JPH11135118A - Positive active material for nonaqueous secondary battery and its manufacture - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve the capacity and cycle characteristic of a lithium nickel composite oxide, and to provide a manufacturing method with less quality dispersion even in a industrial scale manufacture. SOLUTION: The mixed powder of a lithium compound and a compound mainly comprising a transition metal is molded, the molded body is placed on a porous body 5 in a reaction vessel 7 placed on a supporting table 10 of a baking furnace 8 with an electric heater to form a molded body filling layer 6, an oxidizing gas such as air is forced to flow at a constant or higher superficial velocity through a gas pipe 3 to which an air pump 1 for compressing gas, a flow control device 2, and a pre-heater 4 are connected, and gas passing through the filling layer 6 is exhausted from an exhaust opening 9. Thereby, even if amount of baking treatment product is large, a lithium composite oxide active material with uniform quality and superior battery characteristics can be manufactured.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a positive electrode active material used for a non-aqueous electrolyte secondary battery, particularly a lithium secondary battery, a raw material thereof, and a method for producing the same.

[0002]

_2. Description of the Related Art At present, LiCoO ₂ is used as a positive electrode active material of a lithium secondary battery. Capacity 120-14
0 mAh / g, and the cycle characteristics (life) are about 500 cycles. Higher performance, smaller size of electronic equipment,
With the progress of cordless technology, miniaturization and weight reduction of batteries as driving power sources are also required. As a countermeasure, replacement with LiNiO ₂ as a positive electrode active material is considered. LiNiO
₂ has a problem that the capacity is high but the life is short. Attempts have been made to add elements other than Ni as an improvement method, but the effect is not sufficient. Further, optimization of particle size, granulation of active material, and densification have also been proposed, but these have not been able to provide a sufficient effect. LiNiO ₂ has a problem other than life, and it is difficult to manufacture a product having stable characteristics, particularly, as the manufacturing scale is increased, or between lots and even between different parts even within the same lot. is there.

In the case of synthesizing a small amount of lithium composite oxide, a homogeneous one can be obtained in a normal sintering furnace for supplying oxygen gas or air. The battery used as the positive electrode active material had problems such as poor charge / discharge characteristics and large characteristic deviation values. Japanese Patent Application Laid-Open No. 5-62678 proposes forced ventilation.

That is, in the proposed method, when synthesizing the lithium composite oxide in a firing furnace, air or oxygen heated to a predetermined temperature or a mixed gas of oxygen and nitrogen is forcibly passed through the mixed powder layer. An air pump provided outside the furnace, in which a reaction vessel for storing the mixed powder is placed in a firing furnace provided with an electric heater, and a ceramic perforated plate on which the mixed powder does not fall is disposed at the bottom thereof. Compressed air is sent to the bottom of the reaction vessel through a heat exchanger for preheating the compressed air, and is forcibly aerated into the mixed powder layer. However, this method rather increases the variation.

[0005]

SUMMARY OF THE INVENTION Li containing a different element
As well as improving the capacity and cycle characteristics of the composition formula is NiO ₂ Li _a Ni _b M lithium nickel composite oxide of the _c O _d, even in the production of industrial scale, provides no variation manufacturing method.

[0006]

In order to improve the capacity and cycle characteristics, attention is paid to the particle structure as an active material, and the ratio R = D ₅₀ / of the median diameter (D ₅₀ ) to the specific surface area diameter (D _S ).
It was determined an appropriate range of D _S. In order to obtain an active material having excellent characteristics by controlling R, the proper range of powder characteristics of nickel hydroxide or a coprecipitate mainly composed of nickel hydroxide and production conditions were determined, and the firing method was also improved. . In addition, a sintering method that eliminates variations particularly when the scale is enlarged is adopted. That is,
Lithium composite oxide is used as a positive electrode active material for non-aqueous electrolyte secondary batteries.Because it is a powder, it is a primary particle mainly composed of crystalline particles or a secondary particle in which primary particles are aggregated. , The powder properties have an effect on the battery properties.

The effect of the particle diameter is, for example, that the initial capacity decreases as the diameter increases, but the cycle characteristics are improved. The effect of the specific surface area, for example, is that the initial capacity increases as the specific surface area increases. However, it is difficult to combine cycle characteristics and high initial capacity, such that the cycle characteristics are reduced, and proposals to improve the characteristics by adjusting the particle size and the chemical component are known, but sufficiently. It was not satisfactory. The present inventors have found that the median diameter is in an appropriate range as the powder characteristics, and that the ratio between the specific surface area diameter and the median diameter is in an appropriate range, so that the initial capacity is high and the cycle characteristics are good. They found that a lithium composite oxide active material could be obtained.

It is unclear how the powder characteristics R of the active material actually affect the capacity and cycle characteristics. The effect is irrespective of whether the particle appearance is a secondary grain or a single crystal (primary grain), and is presumed to be due to the structure of the surface at the atomic level. The higher the capacity value, the more energy can be stored. The theoretical capacity of LiNiO ₂ is 28
0 mAh / g, but LiCo currently used
130 to 140 mA while O ₂ is equivalent theoretical value
Since only h / g can be used, the actual capacity of LiNiO ₂ was set to a target value of 150 mAh / g or more. What is important as the cycle characteristics is that if the initial capacity decrease before the 15th cycle is large, the capacity after that cannot be recovered, resulting in a shorter life.

As a result of many trials and errors, it has been determined that the amount of cycle reduction after 15 cycles is desirably 12% or less of the initial capacity, and the capacity in the embodiment of the present invention is 150 to 20%.
Since it is between 5 mAh / g, the amount of reduction is desirably 18 mAh / g or less. A method for evaluating battery characteristics will be described later. R mainly depends on the powder characteristics of the raw material and the firing conditions, particularly the aeration conditions and temperature. The powder characteristics of the raw material are determined by the production method (p.
H, temperature, and charging conditions). As a firing method, the raw material during the firing is sufficiently reacted by forcibly passing air through the filling layer of the molded body, and the entire filling layer is fired uniformly and with little variation. As a result, the powder characteristics of the active material are reduced. It has less variation.

That is, in the present invention, first, an alkali and an aqueous solution of a metal salt are continuously or intermittently supplied to a reaction vessel, and the reaction is carried out at a pH in the range of 6.5 to 11 and a temperature of 90 ° C. or lower. A step of continuously or partly taking out a slurry composed of a liquid containing a reactant outside the reaction tank while separating, and a step of separating a solid reactant and a liquid in the slurry into a cake or paste. And a step of removing unnecessary components by washing to obtain a hydroxide of nickel or a coprecipitate of nickel and another element, a method for producing a raw material for a positive electrode active material for a non-aqueous secondary battery; Second, nickel hydroxide or a coprecipitate of nickel and other elements, the crystal phase of which is α-phase and / or β-phase nickel hydroxide, having a tap density of 0.6 to 1.4 g / cc. Raw material for positive electrode active material for non-aqueous secondary batteries Thirdly, an alkali and an aqueous solution of a metal salt are continuously or intermittently supplied to the reaction vessel, and the reactants are reacted at a pH in the range of 6.5 to 11 and a temperature of 90 ° C. or lower. A step of continuously or partly taking out the slurry comprising the liquid out of the reaction tank, a step of separating the solid reactant and the liquid in the slurry into a cake or paste, and unnecessary washing by washing. The crystal phase obtained through the step of removing contains nickel hydroxide of α phase and / or β phase, and has a tap density of 0.6 to 1.4 g.
/ Cc of nickel hydroxide or a co-precipitate of nickel and other elements; a raw material for a positive electrode active material for a non-aqueous secondary battery; fourthly, a lithium compound and a transition metal. To form a coprecipitate of a mixed powder with a compound or a lithium compound and a compound mainly containing a transition metal or a mixture of the mixed powder and the above coprecipitate or a coprecipitate mainly containing lithium and a transition metal. A method for producing a positive electrode active material, comprising: sintering a molded body, wherein an oxidizing gas is passed between filled layers formed of the molded body;
6. The method for producing a positive electrode active material according to the fourth aspect, wherein the atmosphere in the packed bed is pressurized while the atmosphere is pressurized; , A high nickel alloy, a compound mainly composed of nickel or a combination of two or more of these three, or a metal nickel having an oxide film formed on the surface, a high nickel alloy, a metal nickel or a high nickel alloy and nickel as a main component 7. The method for producing a positive electrode active material according to the fifth or sixth aspect, wherein the method is a composite material comprising:
Seventh, a chemical composition represented by Li _a Ni _b M _C O _d (where 0.95 ≦ a ≦ 1.05, b + c = 1, 0 <c
<0.4, d ≒ 2, M is Co, Mn, Fe, V, Ti,
Al, Sn, Zn, Cu, In, Ga, Si, Ge, S
b, B, P, K, Na, Mg, Ca, Ba, Sr, W,
At least one element selected from Mo, Nb, Ta, Y, and lanthanide elements. ) Has a range median diameter of 5 to 30 [mu] m, and a non-aqueous secondary to specific · R = D ₅₀ / D _S for the specific surface area diameter of the median diameter is characterized by a 1.5-6 Eighth, a positive electrode active material for a battery;
9. The positive electrode active material for a non-aqueous secondary battery according to the above item 7, wherein the initial capacity is 150 mAh / g or more, and the capacity decrease after 15 cycles is 18 mAh / g or less;
A nickel hydroxide or a coprecipitate of nickel and another element, the crystal phase of which is α-phase or β-phase or a mixed phase of α- and β-phase nickel hydroxide, and its tap density Is mixed with a lithium compound powder to form a mixed powder, and the obtained molded body is filled in a reaction vessel to form a packed layer. and calcined by bubbling an oxidizing gas into the packed bed, and disintegration, the fired product, Li _a Ni _b M _c O chemical composition as shown by _d (where 0.95 ≦ a ≦ 1.05, b + c = 1,0
<C <0.4, d ≒ 2, M is Co, Mn, Fe, V, T
i, Al, Sn, Zn, Cu, In, Ga, Si, G
e, Sb, B, P, K, Na, Mg, Ca, Ba, S
At least one element selected from r, W, Mo, Nb, Ta, Y, and lanthanide elements. ) Has a median diameter is in the range of 5 to 30 [mu] m, and the ratio · R = D ₅₀ / D _S for the specific surface area diameter of median diameter 1.5
6. A method for producing a positive electrode active material for a non-aqueous secondary battery, which comprises obtaining a powdered material which is No. 6; 10. The method for producing a positive electrode active material for a non-aqueous secondary battery according to the ninth aspect, wherein the capacity decrease after 15 cycles is 18 mAh / g or less; The slurry comprising the liquid containing the reactants is continuously supplied while reacting the alkali and the aqueous solution of the metal salt continuously or intermittently at a pH of 6.5 to 11 and at a temperature of 90 ° C. or lower. Or a step of removing a part of the slurry intermittently from the reaction tank, a step of separating a solid reactant and a liquid in the slurry into a cake or paste, and a step of removing unnecessary components by washing, and With hydroxide or nickel The method for producing a positive electrode active material for a non-aqueous secondary battery according to the ninth or tenth aspect, wherein the calcination is performed as a coprecipitate with the element of The method for producing a positive electrode active material according to any one of the ninth to eleventh aspects, wherein the method is performed by forcibly aerated calcination in a heated state. High nickel alloy, nickel-based compound or combination of two or more of these three, or metal nickel with high surface oxide film, high nickel alloy, metal nickel or high nickel alloy and nickel as main component 13. A method for producing a positive electrode active material according to any one of the ninth to twelfth aspects, wherein the method is a composite material comprising a compound.

[0011]

BEST MODE FOR CARRYING OUT THE INVENTION In the production of nickel hydroxide according to the present invention, an aqueous solution of a nickel salt and an aqueous alkaline solution are continuously or intermittently supplied to the same reaction vessel, and at this time, the pH is adjusted to 6.5 to 6.5. The supply amount of the aqueous alkali solution is adjusted so as to be able to be fixed to a constant value between 11. The reaction temperature is adjusted so as to be a constant temperature of 90 ° C. or lower. If necessary, the nickel salt aqueous solution and / or the alkaline aqueous solution may be heated in advance. Nickel salts include nitrates, sulfates,
Chloride can be used, alkali is NaOH, KOH, Li
OH and NH ₄ OH can be used. The reaction is reaction formula N
Hydroxide precipitates like i ²⁺ + 2OH ⁻ → Ni (OH) ₂ , and as a by-product, a salt is formed by an alkali ion and an acid. However, since it is water-soluble, it is like nickel hydroxide. Does not precipitate.

The reason why the reaction is carried out at a pH of 6.5 to 11 is firstly to control the powder characteristics, and secondly to control the crystal phase to α phase and / or β phase. Temperature 9
The reason for setting the temperature to 0 ° C. or lower is to prevent the formation of secondary compounds. If the pH is lower than 6.5, the amount of unreacted Ni salt is large and the production efficiency is low. It is desirable that the element that can be coprecipitated under such conditions be supplied to the reaction tank as a liquid mixed with an aqueous nickel salt solution. The aqueous solution of hydroxide and salt generated by the reaction becomes a slurry, and the slurry is continuously or intermittently taken out from the upper or lower part of the reaction tank, separated into solid and liquid by a centrifugal dehydrator, and purified water is used to remove unnecessary salts. To obtain a hydroxide cake or paste. The cake or paste is dried and crushed to obtain the hydroxide powder.

This powder is mixed with a lithium compound, preferably lithium hydroxide, formed into a compact, and then fired. After firing, a dense sintered body having substantially the same shape as the molded body is obtained. FIG. 1 is a schematic cross-sectional view showing an upward blowing type firing furnace used in an embodiment of the present invention. That is, a baking furnace 8 in which an electric heater is arranged and whose temperature can be controlled by a thermocouple includes a reaction vessel 7 for accommodating a molded body on a support base 10, and a porous body 5 is provided on the lower side inside. A preheater 4 for preheating an oxidizing gas such as air is provided in the middle of an air supply pipe 3 connecting the air pump 1 for compressing the ventilation and the flow controller 2.

When removing oxygen or the like from the high-pressure cylinder, a pressure reducing valve is used without using the air pump 1. The mixed powder compact is filled on the porous body 5, and the gas that has passed through the filled layer 6 is discharged into the atmosphere through the ventilation port 9. Here, if the air supply pipe after the preheating heater is made of the same material as the powder contact portion, the problem of the contaminant element is eliminated. If the firing furnace 8 is housed in a water-cooled metal case, the atmosphere can be strictly controlled. For example, an atmosphere gas can be charged after an initial vacuum is applied, the atmosphere can be pressurized, and the atmosphere can be prevented from leaking, so that a gas having a constant composition ratio can be used as necessary. The sintering is performed at 600 ° C. or higher, but is desirably performed at a temperature of 800 ° C. or higher to make the primary particles 5 μm or more.

If the hydroxide produced in the present invention is used,
Regardless of whether the particles are primary particles or secondary particles, the battery characteristics are improved if R is in an appropriate range. A further feature is that, even if the sintered body is dense, the primary particles are controlled in size and the grain boundaries are weak, so that the sintered body can be crushed to easily obtain the required primary particles (active material). It is considered that the particle size distribution of 1 to 100 μm is suitable, but the median diameter is 5 to 30 μm.
m is suitable). If the tap density is lower than 0.6 g / cc, the median diameter does not become 5 μm or more,
If it exceeds 1.4 g / cc, the primary particles grow too much, and the same pulverization as in the flux method is required. Cracks are easily generated in the particles and cycle characteristics are deteriorated.

According to the present invention, there is provided a method for producing a raw material powder, wherein the density is increased by molding the raw material powder while passing an oxidizing gas therethrough. Since the air is aerated at a flow rate, the reaction in the entire reaction vessel is performed uniformly and sufficiently even when the amount of baking increases, and as a result, a lithium composite oxide active material having excellent battery characteristics can be obtained. As the raw material, an inorganic acid salt such as an oxide, a hydroxide, and lithium nitrate of Li, and an organic acid salt such as lithium acetate can be used. Similarly, oxides, hydroxides, inorganic acid salts such as nitrates, and organic acid salts such as citrates can be used as the transition metal compound such as Ni. Naturally, the compounds formed by the eutectoid precipitation method or the similar method are also calcined. it can. A hydroxide is particularly preferred as the Ni compound. Similarly, as the compound of the transition metal other than Ni and the other element M, inorganic acid salts such as oxides, hydroxides and nitrates, and organic acid salts such as citrate can be used. Where M is Co, Mn, Fe, V, Ti, Al, Sn, Z
n, Cu, In, Ga, Si, Ge, Sb, B, P,
K, Na, Mg, Ca, Ba, Sr, W, Mo, Nb,
At least one element selected from Ta, Y, and lanthanide elements. Li _a Ni _b M _c O _d is LiNiO ₂
Is a solid solution, and the essential crystal structure is the same as that of LiNiO ₂ . Therefore, a is 0.95 to 1.05 and d is approximately 2. M forms a solid solution in the crystal structure to prevent the crystal structure from deteriorating due to the cycle. Therefore, b + c = 1. Since M is added, naturally 0 <c
Becomes M has a limit of the amount of solid solution depending on the type of element. However, when 0.4 ≦ c, the crystal structure changes, and the characteristics as an active material deteriorate. For mixing, a mixer equipped with a stirrer (attritor, free-type mixer, concrete mixer) or a rotary vessel type (pot mill, V-type mixer) can be used, but other types of machines may be used.

The following method can be used for molding, but other methods may be used depending on the shape. (A) Press (uniaxial press, tablet press, isostatic press, vibratory press), (B) roll briquetter, (C) extruder, (D) rolling granulator. The shape of the molded body may be a sphere, a lens, a rod, a plate, or a noodle, which can be manufactured by a general technique, but may be another shape. A suitable dimension is one side or cross section of 1 mm or more and 20 mm or less in diameter. You may provide a through-hole in a large molded object.
It is also important to make the density not blown off by forced ventilation during firing, and a relative density of 40% or more is desirable.
As described in the examples, in the evaluation of the battery capacity, the evaluation generally improves as the superficial velocity increases, but if the ventilation flow rate is too low, the initial capacity is low, and the variation in the capacity is large. As the oxidizing gas, oxygen, air, a mixed gas of oxygen and nitrogen, a nitrogen oxide gas, or the like can be used.

The furnace may have a plurality of air supply pipes and / or vents. The upper piping may be horizontal or diagonal (showing ventilation vents for upward air flow, air supply piping for downward air flow). Lower pipes (pipe for up-flow, ventilation port for down-flow) may be provided vertically or obliquely from the lower part of the furnace. An air diffuser may be provided at the end of the air supply pipe, or an air collector may be provided at the vent. To increase the pressure, a pressure relief valve may be provided at the ventilation port. In addition, by using a nickel material for the container used for the baking, it is possible to prevent the contamination of foreign substances which may cause a decrease in battery characteristics, thereby obtaining an active material having excellent battery characteristics. The nickel material is used at least for a portion of the inner surface of the reaction vessel which is in contact with the molded body, but may be used for a vent pipe. The nickel material mainly indicates nickel metal, a high nickel alloy, a nickel oxide and a composite material thereof, and the nickel oxide includes a case where the nickel oxide is a composite oxide. The case where an oxide film is formed on the surface of these composite members is also included.
If necessary, the calcination may be carried out in two or more stages and two or more calcinations, and the ventilation gas may be circulated.

The median diameter (D ₅₀ ) is 50% of the weight integrated distribution curve measured by the laser scattering method.
. The specific surface area diameter (D _s ) is determined by the specific surface area S (m ² / g) measured by the so-called BET method for determining the specific surface area using gas adsorption, and the specific gravity ρ (g / cm ³ ) measured by a pycnometer. From D _S = 6 /
It was calculated by the equation ρ · S. D ₅₀ and S-fill properties of the raw materials, particle size and process, in particular controlled by the temperature and the superficial velocity. D ₅₀ Do 5μm smaller, or when 30μm larger is not a satisfactory one of the surface resistance after packing density or mixture formation of the positive electrode mixture is. Therefore, D ₅₀ is preferably ₅ μm to 30 μm. R usually shows a value close to 1, but if R is smaller than 1.5, the initial capacity becomes small and the capacity decrease after 15 cycles is large. On the other hand, when R is larger than 6, the initial capacity is high, but the capacity decrease after 15 cycles increases significantly. Therefore, R is preferably 1.5 or more and 6 or less. In addition, the appearance of the particles was observed by SEM photograph, and primary particles and secondary particles were discriminated.

It has been proposed that in the case of LiNiO ₂ , nickel hydroxide is used as a transition metal compound as a raw material and that a β phase is desirable as a crystal phase. α phase, α
There is no suggestion that the battery characteristics will be improved by using a phase-based, α-phase and β-phase mixed phase raw material. Even for the β phase, no proposal has been made on powder characteristics, designation of a range of tap density, or R of the active material. In addition, there is no proposal that the tap density, which influences the filling property, should be a density lower than 1.4 among the powder properties. In the present invention, since the powder properties of the active material are controlled through the step of firing and sintering the compact, the tap density has a significant effect. 78 of active material powder
After mixing 15% by weight of graphite powder as a conductive material and 7% by weight of a fluororesin powder as a binder, the mixture was molded to form a positive electrode mixture.

Preparation of Test Battery A coin cell battery for test was prepared in order to evaluate the battery capacity by incorporating the obtained positive electrode mixture into the battery. FIG. 4 is a schematic sectional view showing a coin battery prepared as a test battery. The diameter of the coin is 20 mmφ. In FIG.
1 is a stainless steel case, 13 is a sealing plate of the same material, 12 is a polypropylene gasket, 14 is a negative electrode using metallic lithium, 15 is a positive electrode obtained by press-molding a positive electrode mixture, 16
Is a microporous polypropylene separator. In addition,
The electrolyte was a solvent in which propylene carbonate and diethyl carbonate were mixed at a volume ratio of 1: 1 and LiPF ₆ was used as an electrolyte in an amount of 1 mol / l.
The one dissolved at a concentration was used. Charge and discharge were performed at a temperature of 20 ° C. The current is 2 mA and the charge end voltage is 4.3
V and a discharge end voltage of 2.7 V, a charge / discharge cycle test was performed. The quality of the battery was compared between the initial capacity per 1 g of the active material and the amount of deterioration (amount of deterioration) after 15 cycles.

[0022]

Example 1 1.5 mol / l nickel nitrate and 20% N
Nickel hydroxide was synthesized with the aOH solution. That is, nickel nitrate was charged into a 3 l beaker at a rate of 0.2 l / min, and simultaneously, NaOH was supplied to the beaker, and the reaction was carried out while stirring the liquid in the beaker at 60 RPM. At this time, NaOH was constantly measured for pH, and the pump was automatically operated and stopped according to ± 0.1 fluctuation to be injected.
In this case, NaOH is not supplied continuously but is supplied intermittently. It is also possible to supply continuously at a constant ratio. The slurry was collected by overflow, filtered and washed with a Buchner funnel, and then dried at 120 ° C. for 10 hours. The dried product was crushed in a mortar and sieved with a 100-mesh sieve. Tap density is 5
15 g was placed in a 0 ml cylinder and tapped 1,000 times. FIG. 5 shows the measured values of tap density for each pH and each temperature during the synthesis of nickel hydroxide.

Next, a synthesis test of LiNi _1-x Co _x O ₂ was performed. That is, nickel hydroxide, 2 μm cobalt hydroxide and 15 μm lithium hydroxide are converted into N
i: Co: Li was mixed at a ratio of 0.8: 0.2: 1.0, formed into a spherical shape having a diameter of 5 mm at a pressure of 500 kg / cm ² , and fired at 870 ° C. for 15 hours in an oxygen stream. It was formed into a spherical shape, filled into a nickel container having a diameter of 5 cm and a height of 20 cm, and fired by passing oxygen at a superficial velocity of 5 m / min. The fired product was pulverized in a mortar for 10 minutes, and the particle size and specific surface area of the obtained product were determined to calculate R. Table 1 shows the results.
The appearance of the particles was observed with a SEM photograph. Also,
The crystal phase was determined by XRD. Although the raw material hydroxides differed depending on the synthesis conditions, all of the fired products had a single-phase profile similar to that of LiNiO ₂ . All of those of the present invention have an initial capacity of 170 to 190 mAh / g, 1
Although the capacity reduction rate after 5 cycles was 5 to 7%, the ones outside the present invention (shown as Comparative Examples) had an initial capacity of 10 for both types.
At less than 0 mAh / g, the capacity reduction rate was 15 to 18%.

[0024]

[Table 1]

Next, using the same hydroxide, a firing test was performed at 920 ° C. for 10 hours in an oxygen stream using a firing furnace as shown in FIG. XRD of fired product is all single phase and LiNiO
It became the same profile as ₂ . Table 2 shows the test results. Under the synthesis conditions of the present invention, the initial capacity is 150 to 18
0 mAh / g, the rate of capacity reduction after 15 cycles is 4 to 6
%, The initial capacity was 100 mAh / g and the rate of capacity reduction after 15 cycles was 12 to 14% for the ones outside the synthesis conditions of the present invention (shown as Comparative Example in the table).

[0026]

[Table 2]

Next, those synthesized at 50 ° C. and pH 9
Using those synthesized at 0 ° C. and pH 11 and those synthesized at 20 ° C. and pH 10, each was subjected to 24 hours at 820 ° C. in an oxygen stream.
Fired for hours. Table 3 shows the results.

[0028]

[Table 3]

[0029]

Example 2 A hydroxide in which Ni and Co were coprecipitated was used. That is, lithium hydroxide was mixed at a ratio of 1: 1 by atomic number with respect to the total amount of coprecipitated Ni and Co at a ratio of 0.8 and 0.2 by atomic number. Molded in the same manner as in No. 1 and filled the molded body to a height of 50 cm and 20 m /
The mixture was calcined at 825 ° C. for 15 hours while passing oxygen at a superficial velocity of min. Table 4 shows the results.

[0030]

[Table 4]

[0031]

Example 3 Nickel hydroxide synthesized in Example 1 (50
° C, pH 9, tap density 1.03 g / cc)
o and hydroxides of other elements were added during mixing. With a filling height of 7 cm, oxygen is introduced at a superficial velocity of 1 m / min,
It was baked at 850 ° C. for 20 hours. The molded body was molded into a cylindrical shape having a diameter of 5 mm and a height of 15 mm at a pressure of 1 ton / cm ² . In this case, BN is used as a release agent and an additive element.
(Boron nitride): Li: Ni + M: B = 1.03: 1:
It was added so that the atomic ratio was 0.01.

[0032]

[Table 5]

[0033]

Embodiment 4 Ni / Co ratio is 0.85 / 0.1 in atomic number.
Lithium hydroxide was weighed and mixed using a coprecipitated hydroxide as in Example 5 so that the atomic ratio of Li to Ni + Co was 1/1. Next, the mixed powder was formed into an approximate spherical shape having a diameter of 5 mm by a tableting machine, filled into a height of φ50 × 750 mm, and fired. The baking was performed at 700 ° C. for 15 hours, and the influence of the ventilation conditions was examined within the range shown in the table. In the case of firing at a temperature of 700 ° C., the median diameter of the fired product is substantially determined by the median diameter of the coprecipitated hydroxide in the raw material, and is 8 times the median diameter of the hydroxide.
0 to 95%. Since the distribution of the median diameter and specific surface area of the fired product in each part in the reaction vessel was within ± 6% of the average value of the whole, the whole fired product was collectively pulverized, sampled, and the median diameter, The specific surface area, the initial capacity, and the amount of capacity decrease after 15 cycles were measured.

The median diameter and tap density of the three hydroxides were synthesized and controlled under the following conditions. Median diameter Tap density pH temperature α: β Other (μm) (g / cc) 22.5 1.12 8.5 80 3: 7 −7 0.81 9.5 70 1: 9 −35 1.36 7.5 60 6: 4 Add 1% ammonia

[0035]

[Table 6]

[0036]

[Table 7]

[0037]

[Table 8]

In any of the above cases, the powder particles after firing and pulverization are secondary particles, the size of the primary particles is about 0.2 μm, and the specific surface area is originally 6 m ² /
g, but is actually about 0.09 m ² / g, and the median diameter indicates the average diameter of the secondary particles. Table 6-
As can be seen from Table 8, when the superficial velocity is low, the reaction does not proceed sufficiently and the unreacted Li compound remains and becomes liquid, covering the surface and closing the grain boundaries. It is believed that adsorption is hindered. By increasing the superficial velocity to 0.5 m / min or more, the reaction proceeds, unreacted substances are reduced, and both initial capacity and cycle characteristics are improved. On the other hand, if the superficial superficial velocity is too high, sintering between secondary particles or within the particles will proceed and microcracks will be generated,
Since the electrolytic solution is decomposed at the fracture surface, the cycle characteristics deteriorate. Therefore, it is preferable that the superficial velocity does not exceed 250 m / min. Another reason that the specific surface area does not correspond to the size of the primary particles is that the primary particles can confirm the grain boundaries by microscopic observation, but the sintering between the particles is strong,
In the measurement by the BET method, it is considered that no gas is adsorbed, and it cannot be denied that an extremely small amount of the Li compound blocks the grain boundary.

[0039]

Example 5 Tap density 1.15 g / cc Nickel hydroxide, cobalt tetroxide (Co ₃ O ₄ ), and lithium hydroxide (LiOH) having a ratio of α phase and β phase of about 1: 1 were used.
The atomic ratio of Ni: Co: Li is 0.75: 0.25: 1
, IPA (isopropyl alcohol) was added, and the mixture was placed in an alumina pot and mixed with water cooling for 30 minutes. The IPA was filtered, heated and evaporated, and then formed into a column having a diameter of 4 mm and a length of 6 mm using a tableting machine. Next, the compact was put into a reaction vessel and calcined at 925 ° C. for 15 hours.
The distribution of the median diameter and specific surface area of the calcined product in each part of the reaction vessel was within ± 4% of the average value of the whole, so that the whole calcined product was crushed together, and then the median diameter,
Sampling was performed to obtain a sample for measuring the specific surface area, the initial capacity, and the capacity decrease after 15 cycles. The median diameter of the fired product was controlled by changing the pressure during molding after repeating various trials. Median diameter of fired product: 15 μm class (molding pressure: 700 kg / cm ² , molding density: 1.4 g / cc), 5 μm class: molding pressure: 150 kg
/ Cm ² , molding density 1.2 g / c. c. ) And 25μ
m class (molding pressure 1.6 ton / cm ² , molding density 2.3 g)
/ C. c. Table 9 and Table 10 show the measurement results.

[0040]

[Table 9]

[0041]

[Table 10]

In this embodiment, the appearance is primary particle-like except for the case where the median diameter of the calcined product is 15 μm class and the superficial velocity is 250 m / min. Therefore, the specific surface area is almost the same as the median diameter, and R is 1 , But in practice, R of 2.1 to 4.9 was an appropriate range. The exact reason for this is unknown.

[0043]

Embodiment 6 The atomic ratio is Ni: Co: Al: Mg: Li.
= 0.90: 0.08: 0.05: 0.01: 1, and the hydroxide of each element was mixed, and the molding pressure was 500 kg.
/ Cm ² , 6 × 6 × 15 mm rectangular shape, 830
Calcination was performed while flowing oxygen at 24 ° C. for 24 hours. The tap density of Ni hydroxide is 1.27 g / cc, the ratio of α phase to β phase is 7: 3, and the tap density of Co hydroxide is 0.95 g / cc.
Met. Condition 1 Condition 2 Packed bed height about 350 mm about 50 mm * Diameter 50 Superficial velocity 4 m / min 0.2 m / min Active material median diameter 5.2 0.7 Appearance Secondary Secondary R 3.46 3.81 Initial capacity 159 172 Capacity decrease after 15 cycles 6 9

[0044]

EXAMPLE 7 A coprecipitated hydroxide having a tap density of 0.76 with an atomic ratio of Ni: Co = 0.8: 0.2 and a ratio of α phase to β phase of 4: 6 and B ₂ O ₃ .Al Ni + Co: B + Al: Li = 0.9 by the oxide of ₂ O ₃ composition and lithium hydroxide.
7: 0.03: 1 and then molded.
When calcination was performed at 850 ° C. for 24 hours by passing oxygen at a pressure of kg / cm ² and a superficial velocity of 3 m / min, the median diameter was 11.7 μm, the specific surface area was 2.72 μm, that is, R = 4.3. When the capacity is 168 mAh / g. An active material having a decrease of 3 after 15 cycles was obtained.

[0045]

Example 8 Lithium hydroxide (LiO
H.H ₂ O) and a coprecipitated hydroxide having a Ni / Co ratio of 85/15 in atomic number ratio as a transition metal raw material (tap density 0.96 g / cc, ratio of α phase to β phase of 3 : 7), and weighed and mixed such that the atomic ratio of Li to Ni + Co was 1: 1. Next, the mixed powder was formed into an approximately spherical shape having a diameter of 5 mm by a tableting machine, and about 2 kg was placed on a porous body made of nickel oxide provided in a reaction vessel made of metal nickel of the above-mentioned firing furnace.
After filling, the height of the filled molded product was 7.5 cm. The firing was performed at 750 ° C. for 10 hours using the upward blowing type firing furnace shown in FIG. Ventilation volume is cross-sectional area x velocity (superficial velocity)
The flow rate (l / min) calculated in was flowed, and the influence of the superficial velocity was examined. The gas was fired while supplying oxygen. After firing, as shown in the perspective view of FIG. 3, sampling was performed from sampling points A, E, and I of the molded body packed layer, and this was crushed to a particle size of 150 mesh pass, and the powder was used as an active material to obtain a battery characteristic. Was evaluated. The results are shown in Table 11.

[0046]

[Table 11]

The difference between the initial volumes within each sample population is 0,1.
At 5 m / min or more, the average value was within ± 4 to 7%. Even at 0.3 m / min, there is an improvement effect, but the characteristics are not sufficient, so that 0.5 m / min or more is required. The filling height of the compact after firing was about 5 cm, but the height difference on the upper surface was within 5 mm, and the compact was still spherical after firing. No abnormalities such as the formation of a concave portion due to drift on the upper surface immediately below the ventilation port were observed. The surface of the nickel container was blackish, but no peeling or adhesion occurred. No foreign matter or secondary phase was detected in each part by powder X-ray diffraction, and the gap between the side surface of the nickel container and the compact was 2 mm at the G position at the maximum.

[0048]

Embodiment 9 In order to enable the firing atmosphere to be performed under pressure, a firing apparatus is installed in a pressurized container, and after evacuating the atmosphere with a vacuum pump, oxygen gas is supplied and a predetermined internal pressure is set.
Other conditions such as the reaction vessel, the molded body and the filling conditions thereof were the same as in Example 1. The source pressure was supplied while the source pressure was higher than the internal pressure so that the average superficial velocity was 5 m / min. The velocity in this case is not the actually measured velocity of the pressurized ventilation, but the flow rate (l / min) in the flow rate controller divided by the cross-sectional area of the vessel, and the ventilation was discharged without circulation. The furnace pressure (gauge pressure kg / cm ² ) was set to 0.5 at a firing temperature of 750 ° C. for 10 hours.
Use calcined samples ~15kg / cm ^2,
Table 12 shows the results of evaluating the battery capacity using a coin battery.

[0049]

[Table 12]

Next, the results of the same test performed at a firing temperature of 900 ° C. for 10 hours are shown in Table 13.

[0051]

[Table 13]

The state after firing was the same as in Example 1 even in the case of firing under pressure. The surface of the nickel container was completely blackened, but no peeling or cracking occurred. Initial volume differences within each sample population were within ± 4-6%.

[0053]

Embodiment 10 In the above embodiments 8 and 9, the cycle characteristics of the sample on the upper part of the compacted layer tend to be low. For improvement, as shown in FIG.
After passing through the packed layer 6 and the porous body 5, it was discharged outside the furnace. The sintering furnace body was used by sealing seams and the like so as to prevent gas leakage. In the case of pressurization, the furnace body was placed in a pressurized container as in the case of Example 9. Table 14 shows the test results of the initial capacity and the like in the case of holding at the firing temperature of 720 ° C. for 10 hours and in the case of holding at the firing temperature of 875 ° C. for 10 hours.

[0054]

[Table 14]

[0055]

Embodiment 11 Although a composite oxide of Ni and Co containing lithium is used as a positive electrode material of a lithium secondary battery, when an element other than Co is added and combined, for example, nickel hydroxide and manganese oxyhydroxide, For the combinations of nickel hydroxide and magnesium hydroxide, nickel hydroxide, cobalt tetroxide, and boron oxide, as shown in Table 15, the sintering temperature, time, furnace pressure, and superficial velocity were specified to form a molded body. Using the fired sample, the initial capacity of the coin battery and the capacity decrease after 15 cycles were measured, and the results are shown in Table 15.

[0056]

[Table 15]

[0057]

Embodiment 12 In Examples 8 to 11, the size of the molded body fired was spherical with a diameter of 5 mm, but the shape of the molded body was, for example, 5 × 20 × 1 by a roll briquetter.
A similar test was performed on small plate pieces of 4 mm or noodle-like materials having a diameter of 4 mm formed by extrusion. The composition and apparatus were the same as in Example 1, the average superficial velocity was 3 m / min,
It was fired under the condition of keeping time. A battery was prepared using the fired sample, and the initial capacity and the capacity decrease after 15 cycles were measured. The results are shown in Table 16.

[0058]

[Table 16]

[0059]

Embodiment 13 In the case where the transition metal is mainly composed of Ni, oxygen is suitable as the ventilation gas component, but there may be cases where components other than oxygen are included as chemical components. So Ni and C
Using a hydroxide obtained by coprecipitating o with a molar ratio of 70/30, mixing with LiOH · H ₂ O powder, diameter 10 × thickness 5 m
m was molded by a press and baked at 700 ° C. for 15 hours. Ventilation is performed by an air pump at 10 m / min.
Ventilated. A battery was prepared using the fired sample, and the initial capacity and the capacity decrease after 15 cycles were measured. Table 17 shows the results.

[0060]

[Table 17]

[0061]

Example 14 The filling container was enlarged under the same conditions as in Example 8, and the size of the variation was confirmed. Condition 1 Condition 2 Container diameter 1000 mm 500 mm Fill height 200 mm 600 mm Superficial velocity 5 m / min 25 m / min Sampling position A 176-10 180-11 E 184-7 187-7 I 171-9 184-9 Obtained in Example 8 Characteristics almost equivalent to the obtained results were obtained with less variation between positions in the container. From this result, it was clarified that the present method can be industrially produced even when the sintering scale is increased without causing the variation unlike the other methods.

[0062]

As described above, according to the method of the present invention, when a mixture of nickel hydroxide powder and lithium compound powder is formed and fired to obtain a lithium-nickel composite oxide positive electrode active material, By controlling the pH, temperature, and other process elements during the synthesis of nickel hydroxide in order to control the powder characteristics and crystal structure of nickel hydroxide as a component, the resulting sintered body has a median diameter of 5 to 30 μm. And an active material powder in which R is in the range of 1.5 to 6 is obtained.
A positive electrode active material having a small capacity reduction rate after cycling is obtained. In addition, since the density is increased by molding the raw material powder and firing is performed while forcing the inside of the molded body packed layer at a certain flow rate or more, even if the amount of firing increases, the reaction of the entire reaction vessel is uniform. In addition, since there is no scattering of powder and no drift of ventilation, a lithium composite oxide active material having excellent battery characteristics can be advantageously synthesized on an industrial scale.

[Brief description of the drawings]

FIG. 1 is a schematic cross-sectional view showing an upward blowing type firing furnace used in an example of the present invention.

FIG. 2 is a schematic cross-sectional view showing a downward blow type firing furnace used in an example of the present invention.

FIG. 3 is a perspective view showing sampling positions after firing in Examples and Comparative Examples of the present invention.

FIG. 4 is a schematic cross-sectional view showing a coin battery prepared as a test battery in Examples and Comparative Examples of the present invention.

FIG. 5 is a graph showing the influence of liquid temperature and pH on the tap density of nickel hydroxide when synthesizing nickel hydroxide with an aqueous solution of nickel nitrate and caustic soda solution.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 air pump 2 flow rate controller 3 air supply pipe 4 preheater 5 porous body 6 molded body packed layer 7 reaction vessel 8 firing furnace 9 ventilation port 10 support base 11 stainless case 12 gasket 13 sealing plate 14 negative electrode 15 positive electrode 16 separator

──────────────────────────────────────────────────の Continued on the front page (51) Int.Cl. ⁶ Identification code FI H01M 10/40 H01M 10/40 Z (72) Inventor Masaru Nishisako 1-8-2 Marunouchi, Chiyoda-ku, Tokyo Dowa Mining Co., Ltd. In-house (72) Inventor Nagata Nagashou 1-8-2 Marunouchi, Chiyoda-ku, Tokyo Dowa Mining Co., Ltd. (72) Inventor Hikoichi Chokari 1-8-2, Marunouchi, Chiyoda-ku, Tokyo Dowa Mining stock In company

Claims (13)

[Claims] 1. An alkali and an aqueous solution of a metal salt are continuously or intermittently supplied to a reaction vessel, and the reaction is carried out at a pH in the range of 6.5 to 11 and at a temperature of 90 ° C. or lower, and contains the reactants. Unnecessary components are removed by continuously or partially removing the slurry of the liquid from the reaction tank, separating the solid reactant and the liquid in the slurry into a cake or paste, and washing. A method for producing a raw material for a positive electrode active material for a non-aqueous secondary battery, wherein a hydroxide of nickel or a coprecipitate of nickel and another element is obtained through a removing step. 2. A nickel hydroxide or a coprecipitate of nickel and another element, the crystal phase of which is α-phase and / or β-phase nickel hydroxide, and having a tap density of 0.6 to 1.4.
g / cc raw material for a positive electrode active material for a non-aqueous secondary battery. 3. An alkali and an aqueous solution of a metal salt are continuously or intermittently supplied to a reaction vessel, and the reaction is carried out at a pH in the range of 6.5 to 11 and at a temperature of 90 ° C. or lower, and contains the reactants. Unnecessary components are removed by continuously or partially removing the slurry of the liquid from the reaction tank, separating the solid reactant and the liquid in the slurry into a cake or paste, and washing. The crystal phase obtained through the removing step contains nickel hydroxide of α phase and / or β phase, and has a tap density of 0.6 to 1.4 g / cc, and is a nickel hydroxide or nickel and coprecipitated with other elements. A raw material for a positive electrode active material for a non-aqueous secondary battery, comprising: a material. 4. A mixed powder of a lithium compound and a compound mainly composed of a transition metal, a coprecipitate of a lithium compound and a compound mainly composed of a transition metal, or a mixture of the mixed powder and the coprecipitated substance or lithium. A method for producing a positive electrode active material, comprising forming a coprecipitate mainly composed of a transition metal and baking the formed body, wherein an oxidizing gas is passed between filled layers formed of the formed body. 5. The method for producing a positive electrode active material according to claim 4, wherein forced calcination is performed in a state where the atmosphere in the filling layer is pressurized. 6. A filled reaction vessel wherein at least the internal contact portion is metallic nickel, a high nickel alloy, a compound mainly composed of nickel, a combination of two or more of these three, or metallic nickel having an oxide film formed on the surface. 7. The method for producing a positive electrode active material according to claim 5, wherein the composite material is a high nickel alloy, a metallic nickel or a high nickel alloy and a compound mainly composed of nickel. 7. A chemical composition represented by Li _a Ni _b M _C O _d (where 0.95 ≦ a ≦ 1.05, b + c = 1,
0 <c <0.4, d ≒ 2, M is Co, Mn, Fe, V,
Ti, Al, Sn, Zn, Cu, In, Ga, Si, G
e, Sb, B, P, K, Na, Mg, Ca, Ba, S
At least one element selected from r, W, Mo, Nb, Ta, Y, and lanthanide elements. ) Has a median diameter is in the range of 5 to 30 [mu] m, and the ratio · R = D ₅₀ / D _S for the specific surface area diameter of median diameter 1.5
6. A positive electrode active material for a non-aqueous secondary battery, which is 6. 8. The positive electrode active material for a non-aqueous secondary battery according to claim 7, wherein the initial capacity is 150 mAh / g or more, and the capacity decrease after 15 cycles is 18 mAh / g or less. 9. A nickel hydroxide or a coprecipitate of nickel and another element, the crystal phase of which is α-phase or β-phase or a mixed phase of α- and β-phase nickel hydroxide, and A powdered raw material having a tap density of 0.6 to 1.4 g / cc is mixed with a lithium compound powder to form a mixed powder, and the obtained molded body is filled in a reaction vessel to form a packed bed. the make, and fired by venting the oxidizing gas to the packed bed, and disintegration, the fired product, Li _a Ni _b M _c O chemical composition as shown by _d (where 0.95 ≦ a ≦ 1.05 , B +
c = 1, 0 <c <0.4, d ≒ 2, M is Co, Mn, F
e, V, Ti, Al, Sn, Zn, Cu, In, Ga,
Si, Ge, Sb, B, P, K, Na, Mg, Ca, B
a, Sr, W, Mo, Nb, Ta, Y, and at least one element selected from lanthanide elements. ) Has a median diameter is in the range of 5 to 30 [mu] m, and the ratio · R = D ₅₀ / D _S for the specific surface area diameter of the median diameter and wherein the obtaining a powder material is 1.5 to 6 A method for producing a positive electrode active material for a non-aqueous secondary battery. 10. The non-aqueous secondary battery using the powdered substance has an initial capacity of 150 mAh / g or more, and a capacity decrease after 15 cycles is 18 mAh / g or less. A method for producing a positive electrode active material for a non-aqueous secondary battery. 11. The powdery raw material is supplied to a reaction vessel continuously or intermittently with an aqueous solution of an alkali and a metal salt, and has a pH in the range of 6.5 to 11 and a temperature of 90 ° C. or lower. A step of continuously or partly taking out a slurry composed of a liquid containing a reactant outside the reaction tank while reacting, and separating a solid reactant and a liquid in the slurry into a cake or paste. The positive electrode for a non-aqueous secondary battery according to claim 9, wherein the positive electrode is obtained as a hydroxide of nickel or a coprecipitate of nickel and another element through a step of removing unnecessary parts by a step and washing. Active material manufacturing method. 12. The method for producing a positive electrode active material according to claim 9, wherein the baking is performed by forcible aeration baking in a state where the atmosphere in the packed layer is pressurized. 13. A method according to claim 1, wherein at least the internal contact portion of the filled reaction vessel is metallic nickel, a high nickel alloy, a compound mainly composed of nickel, a combination of two or more of these three, or a metal having an oxide film formed on the surface. The method for producing a positive electrode active material according to any one of claims 9 to 12, wherein the method is a composite material comprising nickel, a high nickel alloy, metallic nickel or a high nickel alloy and a compound mainly containing nickel.