KR19980024645A - Positive Electrode Active Material for Non-Aqueous Secondary Battery and Manufacturing Method of the Active Material - Google Patents

Abstract

The mixed powder of the lithium compound and the transition metal based compound is shaped into a shape portion, which is packed to form bed 6 on the porous plate 5 at the bottom of the reaction vessel 7 located on the support 10 in the electric heater-equipped sintering furnace 8. To form; The packed part is sintered with such oxidizing gas as air forced through the bed 6 through the gas feed pipe 3 connecting the air pump 1, the flow regulator 2 and the preheater 4 to a surface speed above a certain value. The gas exiting from 6 exits the air atmosphere through vent 9. Even when sintering an increased amount of mixed powder, the method of the present invention enables the production of a lithium composite oxide, which is a homogeneous active material with excellent battery properties. If the manufacturing conditions are controlled such that the ratio of the median diameter to the specific surface area diameter is within an appropriate range, and at the same time, the manufacturing conditions are controlled so that the median diameter, which is the powder characteristic of the lithium composite oxide, is within the appropriate range, not only high initial capacity but also improved cycle characteristics are achieved. The branch can produce an active material.

Description

Positive Electrode Active Material for Non-Aqueous Secondary Battery and Manufacturing Method of the Active Material

The present invention relates to a positive electrode active material for a non-aqueous secondary battery, in particular for a lithium secondary battery, and also to the starting material of the above-described active material, and a method for producing the same.

Lithium cobalt oxide (LiCoO ₂ ) is currently used as a positive electrode active material in lithium secondary batteries. The active material has an energy density (capacity) of 120-140 mAh / g and a cycle characteristic (life time) of about 500 cycles. Recent electronic models have higher performance in smaller sized cellular units, requiring the use of smaller and lighter batteries as the operating power supply. One of the proposed approaches to meet this need is the replacement of LiNiO ₂ as active material for positive electrode. LiNiO ₂ has a high capacity, but on the other hand it has a short lifetime. As one aspect for solving this problem, it has been attempted to add an element other than Ni, but no satisfactory result has yet been obtained. Optimizing particle size, granulating the active material and increasing its density have also been proposed, but with limited success. In addition to the short lifespan, LiNiO ₂ has other problems, namely that as the scale of production increases, the properties of the product are not only variable with each production lot, but also vary with each part within the same lot, Makes the powder difficult to prepare.

Only in small scale synthesis of lithium complex oxide, homogeneous products can be obtained in conventional sintering furnaces fed with oxygen gas or air. Batteries using positive electrode active materials synthesized with increased workload to achieve higher productivity had problems such as deterioration in charge-discharge characteristics and increase variation in characteristics.

Under such circumstances, Japanese Patent Laid-Open No. 5-62678 has been proposed to perform forced passage of gas to ensure a homogeneous overall reaction despite increased sintering operation workload. According to this proposed method, lithium complex oxide is synthesized in a sintering furnace by sintering a bed of mixed powder while supplying a forced flow of air or oxygen or a mixture of oxygen and nitrogen heated to a certain temperature. The mixed powder is contained in a reaction vessel located in a furnace equipped with an electric heater, and a porous ceramic plate supporting the mixed powder is provided at the bottom of the reaction vessel. Compressed air from an external air pump is preheated to a heat exchanger and forced to pass through the mixed powder bed into the bottom of the reaction vessel. However, this increases rather than reduces the variation in characteristics.

An object of the present invention is to improve the energy density and cycle characteristics of Li _a Ni _b M _c O _d containing dissimilar elements and to prepare the active material for the positive electrode described above on an industrial scale without variation in energy density and cycle characteristics. To provide a way to do this.

In view of improving the energy density and cycle characteristics of the desired positive electrode active material, the inventors paid particular attention to the structure of the active material particles and determined an appropriate range of R = D ₅₀ / D _s , where D ₅₀ is the average of the particles. Represents the diameter and D _s represents the specific surface area diameter (which is the diameter of the particles calculated from the density and specific surface area of the particles according to the formula defined hereinafter). In order to provide an active material with the desired properties while appropriately controlling R, the inventors have prepared not only suitable ranges for the powder properties of nickel hydroxide or nickel hydroxide based coprecipitates used as starting materials, but also manufacturing conditions which ensure this suitable range. Decided. The inventors have also devised an improved sintering method for producing the desired powders, in particular other methods which can eliminate unwanted variations in properties that would occur at increased production scale.

Lithium composite oxide is used as a positive electrode active material in nonaqueous electrolyte secondary batteries. However, since they are in powder form, their powder characteristics have some effect on battery characteristics regardless of whether they are mainly composed of primary crystal grains or secondary crystal grains which are aggregates of primary particles. For example, it increases particle size and lowers initial capacity but improves cycle characteristics; In contrast, increasing the specific surface area lowers initial capacity but degrades cycle characteristics. Therefore, it is difficult to meet both the requirements for good cycle characteristics and high initial capacity. Various proposals have been made to improve the properties of powders by controlling particle size and chemical aspects, but satisfactory results have not been achieved.

The inventors have found that lithium composite oxides having high initial capacity and satisfactory cycle characteristics if the median diameter of the particles are within an appropriate range and if the ratio R between the median diameter and the specific surface diameter is adjusted to be within the appropriate range. It was found that an active material can be obtained.

Indeed, it is not entirely clear how the ratio R, which represents the powder properties of the active material, affects its capacity and cycle properties. Since the effects of the present invention develop regardless of whether the particles are secondary or primary in the form of a single crystal, it is assumed that this is due to the surface structure of the particles at the atomic level. Higher capacity means more energy that can be stored. Lithium nickel dioxide (LiNiO ₂ ) has a theoretical energy density of about 280 mAh / g. Although currently used LiCoO ₂ has a comparable theoretical figure, the availability is only 130-140 mAh / g. Thus, the target value of capacity actually available for LiNiO ₂ is 150 mAh / g or more.

Important to the cycle characteristics, if the capacity drops considerably in the initial period up to 15 cycles, later capacity recovery is not possible and in some cases results in a shorter service life.

As a result of many trials and errors, it was found that the decrease in capacity expressed after 15 cycles is preferably 12% or less of the initial value. Since the active materials prepared in the embodiments of the present invention have a capacity in the range of 150-205 mAh / g, the capacity reduction after 15 cycles is preferably 18 mAh / g or less.

Methods for evaluating battery characteristics will be described in the Examples.

The numerical value R depends a lot on the powder properties of the starting material and the conditions for its sintering, especially the gas passage and temperature conditions. The powder properties of the starting material are controlled by their preparation method (pH, temperature and filling conditions). During the sintering, if a forced gas flow is supplied into the bed packed as the shape part of the starting material, thereby a sintering reaction is carried out while uniform sintering is achieved throughout the bed, thereby producing an active material having uniform powder characteristics.

1 is a schematic cross-sectional view of a phase type sintering furnace used in an embodiment of the present invention;

2 is a schematic cross-sectional view of a bottom anti-sintering furnace used in Example 10 of the present invention;

3 is a perspective view showing a sampling position of the sintered active material in Examples and Comparative Examples of the present invention;

4 is a schematic cross-sectional view of a coin cell manufactured as a test cell in each of the Examples and Comparative Examples of the present invention; And

FIG. 4 is a graph showing the results of the synthesis of nickel hydroxide from aqueous solutions of nickel nitrate and sodium hydroxide, with particular reference to the effect of temperature and pH of the aqueous solution on the targin density of nickel hydroxide.

Accordingly, in one aspect of the present invention, a method of preparing a starting material for synthesizing a positive electrode active material for a non-aqueous secondary battery is provided, which includes providing a hydroxide of nickel or a co-precipitate of nickel with at least one other element. Which includes the following steps:

The reaction vessel is continuously or intermittently supplied with an aqueous solution of alkali and metal salts and the reaction is carried out at a pH of 6.5-11 and at a temperature of 90 ° C. or lower, wherein the slurry of the reaction product in the liquid is continuously recovered from the reaction vessel or Part of the slurry is recovered intermittently;

Separating the solid reaction product in the slurry state from the liquid component to form a cake or paste; And

The cake or paste is washed to remove unwanted components.

In another aspect of the present invention, there is provided a starting material for synthesizing a positive electrode active material for a non-aqueous secondary battery, which is either a hydroxide of nickel or a co-precipitate of nickel and at least one other element, and at least one alpha- And beta-phase nickel hydroxide and have a tap density of 0.6-1.4 g / dl.

In a third aspect of the invention, it is either a hydroxide of nickel or a co-precipitate of nickel with at least one other element, having a crystal phase composed of at least one alpha- and beta-phase nickel hydroxide, and having 0.6-1.4 g A starting material for synthesizing a positive electrode active material for a non-aqueous secondary battery having a permissive density of / is provided, which is prepared by the following steps:

The reaction vessel is continuously or intermittently supplied with an aqueous solution of alkali and metal salts and the reaction is carried out at a pH of 6.5-11 and at a temperature of 90 ° C. or lower, wherein the slurry of the reaction product in the liquid is continuously recovered from the reaction vessel or Part of the slurry is recovered intermittently;

Separating the solid reaction product in the slurry state from the liquid component to form a cake or paste; And

The cake or paste is washed to remove unwanted components.

In a fourth aspect of the present invention, a mixed powder of a co-precipitate of a lithium compound and a transition metal-based compound or a lithium compound and a transition metal-based compound, or the above-mentioned coprecipitates or lithium and at least one kind Prepared by the steps of shaping any one of the mixtures of the co-precipitates based on the transition metals of sintered parts and sintering them, characterized in that an oxidizing gas is passed through a bed packed with these shaped parts. A method for producing a positive electrode active material is provided.

In a fifth aspect of the invention, in the manufacturing method as described in the fourth aspect given above, the shaped portions are sintered with an oxidizing gas that is forced through the bed of the shaped portion under such conditions that the atmosphere in the bed is pressurized. A manufacturing method is provided.

In a sixth aspect of the invention, in the manufacturing method as described in the fourth or fifth aspect given above, only at least an inner region of the reaction vessel to be brought into contact with the shaped portions packed in the reaction vessel described above is metal nickel. , Made of a high nickel alloy, a nickel compound or a combination of at least two of the three materials described above or otherwise made of a metal nickel or high nickel alloy having an oxide film formed on its surface, or made of metal nickel or high A method is provided wherein the composite material is made of a composite material comprising a nickel alloy and a nickel compound, wherein the composite material described above has an oxide film formed on its surface.

In a seventh aspect of the invention, a positive electrode active material for use in a non-aqueous secondary battery is provided, which is represented by the formula Li _a Ni _b M _c O _d where 0.95 ≦ a ≦ 1.05; b + c = 1; 0c0 .4; d ≒ 2; M is Co, Mn, Fe, V, Ti, Al, Sn, Zn, Cu, In, Ga, Si, Ge, Sb, B, P, K, Na, Mg, Ca, Ba , Sr, W, Mo, Nb, Ta, Y, and at least one element selected from the group consisting of lanthanum-based elements), and have an average diameter (D ₅₀ ) of 5-30 μm and R = D ₅₀ / D _S [D _S is the specific surface area given by the formula D _S = 6 / ρ · S when ρ (g / cm ³ ) is the specific gravity measured by the peak nom and S (m ² / g) is the BET specific surface area. Diameter] is in the range of 1.5-6.

In an eighth aspect of the present invention, in the positive electrode active material as described in the seventh aspect given above, the positive electrode active material having an initial capacity of 150 mAh / g and undergoing a capacity reduction of 18 mAh / g or less after 15 cycles is Is provided.

In a ninth aspect of the present invention, a method of preparing a positive electrode active material for a non-aqueous secondary battery is provided, which includes the following steps:

The powder raw material is mixed with the lithium compound powder to obtain a mixed powder, wherein the above-described powder raw material is either a hydroxide of nickel or a co-precipitate of nickel with at least one other element, and the crystalline phase is at least one alpha- and Consisting of beta-phase nickel hydroxide, which has a tasine density of 0.6-1.4 g / ㏄,

The resulting mixed powder is shaped into shape parts,

Packing the reactor with the above-described shaped parts to provide a packed bed thereof in the reactor,

Sintering the shaped portion with an oxidizing gas passing through the packed bed, thereby obtaining a sintered product of the raw material, and

The sintered product disintegrates into a final powder material which is a positive electrode active material for use in a non-aqueous secondary battery, which is Li _a Ni _b M _c O _d (Formula, 0.95 ≦ a ≦ 1.05; b + c = 1; 0c0. 4; d ≒ 2; M is Co, Mn, Fe, V, Ti, Al, Sn, Zn, Cu, In, Ga, Si, Ge, Sb, B, P, K, Na, Mg, Ca, Ba, A chemical composition represented by Sr, W, Mo, Nb, Ta, Y and lanthanum-based elements), and have an average diameter (D ₅₀ ) of 5-30 μm and R = D ₅₀ / D _S [D _S is the specific surface diameter given by Equation D _S = 6 / ρ · S when ρ (g / cm ³ ) is the specific gravity measured in peak nom and S (m ² / g) is the BET specific surface area. Is in the range of 1.5-6.

In a tenth aspect of the present invention, in the method for preparing a positive electrode active material for a non-aqueous secondary battery as described in the ninth aspect given above, the non-aqueous secondary battery produced using the final powder material described above is at least 150 mAh / g. A method of manufacturing a positive electrode active material having an initial capacity of and experiencing a capacity decrease of 18 mAh / g or less after 15 cycles is provided.

In the eleventh aspect of the present invention, in the method for preparing a positive electrode active material for a non-aqueous secondary battery as described in the ninth or tenth aspect given above, the aforementioned powder raw material is:

The reaction vessel is continuously or intermittently supplied with an aqueous solution of alkali and metal salts and the reaction is carried out at a pH of 6.5-11 and at a temperature of 90 ° C. or lower, wherein the slurry of the reaction product in the liquid is continuously recovered from the reaction vessel or Part of the slurry is recovered intermittently;

Separating the solid reaction product in the slurry state from the liquid component to form a cake or paste; And

Provided is a method of making a positive electrode active material that is prepared through steps of washing a cake or paste to remove unwanted components.

In the twelfth aspect of the present invention, in the method for producing a positive electrode active material for a non-aqueous secondary battery as described in the ninth or tenth aspect given above, the above-described shape portions are formed under such conditions that the atmosphere in the bed is pressurized. A method for producing a positive electrode active material that is sintered with an oxidizing gas that is forced through a bed of grass is provided.

In the thirteenth aspect of the present invention, in the method for producing a positive electrode active material for a non-aqueous secondary battery as described in the ninth or tenth aspect given above, the reaction vessel to be brought into contact with the shaped portions packed in the reaction vessel described above. At least the interior area may be made of metal nickel, high nickel alloys, nickel compounds or a combination of at least two of the three materials described above or alternatively made of metal nickel or high nickel alloys having an oxide film formed on the surface thereof. Or a composite material comprising a metal nickel or high nickel alloy and a nickel compound, wherein the above-described composite material has an oxide film formed on its surface.

Brief description of the drawings

1 is a schematic cross-sectional view of a phase type sintering furnace used in embodiments of the present invention;

2 is a schematic cross-sectional view of a bottom anti-sintering furnace used in Example 10 of the present invention;

3 is a perspective view showing a sampling position of the sintered active material in Examples and Comparative Examples of the present invention;

4 is a schematic cross-sectional view of a coin cell manufactured as a test cell in each of the Examples and Comparative Examples of the present invention; And

FIG. 5 is a graph showing the results of the synthesis of nickel hydroxide from aqueous solutions of nickel nitrate and sodium hydroxide, with particular reference to the effect of temperature and pH of the aqueous solution on the targin density of nickel hydroxide.

In order to produce nickel hydroxide in the present invention, an aqueous solution of nickel salt and an aqueous solution of alkali are fed into the same reaction vessel continuously or intermittently while adjusting the supply of the aqueous alkali solution so that a constant pH is maintained between 6.5 and 11. The solution in the reaction vessel is heated to maintain a constant reaction temperature of 90 ° C. or lower. If necessary, the nickel salt aqueous solution and / or the alkaline solution may be preheated.

The nickel salt may be selected from the group consisting of nickel nitrate, nickel sulfate and nickel chloride, and the alkali may be selected from the group consisting of NaOH, KOH, LiOH and NH ₄ OH. The reaction scheme may be represented by Ni ²⁺ + 2OH ⁻ → Ni (OH) ₂ , where nickel hydroxide precipitates out. By-product salts are formed from alkali ions and acids, but because they are water soluble, they do not precipitate.

There are two reasons for carrying out the reaction at a pH between 6.5 and 11. The first reason is to control the powder properties of the resulting active material, and the second is to control the nickel hydroxide crystal phase into alpha- and / or beta-phase. The reaction temperature is adjusted to 90 ° C. or lower to prevent the formation of auxiliary compounds. If the pH is 6.5 or less, a large amount of Ni salt remains unreacted, reducing the efficiency of nickel hydroxide production. The elements that can be co-precipitated under the conditions described above are preferably fed into the reaction vessel in the form of a solution mixed with an aqueous nickel salt solution.

The aqueous solutions of the hydroxides and the salts resulting from the reaction take the form of slurries, which are recovered continuously or intermittently at the top or bottom of the reaction vessel and can carry out solid-liquid separation by centrifugal dehydrator. The unwanted salts are then washed off with purified water to yield a hydroxide cake or paste, which is dried and disintegrates in powder form.

The resulting hydroxide powder is mixed with a lithium compound, preferably lithium hydroxide, and the mixture is shaped into a shaped part and sintered. The sintered product is a dense sinter that essentially has the same geometry as the shape part.

FIG. 1 is a schematic cross section of a phase type sintering furnace used in the examples and the following description should be read with reference to this figure.

As depicted, the sinter plant designated 8 has an electric heater and is capable of temperature control by a thermocouple. The sintering furnace 8 contains a reaction vessel 7 located on a support 10 for receiving shaped portions of mixed powder. Porous plate 5 is provided at the bottom of reaction vessel 7. The air pump 1 and the flow regulator 2 for gas compression to be supplied are connected to the reaction vessel 7 by means of a gas supply pipe 3 having a preheater 4 provided midway in its path for preheating of acidic gases such as air. do.

If oxygen or other oxidizing gases are supplied from the high pressure container, air pump 1 is not used and the pressure reducing valve is replaced. The shaped portions of the mixed powder are packed on top of the porous plate 5 to form bed 6 and the oxidizing gas passing through the bed 6 is discharged through the vent 9 into the air atmosphere. If the gas supply pipe downstream of the preheater is made of the same material used in the area in contact with the shape part, there will be no problem of contamination by foreign elements. If the sinter plant 8 is installed in a water-cooled metal case, accurate control of the process atmosphere can be achieved by various methods; For example, the gas filling the atmosphere may be charged after the initial exhaust, which allows for pressurization of the atmosphere; In addition, it is possible to sufficiently suppress the leakage of the atmosphere to allow the use of any gaseous mixture having a prescribed composition ratio.

Sintering is carried out at a temperature of 600 ° C. or higher. Sintering is preferably performed at a temperature of 800 ° C. or higher to produce primary particles of 5 μm or more.

The use of hydroxides produced by the present invention ensures the production of active materials with improved battery properties, irrespective of whether the particles are primary or secondary, provided only R is controlled to be within the appropriate range. A further advantage is that even if the sinter has a high density, the primary particles of controlled size and the weak granule area are thought to be the primary particles of the required size (particle size distribution of 1-100 μm) as the active material. However, suitable median diameters have been found to be in the range of 5-30 μm), allowing for easy disintegration.

If the peroxide density of the nickel hydroxide powder is 0.6 g / dL or less, particles having a median diameter of at least 5 μm will not be obtained. Beyond 1.4 g / dl, overgrowth of primary particles requires the same degree of fracture as in the flux method and cracks tend to develop in the particles, thus degrading the cycle characteristics of the active material.

According to the invention, the starting powder is sintered as an oxidizing gas passing through it. The starting powder is shaped into densely shaped shaped sections and the bed packed with shaped sections is supplied with an oxidizing gas at a flow rate above a certain value. This provides the advantage that even when an increased amount of starting powder is sintered, a uniform and thorough reaction will occur in all parts of the reaction vessel, yielding the desired lithium composite oxide active material with excellent cell properties.

The starting material may be selected from the group consisting of oxides, hydroxides, inorganic acid salts and organic acid salts of Li. Examples of inorganic acid salts include lithium nitrate. Examples of organic acid salts include lithium acetate. In the case of producing LiNiO ₂ , the use of hydroxide as the starting material is preferred. The transition metal compound may be similarly selected from the group consisting of oxides, hydroxides, inorganic acid salts and organic acid salts of suitable transition metals such as nickel. Examples of inorganic acid salts include nitrates. Examples of organic acid salts include citrate. Needless to say, compounds formed by coprecipitation and similar techniques may also be sintered. Most preferred nickel compound is nickel hydroxide. Compounds of M (transition metals other than nickel and some other elements) may be similarly selected from the group consisting of oxides, hydroxides, inorganic acid salts and organic acid salts, where M is Co, Mn, Fe, V, Ti, Al Select from the group consisting of, Sn, Zn, Cu, In, Ga, Si, Ge, Sb, B, P, K, Na, Mg, Ca, Ba, Sr, W, Mo, Nb, Ta, Y and lanthanide Is at least one element.

Li _a Ni _b M _c O _d represents a solid solution of LiNiO ₂ and M. Therefore, its crystal structure is substantially the same as LiNiO ₂ . Thus, a takes a value in the range of 0.95-1.05, and d is approximately equal to two. M is dissolved in LiNiO ₂ to form a solid solution, thereby preventing deterioration of the crystal structure which will be caused by repeated cycle use. From the standpoint of chemical composition, dissolution of M means that a portion of Ni is replaced by M. Therefore, b + c = 1. M is an element added externally. Therefore, c satisfies the following relationship: 0c. There is a limit to the solubility of M, which varies depending on which element M represents. If c is 0.4 or more (0.4 ≦ c), the crystal structure will change so much that it substantially reduces the desired properties of the active material.

Lithium compounds and transition metal compounds are typically used as mixers (eg, attritors, free mixers or concrete mixers) or rotary mixers (eg pot mills or V-type mixers) equipped with stirrers. Mixed; Other types of rotary mixers can of course be used.

The starting powder is typically shaped into shape parts by means of the following machine, but other machines may be employed depending on the shape to be obtained: (A) a press (eg a single press, a tablet press, a hydraulic press and Vibration press); (B) roll briquettes; (C) extruder and (D) rolling granulator. The shape portions may take various forms such as globules, lens bodies, rods, sheets and strands that can be formed by traditional techniques; Other forms may of course be employed. Suitable size ranges are from 1 mm to 20 mm as measured for one edge of the cross section or across its diameter. A through hole can be drilled in large shaped parts. It is important that the shaped parts have a density large enough to ensure that they do not blow in the wind while being sintered under the conditions of forced flow. In order to satisfy this requirement, the shape portions preferably have a relative density of at least 40% of theory. As will be described in the Examples, the grade of cell capacity improves as surface speed increases; However, at excessively low flow rates, the resulting active material has a low initial capacity and undergoes significant capacity variation. The oxidizing gas to be fed into the bed packed as a shape part of the starting powder may be selected from the group consisting of oxygen, air, a mixture of oxygen and nitrogen gas, and nitrogen oxide gas.

The sintering furnace may be modified to have one or more gas supply pipes and / or exhaust ports. The exhaust port at the top or the gas supply pipe at the bottom may be horizontal or inclined. The air supply pipe in the upwards or the exhaust in the downwards may be arranged vertically or at an angle to the bottom of the furnace. If desired, a gas diffuser may be provided at a distance to the end of the gas supply pipe, or alternatively, a gas collector may be installed at the exhaust port. For pressurization, a relief valve may be provided to the exhaust port.

If the sintering vessel is made of nickel material, it is possible to prevent infiltration of foreign materials that will degrade battery characteristics and to obtain an active material having excellent battery characteristics. Nickel is used on the inner surface of the reaction vessel, in an area at least in contact with the shaped portion; If desired, it may also be used on a gas supply pipe. Nickel materials refer in principle to metal nickel, high nickel alloys, nickel oxides and composites thereof, which nickel oxide is optionally a composite oxide. The metal or composite nickel material may have an oxide film formed on the surface. If necessary, the sintering operation may be carried out in two or more steps and may be repeated one or more times. The oxidizing gas may be circulated in the reaction vessel.

The median diameter D ₅₀ may be defined as a value corresponding to 50% on the weight accumulation distribution curve measured by laser scattering. The specific surface area diameter (D _S ) of the particles is the equation D _S = 6 / ρ · S (where S is the BET specific surface S (m ² / g) measured using the gas adsorption method and ρ (g / cm ³ ) is The specific gravity measured with piconometer).

The specific S and D ₅₀ values are controlled by the packing properties, the particle size of the starting material and the production method thereof, in particular the temperature and surface speed.

If D ₅₀ is less than 5 μm or larger than 30 μm, either the packing density or the surface property of the compound of the positive electrode is unsatisfactory. Therefore, D ₅₀ is preferably in the range of 5-30 μm. Usually, R takes a value close to one. If R (= D ₅₀ / D _S ) is less than 1.5, the initial capacity of the positive electrode active material is unreasonably small and a significant decrease occurs in the capacity after 15 cycles. If R is greater than 6, the initial capacity is high but the capacity drop after 15 cycles is also very large. Therefore, R is preferably in the range of 1.5-6. The appearance of the particles was determined based on the SEM photograph.

In the case of LiNiO ₂ , it has been proposed that nickel hydroxide should preferably be used as the starting transition metal compound and that the crystal phase is preferably beta-phase. However, any suggestion has been made regarding the crystal phase, suggesting that the use of starting materials comprising α-phase, mainly α-phase or mixed α- and β-phase crystals will result in an active material which ensures excellent cell properties. There is no enemy. As for the case where the crystalline phase is the beta-phase, no proposal has been made regarding the powder properties, the specific range of the percussive density and the R value which will affect the properties of the active material. Further, no proposal is made regarding the powder properties of the LiNiO ₂ particles, in particular, the percussion density of 1.4 or less, which affects their packing properties. In the present invention, the powder properties of the active material are controlled through the step of sintering the shaped portions of the starting material to form a sintered product, and therefore the percussion density of the particles is a very decisive factor. The powder of the active material was mixed with 78 wt% graphite powder (conductive material) and 7 wt% fluoroplastic powder (binder) to form a compound of the positive electrode.

Preparation of the Test Cell

In order to evaluate the battery capacity of the active material, a test coin-type battery was produced using the compound of the positive electrode. 4 is a cross-sectional view of a manufactured coin-type battery, wherein a stainless case 11, a sealing plate 13 made of the same material as the stainless case 11, a polypropylene gasket 12, a negative electrode 14 made of metal lithium, and a positive electrode made by pressing of a positive electrode compound 15, and microporous polypropylene separator 16.

A solvent consisting of a 1: 1 (v / v) mixture of propylene carbonate and diethyl carbonate was used as electrolyte after dissolving LiPF ₆ at a concentration of 1 mol / L.

The cycle test was carried out at 20 ° C. under the following conditions: current 2 mA; Final charging voltage 4.3 V; The blocking voltage was performed under 2.7V. The battery characteristics of each sample were evaluated in terms of the initial capacity per gram of active material and the amount of deterioration (capacity reduction) after 15 cycles:

Example 1

Nickel hydroxide was synthesized from 1.5 mol / L of nickel nitrate and 20% aqueous NaOH solution in the following manner. Nickel nitrate was charged to a 3-L beaker at a rate of 0.2 L / min while stirring the solution in the beaker at 60 rpm. While continuously measuring pH, NaOH was injected by automatically flashing the pump corresponding to every pH change of ± 0.1. In this case, the supply of NaOH is not continuous but intermittent. If necessary, NaOH may be fed continuously at a constant rate relative to nickel nitrate in the beaker.

The slurry was recovered in the form of an effluent, filtered using Buchner funnels, washed and dried at 120 ° C. for 10 hours. The dried product was disintegrated in a mortar and sieved through a 100 mesh sieve.

The percussive density of the powder was measured by filling 15 g of powder into a 50-mL cylinder and then tapping it 1000 times. The targin density measurement results are shown in FIG. 5 as a function of pH and temperature employed in the synthesis of nickel hydroxide.

In the next step, the test for synthesizing LiNi _1-x Co _x O ₂ was carried out in the following manner. The powders of nickel hydroxide, cobalt hydroxide (2 μm) and lithium hydroxide (15 μm) were mixed so that the molecular number ratio of Ni, Co, and Li was 0.8: 0.2: 1.0, and the mixture was mixed at a pressure of 500 kg / cm 2. It was formed into a spherical body (5 mm ^Φ ) and sintered in an oxygen air stream at 870 ° C. for 15 hours. During the sintering step, the spheres were packed into a nickel vessel in the form of a cylinder 5 cm in diameter and 20 cm high and oxygen was passed through the nickel vessel at a surface speed of 5 m / min.

The sinter was milled in a mortar for 10 minutes to disintegrate into particles and the R value of this powder was calculated from their particle size and specific surface area. The results are shown in Table 1. Particle appearance was determined based on SEM photographs. The crystal phase of each powder was evaluated by XRD (X-ray diffraction). The crystal phase of the starting hydroxide varied with the synthesis conditions, but in the case of sintered all samples consisted of a single phase with a similar profile to LiNiO ₂ . All samples of the present invention had an initial capacity of 170-190 mAh / g and experienced a capacity degradation of 5-7% after 15 cycles. In contrast, two samples outside the scope of the present invention (which are intended as comparative examples) had an initial capacity of 100 mAh / g or less and a capacity decrease of 15-18%.

870 ℃ X 15 hours Φ50 X 200H 5m / min Example Comparative example Reaction temperature, ℃ 85 50 20 20 85 Synthetic pH 6.5 8 10 6.5 9 11 7.5 1.0 11.5 8.5 ^* Percent Density, g / ㏄ 1.21 1.38 0.82 1.07 1.03 0.63 1.21 0.83 0.47 1.76 Crystal phase α αβ αβ α α ≒ β β α α + β β β Active material Median diameter, (D ₅₀ ) 15.7 13.6 10.2 14.2 14.7 11.4 15.2 12.3 4.7 31.2 Particle appearance 2nd 1st 2nd 1st 1st 2nd 1st 2nd Secondary Second ◎ R 5.1 3.8 5.1 4.2 2.7 5.8 3.2 5.3 6.3 1.4 * 5% ammonia water added. ◎ Primary particles are about 4㎛ in size.

Another sintering test was performed with the same hydroxide in an oxygen stream, but the sintering temperature was 920 ° C. and the time was 10 hours. All the sinters were composed of single phase by XRD and were found to show a similar profile to LiNiO ₂ . The test results are shown in Table 2. The products synthesized in accordance with the present invention had an initial capacity of 150-180 mAh / g and experienced a capacity loss of 4-6% after 15 cycles. In contrast, two samples outside the scope of the present invention (which were intended as comparative examples) had an initial capacity of 100 mAh / g or less and a capacity drop of 12-14% after 15 cycles.

920 ℃ X 10 hours Φ50 X 200H 5m / min Example Comparative example Reaction temperature, ℃ 85 50 20 20 85 Synthetic pH 6.5 8 10 6.5 9 11 7.5 1.0 11.5 8.5 ^* Active material Median diameter, (D ₅₀ ) 23.1 24.2 22.7 26.7 29.1 23.4 24.7 19.6 32.7 30.2 Particle appearance 1st 1st 1st 1st 1st 2nd 1st 1st Second ◎ Secondary R 4.3 2.9 4.9 3.9 2.4 5.7 3.1 5.9 6.6 1.2 ◎ Primary particles are about 11㎛ size.

Using additional samples of three nickel hydroxides synthesized under different conditions (50 ° C. and pH 9; 50 ° C. and pH 11; 20 ° C. and pH 10), the sintering experiment was run for 24 hours at 820 ° C. in an oxygen stream. The results are shown in Table 3.

820 ℃ X 24 hours Φ50 X 200H 10m / min Example Reaction temperature, ℃ 50 20 Synthetic pH 9 11 1.0 Percent Density, g / ㏄ 1.03 0.63 0.83 Middle diameter of active material, (D ₅₀ ) 10.9 6.5 10.2 Particle appearance Mainly primary Primary Mainly primary R 3.5 5.6 3.2 Initial Capacity, mAh / g 172 174 179 % Degradation after 15 cycles 6 8 7

Example 2

Hydroxide was prepared by coprecipitation of Ni and Co at a rate such that the atomic number ratio of Ni to Co was 0.8: 0.2. Then, lithium hydroxide was mixed with the co-precipitate at a ratio such that the ratio of the number of atoms of Li to Ni and Co was 1: 1. The mixture was formed into a spherical body as in Example 1, packed to a height of 50 cm, sintered at 825 ° C. for 15 hours and oxygen supplied at a surface speed of 20 m / min. The results are shown in Table 4.

825 ℃ X 15 hours Φ50 X 500H 20m / min Example Comparative example Reaction temperature, ℃ 40 80 Synthetic pH 6.5 8.5 10.5 8.5 Percent Density, g / ㏄ 1.17 1.36 0.62 1.65 Crystal phase α α ≒ β β αβ Middle diameter of active material, (D ₅₀ ) 10.4 13.2 11.6 22.1 Particle appearance 2nd (1st 6.8) 2nd (1st 7.2) 2nd (1st 6.3) 2nd (1st 5.3) R 4.7 2.9 2.1 6.2 Initial Capacity, mAh / g 182 173 169 112 % Degradation after 15 cycles 8 7 6 21

Example 3

In Example 1 nickel hydroxide synthesized at 50 ° C. and pH 9 and having a gin density of 1.03 g / dl was mixed with hydroxides of Co and other elements. The mixtures were packed to a height of 7 cm and sintered at 850 ° C. for 20 hours and oxygen was supplied at a surface speed of 1 m / min. Prior to packing, the mixture was shaped by die forming at a pressure of 1 ton / cm 2 into cylinders of 5 mmΦ and 15 mmH. In this case, BN (boron nitride), which acts as both a release agent and a dopant element, was added in an amount such that the atomic number ratio of Li: (Ni + M): B would be 1.03: 1: 0.01.

850 ℃ X 20 hours Φ50 X 70H 1m / min Ni 0.85Co 0.1Mn 0.05Li 1B 0.01 Ni 0.85Co 0.1Al 0.01Li 1B 0.01 Ni 0.87Co 0.1Mg 0.02Li 1B 0.01 Active material Median diameter, (D ₅₀ ) 10.7 13.4 10.2 Particle appearance Primary 2nd (1st 6.4) Primary R 1.8 2.7 3.4 Initial Capacity, mAh / g 172 178 162 % Degradation after 15 cycles 8 10 7

Example 4

Coprecipitated hydroxides were prepared from Ni and Co at a ratio such that the atomic number ratio of Ni to Co was 0.85: 0.15. This hydroxide was weighed and mixed in an amount such that the atomic number ratio of lithium hydroxide and Li to Ni + Co was 1: 1. The powder mixture was then shaped into a nearly spherical shape (5 mmΦ) on a tablet press, packed into a cylinder (50 mmΦ x 750 mmH) and sintered at 700 ° C. for 15 hours. Oxygen gas was supplied at the surface velocities described in Tables 6, 7, and 8.

Upon sintering at temperatures around 700 ° C., the median diameter of the sinter was determined by the median diameter of those in the 80-95% range of the starting coprecipitation hydroxides.

The distribution of the median diameter and specific surface area of the sinter in the reaction vessel is such that the values in the various parts of the vessel are within ± 6% of each average; Thus, in each run, the sinter taken as a whole was ground and sampled for the determination of median diameter, specific surface area, initial capacity and capacity drop after 15 cycles.

The median diameter and tasine density of the three nickel hydroxide powders were controlled by performing the synthesis under the conditions described below.

Median diameter, ㎛ Percent Density, g / ㏄ pH Temperature, ℃ α: β Etc 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 1% ammonia added

Median diameter of hydroxide = 22.5 μm Surface speed of air, m / min 0 0.5 15 50 100 D ₅₀ , μm 21.2 20.3 19.7 18.9 18.2 D _S , μm 14.3 8.2 4.7 3.4 2.8 R (= D ₅₀ / D _S ) 1.48 2.47 4.19 5.55 6.5 Initial Capacity, mAh / g 133 168 183 189 190 Capacity drop after 15 cycles, mAh / g 19 11 9 13 22

Median diameter of hydroxide = 7 μm Surface speed of air, m / min 0 0.5 10 30 50 D ₅₀ , μm 6.8 6.6 6.3 5.9 5.7 D _S , μm 5.2 4.2 1.96 1.2 0.92 R (= D ₅₀ / D _S ) 1.3 1.57 3.21 4.9 6.2 Initial Capacity, mAh / g 121 157 168 172 176 Capacity drop after 15 cycles, mAh / g 24 17 12 15 21

Median diameter of hydroxide = 35 μm Surface speed of air, m / min 0 0.5 30 150 200 D ₅₀ , μm 31.0 29.5 28.6 28.1 27.3 D _S , μm 21.9 14.9 7.3 5.8 4.2 R (= D ₅₀ / D _S ) 1.41 1.98 3.91 4.84 6.51 Initial Capacity, mAh / g 89 152 162 166 172 Capacity drop after 15 cycles, mAh / g 20 16 8 11 24

In each case described above, the sintered powder after disintegration consists of secondary particles having a specific surface area of about 0.09 m ² / g, which means if the powder has primary particles having a size of about 0.2 μm It is assumed that it has a value of 6 m ² / g uniquely. Thus, the median diameter of the powder represents the mean value for the secondary particles. The sintering reaction did not proceed properly at very low surface velocities and the unreacted Li compound formed a liquid film on the surface of the particles to cover the granular region, which probably prevented gas adsorption in the surface area measurement by the BET method. .

The sintering reaction was allowed to proceed by increasing the surface velocity above 0.5 m / min and unreacted Li compounds were formed in small amounts and thus an improvement in both initial capacity and cycle characteristics was achieved. On the other hand, if the surface velocity is excessively high, the sintering will proceed between or within the secondary particles, causing microcracks and the liquid electrolyte decomposes on the fractured surface, thereby degrading the cycle characteristics. Therefore, the surface speed is preferably controlled so as not to exceed 250 m / min.

The stage coherence between the specific surface area and the size of the primary particles can be explained for another reason: the primary particles have granular regions recognizable under microscopic observations, but perhaps due to the strong sintering that occurs between them , The gas used in the measurement by the BET method will not be adsorbed on the primary particles. In addition, it is not denied that trace amounts of the Li compound present cover the granular region of the primary particles.

Example 5

Powders of nickel hydroxide (titanium density 1.15 g / dl, α-phase to β-phase ratio of about 1: 1), tricobalt tetraoxide (Co ₃ O ₄ ) and lithium hydroxide (LiOH) were subjected to atomic number between Ni, Co and Li Weighed at a rate such that the ratio was 0.75: 0.25: 1. Each powder was mixed in the presence of IPA (isopropyl alcohol) for 30 minutes while cooling with water in an alumina pot. The mixture is filtered and heated to evaporate IPA; The residue was shaped into a cylinder (4 mmΦ X 6 mmH) with a tablet machine. The shaped portion (cylinders) was then placed in the reaction vessel and sintered at 925 ° C. for 15 hours. The distribution of the median diameter and specific surface area of the sinter in the reaction vessel was such that the values in the various parts of the vessel were within ± 4% of each average; Thus, in each run, the sinter taken as a whole was disintegrated and sampled for the measurement of median diameter, specific surface area, initial capacity, and capacity drop after 15 cycles. The median diameter of each production lot of sinter was controlled by varying the forming pressure after repeated trial and error.

Measurements were performed on median diameters of various classes of sintered products: 15 μm (forming pressure 700 kg / cm 2; product density 1.4 g / dl); 5 μm (forming pressure 150 kg / cm 2; product density 1.2 g / dl); 25 μm (forming pressure 1.6 ton / cm 2; product density 2.3 g / dl). The measurement results are shown in Tables 9a and 9b.

Median diameter of sintered material of about 15 μm (forming pressure 700 kg / cm 2; product density 1.4 g / kPa) Surface speed of air, m / min 0 0.5 20 70 150 200 D ₅₀ , μm 18.3 17.2 15.5 14.7 13.6 10.6 D _S , μm 13.5 8.19 4.8 3.9 2.77 1.65 R (= D ₅₀ / D _S ) 1.35 2.2 3.22 3.77 4.9 6.4 Initial Capacity, mAh / g 125 160 167 169 171 173 Capacity drop after 15 cycles, mAh / g 22 17 4 7 16 24

Median diameter of sintered material of about 5 μm or 25 μm Surface speed of air, m / min 5 2 D ₅₀ , μm 5.4 26.7 D _S , μm 1.45 8.34 R (= D ₅₀ / D _S ) 3.7 3.2 Initial Capacity, mAh / g 178 164 Capacity drop after 15 cycles, mAh / g 8 3

In Example 5, all of the sintered samples had an appearance resembling primary particles, except for one with a median diameter of 15 μm made at a surface air velocity of 250 m / min. Therefore, the specific surface area diameter had to be substantially equal to the median diameter, so R was assumed to be close to one. In practice, however, appropriate R values ranged from 2.1-4.9. No definite reason for explaining this phenomenon can be derived.

Example 6

The hydroxides of Ni, Co, Al, Mg, and Li were mixed at a ratio such that the atomic number ratio between the elements was 0.90: 0.08: 0.05: 0.01: 1. Two of these mixtures were shaped into rectangular parallelepipeds (6 × 6 × 15 mm) at a pressure of 500 kg / cm 2 and sintered at 830 ° C. under oxygen for two hours under two different conditions. Nickel hydroxide had a tasine density of 1.27 g / dL and a ratio of α- to β-phase of 7: 3, and cobalt hydroxide had a tasine density of 0.95 g / dL.

Condition 1 Condition 2 Packing bed height About 350 mm (50 mm Φ) About 50 mm (50 mm Φ) Surface speed 4 m / min 0.2 m / min Active material Median diameter 5.2 0.7 Particle appearance Secondary Secondary R 3.46 3.81 Initial Capacity, mAh / g 159 172 Capacity drop after 15 cycles, mAh / g 6 9

Example 7

Co-precipitated hydroxides (atomic number ratio Ni: Co = 0.8: 0.2; perine density = 0.76; ratio of α-phase to β-phase = 4: 6), complex oxides (B ₂ O ₃ · Al ₂ O ₃ ) and hydroxide Powders of lithium were mixed at a ratio such that the atomic number ratio of (Ni + Co), (B + Al) and Li was 0.97: 0.03: 1. The mixture was shaped into its shapes and sintered at 850 ° C. for 24 hours, feeding oxygen at a pressure of 7 kg / cm 2 and a surface speed of 3 m / min; As a result, an active material was prepared, with an R value of 4.3 (D ₅₀ / D _s = 11.7 μm / 2.72 μm) and an initial capacity of 168 mAh / g, which was reduced by 3 mAh / g after 15 cycles.

Example 8

Lithium hydroxide (LiOH.H ₂ O) powder as a Li source and co-precipitated hydroxide powder as a transition metal source (sine density 0.96 ㏄ / g, ratio of α-to β-phase = 3: 7, atomic number ratio Ni to Co 85:15) was weighed at a ratio such that the ratio of Li to (Ni + Co) was 1: 1, and the two powders were mixed. The mixed powders were then shaped into a nearly spherical shape (5 mmΦ) and packed on a nickel oxide porous plate at the bottom of the metal nickel reaction vessel at a weight of about 2 kg; The packing height was 7.5 cm.

The packed spheres were sintered at 750 ° C. for 10 hours, and oxygen was supplied at a flow rate (L / min) calculated as the surface velocity multiplied by the cross sectional area. After sintering, the parts of the sinter were sampled from positions A, E and I of the bed packed into the shape parts (see FIG. 3), and each sampled site was broken into particles of -150 mesh. The results are shown in Table 11.

Initial Capacity (mAh / g) and Decrease After 15 Cycles Sampling location Average surface speed, m / min 0.3 0.5 5 30 A 131-21 160-13 172-11 183-9 E 147-17 174-10 186-5 191-5 I 109-16 153-9 169-6 182-5

Within each sample frequency, the difference in initial capacity ranged from ± 4% to ± 7% on average at surface speeds of 0.5 m / min and higher. Any improvement was achieved at 0.3 m / min, but the battery characteristics were not satisfactory; Therefore, the surface velocity should be at least 0.5 m / min.

At the end of the sintering, the packing height of the shaped parts was lowered to about 5 cm; However, the level difference between the bed tops was within 5 mm and the sintered shapes remained spherical. There were no abnormal events such as sinking the top of the bed due to the channeling of the oxygen supplied just below the vent. The inner surface of the nickel container turned slightly black, but no debris or sticking occurred. Several parts of each production lot were examined by powder X-ray diffraction and no foreign matter or secondary phase was detected. The maximum clearance between the inner lateral surface and the shaped portions of the nickel container was 2 mm at position G.

Example 9

In order to provide pressurization of the sintering atmosphere, a sintering furnace was installed in a pressure vessel, and after evacuating the air atmosphere with a vacuum pump, oxygen was supplied to set a specific internal pressure. In addition to these modifications, the experiment was performed under the same conditions as in Example 1, including the reaction vessel, the shape portions, and their packing. Oxygen was fed at the main pressure set to a value higher than the internal pressure to give an average surface velocity of 5 m / min. In this case the velocity was not the value actually measured for the pressurized oxygen, but the flow through the flow regulator (L / min) divided by the cross-sectional area of the vessel. The oxygen supplied was not circulated but simply released into the air atmosphere.

The sintering operation was performed with a furnace internal pressure (kg / cm 2 gauge) variable at 0.5 to 15 kg / cm 2 for 10 hours at 750 ° C., using the obtained samples to prepare a coin-type cell for evaluation of cell capacity. . The results are shown in Table 12.

Initial Capacity (mAh / g) and Decrease After 15 Cycles Sampling location Furnace withstand pressure, kg / ㎠ gauge 0.5 2 5 15 A 174-9 183-7 190-5 196-4 E 189-8 191-6 195-4 203-3 I 172-6 179-5 187-5 195-4

The same test was performed by changing the sintering conditions to 900 ° C. × 10 hours. The results are shown in Table 13.

Initial Capacity (mAh / g) and Decrease After 15 Cycles Sampling location Furnace withstand pressure, kg / ㎠ gauge 0.5 2 5 15 A 169-9 174-8 182-4 188-4 E 172-7 179-7 185-5 191-4 I 170-8 180-7 187-4 190-3

Even when sintering was carried out under pressurized conditions, the result was the same as in Example 1. The inner surface of the nickel container was completely covered with a black skin but no difficulties such as debris or cracks occurred. Within each sample frequency, the difference in initial capacity was in the range of ± 4 to ± 6%.

Example 10

In Examples 8 and 9, samples taken in the upper region of the packed bed of the shaped portion were rather low in cycle characteristics. In order to cope with this situation, a lower sintering furnace 8 of the type described in FIG. 2 was used to allow oxidizing gas to be fed from the top of the sintering furnace 8 and passed through the packing bed 6 and the porous plate 5 to the air atmosphere. To prevent gas leakage, the joints and other leaking sites of the sintering furnace were sealed; When sintering was to be performed under pressure, a sintering furnace was installed in the same pressurized vessel as in Example 9.

Sintering temperatures (720 ° C. and 875 ° C.) are used; The sintering time was fixed at 10 hours. The evaluation results of the initial capacity and the capacity drop after 15 cycles are shown in Table 14.

Initial Capacity (mAh / g) and Decrease After 15 Cycles Sintering temperature, ℃ 720 875 Furnace Withstand Pressure, ㎏ / ㎠ 0.1 3 7.5 5 Average surface speed, m / min 10 7 5 10 Sample Collection Location A 173-6 186-4 194-3 197-3 E 188-5 192-4 205-3 198-3 I 177-7 187-6 197-4 195-4

Example 11

Lithium containing a composite oxide of Ni and Co is currently used as a positive electrode material in lithium secondary batteries. In Example 11, a combination of nickel and other elements other than cobalt was selected, for example, by employing combinations of nickel hydroxide / manganese hydroxide, nickel hydroxide / manganese hydroxide, and nickel hydroxide / tricobalt tetrahydrate / boron oxide. Shaped portions of these starting materials were sintered at various temperatures, times, internal pressures and surface velocities (see Table 15); Coin-type cells were prepared using the obtained samples and subjected to an evaluation for initial capacity and capacity reduction after 15 cycles. The results are shown in Table 15.

Initial Capacity (mAh / g) and Decrease After 15 Cycles Composition of starting material, mol% Ni Mn95 5 Ni Mg98 2 Ni Co B79 20 1 Sintering Temperature (℃) and Time (h) 800X10 750x5 850 X 15 Furnace Withstand Pressure (kg㎠) and Average Surface Speed (m / min) 0.5X3 2.5X1.5 7X5 Sample Collection Location A 157-11 168-12 183-6 E 160-8 172-9 190-4 I 153-8 167-11 179-4

Example 12

In Examples 8-11, spherical bodies having a diameter of 5 mm were sintered. In Example 12, the shaped parts to be sintered were transformed into small pieces of size 5 mm X 20 mm X 1 mm or strands extruded into a diameter of 4 mm formed by a roll briquette. These parts were sintered using the same composition and equipment as in Example 1, but the average surface speed was 3 m / min and the sintering temperature and time were 750 ° C. and 7 hours, respectively. Using the sintered samples, the cells were prepared and evaluated for initial capacity and capacity drop after 15 cycles. The results are shown in Table 16.

Initial Capacity (mAh / g) and Decrease After 15 Cycles Shaped part Intestinal tooth size and geometry Roll Briquette 5mm ^W X20mm ^L X1mm ^T Extruder 4 mm ^Φ strand Sample Collection Location A 167-11 170-8 E 179-8 176-7 I 162-9 168-7

Example 13

When Ni is used as the base transition metal, oxygen is fed into the bed suitably packed into the shape portions of the starting powder mixture; However, in some cases, species other than oxygen may be included in the gas to be supplied. To test this case, Ni and Co were co-precipitated at a molar ratio of 70:30 to form a hydroxide powder, which was mixed with a powder of LiOH.H ₂ O, followed by a shaped portion (10 mmΦ X 5 mmT). Press formed and sintered at 700 ℃ for 15 hours. Air was fed into the bed of shaped portions at a surface speed of 10 m / min using an air pump. Using the sintered samples, the cells were prepared and measurements were taken for initial capacity and capacity drop after 15 cycles. The results are shown in Table 17.

Initial capacity and capacity degradation after 15 cycles Sampling location A 162-5 E 166-4 I 159-5

Example 14

The procedure of Example 8 was repeated but the size of the sintering furnace was increased to check for expression of increased variation in cell characteristics.

Condition 1 condition 2

Sintering furnace diameter 1000 mm 500 mm

Packing height 200 mm 600 mm

Surface speed 5 m / min 25 m / min

Sampling position A 176-10 180-11

B 184-7 187-7

C 171-9 184-9

Clearly, cell characteristics comparable to that of Example 8 were reproduced without any substantial variation in the various locations of the sintering furnace. Thus, it is evident that the method of the present invention enables the production of the desired active material on an industrially scaled scale, without being compromised by unwanted variations in battery characteristics that would otherwise occur in the prior art.

As described in the previous section, the present invention provides a lithium-nickel based composite oxide as a positive electrode active material by mixing nickel hydroxide powder with a powder of a lithium compound, forming the mixed powder into a shape portion and sintering the formed portion. It provides a way to; In order to control the powder properties of the nickel hydroxide used as starting material and its crystal structure, this method uses the pH, temperature and other process coefficients for the synthesis of nickel hydroxide in the range of 5-30 μm in average diameter and in the range of 1.5-6. And adjust to obtain an active material powder having a D ₅₀ / D _S ratio R; Thus, the method of the present invention provides a positive electrode active material having excellent cell properties exemplified by high initial capacity and small capacity drop after 15 cycles.

In another aspect of the present invention, the mixed powder of starting material is shaped as a densely increased shape and the bed packed as part of the shape is an oxygen-containing gas that is forced through the bed at a higher flow rate than a certain value. Sintered; Thus, even when an increased amount of powder has to be sintered, a homogeneous reaction can occur without scattering of the powder and channeling of the oxygen-containing gas in all parts of the reaction vessel, thereby providing an excellent It is ensured that lithium composite oxides having battery characteristics can be advantageously synthesized on an industrial scale as a positive electrode active material.

Claims (13)

Co-precipitates of hydroxides of nickel or nickel with at least one other element are as follows: The reaction vessel is continuously or intermittently supplied with an aqueous solution of alkali and metal salts and the reaction is carried out at a pH of 6.5-11 and at a temperature of 90 ° C. or less, and the slurry of the reaction product in the liquid is continuously recovered from the reaction vessel or Part of the slurry is recovered intermittently; Separating the solid reaction product in the slurry state from the liquid component to form a cake or paste; And A method of producing a starting material for synthesizing a positive electrode active material for a non-aqueous secondary battery, comprising the step of washing the cake or paste to remove unwanted components. Any one of a hydroxide of nickel or a co-precipitate of nickel and at least one other element, having a crystal phase composed of at least one alpha- and beta-phase nickel hydroxide, and having a percussion density of 0.6-1.4 g / ㏄, Starting material for synthesizing a positive electrode active material for a non-aqueous secondary battery. Any one of a hydroxide of nickel or a co-precipitate of nickel and at least one other element, having a crystal phase composed of at least one alpha- and beta-phase nickel hydroxide, and having a percussion density of 0.6-1.4 g / ㏄, In the starting material for synthesizing the positive electrode active material for a non-aqueous secondary battery, the starting material is: The reaction vessel is continuously or intermittently supplied with an aqueous solution of alkali and metal salts and the reaction is carried out at a pH of 6.5-11 and at a temperature of 90 ° C. or less, and the slurry of the reaction product in the liquid is continuously recovered from the reaction vessel or Part of the slurry is recovered intermittently; Separating the solid reaction product in the slurry state from the liquid component to form a cake or paste; And A method of preparing a starting material for synthesizing a positive electrode active material for a non-aqueous secondary battery, which is prepared by washing a cake or a paste to remove unwanted components. A mixed powder of a lithium compound and a transition metal based compound or a coprecipitate of a lithium compound and a transition metal based compound, or the above-mentioned mixed powders and the aforementioned coprecipitate or a coprecipitation based on lithium and at least one transition metal Forming any one of the mixtures of these mixtures and sintering the shaped portions, and the oxidizing gas is passed through a bed packed with the shaped portions. 5. The method of claim 4, wherein the shaped portions are sintered with an oxidizing gas that is forced through the bed of the shaped portion under such conditions that the atmosphere in the bed is pressurized. 6. The method according to claim 4 or 5, wherein only at least the inner region of the reaction vessel to be brought into contact with the packed shape portions in the above-described reaction vessel is made of metal nickel, high nickel alloy, nickel compound or a combination of at least two of the three materials described above. The composite material described above, or made of metal nickel or high nickel alloy having an oxide film formed on its surface or otherwise, or made of a composite material comprising a metal nickel or high nickel alloy and a nickel compound, Silver has an oxide film formed on the surface, The manufacturing method of the positive electrode active material characterized by the above-mentioned. Li _a Ni _b M _c O _d (wherein 0.95 ≦ a ≦ 1.05; b + c = 1; 0c0.4; d ≒ 2; M is Co, Mn, Fe, V, Ti, Al, Sn, Zn, Cu , In, Ga, Si, Ge, Sb, B, P, K, Na, Mg, Ca, Ba, Sr, W, Mo, Nb, Ta, Y, and lanthanum-based elements) Having a chemical composition represented by, and having an average diameter (D ₅₀ ) of 5-30 μm, R = D ₅₀ / D _S [D _S is the specific gravity of ρ (g / cm ³ ) measured by the peak nom and S ( m ² / g) is the specific surface area diameter given by the formula D _S = 6 / ρ · S when the BET specific surface area is in the range of 1.5-6, positive electrode active material for use in non-aqueous secondary batteries. 8. The positive electrode active material of claim 7, wherein the positive electrode active material has an initial capacity of 150 mAh / g and experiences a capacity drop of 18 mAh / g or less after 15 cycles. The powder raw material is mixed with the lithium compound powder to obtain a mixed powder, wherein the above-described powder raw material is either a hydroxide of nickel or a co-precipitate of nickel with at least one other element, and the crystalline phase is at least one alpha- and Consisting of beta-phase nickel hydroxide, which has a tasine density of 0.6-1.4 g / ㏄, The resulting mixed powder is shaped into shape parts, Packing the reactor with the above-described shaped parts to provide a packed bed thereof in the reactor, Sintering the shaped portion with an oxidizing gas passing through the packed bed, thereby obtaining a sintered product of the raw material, and Disintegrating the sintered product into a final powder material which is a positive electrode active material for use in a non-aqueous secondary battery, The positive electrode active material for use in the aforementioned non-aqueous secondary battery is Li _a Ni _b M _c O _d (wherein 0.95 ≦ a ≦ 1.05; b + c = 1; 0c0.4; d ≒ 2; M is Co, Mn, Fe, V, Ti, Al, Sn, Zn, Cu, In, Ga, Si, Ge, Sb, B, P, K, Na, Mg, Ca, Ba, Sr, W, Mo, Nb, Ta, Y and Has a chemical composition represented by at least one element selected from the group consisting of lanthanides, and has an average diameter (D ₅₀ ) of 5-30 μm and R = D ₅₀ / D _S [D _S is ρ (g / cm ³ ) is the specific gravity measured by the peak nom and S (m ² / g) is the specific surface area given by the formula D _S = 6 / ρ · S when S (m ² / g) is the BET specific surface area]. Method for producing a positive electrode active material for a secondary battery. 10. The non-aqueous secondary battery of claim 9, wherein the non-aqueous secondary battery produced using the final powder material described above has an initial capacity of at least 150 mAh / g and experiences a capacity drop of 18 mAh / g or less after 15 cycles. Method for producing a positive electrode active material for batteries. The method of claim 9 or 10, wherein the aforementioned powder raw material is: The reaction vessel is continuously or intermittently supplied with an aqueous solution of alkali and metal salts and the reaction is carried out at a pH of 6.5-11 and at a temperature of 90 ° C. or less, and the slurry of the reaction product in the liquid is continuously recovered from the reaction vessel or Part of the slurry is recovered intermittently; Separating the solid reaction product in the slurry state from the liquid component to form a cake or paste; And A method of manufacturing a positive electrode active material for a non-aqueous secondary battery, which is prepared by washing a cake or a paste to remove unwanted components. The method according to claim 9 or 10, wherein the aforementioned shaped portions are sintered with an oxidizing gas that is forced through the bed of shaped portions under such conditions that the atmosphere in the bed is pressurized. The method according to claim 9 or 10, wherein only at least an inner region of the reaction vessel to be brought into contact with the packed shape portions in the above-described reaction vessel is made of metal nickel, high nickel alloy, nickel compound or a combination of at least two of the three materials described above. The composite material described above, or made of metal nickel or high nickel alloy having an oxide film formed on its surface or otherwise, or made of a composite material comprising a metal nickel or high nickel alloy and a nickel compound, The manufacturing method of the positive electrode active material for nonaqueous secondary batteries which has an oxide film formed on the surface.