 except that a zirconium aqueous solution having a zirconium concentration of 3000 ppm was used, and each characteristic was measured. PH of the zirconium aqueous solution was 9.3, and pH of the zirconium aqueous solution after separation was 9.8. As a result, the average particle diameter D50 of the obtained positive electrode material was 14.7 µm, D10 was 8.1 µm, D90 was 26.7 µm, the specific surface area was 0.25 m 2 / g, and the press density was 2.82 g / cm 3. The free alkali amount of this positive electrode material was 0.46 mol%, and the residual amount of zirconium was 1600 ppm. The initial discharge capacity was 162.4 mAh / g, and the capacity retention rate was 93.4%.

[Example 10]

Water was added to 1.33 g of aqueous zirconium ammonium carbonate solution (manufactured by Nippon Light Metal Co., Ltd.) having a zirconium content of 14.1% by mass to obtain 30 g, thereby obtaining an aqueous zirconium solution. Further, the general formula of ammonium zirconium carbonate used is _{(NH 4) 2 [Zr (} CO 3) 2 (OH) 2]. Subsequently, this zirconium aqueous solution was added to the powder (200 g) of the lithium composite oxide having a composition of Li _1.02 (Ni _0.6 Co _0.2 Mn _0.2 ) _0.98 O ₂ , which was synthesized in the same manner as in Example 1, without mixing and filtration. The mixture was heated at 80 ° C while stirring and dried to obtain a mixture. Furthermore, this mixture was heated at 400 degreeC for 5 hours, and the powder of positive electrode material was obtained. The average particle diameter of this positive electrode material was 13.6 µm, D10 was 6.9 µm, D90 was 25.3 µm, the specific surface area was 0.54 m 2 / g, and the press density was 2.73 g / cm 3. The free alkali amount of this positive electrode material was 1.01 mol%, and the residual amount of zirconium was 940 ppm. As a result of coating the electrode by the same operation as in Example 1, it was confirmed that the coating property was poor, and that the positive electrode material was peeled off from the aluminum foil in a part of the electrode after coating, drying, and roller pressing. As a result of producing a battery using the electrode portion which did not come off, the initial discharge capacity was 168.0 mAh / g, and the capacity retention rate was 94.0%.

Example 11

In an aqueous solution in which cobalt sulfate, aluminum sulfate, magnesium sulfate, and zirconium sulfate were dissolved such that the atomic ratio of cobalt, aluminum, magnesium, and zirconium was Co: Al: Mg: Zr = 0.969: 0.015: 0.015: 0.001, the pH was 11.0 and the temperature was The aqueous solution of ammonium sulfate and aqueous sodium hydroxide solution were continuously supplied to 50 ° C while stirring to precipitate the coprecipitate. The powder of the cobalt aluminum magnesium zirconium compound hydroxide was obtained by adjusting the amount of liquid in a reaction system by the overflow system, filtering the copulation slurry which overflowed, washing with water, and then drying at 80 degreeC. The specific surface area of the powder of the composite hydroxide was 5.0 m 2 / g, the average particle diameter D50 was 12.7 µm, and the amount of zirconium contained in the powder was 930 ppm.

Lithium carbonate having a composition of Li _1.02 (Co _0.969 Al _0.015 Mg _0.015 Zr _0.001 ) _0.98 O ₂ by mixing a predetermined amount of lithium carbonate with a predetermined amount of the composite hydroxide thus obtained, calcining at 1000 ° C. for 15 hours in an air atmosphere. Powder was obtained. Regarding the particles of this lithium composite oxide, when observed by SEM, the particles were almost spherical or elliptic particles composed of primary particles. The specific surface area of the powder of the lithium composite oxide was 0.22 m 2 / g, and the average particle diameter D50 was 12.2 µm. Except having used this lithium composite oxide, it contacted with the zirconium aqueous solution similarly to Example 1, and filtered, the zirconium aqueous solution was isolate | separated from the lithium composite oxide, and the powder of positive electrode material was obtained. PH of the zirconium aqueous solution was 9.0, and pH of the zirconium aqueous solution after separation was 10.8.

The average particle diameter D50 of the obtained positive electrode material was 12.5 μm, D10 was 7.1 μm, D90 was 22.3 μm, the specific surface area was 0.17 m 2 / g, and the press density was 3.06 g / cm 3. The free alkali amount of this positive electrode material was 0.04 mol%, the amount of zirconium contained in particle | grains was 1070 ppm, In other words, the amount of zirconium derived from the zirconium aqueous solution, ie, the amount of zirconium remainders (Zr residual amount), was 140 ppm. The initial discharge capacity was 146.0 mAh / g, and the capacity retention rate was 86.0%.

[Example 12]

In an aqueous solution in which nickel sulfate, cobalt sulfate, and manganese sulfate were dissolved such that the atomic ratio of nickel, cobalt, and manganese was Ni: Co: Mn = 3: 3: 3, the ammonium sulfate solution had a pH of 11.0 and a temperature of 50 ° C. The aqueous solution and the aqueous sodium hydroxide solution were continuously fed while stirring to precipitate a coprecipitate. The powder of the nickel cobalt manganese composite hydroxide was obtained by adjusting the liquid amount in a reaction system by the overflow system, filtering the copulation slurry which overflowed, washing with water, and then drying at 80 degreeC. The specific surface area of the powder of the composite hydroxide was 11.0 m 2 / g, the average particle diameter D50 was 10.8 µm, and zirconium contained in the powder was not detected.

Lithium carbonate having a composition of Li _1.02 (Ni _0.333 Co _0.333 Mn _0.333 ) _0.98 O ₂ by mixing a predetermined amount of lithium carbonate powder with the powder of the composite hydroxide thus obtained, calcining at 1000 ° C. for 15 hours in an air atmosphere. A powder of the composite oxide was obtained. Regarding the particles of this lithium composite oxide, when observed by SEM, many primary particles were agglomerated secondary particles, and the shape of the secondary particles was almost spherical or elliptic. The specific surface area of the powder of the lithium composite oxide was 0.35 m 2 / g and the average particle diameter D50 was 11.0 μm. Except having used this lithium composite oxide, it contacted with the zirconium aqueous solution similarly to Example 1, and filtered, the zirconium aqueous solution was isolate | separated from the lithium composite oxide, and the powder of positive electrode material was obtained. PH of the zirconium aqueous solution was 9.0, and pH of the zirconium aqueous solution after separation was 11.2.

The average particle diameter D50 of the obtained positive electrode material was 11.5 µm, D10 was 5.6 µm, D90 was 23.3 µm, the specific surface area was 0.39 m 2 / g, and the press density was 2.58 g / cm 3. The free alkali amount of this positive electrode material was 0.14 mol%, and the zirconium residual amount was 130 ppm. The initial discharge capacity was 147.2 mAh / g, and the capacity retention rate was 96.9%.

Example 13

As the zirconium aqueous solution, a powder of the positive electrode material was synthesized in the same manner as in Example 1 except that zirconium ammonium fluoride was used as the zirconium source and an aqueous zirconium solution having a zirconium concentration of 100 ppm was used. In addition, the formula of the zirconium ammonium fluoride used is _{(NH 4) 2 [ZrF 6} ]. Moreover, pH of the zirconium aqueous solution was 3.3, and pH of the zirconium aqueous solution after separation was 11.5. The average particle diameter of the positive electrode material was 14.4 µm, D10 was 7.7 µm, D90 was 26.5 µm, the specific surface area was 0.31 m 2 / g, and the press density was 2.78 g / cm 3. The free alkali amount of this positive electrode material was 0.53 mol%, and the residual amount of zirconium was 150 ppm. The initial discharge capacity was 167.0 mAh / g, and the capacity retention rate was 93.0%.

Example 14

Instead of an aqueous zirconium solution, an isopropanol solution in which Zr (OC ₃ H ₇ ) ₄ was dissolved so as to have a concentration of 0.01% by mass, that is, an isopropanol solution having a zirconium concentration of 8 ppm, was heated at 500 ° C. for 1 hour. A powder of the positive electrode material was synthesized in the same manner as in Example 1 except for the above. The average particle diameter of the positive electrode material was 13.6 µm, D10 was 7.0 µm, D90 was 26.0 µm, the specific surface area was 0.29 m 2 / g, and the press density was 2.85 g / cm 3. The free alkali amount of this positive electrode material was 1.31 mol%. As a result of coating the electrode by the same operation as in Example 1, it was confirmed that the coating property was poor, and that the positive electrode material was peeled off from the aluminum foil in a part of the electrode after coating, drying, and roller pressing. As a result of producing a battery using the electrode portion which did not come off, the initial discharge capacity was 167.3 mAh / g, and the capacity retention rate was 87.8%.

Example 15 [Example 21]

In these Examples, the positive electrode material was synthesized in the same manner as in Example 1 except that the heating temperature in the heating step after the lithium composite oxide was separated from the zirconium aqueous solution was set to the temperature shown in Table 1. Moreover, the result of having measured each characteristic similarly to Example 1 is shown in Table 1 together.

Industrial availability

According to the present invention, there is provided a production method in which a lithium composite oxide having excellent charge and discharge cycle durability, low free alkali amount, high discharge capacity, high chargeability, and high volume capacity density, which is useful as a positive electrode of a lithium ion secondary battery, is obtained. do. Moreover, the positive electrode for lithium ion secondary batteries and lithium ion secondary battery which have the outstanding battery performance using the lithium composite oxide obtained by the said manufacturing method are provided.

In addition, the content of the JP Patent application 2009-249372, the claim, and the abstract for which it applied on October 29, 2009 are referred here, and it introduces as an indication of the specification of this invention.

Claims (12)

General formula Li _a Ni _b Co _c M n _d M _e O ₂ (wherein M is at least one element selected from the group consisting of transition metal elements other than Ni, Co and Mn, aluminum, tin, zinc and alkaline earth metals). The concentration of zirconium in a lithium composite oxide represented by 0.95 ≦ a ≦ 1.2, 0 ≦ b ≦ 1, 0 ≦ c ≦ 1, 0 ≦ d ≦ 0.6, 0 ≦ e ≦ 0.2, a + b + c + d + e = 2). A method for producing a positive electrode material for a lithium ion secondary battery, comprising contacting an aqueous 1000 ppm zirconium solution and then separating the aqueous zirconium solution from the lithium composite oxide. The method of claim 1,
50% of the positive electrode material; The manufacturing method which heats at the temperature of 1000 degreeC. The method according to claim 1 or 2,
The zirconium aqueous solution is at least one selected from the group consisting of ammonium zirconium carbonate, ammonium zirconium fluoride, zirconyl chloride, zirconyl nitrate, zirconyl carbonate, basic zirconium carbonate, potassium zirconium carbonate, and a water-soluble zirconium salt cheated with an organic acid. The manufacturing method which is an aqueous solution which melt | dissolves a compound of a species. The method according to any one of claims 1 to 3,
PH of the said zirconium aqueous solution is 3? 12 phosphorus, manufacturing method. The method according to any one of claims 1 to 4,
The zirconium aqueous solution is contained at a mass ratio of 1? Contacted 20 times, manufacturing method. 6. The method according to any one of claims 1 to 5,
The amount of zirconium contained in the positive electrode material is 10? 800 ppm, manufacturing method. 7. The method according to any one of claims 1 to 6,
The manufacturing method of the amount of free alkali contained in the said positive electrode material is 0.8 mol% or less. The method according to any one of claims 1 to 7,
The lithium composite oxide is represented by 0.97 ≦ a ≦ 1.1, 0.2 ≦ b ≦ 0.8, 0.1 ≦ c ≦ 0.4, 0.1 ≦ d ≦ 0.4, and 0 ≦ e ≦ 0.1 in the above general formula. The solvent is removed by heating after apply | coating the slurry obtained by mixing the positive electrode material, electrically conductive agent, binder, and solvent which are obtained by the manufacturing method in any one of Claims 1-8 to metal foil, It is characterized by the above-mentioned. The manufacturing method of the positive electrode for lithium ion secondary batteries. A separator and a negative electrode are laminated | stacked on the positive electrode obtained by the manufacturing method of Claim 9, and after storing this in a battery case, electrolyte solution is inject | poured, The manufacturing method of the lithium ion secondary battery characterized by the above-mentioned. The positive electrode containing a positive electrode material, a electrically conductive agent, and a binder, The said positive electrode material is a positive electrode material obtained by the method in any one of Claims 1-10, The positive electrode for lithium ion secondary batteries characterized by the above-mentioned. A positive electrode, a negative electrode, and electrolyte solution, The said positive electrode is a positive electrode of Claim 11, The lithium ion secondary battery characterized by the above-mentioned.