JP6303279B2 - Positive electrode active material particle powder, method for producing the same, and nonaqueous electrolyte secondary battery - Google Patents

Description

  Provided is a positive electrode active material particle powder for a non-aqueous electrolyte secondary battery having high initial efficiency and excellent rate characteristics and cycle characteristics.

  In recent years, electronic devices such as AV devices and personal computers are rapidly becoming portable and cordless, and there is an increasing demand for secondary batteries having a small size, light weight, and high energy density as power sources for driving these devices. In recent years, in consideration of the global environment, electric vehicles and hybrid vehicles have been developed and put into practical use, and the demand for a lithium ion secondary battery having excellent storage characteristics as a large-scale application is increasing. Under such circumstances, a lithium ion secondary battery having an advantage of a large charge / discharge capacity has attracted attention.

Conventionally, as positive electrode active substances useful for high energy-type lithium ion secondary batteries having 4V-grade voltage, LiMn ₂ O ₄ of spinel structure, LiMnO ₂ having a zigzag layer structure, LiCoO ₂ of layered rock-salt structure, LiNiO _{2 and the} like are generally known. Among them, lithium ion secondary batteries using LiNiO ₂ have attracted attention as batteries having a high charge / discharge capacity. Since the cycle characteristics are inferior, further improvement in characteristics is required.

In recent years, in response to a demand for higher capacity, it has been found that a positive electrode active material containing a higher capacity Li ₂ MnO ₃ exhibits a higher discharge capacity, but this material has an initial efficiency and rate characteristics. It is known that the secondary battery is bad and has a fatal defect as a secondary battery having poor cycle characteristics because of being charged at a high potential (Patent Document 1).

  There are reports that the cycle characteristics have been improved by the charge / discharge method (Patent Document 2) and reports that the composition has been improved by imparting a composition gradient to the secondary particles (Patent Document 3). The initial efficiency of the Ni, Co, and Mn material systems is limited to about 90%, and no further improvement is possible.

  There are reports that the rate characteristics have been improved by additives such as Zr (Patent Document 4) and reports that the composition has been improved by adding a composition gradient to secondary particles (Patent Document 3). The initial efficiency of the existing Ni, Co, and Mn material systems is limited to about 90%, and no further improvement is possible.

  Although there is a report (Patent Document 5) that the initial efficiency has been improved by the method of mixing the Li storage material with the positive electrode, simply mixing does not fundamentally improve the cycle characteristics of the positive electrode material and is still effective. Is not sufficient, and it cannot be used as a positive electrode material unless these characteristics are compatible at a high level.

JP-A-9-55211 JP 2008-270201 A JP 2011-134670 A JP 2012-138197 A International Publication No. 2008/081839

  A positive electrode active material for a non-aqueous electrolyte secondary battery excellent in initial efficiency, cycle characteristics, and rate characteristics is currently most demanded, but a material that satisfies the necessary and sufficient requirements has not yet been obtained.

  In particular, in an electric vehicle or the like, a lightweight and large-capacity secondary battery is desired.

An object of the present invention is composed of a positive electrode initial efficiency is high, contains a positive electrode active method of manufacturing material particles Powder and positive electrode active material particles for rate characteristics and good non-aqueous electrolyte secondary battery in cycle characteristics It is providing the manufacturing method of a nonaqueous electrolyte secondary battery.

The present invention provides a method for producing a positive electrode active material particle powder as described below, wherein a mixture containing a precursor particle powder containing at least Ni and Mn and a lithium compound is fired, and the obtained intermediate fired product is converted into an acid. And a method for producing a positive electrode active material particle powder, wherein the powder is immersed in a mixed aqueous solution of Al and Al, filtered, dried, and refired (Invention 1).
[Positive electrode active material powder]
A positive electrode active material particle powder comprising a composite oxide containing at least Li, Ni, Mn and Al but not B, wherein the Mn content of the composite oxide is 0 in terms of molar ratio (Mn / (Ni + Co + Mn)). 0.5 or more, the Al content is 0.03 to 3% by weight, and the maximum at 2θ = 20.8 ± 1 ° of the powder X-ray diffraction diagram using Cu—Kα ray of the positive electrode active material particle powder. The relative intensity ratio (a) / (b) between the intensity (a) of the diffraction peak and the intensity (b) of the maximum diffraction peak at 2θ = 18.6 ± 1 ° is 0.02 to 0.2, and the positive electrode In a secondary battery using a positive electrode using active material particle powder and a negative electrode made of metallic lithium, the upper limit potential is converted to a lithium counter electrode of 4.6 V, and the lower limit potential is converted to a lithium counter electrode of 2.0 V. First when charging / discharging at a current rate of 20 mA / g Efficiency is 95% or more, the positive electrode active material particles the initial discharge capacity is equal to or is 220 mAh / g or more.

This invention is a manufacturing method of the positive electrode active material particle powder of this invention 1 whose positive electrode active material particle powder which consists of complex oxide containing at least Li, Ni, Mn, and Al contains a fluorine (this invention) 2).

This invention is a manufacturing method of the positive electrode active material particle powder of this invention 1 or 2 with which the positive electrode active material particle powder which consists of complex oxide containing at least Li, Ni, Mn, and Al contains Co ( Invention 3).

This invention is a manufacturing method of the positive electrode active material particle powder in any one of this invention 1-3 whose Li / (Ni + Mn + Co) is 1.25-1.65 in molar ratio (invention 4).

In the present invention, a mixture containing precursor powder containing at least Ni and Mn and a lithium compound is fired, and the obtained intermediate fired product is immersed in a fluoride aqueous solution, and then a mixed aqueous solution of acid and Al salt. It is the manufacturing method of the positive electrode active material particle powder of this invention 4 which dipped in, filtered, dried, and rebaked ( this invention 5 ).

The present invention provides a method for producing a positive electrode active material particle powder as described below, wherein a mixture containing a precursor particle powder containing at least Ni and Mn and a lithium compound is fired, and the obtained intermediate fired product is converted into an acid. , Al salt and at least one element salt selected from Ni, Mn, and Co, soaked in an aqueous solution, filtered, dried, and re-fired positive electrode active material particle powder manufacturing method ( Invention 6 ) .
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[Positive electrode active material powder]
A positive electrode active material particle powder comprising a composite oxide containing at least Li, Ni, Mn and Al but not B, wherein the Mn content of the composite oxide is 0 in terms of molar ratio (Mn / (Ni + Co + Mn)). 0.5 or more, the Al content is 0.03 to 3% by weight, and the maximum at 2θ = 20.8 ± 1 ° of the powder X-ray diffraction diagram using Cu—Kα ray of the positive electrode active material particle powder. The relative intensity ratio (a) / (b) between the intensity (a) of the diffraction peak and the intensity (b) of the maximum diffraction peak at 2θ = 18.6 ± 1 ° is 0.02 to 0.2, and the positive electrode In a secondary battery using a positive electrode using active material particle powder and a negative electrode made of metallic lithium, the upper limit potential is converted to a lithium counter electrode of 4.6 V, and the lower limit potential is converted to a lithium counter electrode of 2.0 V. First when charging / discharging at a current rate of 20 mA / g Efficiency is 95% or more, the positive electrode active material particles the initial discharge capacity is equal to or is 220 mAh / g or more.

In the present invention, a mixture containing a precursor particle powder containing at least Ni and Mn and a lithium compound is fired, and the obtained intermediate fired product is immersed in an aqueous fluoride solution, and then an acid, an Al salt, and Ni The method for producing positive electrode active material particle powder according to the sixth aspect of the present invention , wherein the positive electrode active material particle powder according to the sixth aspect of the present invention is soaked in a mixed aqueous solution of at least one element selected from Mn and Co, filtered, dried and refired ( Invention 7 ).

The present invention is a method for producing a nonaqueous electrolyte secondary battery, the step of obtaining positive electrode active material particle powder by the production method according to any one of the present invention 1 to 7, and the obtained positive electrode active material particle powder A method for producing a non-aqueous electrolyte secondary battery, comprising the step of producing a positive electrode containing (invention 8).

  The positive electrode active material particle powder according to the present invention is suitable as a positive electrode active material particle powder for a non-aqueous electrolyte secondary battery because it has high discharge capacity and initial efficiency and can improve cycle characteristics and rate characteristics.

2 is an X-ray diffraction diagram of positive electrode active material particle powder obtained in Example 1. FIG.

  The configuration of the present invention will be described in more detail as follows.

  The positive electrode active material according to the present invention is composed of a composite oxide containing at least Li, Ni, Mn, and Al, and in a secondary battery using a positive electrode using the positive electrode active material particle powder and a negative electrode made of metallic lithium. The initial efficiency is 95% or more when charging / discharging at a current rate of 20 mA / g when the upper limit potential is 4.6 V in terms of the lithium counter electrode and the lower limit potential is 2.0 V in terms of the lithium counter electrode. It is a compound having a discharge capacity of 220 mAh / g or more.

The composite oxide is made of a compound having a compound having a crystal system belonging to the space group R-3m, a crystal system belonging to the space group C2 / m, C2 / c or _P3 1 12.

The compound having a crystal system belonging to the space group R-3m is preferably LiM _x Mn _1-x O ₂ (M is Ni and / or Co, and the range of x is 0 <x ≦ 1). _{Specifically, LiCo x Mn 1-x O} 2, LiNi x Mn 1-x O 2, Li (Ni, Co) such as _{x Mn 1-x O 2} is preferred.
The space group R-3m is officially written with a bar on 3 of R3m, but for the sake of convenience, it is described as R-3m.

As a compound having a crystal system belonging to space group C2 / m, C2 / c or P3 ₁ 12, Li ₂ M ′ _(1-y) Mn _y O ₃ (M ′ is in the range of Ni and / or Co, y) 0 <y ≦ 1) is preferred.

When positive electrode active material particles according to the present invention are subjected to powder X-ray diffraction using Cu—Kα rays as a source, LiM _x Mn _1-x which is a compound belonging to a crystal system belonging to space group R-3m One of the peaks characteristic of O ₂ appears at 2θ = 18.6 ± 1 °, and Li ₂ M ′ ₍ 1−1) is a compound belonging to a crystal system belonging to space group C2 / m, C2 / c or P3 ₁ 12. _y) One of the peaks characteristic of Mn _y O ₃ appears at 2θ = 20.8 ± 1 °.

The relative intensity ratio between the intensity (a) of the maximum diffraction peak at 2θ = 20.8 ± 1 ° and the intensity (b) of the maximum diffraction peak at 2θ = 18.6 ± 1 ° of the positive electrode active material powder according to the present invention. (A) / (b) is 0.02-0.2. When the relative intensity ratio (a) / (b) is less than 0.02, sufficient charge and discharge capacity is too small, the compound having a crystal system belonging to the space group C2 / m, C2 / c or _P3 1 12 is not obtained, when the relative intensity ratio (a) / (b) is more than 0.2, a smoothly too many compounds having a crystal system belonging to the space group C2 / m, C2 / c or _P3 1 12 Lithium ion cannot move and sufficient charge / discharge capacity cannot be obtained. A preferred relative intensity ratio (a) / (b) is 0.02 to 0.15, more preferably 0.04 to 0.12, and even more preferably 0.05 to 0.1.

  The positive electrode active material particle powder according to the present invention preferably has a (Li / (Ni + Mn + Co)) molar ratio of 1.25 to 1.65. When (Li / (Ni + Mn + Co)) is less than 1.25, the amount of lithium that can contribute to charging is reduced and the charge capacity is lowered. On the other hand, when it exceeds 1.65, the lithium is excessively increased and the discharge capacity is lowered. More preferably, it is 1.28-1.6, More preferably, it is 1.28-1.55.

The positive electrode active material particle powder according to the present invention has a Mn content in a molar ratio of Mn / (Ni + Co + Mn) of 0.5 or more. Below this range, a compound having a crystal system belonging to the space group C2 / m, C2 / c or P3 ₁ 12 is not sufficiently formed, and the charge / discharge capacity decreases. The preferable Mn content is 0.55 or more, more preferably 0.6 or more, and even more preferably 0.65 or more. The upper limit is preferably about 0.95.

  The positive electrode active material particle powder according to the present invention preferably has a Ni content in a molar ratio of Ni / (Ni + Co + Mn) of 0.05 to 0.45. Exceeding 0.45 is not preferable because the thermal stability is lowered. The Ni content is more preferably 0.08 to 0.4, and even more preferably 0.10 to 0.35.

  The positive electrode active material powder according to the present invention preferably has a Co content in a molar ratio of Co / (Ni + Co + Mn) of 0 to 0.45. If it exceeds 0.45, the structure becomes unstable, such being undesirable. The more preferable Co content is 0.05 to 0.4, and even more preferably 0.10 to 0.35.

  The positive electrode active material particle powder according to the present invention contains 0.03 to 3 wt% of Al. When the Al content is less than 0.03 wt%, the cycle characteristics and thermal stability of a secondary battery using the positive electrode active material particle powder cannot be improved. When it exceeds 3 wt%, the charge / discharge capacity is remarkably lowered, which is not preferable. The preferred content is 0.05 to 1 wt%, more preferably 0.1 to 1 wt%, and even more preferably 0.1 to 0.7 wt%.

  The positive electrode active material particle powder according to the present invention preferably contains 0.03 to 5 wt% of fluorine. When the fluorine content is less than 0.03 wt%, the effect of further improving the thermal stability of the secondary battery using the positive electrode active material particle powder does not appear. When it exceeds 5 wt%, the charge / discharge capacity is remarkably reduced, which is not preferable. The preferred content is 0.05 to 1.7 wt%, more preferably 0.10 to 1.7 wt%, and even more preferably 0.12 to 1.2 wt%.

  The positive electrode active material particle powder according to the present invention may contain other additive elements, and more preferable additive elements include Mg and Ti. The additive element is preferably contained in an amount of 0.05 to 3 wt%.

The positive electrode active material particle powder according to the present invention preferably has a specific surface area of 0.5 to 30 m ² / g, more preferably 1 to 20 m ² / g, even more preferably ² to 15 m, according to the BET method. ² / g.

  The positive electrode active material particle powder according to the present invention is a positive electrode active material particle powder composed of secondary particles in which primary particles are aggregated, and an average primary particle diameter observed with a scanning electron microscope is preferably 5 μm or less, More preferably, it is 0.005-2 micrometers, More preferably, it is 0.01-0.8 micrometers.

  The average secondary particle diameter of the positive electrode active material particle powder according to the present invention is preferably 1 to 50 μm. When the average secondary particle diameter is less than 1 μm, the contact area with the electrolytic solution increases too much, so that the reactivity with the electrolytic solution increases and the stability during charging decreases. When the average particle diameter exceeds 50 μm, the resistance in the electrode increases, and the charge / discharge rate characteristics deteriorate. A more preferable average secondary particle diameter is 1 to 40 μm, and further preferably 2 to 30 μm.

  Next, the manufacturing method of the positive electrode active material particle powder according to the present invention will be described.

  The positive electrode active material particle powder according to the present invention is prepared by mixing a precursor particle powder containing a transition metal prepared in advance and a lithium compound, firing, and immersing the intermediate fired product in a mixed aqueous solution of an acid and an Al salt. It can be obtained by drying and baking.

  The precursor particle powder containing a transition metal in the present invention supplies a mixed solution containing a predetermined concentration of nickel salt, cobalt salt and manganese salt and an aqueous alkaline solution to the reaction vessel so that the pH is 6 to 13. Controlling and circulating the overflowed suspension to the reaction tank while adjusting the concentration rate in the concentration tank connected to the overflow pipe, the concentration of precursor particles in the reaction tank and the settling tank is 0.1 to 15 mol / l. The reaction can be carried out until Moreover, you may obtain precursor particle powder by overflow, without providing a concentration tank. After the reaction, washing with water, drying and pulverization may be performed according to a conventional method.

  As the precursor particle powder containing a transition metal in the present invention, various transition metal compounds can be used without any particular limitation. For example, oxides, hydroxides, carbonates or mixtures thereof are preferable, More preferred are transition metal hydroxides or carbonates.

The precursor particle powder in the present invention preferably has an average particle size of 0.15 to 50 μm and a BET specific surface area of 0.5 to 300 m ² / g.

  The lithium compound used in the present invention is not particularly limited, and various lithium salts can be used. For example, lithium hydroxide monohydrate, lithium nitrate, lithium carbonate, lithium acetate, lithium bromide, Examples include lithium chloride, lithium citrate, lithium fluoride, lithium iodide, lithium lactate, lithium oxalate, lithium phosphate, lithium pyruvate, lithium sulfate, and lithium oxide, with lithium carbonate being preferred. The mixing ratio in the case of mixing a lithium compound is preferably 20 to 100 wt% with respect to the precursor particles.

  Moreover, it is preferable that the lithium compound to be used has an average particle diameter of 50 micrometers or less. More preferably, it is 30 μm or less. When the average particle diameter of the lithium compound exceeds 50 μm, mixing with the precursor particles becomes non-uniform, and it becomes difficult to obtain composite oxide particle powder having good crystallinity.

  The mixing treatment of the precursor particle powder containing the transition metal and the lithium compound may be either dry or wet as long as it can be uniformly mixed.

  The mixing treatment of the precursor particle powder containing the transition metal and the lithium compound may be performed once. The Li compound is added again to the fired product obtained by mixing the precursor particle powder containing the transition metal and the Li compound and calcining, and again. You may bake.

  At this time, it is preferable that a calcination temperature is 400-1500 degreeC. When the temperature is lower than 400 ° C., the reaction between Li and Ni, Co, and Mn does not proceed sufficiently and is not sufficiently combined. If the temperature exceeds 1500 ° C., the sintering proceeds excessively, which is not preferable. More preferably, it is a temperature range of 600-1200 degreeC, More preferably, it is a temperature range of 750-1050 degreeC. The atmosphere during firing is preferably an oxidizing gas atmosphere, and more preferably normal air. The firing time is preferably 1 to 30 hours.

  The cathode active material particle powder of the present invention is obtained by immersing an intermediate fired product obtained by firing a mixture containing a precursor particle powder containing at least Ni and Mn and a lithium compound in a mixed aqueous solution of an acid and an Al salt, followed by filtration and drying. It can be obtained by refiring. The mixed aqueous solution of the acid and Al salt may be a mixed aqueous solution containing a salt of at least one element selected from Ni, Mn, and Co in addition to the acid and Al salt. By immersing the intermediate fired product in a mixed aqueous solution of an acid and an Al salt, the effect of removing excess lithium by the acid and the loading of Al on the particle surface can be performed simultaneously. Element loading can also be easily performed.

  The mixed aqueous solution of acid and Al salt may be a mixed aqueous solution containing a salt of another element. When the mixed aqueous solution of the acid and Al salt contains a salt of another element, the intermediate fired product can be easily loaded with another element that improves battery characteristics. Other elements contained in the mixed aqueous solution of acid and Al salt are preferably Mg and Ti.

  The acid in the mixed aqueous solution in which the intermediate fired product is immersed is not particularly limited, and various acids can be used. For example, sulfuric acid, nitric acid, hydrochloric acid, phosphoric acid, hypochlorous acid, chlorous acid, chloric acid, Inorganic acids and organic acids such as perchloric acid, succinic acid, acetic acid, citric acid and formic acid can be used, and sulfuric acid, nitric acid and hydrochloric acid are preferred, and sulfuric acid is particularly preferred.

  The concentration of the acid in the mixed aqueous solution in which the intermediate fired product is immersed is 0.005 to 1 mol / l. If the concentration is too high, the intermediate fired product is dissolved, and if it is too low, the effect of eluting Li cannot be obtained. Preferably it is 0.01-0.5 mol / l, More preferably, it is 0.03-0.3 mol / l.

  The salt of Al, the salt of at least one element selected from Ni, Mn, and Co in the mixed aqueous solution soaking the intermediate fired product, and the salt of other elements are not particularly limited, and various water-soluble salts can be used. For example, sulfates, nitrates, chlorides, phosphates, oxalates, acetates, citrates, etc. can be used, preferably sulfates, nitrates, chlorides, particularly sulfates. preferable.

  The concentration of the Al salt in the mixed aqueous solution in which the intermediate fired product is immersed is preferably 0.01 to 2.5 mol / l. If the concentration is too high, the salt of Al is not uniformly supported on the intermediate baked product, and if it is too low, it remains in the solution without being supported on the intermediate baked product. More preferably, it is 0.05-2.5 mol / l, More preferably, it is 0.8-2.2 mol / l.

  The total concentration of the salt of Al, the salt of at least one element selected from Ni, Mn, and Co in the mixed aqueous solution in which the intermediate fired product is immersed is 0.01 to 2.5 mol / l. Preferably there is. If the concentration is too high, the intermediate fired product will not uniformly support the salt of Al, at least one element selected from Ni, Mn, and Co, and the salt of other elements, and if it is too low, it will be supported on the intermediate fired product. Instead, it remains in the solution. More preferably, it is 0.05-2.5 mol / l, More preferably, it is 0.1-2.5 mol / l.

  In producing the positive electrode active material particle powder according to the present invention, when the mixed aqueous solution in which the intermediate fired product is immersed contains at least one element selected from Ni, Mn, and Co, the mixed aqueous solution Al and Ni, Mn, Co The ratio of the at least one element selected from the above is 0.1 or more in terms of mol ratio of Al. If the Al ratio is too small, the effect of improving the cycle characteristics cannot be obtained. A preferable Al content is 0.2 or more, more preferably 0.3 or more, and still more preferably 0.4 or more.

  The amount of the mixed aqueous solution in which the intermediate baked product is immersed is preferably 1 to 300 ml with respect to 100 g of the intermediate baked product. If the amount is too small, the intermediate baked product will not be uniformly supported with the salt of Al and at least one element selected from Ni, Mn, and Co. It will remain. Preferably it is 1-150 ml, More preferably, it is 1-20 ml.

  The positive electrode active material particle powder of the present invention is manufactured by including a step of immersing an intermediate fired product obtained by firing a mixture containing a precursor particle powder containing at least Ni and Mn and a lithium compound in an aqueous fluoride solution. Also good.

  The aqueous fluoride solution in the case of immersing the intermediate baked product in the aqueous fluoride solution is not particularly limited, and various water-soluble fluorine compounds can be used. For example, sodium fluoride, potassium fluoride, ammonium fluoride, Sodium fluoroacetate or the like can be used, preferably potassium fluoride or ammonium fluoride, particularly preferably ammonium fluoride.

  The concentration of the aqueous fluoride solution when the intermediate baked product is immersed in the aqueous fluoride solution is preferably 0.02 to 1 mol / l as the fluorine concentration. If the concentration is too high, fluorine is not uniformly supported on the intermediate baked product, and if it is too low, it remains in the solution without being supported on the intermediate baked product. More preferably, it is 0.1-1 mol / l, More preferably, it is 0.5-1 mol / l.

  The amount of the aqueous fluoride solution when the intermediate fired product is immersed in the aqueous fluoride solution is preferably 10 to 200 ml with respect to 100 g of the intermediate fired product. If the amount is too small, fluorine is not uniformly supported on the intermediate baked product, and if it is too large, it remains in the solution without being supported on the intermediate baked product. More preferably, it is 10-150 ml, More preferably, it is 10-100 ml.

  In the method for producing a positive electrode active material according to the present invention, after the intermediate fired product is put into water or a fluoride aqueous solution to form a slurry, a mixed aqueous solution of acid and Al salt is put into the slurry while stirring the slurry. Is preferred. At this time, the water or fluoride aqueous solution in which the intermediate baked product is immersed is 10 to 200 ml, preferably 10 to 150 ml, more preferably 10 to 100 ml, with respect to 100 g of the intermediate baked product. Moreover, 0-80 degreeC is preferable and the processing temperature at this time has especially preferable 20-60 degreeC.

  The time for immersing the intermediate fired product in the mixed aqueous solution is preferably within 30 hours. When soaked for 30 hours or more, Mn is excessively eluted from the intermediate fired product, and the cycle characteristics deteriorate. More preferably, it is within 10 hours, and even more preferably within 5 hours.

  The slurry is filtered after the intermediate fired product is soaked in the mixed aqueous solution. After filtration, the slurry may be washed with a small amount of water. Thereafter, drying and firing are performed, and the heat treatment temperature at this time is preferably 100 ° C to 1100 ° C. More preferably, it is a temperature range of 200-900 degreeC, More preferably, it is a temperature range of 300-500 degreeC. The atmosphere during the heat treatment is preferably an oxidizing gas atmosphere, more preferably normal air. The heat treatment time is preferably 1 to 30 hours.

  In the present invention, it is considered that the initial efficiency could be improved by removing excess lithium extracted from the intermediate baked product by the treatment of immersing the intermediate baked product in the mixed aqueous solution. Accordingly, after the intermediate fired product is soaked in the mixed aqueous solution, the slurry is filtered, dried and fired to reduce excess lithium remaining in the positive electrode active material particle powder.

In the present invention, the obtained positive electrode active material particle powder is a compound having at least a crystal system belonging to the space group R-3m and a crystal system belonging to the space group C2 / m, C2 / c, or P3 ₁ 12 in a specific ratio. It is necessary to consist of. In order for the compound obtained by firing to have such two types of crystal systems at a specific ratio, the Mn content is basically a molar ratio and Mn / (Ni + Co + Mn) is 0.5 or more, preferably 0. The precursor particles may be prepared in the range of .55 to 0.9. As a method of preparing Mn / (Ni + Co + Mn) of the precursor particles within the above range, a method of adjusting the amount of nickel salt, cobalt salt and manganese salt as raw materials, a method of adjusting the pH of the reaction solution, ammonia, etc. The method of adjusting a complexing agent is mentioned. The crystal system belonging to the space group R-3m is derived from the above LiM _x Mn _1-x O ₂ compound, and the crystal system belonging to the space group C2 / m, C2 / c or P3 ₁ 12 is Although it is derived from Li ₂ M ′ _(1-y) Mn _y O ₃ , these compounds are formed simultaneously by a series of production methods, and the ratio is basically the precursor as described above. This is determined by the Li and Mn contents.

In the method of adjusting the pH of the reaction solution, when the pH is lowered, the peak intensity ratio (a) / (b) tends to decrease, that is, the crystal system belonging to the space group C2 / m, C2 / c or P3 ₁ 12 is reduced. Li ₂ M ′ _(1-y) Mn _y O ₃ has a tendency to decrease. Conversely, when the pH is increased, the peak intensity ratio (a) / (b) tends to increase, that is, Li ₂ M ′ _(1-y having a crystal system belonging to the space group C2 / m, C2 / c, or P3 ₁ 12 ₎ Mn _y O ₃ tends to increase.

In the method of adjusting the complexing agent in the reaction solution, when a small amount of complexing agent is added, the peak intensity ratio (a) / (b) tends to decrease, that is, the space group C2 / m, C2 / c or P3 ₁ 12 Li ₂ M ′ _(1-y) Mn _y O ₃ having a crystal system belonging to the group tends to decrease. Conversely, when a large amount of complexing agent is added, the peak intensity ratio (a) / (b) tends to increase, that is, Li ₂ M ′ ₍ having a crystal system belonging to space group C2 / m, C2 / c or P3 ₁ 12 _1-y) Mn _y O ₃ tends to increase.

  As the complexing agent, one or more selected from a complexing agent selected from ammonium ion donor, hydrazine, ethylenediaminetetraacetic acid, nitritotriacetic acid, uracil diacetic acid, dimethylglyoxime, dithizone, oxine, acetylacetone or glycine. Can be used.

Further, even when the firing conditions are adjusted, the peak intensity ratio (a) / (b) is different, and as the firing temperature is increased, the peak intensity ratio (a) / (b) tends to decrease, that is, the space group C2 / m. , C 2 / c or P 3 ₁ 12 having a crystal system belonging to P 2 ₁ 12 tends to decrease in Li ₂ M ′ _(1-y) Mn _y O ₃ . On the contrary, when the firing temperature is lowered, the peak intensity ratio (a) / (b) tends to increase, that is, Li ₂ M ′ ₍₁₋₁₎ having a crystal system belonging to the space group C2 / m, C2 / c or P3 ₁ 12. _y) Mn _y O ₃ tends to increase.

  Next, the positive electrode containing the positive electrode active material particle powder according to the present invention will be described.

  When manufacturing the positive electrode containing the positive electrode active material particle powder according to the present invention, a conductive agent and a binder are added and mixed according to a conventional method. As the conductive agent, acetylene black, carbon black, graphite and the like are preferable, and as the binder, polytetrafluoroethylene, polyvinylidene fluoride and the like are preferable.

  The secondary battery manufactured using the positive electrode containing the positive electrode active material particle powder which concerns on this invention is comprised from the said positive electrode, a negative electrode, and electrolyte.

  As the negative electrode active material, lithium metal, lithium / aluminum alloy, lithium / tin alloy, graphite, graphite, or the like can be used.

  In addition to the combination of ethylene carbonate and diethyl carbonate, an organic solvent containing at least one of carbonates such as propylene carbonate and dimethyl carbonate and ethers such as dimethoxyethane can be used as the solvent for the electrolytic solution.

  Further, as the electrolyte, in addition to lithium hexafluorophosphate, at least one lithium salt such as lithium perchlorate and lithium tetrafluoroborate can be dissolved in the above solvent and used.

  The secondary battery manufactured using the positive electrode containing the positive electrode active material particle powder according to the present invention has an initial discharge capacity of 220 mAh / g or more, preferably 240 mAh / g or more, more preferably 260 mAh according to an evaluation method described later. / G or more, even more preferably 270 mAh / g or more, the higher the better.

  The secondary battery manufactured using the positive electrode containing the positive electrode active material particle powder according to the present invention is evaluated for rate characteristics by the evaluation method described later, and the discharge capacity in the second charge / discharge is 180 mAh / g or more, Preferably it is 200 mAh / g or more, More preferably, it is 210 mAh / g or more, More preferably, it is 220 mAh / g or more, and it is so good that it becomes high.

  The secondary battery manufactured using the positive electrode containing the positive electrode active material particle powder according to the present invention has a cycle characteristic of 75% or more, preferably 80% or more, more preferably 85% or more, by an evaluation method described later. Even more preferably, it is 90% or more, and the higher the better.

<Action>
In the positive electrode active material particle powder according to the present invention, Al hardly dissolves in the composite oxide and is present on the primary particle surface of the positive electrode active material, and the interaction between Al and the Li-Mn compound present on the particle surface is electrolyzed. The present inventors consider that cycle characteristics, rate characteristics, and initial efficiency are improved by suppressing excessive contact between the liquid and the positive electrode active material.

  In addition, according to the production method of the present invention, excess Li can be removed by immersing the intermediate baked product in a mixed aqueous solution of an acid and Al salt, and Al can be supported simultaneously. And the positive electrode active material particle powder of the said structure excellent in initial efficiency can be obtained easily.

  A typical embodiment of the present invention is as follows.

  The BET specific surface area value was measured using MONOSORB [manufactured by Yuasa Ionics Co., Ltd.] after drying and deaeration of the sample under nitrogen gas at 120 ° C. for 45 minutes.

  The content of lithium, nickel, cobalt, manganese, magnesium, titanium, and aluminum constituting the positive electrode active material particle powder was obtained by dissolving 0.2 g of the positive electrode active material particle powder with an acid, and ICAP [SPS-4000 Seiko Quantitative determination was performed using “Electronic Industry Co., Ltd.”.

  The content of fluorine constituting the positive electrode active material particle powder is determined by immersing the positive electrode active material particle powder in pure water to boil and elute the fluorine, and ion chromatography measurement of the filtrate [ICA-2000 Toa DKK Co., Ltd. This was repeated until the fluorine content was no longer detected in the filtrate.

  The average secondary particle diameter (D50) is a volume-based average particle diameter measured by a wet laser method using a laser type particle size distribution measuring device Microtrac HRA [manufactured by Nikkiso Co., Ltd.].

  Phase identification and strength measurement were performed by X-ray diffraction measurement. The X-ray diffractometer is a powder X-ray diffractometer SmartLab [manufactured by Rigaku Corporation] (tube: Cu, tube voltage: 45 kV, tube current: 200 mA, step angle: 0.010 °, counting time: 0.9 s, incidence Slit: 0.650 °, light receiving slit 1: 0.650 °, light receiving slit 2: 0.200 mm).

  Charge / discharge characteristics and cycle characteristics were evaluated by a coin cell using positive electrode active material particle powder.

First, 84% by weight of the composite oxide as the positive electrode active material, 4% by weight of acetylene black as the conductive material, 4% by weight of graphite KS-6, and 8% by weight of polyvinylidene fluoride dissolved in N-methylpyrrolidone as the binder. After mixing, it was applied to an Al metal foil and dried at 110 ° C. The sheet was punched out to 15 mmφ, and then pressure-bonded at 3 t / cm ² was used for the positive electrode. A CR2032-type coin cell was manufactured using a lithium mixed with 1 mol / l of LiPF ₆ dissolved in EC and DMC at a volume ratio of 1: 2 with a negative electrode made of metallic lithium punched to 16 mmφ.

  The first charge / discharge is performed at 25 ° C. and charged to 4.6 V at 20 mA / g, then charged at a constant pressure until the current value becomes 1/100, and discharged to 2.0 V at 20 mA / g. It was. The initial efficiency was ((discharge capacity / charge capacity) × 100) at this time.

  The second charge / discharge was carried out at 25 ° C. and charged at 27 mA / g up to 4.6 V, and then was performed at 270 mA / g up to 2.0 V without performing constant pressure charging. The discharge capacity at this time was evaluated as a rate characteristic.

  After the third charge / discharge, after charging at 54 mA / g up to 4.6 V at 25 ° C., discharging was carried out at 135 mA / g up to 2.0 V without performing constant pressure charging. ((22nd discharge capacity / third discharge capacity) × 100) was defined as the cycle characteristics.

Example 1
8 L of water was placed in a closed reaction tank and maintained at 50 ° C. while nitrogen gas was circulated. Further, a mixed sulfate aqueous solution of Ni, Co, and Mn and an aqueous sodium carbonate solution were continuously added with stirring so that the pH was 8.5 (± 0.1). During the reaction, only the filtrate was discharged out of the system with a concentrating device, and the solid content was retained in the reaction tank. After the reaction, a slurry of the coprecipitation product was collected. The collected slurry was filtered, washed with water, and dried at 120 ° C. overnight to obtain a coprecipitation precursor powder.

  The obtained coprecipitation precursor and lithium carbonate powder were weighed and mixed thoroughly. This was baked for 5 hours at 880 ° C. under air flow using an electric furnace to obtain an intermediate baked product. 100 g of this intermediate fired product was added to 20 ml of pure water kept at 30 ° C. with stirring. Next, 3 ml of a mixed aqueous solution adjusted to have a sulfuric acid concentration of 0.05 mol / l, an aluminum sulfate concentration of 1 mol / l, and a manganese sulfate concentration of 1 mol / l was dropped into the slurry of the intermediate fired product, filtered, washed with water, and 120 ° C. And dried. This was fired at 400 ° C. for 5 hours using an electric furnace to obtain positive electrode active material particle powder.

As a result of the X-ray diffraction measurement, the obtained positive electrode active material particle powder had a peak intensity ratio (a) / (b) of 0.069. As a result of ICP composition analysis, the molar ratios are Li / (Ni + Co + Mn) = 1.38, Ni: Co: Mn = 0.19: 0.12: 0.69 (Mn / (Ni + Co + Mn) = 0.69), respectively. Al = 0.149 wt%. It was observed that the BET specific surface area was 5.5 m ² / g and secondary particles having an average secondary particle diameter of 11.6 μm were formed.

Example 2
8 L of water was placed in a closed reaction tank and kept at 45 ° C. while flowing nitrogen gas. Further, a mixed sulfate aqueous solution of Ni and Mn and an aqueous sodium carbonate solution were continuously added with stirring so that the pH was 8.3 (± 0.1). During the reaction, only the filtrate was discharged out of the system with a concentrating device, and the solid content was retained in the reaction tank. After the reaction, a slurry of the coprecipitation product was collected. The collected slurry was filtered, washed with water, and dried at 120 ° C. overnight to obtain a coprecipitation precursor powder.

  The obtained coprecipitation precursor and lithium carbonate powder were weighed and mixed thoroughly. This was fired at 850 ° C. for 6 hours under an air flow using an electric furnace to obtain an intermediate fired product. 100 g of this intermediate fired product was added to 30 ml of pure water maintained at 35 ° C. with stirring. Next, 6 ml of a mixed aqueous solution adjusted to have a sulfuric acid concentration of 0.04 mol / l, an aluminum sulfate concentration of 0.6 mol / l, and a manganese sulfate concentration of 1.4 mol / l is dropped into the slurry of the intermediate baked product, filtered, washed with water Then, it dried at 100 degreeC. Using an electric furnace, this was fired at 450 ° C. for 4 hours under air flow to obtain positive electrode active material particle powder.

Example 3
6.5 L of water was put into the sealed reaction tank and kept at 40 ° C. while circulating nitrogen gas. Further, a mixed sulfate aqueous solution of Ni, Co, and Mn, a sodium carbonate aqueous solution, and an aqueous ammonia solution were continuously added with stirring so that the pH was 7.8 (± 0.1). During the reaction, only the filtrate was discharged out of the system with a concentrating device, and the solid content was retained in the reaction tank. After the reaction, a slurry of the coprecipitation product was collected. The collected slurry was filtered, washed with water, and dried at 110 ° C. overnight to obtain a coprecipitation precursor powder.

  The obtained coprecipitation precursor and lithium carbonate powder were weighed and mixed thoroughly. This was fired at 830 ° C. for 6 hours under an air flow using an electric furnace to obtain an intermediate fired product. 100 g of this intermediate fired product was added to 25 ml of pure water kept at 40 ° C. with stirring. Next, 3 ml of a mixed aqueous solution adjusted to have a sulfuric acid concentration of 0.09 mol / l, an aluminum sulfate concentration of 1.6 mol / l, and a manganese sulfate concentration of 0.4 mol / l was dropped into the slurry of the intermediate fired product, filtered, Dried at 100 ° C. This was fired at 300 ° C. for 5 hours under an air flow using an electric furnace to obtain positive electrode active material particle powder.

Example 4
8 L of water was placed in a closed reaction tank and kept at 45 ° C. while flowing nitrogen gas. Further, a mixed sulfate aqueous solution of Ni, Co, and Mn and an aqueous sodium carbonate solution were continuously added while stirring so that the pH was 8.0 (± 0.1). During the reaction, only the filtrate was discharged out of the system with a concentrating device, and the solid content was retained in the reaction tank. After the reaction, a slurry of the coprecipitation product was collected. The collected slurry was filtered, washed with water, and dried at 100 ° C. overnight to obtain a coprecipitation precursor powder.

  The obtained coprecipitation precursor and lithium carbonate powder were weighed and mixed thoroughly. This was fired at 870 ° C. for 10 hours under an air flow using an electric furnace to obtain an intermediate fired product. 100 g of this intermediate fired product was added to 20 ml of a 0.95 mol / l aqueous ammonium fluoride solution maintained at 30 ° C. with stirring. Next, 3 ml of a mixed aqueous solution adjusted to have a sulfuric acid concentration of 0.05 mol / l, an aluminum sulfate concentration of 1 mol / l, and a manganese sulfate concentration of 1 mol / l was dropped into the slurry of the intermediate fired product, filtered, washed with water, and 90 ° C. And dried. Using an electric furnace, this was fired at 450 ° C. for 3 hours under air flow to obtain a positive electrode active material particle powder.

Example 5
8 L of water was placed in a closed reaction tank and maintained at 50 ° C. while nitrogen gas was circulated. Further, a mixed sulfate aqueous solution of Ni, Co, and Mn and an aqueous sodium carbonate solution were continuously added with stirring so that the pH was 7.9 (± 0.1). During the reaction, only the filtrate was discharged out of the system with a concentrating device, and the solid content was retained in the reaction tank. After the reaction, a slurry of the coprecipitation product was collected. The collected slurry was filtered, washed with water, and dried at 105 ° C. overnight to obtain a coprecipitation precursor powder.

  The obtained coprecipitation precursor and lithium carbonate powder were weighed and mixed thoroughly. This was baked for 5 hours at 880 ° C. under air flow using an electric furnace to obtain an intermediate baked product. 100 g of this intermediate fired product was added to 30 ml of pure water maintained at 40 ° C. with stirring. Next, 3 ml of a mixed aqueous solution adjusted to have a sulfuric acid concentration of 0.1 mol / l and an aluminum sulfate concentration of 2 mol / l was dropped into the slurry of the intermediate fired product, filtered, washed with water, and dried at 100 ° C. This was baked for 10 hours at 350 ° C. under an air flow using an electric furnace to obtain positive electrode active material particle powder.

Example 6
8 L of water was placed in a closed reaction tank and kept at 45 ° C. while flowing nitrogen gas. Further, a mixed sulfate aqueous solution of Ni, Co, and Mn and an aqueous sodium carbonate solution were continuously added while stirring so that the pH was 8.3 (± 0.1). During the reaction, only the filtrate was discharged out of the system with a concentrating device, and the solid content was retained in the reaction tank. After the reaction, a slurry of the coprecipitation product was collected. The collected slurry was filtered, washed with water, and dried at 100 ° C. overnight to obtain a coprecipitation precursor powder.

  The obtained coprecipitation precursor and lithium carbonate powder were weighed and mixed thoroughly. This was fired at 850 ° C. for 7 hours under an air flow using an electric furnace to obtain an intermediate fired product. 100 g of this intermediate fired product was added to 20 ml of a 0.95 mol / l aqueous ammonium fluoride solution maintained at 35 ° C. with stirring. Next, 3 ml of a mixed aqueous solution adjusted to have a sulfuric acid concentration of 0.1 mol / l and an aluminum sulfate concentration of 2 mol / l was dropped into the slurry of the intermediate fired product, filtered, washed with water, and dried at 100 ° C. This was fired at 400 ° C. for 5 hours using an electric furnace to obtain positive electrode active material particle powder.

Example 7
8 L of water was put into a closed reaction tank and kept at 40 ° C. while circulating nitrogen gas. Further, a mixed sulfate aqueous solution of Ni, Co, and Mn, a sodium carbonate aqueous solution, and an aqueous ammonia solution were continuously added while stirring so that the pH was 8.5 (± 0.1). During the reaction, only the filtrate was discharged out of the system with a concentrating device, and the solid content was retained in the reaction tank. After the reaction, a slurry of the coprecipitation product was collected. The collected slurry was adjusted to pH = 11 by adding an aqueous sodium hydroxide solution, and an aqueous magnesium sulfate solution was added dropwise with stirring so that the Mg / (Ni + Co + Mn) molar ratio was 0.05, followed by filtration and washing with water. And dried at 80 ° C. overnight to obtain a coprecipitation precursor powder.

  The obtained coprecipitation precursor and lithium carbonate powder were weighed and mixed thoroughly. This was fired at 900 ° C. for 6 hours under an air flow using an electric furnace to obtain an intermediate fired product. 100 g of this intermediate fired product was added to 30 ml of pure water kept at 30 ° C. with stirring. Next, 3 ml of a mixed aqueous solution adjusted to have a sulfuric acid concentration of 0.06 mol / l, an aluminum sulfate concentration of 1 mol / l, and a manganese sulfate concentration of 1 mol / l was dropped into the slurry of the intermediate fired product, filtered, washed with water, and 100 ° C. And dried. This was fired at 400 ° C. for 3 hours using an electric furnace to obtain positive electrode active material particle powder.

Example 8
10 L of water was placed in a closed reaction vessel and maintained at 50 ° C. while nitrogen gas was circulated. Further, a mixed sulfate aqueous solution of Ni, Co, and Mn and an aqueous sodium carbonate solution were continuously added while stirring so that the pH was 8.3 (± 0.1). During the reaction, the slurry was overflowed to continuously collect a slurry of the coprecipitation product. The collected slurry was adjusted to pH = 8.0 by adding an aqueous sodium hydroxide solution, and an aqueous solution of titanyl sulfate was added dropwise with stirring so that the Ti / (Ni + Co + Mn) molar ratio was 0.03, followed by filtration, It was washed with water and dried at 100 ° C. overnight to obtain a coprecipitation precursor powder.

  The obtained coprecipitation precursor and lithium hydroxide monohydrate powder were weighed and mixed well. This was fired at 720 ° C. for 15 hours under an oxygen flow using an electric furnace to obtain an intermediate fired product. 100 g of this intermediate fired product was added to 25 ml of pure water maintained at 55 ° C. with stirring. Next, 12 ml of a mixed aqueous solution adjusted to have a sulfuric acid concentration of 0.15 mol / l, an aluminum sulfate concentration of 0.25 mol / l, and a manganese sulfate concentration of 0.25 mol / l is dropped into the slurry of the intermediate fired product, filtered and washed with water. Then, it dried at 100 degreeC. This was fired at 250 ° C. for 5 hours under an oxygen flow using an electric furnace to obtain positive electrode active material particle powder.

Example 9
8 L of water was put into a closed reaction tank and kept at 40 ° C. while circulating nitrogen gas. Further, a mixed sulfate aqueous solution of Ni, Co, and Mn, a sodium hydroxide aqueous solution, and an aqueous ammonia solution were continuously added with stirring so that the pH = 11.0 (± 0.1). During the reaction, only the filtrate was discharged out of the system with a concentrating device, and the solid content was retained in the reaction tank. After the reaction, a slurry of the coprecipitation product was collected. The collected slurry was filtered, washed with water, and dried at 120 ° C. overnight to obtain a coprecipitation precursor powder.

  The obtained coprecipitation precursor and lithium carbonate powder were weighed and mixed thoroughly. This was fired at 860 ° C. for 5 hours in an air stream using an electric furnace to obtain an intermediate fired product. 100 g of this intermediate fired product was added to 100 ml of pure water kept at 50 ° C. with stirring. Next, 6 ml of a mixed aqueous solution adjusted to have a sulfuric acid concentration of 0.11 mol / l, an aluminum sulfate concentration of 1 mol / l, and a manganese sulfate concentration of 1 mol / l is dropped into the slurry of the intermediate fired product, filtered, and dried at 120 ° C. did. This was fired at 500 ° C. for 5 hours under an air flow using an electric furnace to obtain positive electrode active material particle powder.

Example 10
8 L of water was placed in a closed reaction tank and kept at 45 ° C. while flowing nitrogen gas. Further, a mixed sulfate aqueous solution of Ni, Co, and Mn, a sodium hydroxide aqueous solution, and an aqueous ammonia solution were continuously added with stirring so that pH = 11.1 (± 0.1). During the reaction, only the filtrate was discharged out of the system with a concentrating device, and the solid content was retained in the reaction tank. After the reaction, a slurry of the coprecipitation product was collected. The collected slurry was adjusted to pH = 11.3 by adding an aqueous sodium hydroxide solution, and the magnesium sulfate aqueous solution was added dropwise with stirring so that the Mg / (Ni + Co + Mn) molar ratio was 0.03. It was washed with water and dried at 100 ° C. overnight to obtain a coprecipitation precursor powder.

  The obtained coprecipitation precursor and lithium carbonate powder were weighed and mixed thoroughly. This was fired at 840 ° C. for 8 hours under an air flow using an electric furnace to obtain an intermediate fired product. 100 g of this intermediate fired product was added to 150 ml of pure water maintained at 45 ° C. with stirring. Next, 6 ml of a mixed aqueous solution adjusted to have a sulfuric acid concentration of 0.05 mol / l, an aluminum sulfate concentration of 1 mol / l, and a manganese sulfate concentration of 1 mol / l is dropped into the slurry of the intermediate fired product, filtered and dried at 100 ° C. did. This was fired at 450 ° C. for 5 hours under an air flow using an electric furnace to obtain positive electrode active material particle powder.

Example 11
8 L of water was put into a closed reaction tank and kept at 40 ° C. while circulating nitrogen gas. Further, a mixed sulfate aqueous solution of Ni, Co, and Mn, a sodium hydroxide aqueous solution, and an aqueous ammonia solution were continuously added with stirring so that the pH = 10.8 (± 0.1). During the reaction, only the filtrate was discharged out of the system with a concentrating device, and the solid content was retained in the reaction tank. After the reaction, a slurry of the coprecipitation product was collected. The collected slurry was filtered, washed with water, and dried at 100 ° C. overnight to obtain a coprecipitation precursor powder.

  The obtained coprecipitation precursor and lithium carbonate powder were weighed and mixed thoroughly. This was fired at 860 ° C. for 7 hours under an air flow using an electric furnace to obtain an intermediate fired product. 100 g of this intermediate fired product was added to 100 ml of pure water kept at 30 ° C. with stirring. Next, 3 ml of a mixed aqueous solution adjusted to have a sulfuric acid concentration of 0.1 mol / l and an aluminum sulfate concentration of 2 mol / l was dropped into the slurry of the intermediate fired product, filtered, and dried at 100 ° C. This was fired at 500 ° C. for 5 hours under an air flow using an electric furnace to obtain positive electrode active material particle powder.

Example 12
8 L of water was put into a closed reaction tank and kept at 40 ° C. while circulating nitrogen gas. Further, a mixed nitrate aqueous solution of Ni, Co, and Mn and an aqueous lithium carbonate solution were continuously added while stirring so that the pH was 9.0 (± 0.1). During the reaction, only the filtrate was discharged out of the system with a concentrating device, and the solid content was retained in the reaction tank. After the reaction, a slurry of the coprecipitation product was collected. The collected slurry was filtered, washed with water, and dried at 120 ° C. overnight to obtain a coprecipitation precursor powder.

  The obtained coprecipitation precursor and lithium nitrate powder were weighed and mixed well. This was fired at 1100 ° C. for 5 hours under an air flow using an electric furnace to obtain an intermediate fired product. 100 g of this intermediate fired product was added to 120 ml of pure water maintained at 70 ° C. with stirring. Next, 101 ml of a mixed aqueous solution adjusted to have a nitric acid concentration of 0.6 mol / l, an aluminum nitrate concentration of 0.008 mol / l, and a cobalt sulfate concentration of 0.072 mol / l was dropped into the slurry of the intermediate fired product, filtered, Dried at 100 ° C. This was fired at 950 ° C. for 3 hours in an air stream using an electric furnace to obtain positive electrode active material particle powder.

Example 13
8 L of water was placed in a closed reaction tank and kept at 45 ° C. while flowing nitrogen gas. Further, a mixed chloride aqueous solution of Ni, Co, and Mn, a sodium carbonate aqueous solution, and an aqueous ammonia solution were continuously added with stirring so that the pH was 8.8 (± 0.1). During the reaction, only the filtrate was discharged out of the system with a concentrating device, and the solid content was retained in the reaction tank. After the reaction, a slurry of the coprecipitation product was collected. The collected slurry was filtered, washed with water, and dried at 100 ° C. overnight to obtain a coprecipitation precursor powder.

  The obtained coprecipitation precursor and lithium hydroxide monohydrate powder were weighed and mixed well. This was fired at 980 ° C. for 5 hours under an oxygen flow using an electric furnace to obtain an intermediate fired product. 100 g of this intermediate fired product was added to 100 ml of pure water kept at 50 ° C. with stirring. Next, 75 ml of a mixed aqueous solution adjusted to have a hydrochloric acid concentration of 0.4 mol / l, an aluminum chloride concentration of 0.4 mol / l, and a nickel sulfate concentration of 1.6 mol / l was dropped into the slurry of the intermediate fired product, filtered, Dried at 100 ° C. This was fired at 550 ° C. for 3 hours in an air stream using an electric furnace to obtain positive electrode active material particle powder.

Example 14
8 L of water was put into a closed reaction tank and kept at 40 ° C. while circulating nitrogen gas. Further, a mixed sulfate aqueous solution of Ni, Co, and Mn, a sodium hydroxide aqueous solution, and an aqueous ammonia solution were continuously added with stirring so that the pH = 11.5 (± 0.1). During the reaction, only the filtrate was discharged out of the system with a concentrating device, and the solid content was retained in the reaction tank. After the reaction, a slurry of the coprecipitation product was collected. The collected slurry was filtered, washed with water, and dried at 110 ° C. overnight to obtain a coprecipitation precursor powder.

  The obtained coprecipitation precursor and lithium carbonate powder were weighed and mixed thoroughly. This was fired at 860 ° C. for 5 hours in an air stream using an electric furnace to obtain an intermediate fired product. 100 g of this intermediate fired product was added to 100 ml of pure water kept at 40 ° C. with stirring. Next, 6 ml of a mixed aqueous solution adjusted to have a sulfuric acid concentration of 0.033 mol / l, an aluminum sulfate concentration of 1 mol / l, a manganese sulfate concentration of 0.5 mol / l, and a magnesium sulfate concentration of 0.5 mol / l, The solution was added dropwise to the solution, filtered, and dried at 100 ° C. This was baked for 10 hours at 450 ° C. under air flow using an electric furnace to obtain positive electrode active material particle powder.

Example 15
8 L of water was put into a closed reaction tank and kept at 40 ° C. while circulating nitrogen gas. Further, a mixed sulfate aqueous solution of Ni, Co, and Mn and an aqueous sodium carbonate solution were continuously added while stirring so that the pH was 8.4 (± 0.1). During the reaction, only the filtrate was discharged out of the system with a concentrating device, and the solid content was retained in the reaction tank. After the reaction, a slurry of the coprecipitation product was collected. The collected slurry was filtered, washed with water, and dried at 150 ° C. overnight to obtain a coprecipitation precursor powder.

  The obtained coprecipitation precursor and lithium carbonate powder were weighed and mixed thoroughly. This was fired for 7 hours at 870 ° C. under air flow using an electric furnace to obtain an intermediate fired product. 100 g of this intermediate fired product was added to 180 ml of a 0.11 mol / l aqueous ammonium fluoride solution maintained at 15 ° C. with stirring. Next, 209 ml of a mixed aqueous solution adjusted to have a sulfuric acid concentration of 0.008 mol / l, an aluminum sulfate concentration of 0.01 mol / l, a manganese sulfate concentration of 0.01 mol / l, and a titanyl sulfate concentration of 0.01 mol / l, The solution was added dropwise to the slurry, filtered, washed with water, and dried at 100 ° C. Using an electric furnace, this was fired at 150 ° C. for 15 hours under air flow to obtain a positive electrode active material particle powder.

Comparative Example 1
8 L of water was placed in a closed reaction tank and maintained at 50 ° C. while nitrogen gas was circulated. Further, a mixed sulfate aqueous solution of Ni, Co, and Mn and an aqueous sodium carbonate solution were continuously added with stirring so that the pH was 8.5 (± 0.1). During the reaction, only the filtrate was discharged out of the system with a concentrating device, and the solid content was retained in the reaction tank. After the reaction, a slurry of the coprecipitation product was collected. The collected slurry was filtered, washed with water, and dried at 120 ° C. overnight to obtain a coprecipitation precursor powder.

  The obtained coprecipitation precursor and lithium carbonate powder were weighed and mixed thoroughly. This was baked for 5 hours at 880 ° C. under air flow using an electric furnace to obtain positive electrode active material particle powder.

Comparative Example 2
8 L of water was placed in a closed reaction tank and maintained at 50 ° C. while nitrogen gas was circulated. Further, a mixed sulfate aqueous solution of Ni, Co, and Mn and an aqueous sodium carbonate solution were continuously added with stirring so that the pH was 7.9 (± 0.1). During the reaction, only the filtrate was discharged out of the system with a concentrating device, and the solid content was retained in the reaction tank. After the reaction, a slurry of the coprecipitation product was collected. The collected slurry was filtered, washed with water, and dried at 110 ° C. overnight to obtain a coprecipitation precursor powder.

  The obtained coprecipitation precursor and lithium carbonate powder were weighed and mixed thoroughly. This was fired at 850 ° C. for 6 hours under an air flow using an electric furnace to obtain an intermediate fired product. 100 g of this intermediate fired product was added to 25 ml of pure water kept at 40 ° C. with stirring. Next, 3 ml of 0.1 mol / l sulfuric acid was dropped into the slurry of the intermediate fired product, filtered and dried at 100 ° C. This was fired at 400 ° C. for 3 hours using an electric furnace to obtain positive electrode active material particle powder.

Comparative Example 3
8 L of water was placed in a closed reaction tank and maintained at 50 ° C. while nitrogen gas was circulated. Further, a mixed sulfate aqueous solution of Ni, Co, and Mn and an aqueous sodium carbonate solution were continuously added while stirring so that the pH was 8.0 (± 0.1). During the reaction, only the filtrate was discharged out of the system with a concentrating device, and the solid content was retained in the reaction tank. After the reaction, a slurry of the coprecipitation product was collected. The collected slurry was filtered, washed with water, and dried at 120 ° C. overnight to obtain a coprecipitation precursor powder.

  The obtained coprecipitation precursor and lithium hydroxide monohydrate powder were weighed and mixed well. This was fired at 900 ° C. for 4 hours under an oxygen flow using an electric furnace to obtain an intermediate fired product. 100 g of this intermediate fired product was added to 30 ml of pure water maintained at 50 ° C. with stirring. Next, 144 ml of a mixed aqueous solution adjusted to have a sulfuric acid concentration of 0.05 mol / l, an aluminum sulfate concentration of 1 mol / l, and a manganese sulfate concentration of 1 mol / l is dropped into the slurry of the intermediate fired product, filtered, washed with water, And dried. This was fired at 550 ° C. for 5 hours under an air flow using an electric furnace to obtain positive electrode active material particle powder.

Comparative Example 4
8 L of water was placed in a closed reaction tank and kept at 45 ° C. while flowing nitrogen gas. Further, a mixed sulfate aqueous solution of Ni, Co, and Mn and an aqueous sodium carbonate solution were continuously added with stirring so that the pH was 8.5 (± 0.1). During the reaction, only the filtrate was discharged out of the system with a concentrating device, and the solid content was retained in the reaction tank. After the reaction, a slurry of the coprecipitation product was collected. The collected slurry was filtered, washed with water, and dried at 100 ° C. overnight to obtain a coprecipitation precursor powder.

  The obtained coprecipitation precursor and lithium carbonate powder were weighed and mixed thoroughly. This was baked for 8 hours at 820 ° C. under air flow using an electric furnace to obtain an intermediate baked product. 100 g of this intermediate fired product was added to 20 ml of a 0.95 mol / l aqueous ammonium fluoride solution maintained at 35 ° C. with stirring, filtered, washed with water, and dried at 110 ° C. This was fired at 500 ° C. for 3 hours in an air stream using an electric furnace to obtain positive electrode active material particle powder.

Comparative Example 5
8 L of water was placed in a closed reaction tank and kept at 45 ° C. while flowing nitrogen gas. Further, a mixed sulfate aqueous solution of Ni, Co, and Mn and an aqueous sodium carbonate solution were continuously added while stirring so that the pH was 8.2 (± 0.1). During the reaction, only the filtrate was discharged out of the system with a concentrating device, and the solid content was retained in the reaction tank. After the reaction, a slurry of the coprecipitation product was collected. The collected slurry was filtered, washed with water, and dried at 100 ° C. overnight to obtain a coprecipitation precursor powder.

  The obtained coprecipitation precursor and lithium carbonate powder were weighed and mixed thoroughly. This was fired at 850 ° C. for 6 hours under an air flow using an electric furnace to obtain an intermediate fired product. 100 g of this intermediate baked product was added to 120 ml of pure water maintained at 20 ° C. with stirring, filtered, washed with water, and dried at 100 ° C. This was fired at 350 ° C. for 3 hours in an air stream using an electric furnace to obtain positive electrode active material particle powder.

  Table 1 shows the characteristics of the positive electrode active material particle powders obtained in Examples 1 to 15 and Comparative Examples 1 to 5, and Table 2 shows the characteristics of batteries produced using the positive electrode active material particle powders.

The positive electrode active material particle powders obtained in Examples 1 to 15 each have a first discharge capacity of 220 mAh / g or more, an initial efficiency of 95% or more, and a second discharge capacity of 180 mAh / g or more. is there. Further, the percentage of the discharge capacity at the 22nd time and the discharge capacity at the 3rd time is 75% or more. The positive electrode active material particle powder according to the present invention has a large discharge capacity due to the presence of Li ₂ M ′ _(1-y) Mn _y O ₃ , and is further initially immersed in an aluminum aqueous solution containing an acid in the intermediate fired product. It is a positive electrode material excellent in efficiency, rate characteristics and cycle characteristics.

  Those that do not contain aluminum as in Comparative Examples 1, 2, 4, and 5 are inferior in cycle characteristics as compared to the Examples. As compared with Example, the lithium containing excess aluminum as in Comparative Example 3 is inhibited from entering and exiting lithium during charging and discharging, and the discharge capacity is reduced. An appropriate amount of aluminum is present, and lithium extracted from the intermediate baked product by the acid is discharged as an aqueous lithium solution, and the peak intensity ratio (a) / (b), Li / (Ni + Co + Mn) molar ratio, Ni: Co: Mn It can be seen that when the molar ratio is in an appropriate range, a positive electrode active material for a nonaqueous electrolyte secondary battery excellent in discharge capacity, initial efficiency, rate characteristics, and cycle characteristics can be obtained.

  From the above results, it was confirmed that the positive electrode active material particle powder according to the present invention has a large discharge capacity and is effective as a positive electrode active material for a non-aqueous electrolyte secondary battery excellent in initial efficiency, rate characteristics and cycle characteristics. .

  Since the positive electrode active material particle powder according to the present invention has a large discharge capacity and improved initial efficiency, rate characteristics, and cycle characteristics, it is suitable as a positive electrode active material particle powder for a non-aqueous electrolyte secondary battery.

Claims (8)

A method for producing a positive electrode active material particle powder as described below, wherein a mixture containing a precursor particle powder containing at least Ni and Mn and a lithium compound is fired, and the resulting intermediate fired product is converted to an acid and an Al salt. A method for producing a positive electrode active material particle powder, which is soaked in a mixed aqueous solution, filtered, dried, and refired.
[Positive electrode active material powder]
A positive electrode active material particle powder comprising a composite oxide containing at least Li, Ni, Mn and Al but not B, wherein the Mn content of the composite oxide is 0 in terms of molar ratio (Mn / (Ni + Co + Mn)). 0.5 or more, the Al content is 0.03 to 3% by weight, and the maximum at 2θ = 20.8 ± 1 ° of the powder X-ray diffraction diagram using Cu—Kα ray of the positive electrode active material particle powder. The relative intensity ratio (a) / (b) between the intensity (a) of the diffraction peak and the intensity (b) of the maximum diffraction peak at 2θ = 18.6 ± 1 ° is 0.02 to 0.2, and the positive electrode In a secondary battery using a positive electrode using active material particle powder and a negative electrode made of metallic lithium, the upper limit potential is converted to a lithium counter electrode of 4.6 V, and the lower limit potential is converted to a lithium counter electrode of 2.0 V. First when charging / discharging at a current rate of 20 mA / g Efficiency is 95% or more, the positive electrode active material particles the initial discharge capacity is equal to or is 220 mAh / g or more.   The method for producing a positive electrode active material particle powder according to claim 1, wherein the positive electrode active material particle powder comprising a composite oxide containing at least Li, Ni, Mn and Al contains fluorine.   The manufacturing method of the positive electrode active material particle powder of Claim 1 or 2 with which the positive electrode active material particle powder which consists of complex oxide containing at least Li, Ni, Mn, and Al contains Co.   Li / (Ni + Mn + Co) is a 1.25 to 1.65 molar ratio, The manufacturing method of the positive electrode active material particle powder in any one of Claims 1-3.   After firing the mixture containing the precursor particle powder containing at least Ni and Mn and the lithium compound, the obtained intermediate fired product is immersed in an aqueous fluoride solution, and further immersed in a mixed aqueous solution of acid and Al salt for filtration. The method for producing positive electrode active material particle powder according to claim 1, wherein the powder is dried and refired. A method for producing a positive electrode active material particle powder as described below, wherein a mixture containing a precursor particle powder containing at least Ni and Mn and a lithium compound is fired, and the resulting intermediate fired product is converted to an acid, an Al salt. And a method for producing positive electrode active material particle powders that are immersed in a mixed aqueous solution of a salt of at least one element selected from Ni, Mn, and Co, filtered, dried, and refired.
[Positive electrode active material powder]
A positive electrode active material particle powder comprising a composite oxide containing at least Li, Ni, Mn and Al but not B, wherein the Mn content of the composite oxide is 0 in terms of molar ratio (Mn / (Ni + Co + Mn)). 0.5 or more, the Al content is 0.03 to 3% by weight, and the maximum at 2θ = 20.8 ± 1 ° of the powder X-ray diffraction diagram using Cu—Kα ray of the positive electrode active material particle powder. The relative intensity ratio (a) / (b) between the intensity (a) of the diffraction peak and the intensity (b) of the maximum diffraction peak at 2θ = 18.6 ± 1 ° is 0.02 to 0.2, and the positive electrode In a secondary battery using a positive electrode using active material particle powder and a negative electrode made of metallic lithium, the upper limit potential is converted to a lithium counter electrode of 4.6 V, and the lower limit potential is converted to a lithium counter electrode of 2.0 V. First when charging / discharging at a current rate of 20 mA / g Efficiency is 95% or more, the positive electrode active material particles the initial discharge capacity is equal to or is 220 mAh / g or more.   After firing the mixture containing the precursor particle powder containing at least Ni and Mn and the lithium compound and immersing the obtained intermediate fired product in an aqueous fluoride solution, the acid, Al salt, and Ni, Mn, Co The manufacturing method of the positive electrode active material particle powder of Claim 6 which is immersed in the mixed aqueous solution of the salt of the at least 1 sort (s) of element chosen from, drying, and rebaking. It is a manufacturing method of a nonaqueous electrolyte secondary battery, Comprising: The process of obtaining positive electrode active material particle powder with the manufacturing method in any one of Claims 1-7 , The positive electrode containing the obtained positive electrode active material particle powder And a process for producing a non-aqueous electrolyte secondary battery.

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