KR101183748B1 - Method for Preparing Single phase lithium metal oxides - Google Patents

Abstract

The present invention relates to a single-phase lithium metal oxide and a method for manufacturing the same, (a) adding a lithium compound and an alkalizing agent to an aqueous solution of at least one metal compound selected from nickel compounds, manganese compounds, and cobalt compounds at a pH of 10 or more. Precipitating the metal hydroxide to obtain a precipitate mixture; (b) reacting the precipitate mixture by adding water heated to a temperature of 200 to 700 ° C. under a pressure of 180 to 550 bar.

Metal hydroxide, alkalizing agent, ammonia water, continuous mixer, single phase, lithium cobalt acid, lithium manganate, lithium metal oxide, positive electrode active material, lithium ion battery

Description

Method for preparing single phase lithium metal oxides

1 is (a) FESEM image (10,000 times magnification), (b) XRD image of LiCoO ₂ synthesized by Example 1 of the present invention.

Figure 2 is a (a) FESEM image (20,000 times magnification), (b) XRD image of the cobalt oxide synthesized by Comparative Example 1 of the present invention.

3 is (a) FESEM image (10,000 times magnification), (b) XRD image of LiMn ₂ O ₄ synthesized by Example 6 of the present invention.

4 is (a) FESEM image (30,000-fold magnification) and (b) XRD image of manganese oxide synthesized by Comparative Example 6 of the present invention.

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a single phase lithium metal oxide and a method of manufacturing the same. More specifically, a single phase lithium metal oxide and a method of manufacturing the same can be used as a cathode active material such as a lithium ion battery or a lithium ion polymer battery. It is about.

Recently, as the mobility and portability of electric and electronic devices increase, the demand for secondary batteries has increased dramatically. Lithium secondary battery, which was produced industrially by Sony Japan in the early 1990s, has a light and high capacity advantage compared to conventional Ni-Cd and Ni-MH batteries, and occupies most of the mobile phone and notebook computer markets. Recently, the market is rapidly expanding to high power medium and large batteries such as electric tools, electric bicycles, electric scooters, game machines, wireless cleaners, service robots, and hybrid cars. Lithium ion secondary batteries use lithium cobalt oxide (LiCoO ₂ ) as a positive electrode active material, carbon as a negative electrode active material, and lithium hexafluorophosphate (LiPF ₆ ) as an electrolyte. As the demand for large capacity and high output increases and the amount of usage increases, new materials having high performance and low cost and a manufacturing method thereof are required.

Lithium cobalt oxide (LiCoO ₂ ), lithium nickelate (LiNiO ₂ ) and lithium manganate (LiMn ₂ O ₄ ) having a spinel structure are known as the positive electrode active material. Mostly. However, as the supply and demand of cobalt, a main component metal of lithium cobalt acid, is unstable and the price increases, a material in which cobalt is partially substituted with other transition metals such as Ni and Mn, or spinel-structure lithium manganate containing almost no cobalt It began to be used commercially. New compounds that are more structurally stable at high voltages or materials that improve stability by doping or coating other metal oxides on existing cathode active materials are also being developed.

The most widely known methods for preparing a positive electrode active material include a dry firing method and a wet precipitation method. Dry firing is a method of preparing a positive electrode active material by mixing a transition metal oxide such as cobalt (Co), hydroxide and lithium source lithium carbonate or lithium hydroxide in a dry state and firing at a high temperature of 700 to 1000 for 5 hours to 48 hours. . This dry firing method is a technique that has been used traditionally for the production of metal oxides, so it is easy to access, but it is difficult to homogeneously mix raw materials, it is difficult to obtain a single phase product, and in the case of a positive electrode active material composed of two or more transition metals It is difficult to homogeneously arrange two or more kinds of elements at the atomic level. The wet precipitation method dissolves salts of transition metals such as cobalt (Co) in water, adds alkalis such as sodium hydroxide, and precipitates them in the form of hydroxides of transition metals mainly by neutralization reaction, and precipitates are filtered and dried again. It is a method of manufacturing a positive electrode active material by mixing lithium carbonate or lithium hydroxide as a lithium source in a dry state and firing at a high temperature of 700 to 1000 ° C for 5 to 48 hours. The wet precipitation method is known to be easy to obtain a homogeneous mixture by coprecipitating two or more transition metal elements, but there are problems such as a long time required for the precipitation reaction, a complicated process, and waste acid.

In addition, various methods such as sol-gel method, hydrothermal method, spray pyrolysis method, and ion exchange method are proposed as a method of preparing a positive electrode active material for lithium secondary batteries.

Recently, a method of manufacturing LiCoO ₂ , LiMn ₂ O ₄ particles, etc. using supercritical water has been published (K. Kanamura, et al., Key Engineering Materials, 181-162 (2000), pp.147-150). .

Japanese Laid-Open Patent Publication No. 2000-72445A discloses a method for producing a metal oxide for a positive electrode active material by reacting lithium ions and transition metal ions in a supercritical or subcritical state in a batch type reactor, and 2001-163700 in a batch and continuous reactor. have. In the case of batch type, it is disclosed that the higher the Li / Co ratio, the higher the alkali molar ratio, the higher the nitric acid concentration, the higher the oxidizing agent, the lower the content of Co ₃ O ₄ as impurities and the LiCoO ₂ content of single phase is increased. However, the obtained particles have a purity of only 97.8% of the LiCoO ₂ crystal phase, which is not suitable for practical use as a positive electrode active material. In the case of the continuous type, the cobalt salt solution or the manganese salt solution and the lithium hydroxide solution are continuously pumped under pressure to synthesize supercritical water and hydrogen peroxide (H ₂ O ₂ ) at about 400 ° C. and 300 bar. Although the reaction time is short within 30 seconds, it is known that the synthetic product is not a single phase and various phases of metal oxides are mixed, resulting in poor purity and poor electrochemical properties.

As can be seen from the above review of the prior art, as a demand for a large capacity and a high output of a lithium ion secondary battery increases and the amount of usage increases, a new high-performance, low-cost new cathode active material and a method of manufacturing the same are required. Most commonly used commercially available materials such as cobalt partially substituted with other transition metals such as nickel or manganese, or cobalt, are rarely included as supply and demand of cobalt, a main component metal of lithium cobalt oxide, a cathode active material, is unstable and the price is rising. Spinel structure lithium manganate and the like have begun to be used commercially. New compounds that are more structurally stable at high voltages or materials that improve stability by doping or coating other metal oxides on existing cathode active materials are also being developed. However, the dry firing method, which is a method of preparing a positive electrode active material, is difficult to homogeneously mix raw materials, and it is difficult to obtain a single phase product. Another conventional method, the wet precipitation method, requires a long time for the precipitation reaction, and the process is complicated. There are problems such as generation of waste acid. The conventional supercritical hydrothermal method requires an expensive oxidizer, and there is a problem in that the lithium metal oxide produced is not a single phase but is mixed with various phases, and thus is practically difficult to use. Therefore, it is necessary to develop a manufacturing process capable of easily and economically manufacturing a lithium cobalate as well as a material in which cobalt is substituted with another transition metal or a cathode active material containing no cobalt at all in a single phase.

Accordingly, the present inventors have diligently studied to solve the above problems, and as a result, precipitate the metal hydroxide in the condition of pH 10 or more, and react the precipitate mixture with lithium using subcritical or supercritical water, By continuously synthesizing a single phase lithium metal oxide rather than a mixed phase, it has come to create a technology capable of producing a large amount of a positive electrode active material exhibiting excellent physical properties.

An object of the present invention is to provide a single phase metal oxide that can be used as anodization material, such as a lithium ion secondary battery or a lithium ion polymer battery, and a method of manufacturing the same.

Method for producing a single-phase lithium metal oxide according to the present invention for achieving the above object:

(a) adding a lithium compound and an alkalizing agent to an aqueous solution of at least one metal compound selected from nickel compounds, manganese compounds, and cobalt compounds to precipitate metal hydroxides under a pH of 10 or more to obtain a precipitate mixture solution;

(b) reacting the precipitate mixture by adding water heated to a temperature of 200 to 700 ° C. under a pressure of 180 to 550 bar;

Characterized in that it comprises a.

Preferably, the alkalizing agent is selected from the group consisting of alkali metal hydroxides, alkaline earth metal hydroxides and ammonia compounds.

Preferably, the metal compound is a metal nitrate, the alkalizing agent is characterized in that ammonia water.

Preferably, the lithium compound is characterized in that the lithium hydroxide, lithium nitrate or a mixture thereof.

Preferably, the step (a) and step (b) is characterized in that it is carried out in a continuous mixer.

Preferably, the alcohol of 1 to 10 carbon atoms is further added in step (a).

Preferably, a dopant or a coating agent is further added before or after step (a), step (b), or after.

Preferably, further comprising the step of cooling, concentrating and drying the mixture of the lithium metal oxide obtained in step (b).

In order to achieve the above object, a single phase lithium metal oxide according to the present invention is prepared by the above method, and is represented by the following Chemical Formula 1 or Chemical Formula 2.

Li _{1 + a} [Ni _x Mn _y Co _z ] O ₂

(In Formula 1, the ranges of a, x, y, z are -0.1≤a≤ + 0.1, 0≤x≤1, 0≤y≤1, and 0≤z≤1, respectively.)

LiMn ₂ O ₄

Preferably, the average particle size of the single-phase lithium metal oxide is characterized in that 0.1 to 50㎛.

The present invention also includes using the single-phase lithium metal oxide for the positive electrode active material of a lithium ion battery.

Here, the lithium ion battery includes a positive electrode including a single phase lithium metal oxide as a positive electrode active material; A negative electrode including a negative electrode active material; And an electrolyte impregnated in the positive electrode and the negative electrode.

Hereinafter, the present invention will be described in more detail.

The metal compound used in the present invention is at least one selected from nickel compounds, manganese compounds and cobalt compounds. The nickel compound, manganese compound, and cobalt compound are preferably water-soluble, and nitrates, sulfates, acetates, and the like can all be used. The nickel compound, manganese compound, and cobalt compound may be used alone or in combination of one or more of nickel-manganese, nickel-cobalt, nickel-manganese-cobalt, and the like.

According to the present invention, the alkalizing agent renders the reaction solution alkaline, providing conditions that allow nickel, manganese, and cobalt compounds to be hydrolyzed and precipitated as hydroxides, and impurity (e.g., cobalt) in the final product lithium metal oxide. When the compound is used to reduce the content of Co ₃ O ₄ , CoO, etc.). Alkali metal hydroxides (NaOH, KOH, etc.), alkaline earth metal hydroxides (Ca (OH) ₂ , Mg (OH) _2, etc.), ammonia compounds (ammonia water, ammonium nitrate, etc.) can all be used. In particular, when the metal compound is a nitrate, when an alkalizing agent is used as an ammonia compound, most of the nitrate ions generated as by-products can be decomposed in the same process, and the remaining ions are easily removed by washing, drying or firing in the post-synthesis process. Because it is most suitable. Furthermore, ammonia ions may form a complex with the ions of the metal to serve to assist the hydrolysis reaction. The amount of alkalizer is suitable such that the pH can be 10 or more after mixing.

According to the present invention, the lithium compound may be both lithium hydroxide, lithium nitrate and the like. In particular, lithium hydroxide is most suitable because it plays a role of increasing alkalinity as well as a lithium source.

The water, the alkalizing agent and the lithium compound may be mixed all at once, or the water and the alkalizing agent may be mixed and then mixed with the lithium compound, or the alkalizing agent and the lithium compound may be mixed first and then mixed with water. When mixing, the temperature and pressure should be avoided subcritical or supercritical conditions to prevent the precipitation of lithium compounds, and after mixing, the transition metal hydroxide precipitates into fine particles, and the lithium hydroxide is dissolved in an aqueous solution.

The mixing pressure is not particularly limited but is preferably atmospheric pressure. The mixing temperature should be less than or equal to the temperature at which the precipitated hydroxide dehydrates and begins to become an oxide. The temperature at which the precipitated hydroxide dehydrates and begins to form oxides is usually below 200 ° C, depending on the type of metal.

The pH of the aqueous solution after mixing and before encountering supercritical water or subcritical water is 10 or more, preferably 10 to 13. When the pH is less than 10, various impurities (eg, Co ₃ O ₄ , CoO, etc. when using cobalt compounds, Mn ₂ O ₃ , Mn ₃ O ₄ , λ-MnO, etc.) are present in the final product lithium metal oxide. Done. In the present invention, the upper limit of the pH is not limited, but when the pH is excessively high, the neutralization cost of the discharged liquid is increased.

The reaction pressure and temperature should have a temperature and pressure suitable to react the metal hydroxide precipitate produced in step (a) with lithium ions in aqueous solution or to precipitate lithium ions in aqueous solution into hydroxide. Therefore, according to the invention, the reaction temperature in step (b) is suitably between 200 and 700 ° C. If the temperature is lower than 200 ° C, it is unsuitable for obtaining a single phase lithium metal oxide, and if the temperature is higher than 700 ° C, the material cost of the manufacturing apparatus increases.

Alkali metal hydroxides such as lithium, sodium, and potassium have high solubility in water at room temperature and normal pressure, but when the density of water decreases due to high temperature and high pressure, solubility decreases significantly. For example, in the case of KOH, the solubility is 2.6 mol (14.58 wt%) at room temperature and density of 1.0 g / cc, but decreases to 0.1 mol (0.561 wt%) at 400 ° C. and 0.3 g / cc (WT Wofford, PC Dell 'Orco and EF Gloyna, J. Chem. Eng. Data, 1998, 43, 162-170). In the case of LiOH, it is necessary to maintain a pressure of 180 to 550 bar and a temperature of 200 to 700 ° C. together to significantly reduce the solubility. The reaction temperature should be a temperature suitable for the reaction of the metal hydroxide precipitate obtained in step (a) with the lithium ion or LiOH precipitate to form a single phase lithium metal oxide crystal.

In order to further reduce the solubility of LiOH in the supercritical water, alcohols having 1 to 10 carbon atoms may be added, and preferably methanol, ethanol, propanol, or the like may be added.

Here, the mixing and reaction are suitably carried out in a continuous mixer, such as in the form of a tube. The instantaneous mixing of the mixed precipitated hydroxide and lithium aqueous solution obtained in step (a) with hot water instantaneously raises the temperature to subcritical or supercritical temperature at room temperature and impurity phases that may be produced in the low temperature step. It is possible to minimize the opportunity for the generation of (phase).

Therefore, according to the present invention, the reaction time in step (b) is preferably 0.1 seconds to 30 minutes, preferably 1 second to 10 minutes. If it is less than 0.1 second, the reaction and crystallinity of the produced lithium metal oxide is lowered and the crystal size is too small. If it is 30 minutes or more, the reactor length becomes longer and the economic efficiency is deteriorated.

The molar ratio of Li / (Ni + Mn + Co) in the mixed solution should be from the stoichiometric ratio less than or equal to 50 as can be seen from the structural formula of the material to be synthesized. For example, lithium cobaltate (LiCoO ₂ ) should be at least 1, and spinel lithium manganate (LiMn ₂ O ₄ ) should be at least 0.5. It is assumed that the mixture with lithium ions encounters hot water and reacts with lithium metal oxide or precipitates with fine lithium hydroxide. Precipitated lithium hydroxide has little chance of contact with transition metal hydroxide, so it does not participate in the reaction and is discharged at room temperature. The lithium hydroxide precipitate is dissolved again in the discharge liquid at room temperature and atmospheric pressure and discarded as an aqueous solution. Therefore, it is necessary to add lithium in excess of the amount released without participating in the reaction. When lithium is added in less than the stoichiometric ratio, impurities such as cobalt oxide, nickel oxide, or manganese oxide that cannot react with lithium are formed, thereby lowering the purity of the target material. However, when the molar ratio of Li / (Ni + Mn + Co) is excessively high, such as 50 or more, the economical efficiency is deteriorated because Li of more than the stoichiometric ratio remains and must be recovered or discarded from the discharge.

At least one or more additives may be further added for the purpose of the dopant, coating agent before or after the synthesis step (a), (b), or thereafter. The dopant and the coating agent are intended to coat ultrafine metal oxide particles on the outside of the positive electrode active material crystal in order to improve durability, and metal oxides such as alumina, zirconia, titania, or precursors thereof may be used.

The invention further includes the process of cooling, concentrating and drying the final reaction mixture obtained through step (b). Preferably, the cooling may use cooling water in a conventional cooling method, for example in a heat exchanger, in order to lower the temperature of the reaction product of 200 ° C or more to 60 ° C or less. Concentration is carried out to increase the concentration of the synthesized lithium metal oxide to a concentration suitable for use, and a filtration method using a conventional filter may be used. Water is discharged by a conventional filtering device and lithium metal oxide particles are collected in the filtering device, thereby increasing the concentration. The drying is carried out to remove the moisture of the lithium metal oxide concentrate, and a conventional drying apparatus (hot air dryer, spray dryer, vacuum dryer, etc.) may be used. The first drying may be performed at a temperature of 150 ° C. or lower to remove moisture, and then secondly dried at a temperature of 100 to 600 ° C. to further lower the content of water in the dried particles. If necessary to grow the crystal size or stabilize the crystal phase, it may be subjected to a calcination treatment for 5 to 24 hours at a temperature of 700 to 1100 ℃. However, the process of cooling, concentrating and drying are not limited thereto and may be performed by other methods known to those skilled in the art.

Single-phase lithium metal oxide produced therefrom is represented by the following formula (1) or (2).

Formula 1

Li _{1 + a} [Ni _x Mn _y Co _z ] O ₂

(In Formula 1, the ranges of a, x, y, and z are -0.1≤a≤ + 0.1, 0≤x≤1, 0≤y≤1, and 0≤z≤1, respectively.)

(2)

LiMn ₂ O ₄

In Formula 1, when a is less than -0.1, crystallinity is not sufficient, and when more than +0.1, excess Li is present to form impurities such as Li ₂ CO ₃ , thereby degrading the performance and stability of the lithium ion secondary battery. You can. In Formula 1, when x = 1, y = 0, z = 0, x = 0, y = 1, z = 0, x = 0, y = 0, z = 1, respectively, LiNiO ₂ , LiMnO ₂ and LiCoO ₂ .

Meanwhile, the lithium metal oxide has an average particle size of about 0.1 μm to 50 μm (median value of 2 μm to 20 μm), preferably about 0.5 to 30 μm, so that the lithium metal oxide may be used as a cathode active material of a lithium ion secondary battery. good. If the average particle size is less than 0.1 µm, the specific surface area is too large to facilitate electrode production and easily to be dissolved in the electrolyte. If the particle size after calcination is larger than 50 µm, there is a concern that the thickness uniformity of the thin layer may be deteriorated at the time of electrode production, resulting in battery failure.

The present invention also includes using a lithium metal oxide prepared by the above manufacturing method for a positive electrode active material such as a lithium ion secondary battery or a lithium ion polymer battery.

The lithium ion secondary battery is composed of a positive electrode, a negative electrode, an electrolyte, a separator, and the like. The positive electrode is composed of a positive electrode active material, a conductive material, a binder, and the like. The conductive material is not particularly limited as long as it is an electron conductive material that does not cause chemical change in the battery. Examples thereof include carbon black, graphite, carbon fibers, carbon nanotubes, metal powders, conductive metal oxides, and organic conductive materials. The binder is preferably a polymer having a relatively high decomposition temperature. For example, polyethylene (PE), polyvinylidene fluoride (PVDF), polyethylene tetrafluoride (PTFE), and the like. The current collector is not particularly limited as long as it is an electron conductive material that does not cause chemical change in the battery configured. For example, it is aluminum, aluminum alloy, nickel, titanium, etc.

The negative electrode is composed of a negative electrode active material, a conductive material, a binder, a current collector, and the like. As the negative electrode active material, lithium, lithium alloy, carbon, an organic compound, an inorganic compound, a polymer, or the like capable of storing and releasing lithium ions may be used. The conductive material is not particularly limited as long as it is an electroconductive material which does not cause chemical change in the battery configured as in the positive electrode. When the negative electrode active material is carbon, carbon itself does not need to be added separately because it has electron conductivity. The binder is preferably a polymer having a relatively high decomposition temperature as in the anode. For example, polyethylene (PE), polyvinylidene fluoride (PVDF), polyethylene tetrafluoride (PTFE), styrene-butadiene rubber, and the like. The current collector is not particularly limited as long as it is an electron conductive material that does not cause chemical change in the battery configured. For example, it is copper, a copper alloy, nickel, titanium.

The electrolyte consists of a solvent and a lithium salt dissolved in the solvent. The solvent may be a single or mixed solvent such as cyclic carbonate, cyclic carboxylic acid ester, acyclic carbonate or aliphatic carboxylic acid ester. For example, ethylene carbonate (EC), propylene carbonate (PC), dimethyl carbonate (DMC), ethyl methyl carbonate (EMC) and the like. Lithium salts are LiPF ₆ , LiBF ₄ , LiAlCl ₄ and the like. Especially preferred is an electrolyte solution in which LiPF ₆ is dissolved in a mixed solvent containing ethylene carbonate and ethyl methyl carbonate. The separator is preferably a porous polymer membrane or a multilayer membrane having a high ion permeability, having a certain mechanical strength or higher and melting at a low temperature. For example, a polyethylene-polypropylene two-layer film (PE / PP), an ultra high molecular weight polyethylene (UHMWPE) porous film, and the like.

Looking at the present invention in more detail through the following examples, the present invention is not limited to the following examples.

Examples 1-5 (Synthesis of LiCoO ₂ )

A 21.0 wt% aqueous solution of cobalt nitrate (Co (NO ₃ ) ₂ H ₂ O) was pumped under pressure at 250 bar at room temperature at a rate of 8 ml / min through a 1 / 4-inch tube, ammonia water and lithium compound (Table 1) aqueous solution. The mixture was pumped under pressure and mixed at 250 bar at room temperature at a rate of 8 ml / min to allow precipitation. The concentration of ammonia water and lithium compound was adjusted to satisfy Table 1. The pH of the precipitate was measured and shown in Table 1. Ultrapure water heated to about 450 ° C. was mixed with the precipitate mixture by pressure pumping at 250 bar at a rate of 96 ml / min through a 1/4 inch tube. The final mixture was held for 7 seconds in a reactor maintained at 400 ° C., then cooled and concentrated. The concentrate was dried in an oven at 100 ° C. for about 12 hours. The size and shape (SEM), crystal phase (XRD) and the like of the dried sample of the prepared oxide were analyzed. The particles synthesized in Example 1 were well-developed crystals having a size of about 1-2 μm as shown in FIG. 1 (a). As a result of XRD analysis, only characteristic peaks of LiCoO ₂ appeared as shown in FIG. 1 (b). It was found to be a single phase. Table 1 shows the particle size, shape and the like which can be known from the phase and SEM analysis estimated from the XRD analysis of the particles synthesized by Examples 1 to 5. It was a single phase and appeared as a well-developed rectangle (mostly plate-shaped) of 1-5 탆 in size.

Example Molar ratio of the mixture Sediment
pH Generated
Particle phase
(phase) Crystal size
(Μm) Crystal form Cobalt nitrate
(Co (NO ₃ ) ₂ ˜6H ₂ O) Hydroxide
lithium
(LiOH) nitric acid
lithium
(LiNO ₃ ) ammonia
Number Example 1 One 2 - 5 11.1 LiCoO ₂ 1-4 Square Example 2 One 3 - 3 11.3 LiCoO ₂ 1-5 Square Example 3 One 5 - 1.5 11.5 LiCoO ₂ 1-4 Square Example 4 One 10 - 1.5 12.4 LiCoO ₂ 1-4 Square Example 5 One - 2 5 10.5 LiCoO ₂ 1-3 Square

Comparative Examples 1-5 (Synthesis of LiCoO ₂ )

The concentration of ammonia water and lithium compound was adjusted to satisfy Table 2. The rest is the same as in Example 1. The size and shape (SEM), crystal phase (XRD) and the like of the dry sample of the oxide prepared according to Comparative Example 1 were analyzed. As shown in (a) of FIG. 2, the dried particles prepared in Comparative Example 1 synthesized particles having a spherical shape and a square of <1 μm in size, and as a result of XRD analysis, Co ₃ O as shown in FIG. 2 (b). The characteristic peak of ₄ was mixed. Table 2 shows the crystal size, crystal shape and the like which can be estimated from the phase and SEM analysis estimated from the XRD analysis of the particles synthesized in Comparative Examples 1 to 5. It is a mixture of various phases, and the particle shape is shown to be a mixture of spherical and square. Therefore, when the pH is 10 or less during precipitation as in the present comparative example, it can be seen that the lithium metal oxide synthesized is not a single phase but a mixed phase including cobalt acid.

Comparative example Molar ratio of the mixture Sediment
pH Generated
Particle phase
(phase) Crystal size
(Μm) Crystal form Cobalt nitrate
(Co (NO ₃ ) ₂ ˜6H ₂ O) Hydroxide
lithium
(LiOH) nitric acid
lithium
(LiNO ₃ ) ammonia
Number Comparative Example 1 One 2 - - 9.0 Co ₃ O ₄ ,
LiCoO ₂ 0.05-1 Sphere + Square Comparative Example 2 One 2 - 1.5 9.5 Co ₃ O ₄ ,
LiCoO ₂ 0.05-1 Sphere + Square Comparative Example 3 One 3 - - 9.5 Co ₃ O ₄ ,
LiCoO ₂ 0.05-1 Sphere + Square Comparative Example 4 One - 3 1.5 8.1 Co ₃ O ₄ ,
LiCoO ₂ 0.05-1 Sphere + Square Comparative Example 5 One - 5 3 9.0 Co ₃ O ₄ ,
LiCoO ₂ 0.05-1 Sphere + Square

Examples 6-8 (Synthesis of LiMn ₂ O ₄ , Performance Test)

21.0 wt% aqueous solution of manganese nitrate was pressurized and pumped to 250 bar at room temperature at a rate of 8 ml / min. Through a 1/4 inch tube, and a mixed solution of aqueous ammonia and lithium hydroxide solution was pressurized to 250 bar at room temperature at a rate of 8 ml / min. Mixed. The concentration of ammonia water and lithium compound was adjusted to satisfy Table 3. The pH of the precipitate was measured and shown in Table 3. Ultrapure water heated to about 450 DEG C was mixed with the mixture by pressure pumping at 250 bar at a rate of 96 ml / min. The final mixture was kept for 7 seconds in a reactor maintained at 400 ° C. and then cooled, concentrated and dried. The size and shape (SEM), crystallinity (XRD) and the like of the dried sample of the prepared oxide were analyzed. Example 6 was the sample appeared as a degree 2-5㎛ rectangular as shown in 3 (a) is also produced according to, the characteristics of the LiMn ₂ O ₄ a peak as shown in Fig. 3 (b) was a clear . Table 3 shows the particle size, shape, and the like, which are estimated from the phase and SEM analysis estimated from the XRD analysis of the particles synthesized by Examples 6 to 8. It is a single phase of manganese spinel structure (LiMn ₂ O ₄ ) and appears to be a well-developed rectangle (mostly plate-shaped) of 1-5 μm in size.

Example Molar ratio of the mixture Sediment
pH Phase of particles produced
(phase) decision
size
(Μm) decision
shape Manganese Nitrate
(Mn (NO ₃ ) ₂ ) Hydroxide
lithium
(LiOH) nitric acid
lithium
(LiNO ₃ ) ammonia
Number Example 6 One 0.5 - 5 10.7 LiMn ₂ O ₄ 1-3 Square Example 7 One 1.0 - 5 11.0 LiMn ₂ O ₄ 1-5 Square Example 8 One - 1.0 5 10.3 LiMn ₂ O ₄ 1-5 Square

Comparative Example 6-8

The concentration of ammonia water and lithium compound was adjusted to satisfy Table 2. The rest is the same as in Example 6. As shown in FIG. 4 (a), the particles synthesized by Comparative Example 6 were composed of particles having a spherical or square shape having a size of <1 μm, and Mn ₂ O ₃ as shown in FIG. 4 (b) as a result of XRD analysis. , Characteristic peaks such as Mn ₃ O ₄ , LiMn ₂ O _4, and the like. Table 4 shows the size and shape of the particles as can be seen from the phase and SEM analysis of the resulting particles estimated from the XRD analysis of the particles synthesized by Comparative Examples 6 to 8. When the pH is less than 10 at the time of precipitation, the synthesized lithium metal oxide was found to contain a phase other than manganese spinel phase or manganese acid.

Comparative example Molar ratio of the mixture Sediment
pH Generated
Particle phase
(phase) decision
size
(Μm) Crystal shape Manganese Nitrate
(Mn (NO ₃ ) ₂ ) Hydroxide
lithium
(LiOH) nitric acid
lithium
(LiNO ₃ ) ammonia
Number Comparative Example 6 One 0.5 - - 8.0 Mn ₂ O ₃ ,
Mn ₃ O ₄ ,
LiMn ₂ O ₄ 0.05-1 Sphere + Square Comparative Example 7 One 1.0 - 1.5 9.8 LiMn ₂ O ₄ ,
Li ₂ MnO ₃ 0.05-1 Sphere + Square Comparative Example 8 One - 1.0 1.5 9.5 Mn ₂ O ₃ ,
LiMn ₂ O ₄ 0.05-1 Sphere + Square

As can be seen from the foregoing example, it was possible to continuously produce a single phase cathode active material by using the present technology. Unlike conventional supercritical thermal synthesis method, without using expensive oxidizing agent, alkalizing agent and lithium compound are first mixed with metal salt solution and precipitated with metal hydroxide under the condition of pH 10 or higher, and then supercritical or subcritical water is added again. By using a method of reacting with lithium ions, it was possible to synthesize a single-phase lithium metal oxide instead of a mixed phase in which various phases were mixed.

Claims (11)

(a) adding a lithium compound and an alkalizing agent to an aqueous solution of at least one metal compound selected from nickel compounds, manganese compounds, and cobalt compounds to precipitate metal hydroxides under a pH of 10 or more to obtain a precipitate mixture solution; And b) reacting the precipitate mixture by adding water heated to a temperature of 200 to 700 ° C. under a pressure of 180 to 550 bar; Method for producing a single-phase lithium metal oxide comprising a. The method of claim 1, wherein the alkalizing agent is selected from the group consisting of alkali metal hydroxides, alkaline earth metal hydroxides and ammonia compounds. The method of claim 1, wherein the metal compound is a metal nitrate, and the alkalizing agent is ammonia water. The method of claim 1, wherein the lithium compound is lithium hydroxide, lithium nitrate, or a mixture thereof. The method of claim 1, wherein step (a) and step (b) are performed in a continuous mixer. The method of claim 1, wherein the alcohol having 1 to 10 carbon atoms is further added in the step (a). The method of claim 1, wherein at least one of the dopant and the coating agent is further added during the step (a), during the step (b), before the step b) or after the step b). Method for producing single phase lithium metal oxide. The method of claim 1, wherein the method further comprises the step of cooling, concentrating and drying the mixed liquid of the lithium metal oxide obtained through step (b). delete delete delete

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