Lithium battery cathode material and method for manufacturing the same

Abstract

To provide a lithium battery positive electrode material and a manufacturing method thereof, which effectively increase the specific discharge capacity and thereby reduce the costs.SOLUTION: A lithium battery positive electrode material includes lithium nickel manganese oxide (LNMO) doped with copper, titanium, nitrogen, and carbon. A manufacturing method of a lithium battery positive electrode material includes: using a copper source, a titanium source, and lithium nickel manganate powder to form a precursor of lithium nickel manganese oxide doped with copper and titanium by performing a co-precipitation method, a filtration process, and a sintering process; and mixing the precursor of the lithium nickel manganese oxide doped with copper and titanium with a carbon source, and coating a nitrogen source by a supercritical fluid extraction method to obtain the lithium nickel manganese oxide doped with copper, titanium, nitrogen, and carbon.SELECTED DRAWING: None

Description

Technical Field

[0001] The present invention relates to a lithium battery cathode material and a method for manufacturing the same.

Background Art

[0002] Currently, lithium nickel manganate materials have a three-dimensional large tunnel structure, have good electrical conductivity, and are very suitable for the diffusion of lithium ions. Therefore, attempts have been made to use them as cathode materials for lithium batteries. However, due to the low specific discharge capacity, the cost increases significantly. Therefore, a method for effectively improving the cathode material for lithium batteries, increasing the specific discharge capacity, and thereby reducing the cost has become an issue.

Summary of the Invention

Problems to be Solved by the Invention

[0003] The present invention provides a lithium battery cathode material and a method for manufacturing the same that can effectively increase the specific discharge capacity and thereby reduce the cost.

Means for Solving the Problems

[0004] The lithium battery cathode material according to the present invention includes lithium nickel manganate doped with copper, titanium, nitrogen, and carbon.

[0005] In one embodiment of the present invention, the weight ratio of lithium nickel manganate: copper / titanium: nitrogen / carbon in the lithium nickel manganate doped with copper, titanium, nitrogen, and carbon is in the range of 1:0.4:0.1 to 1:0.1:0.1.

[0006] In one embodiment of the present invention, the average particle size of the lithium nickel manganate doped with copper, titanium, nitrogen, and carbon is in the range of 0.5 micron to 20 microns.

[0007] The manufacturing method of the lithium battery cathode material according to the present invention includes at least the following steps. By using a copper source, a titanium source, and lithium nickel manganate powder, performing a coprecipitation method, a filtration step, and a sintering step, a precursor of lithium nickel manganate oxide doped with copper and titanium is formed. Mix the precursor of lithium nickel manganate oxide doped with copper and titanium with a carbon source, and coat it with a nitrogen source by the supercritical fluid extraction method to obtain lithium nickel manganate oxide doped with copper, titanium, nitrogen, and carbon.

[0008] In one embodiment of the present invention, the copper source includes copper chloride, copper sulfate (CuSO4), copper sulfite (Cu2SO4), copper nitrate, copper acetate, or a combination thereof.

[0009] In one embodiment of the present invention, the titanium source includes titanium chloride, titanium sulfate, titanium nitrate, or a combination thereof.

[0010] In one embodiment of the present invention, the nitrogen source includes dopamine, p-phenylenediamine, or a combination thereof.

[0011] In one embodiment of the present invention, the carbon source includes graphene, glucose, or a combination thereof.

[0012] In one embodiment of the present invention, the coprecipitating agent used in the coprecipitation method includes water, ethanol, isopropyl alcohol, acetone, methyl ethyl ketone, ammonia, sodium hydroxide, sodium carbonate, or a combination thereof. The coprecipitation reaction temperature in the coprecipitation method is in the range of room temperature (25°C) to 100°C, and the coprecipitation reaction time in the coprecipitation method is 1 minute to 30 minutes.

[0013] In one embodiment of the present invention, the temperature of the sintering step is in the range of 400°C to 1000°C.

Advantages of the Invention

[0014] Based on the above, at least one embodiment of the present invention improves the energy density of the lithium nickel manganese oxide material and solves the problem of low specific discharge capacity by means of copper / titanium-nitrogen / carbon doping technology. Therefore, the positive electrode material of the lithium battery of the present invention effectively increases the specific discharge capacity, thereby reducing the cost.

Embodiments for Carrying Out the Invention

[0015] For purposes of illustration and not limitation, the following detailed description describes exemplary embodiments that disclose specific details in order to provide a complete understanding of the various principles of the present invention. However, it will be apparent to those skilled in the art that the present invention may be practiced in other embodiments that depart from the specific details disclosed herein. Further, descriptions of well-known devices, methods, materials, and other specific details may be omitted so as not to obscure the various principles of the present invention.

[0016] In addition, in this specification, the range of "from one value to another value" is a summary expression to avoid listing all the values within that range one by one in the specification. Therefore, the description of a specific numerical range includes any numerical value within that range and any smaller numerical range defined by any numerical value within that range, as if any numerical value and any smaller numerical range within that range were described in the specification.

[0017] Unless otherwise specified, the term "range of ~" used in this specification to define a numerical range is intended to include ranges equal to the recited end values and ranges therebetween. For example, "the size range is from a first value to a second value" means that the size range can include the first value, the second value, and any value between the first value and the second value.

[0018] In this specification, non-limiting terms (such as can, may, for example, or other similar terms) refer to something that is not essential or to any implementation, inclusion, addition, or existence.

[0019] Unless otherwise defined, all terms (including technical and scientific terms) used in this specification shall have the same meaning as commonly understood by one of ordinary skill in the art. It should also be understood that terms (such as those defined in commonly used dictionaries) should be interpreted as having a meaning that conforms to their meaning in the relevant technical context, and should not be interpreted in an idealized or overly formal sense unless explicitly defined as such in this specification.

[0020] In an embodiment, the lithium battery cathode material includes lithium nickel manganese oxide (LNMO) doped with copper (Cu), titanium (Ti), nitrogen (N), and carbon (C). Therefore, the present invention uses copper / titanium-nitrogen / carbon doping technology to improve the energy density of the lithium nickel manganese oxide material and solve the problem of low specific discharge capacity. In this way, the lithium battery cathode material of the present invention effectively increases the specific discharge capacity, thereby reducing costs. Here, in the lithium nickel manganese oxide doped with copper, titanium, nitrogen, and carbon, the weight ratio of lithium nickel manganese oxide: copper / titanium: nitrogen / carbon is 1:0.4:0.1 to 1:0.1:0.1, and the average particle size of the lithium nickel manganese oxide doped with copper, titanium, nitrogen, and carbon is, for example, 0.5 micron (μm) to 20 microns. Here, copper / titanium represents the total ratio of the copper element and the titanium element in the lithium nickel manganese oxide doped with copper, titanium, nitrogen, and carbon, and nitrogen / carbon represents the total ratio of the nitrogen element and the carbon element in the lithium nickel manganese oxide doped with copper, titanium, nitrogen, and carbon.

[0021] The method for manufacturing lithium nickel manganese oxide doped with copper, titanium, nitrogen, and carbon according to the present invention may include at least the following steps. By using a copper source, a titanium source, and lithium nickel manganese oxide powder, performing a coprecipitation method, a filtration step, and a sintering step, a step of forming a precursor of lithium nickel manganese oxide doped with copper and titanium (first stage); and mixing the precursor of lithium nickel manganese oxide doped with copper and titanium with a carbon source and coating the nitrogen source by a supercritical fluid extraction method to obtain lithium nickel manganese oxide doped with copper, titanium, nitrogen, and carbon (second stage).

[0022] Hereinafter, each step of the method for manufacturing lithium nickel manganese oxide doped with copper, titanium, nitrogen, and carbon in an embodiment of the present invention will be described.

[0023] Synthesis of Lithium Nickel Manganese Oxide Powder

[0024] Step 1: Coprecipitate a nickel source, a manganese source, and a polymerization agent to synthesize a Ni 0.5 Mn 1.5 O4 precursor, then wash and dry to prepare a powder, and bake the obtained powder to obtain a calcined precursor. Step 2: Add a lithium source, a dopant, and an organic medium to the calcined precursor obtained in Step 1 to form a stable slurry. Step 3: Bake the powder obtained by spraying and drying the slurry in Step 2 to obtain a calcined sample LiNi 0.5 Mn 1.5 O4 powder.

[0025] In some embodiments, the nickel source is a nickel salt (such as nickel sulfate, nickel nitrate, nickel acetate, etc.), the manganese source is a manganese salt (such as manganese sulfate, lithium manganese nitrate, manganese acetate, manganese chloride, etc.), the lithium source is a lithium salt (such as lithium sulfate, lithium carbonate, lithium chloride, etc.), and the solvent is distilled water or the like.

[0026] In some embodiments, the specific manufacturing method is as follows.

[0027] First, add water to the experimental glassware to form a reaction solution. Gradually add manganese sulfate to the above solution, and stir with a three-dimensional mixer, shaker, magnetic stirrer, etc. to mix thoroughly.

[0028] Next, dissolve 41.83 g (0.168 mol) of nickel acetate (Ni(CH3COO)2·4H2O) and 10.38 g (0.06 mol) of manganese acetate (Mn(CH3COO)2) in 228 ml of ethylenediamine according to a molar ratio of elements of 1:2.8. The total concentration of metal ions is 1.0 M. Add 27.5 g (0.458 mol) of urea according to a molar ratio of urea:metal ions of 2:1, and stir magnetically for 30 minutes. After magnetically stirring this mixed solution for 2 hours, transfer it to a reaction tank, react at 80°C to 170°C for 10 hours, and cool naturally to room temperature. Centrifuge the obtained solution at a rotational speed of 10,000 RPM with a centrifuge to precipitate, and remove the upper clear washing liquid. Next, wash the precipitate with water and dry it in an oven at 120°C. After drying, Ni 0.25 Mn 0.75 CO3 precursor is obtained.

[0029] In addition to the above, the obtained Ni 0.25 Mn 0.75 CO3 precursor is first sintered at 400°C to 700°C for 3 hours, and then mechanically mixed with LiOH·H2O by a three-dimensional mixer according to Li:(Ni + Mn)=1.05:2 (molar ratio). After uniformly mixing, the obtained mixture is constantly fired in air at 600°C to 800°C for 12 hours, and then heated to 800°C to 1000°C and sintered for 10 hours. After natural cooling and pulverization, LiNi 0.5 Mn 1.5 O4 cathode material is obtained. That is, lithium nickel manganese oxide powder is obtained. Here, all the diffraction peaks of the X-ray diffraction pattern of the LiNi 0.5 Mn 1.5 O4 cathode material are, the standard LiNi 0.5 Mn 1.5It coincides with the diffraction peaks of O4 (JCPDS card number 80-2162). This indicates that the sample has a cubic spinel structure and an Fd-3m space group, each diffraction peak is strong and sharp, the material is sufficiently crystallized, and there is no Li x Ni 1-x O impurity phase.

[0030] Step 4: Perform infiltration, doping, and modification on the calcined sample obtained in Step 3, and then perform firing and sieving to obtain LiNi 0.5-y-x Mn 1.5-y-x Cu x Ti y O4 powder, where 0 < x + y ≤ 0.1, x > 0, y > 0. The specific production method is as follows.

[0031] By using a copper source, a titanium source, and lithium nickel manganate powder, and performing a coprecipitation method, a filtration process, and a sintering process, a precursor of copper- and titanium-doped lithium nickel manganate oxide is formed.

[0032] First, perform the coprecipitation method by adding the copper source and the titanium source to the lithium nickel manganate powder and mixing them uniformly. The copper source includes copper chloride, copper sulfate, copper sulfite, copper nitrate, copper acetate, or a combination thereof. The titanium source includes titanium chloride, titanium sulfate, titanium nitrate, or a combination thereof. The coprecipitants used in the coprecipitation method include water, ethanol, isopropyl alcohol, acetone, methyl ethyl ketone, ammonia, sodium hydroxide, sodium carbonate, oxalic acid, or a combination thereof. The coprecipitation reaction temperature in the coprecipitation method ranges from room temperature (e.g., 25°C) to 100°C. The coprecipitation reaction time in the coprecipitation method ranges from 1 minute to 30 minutes.

[0033] Furthermore, as a specific embodiment of the coprecipitation method, for example, the aforementioned materials are mixed in a solvent (water) to prepare a 2M metal solution, the corresponding materials are stirred and suspended, and then LiNi 0.5 Mn 1.5Based on the property that the O4 precursor and the dopant are insoluble in solvents (IPA, MEK, methanol, toluene), a solvent is added to the above materials at a ratio of 1:1 to precipitate the materials.

[0034] Next, a filtration process is performed to remove the solvent (e.g., water) of the precursor of lithium nickel manganese oxide doped with copper and titanium, and the solid part is taken out. A sintering process is performed to complete the lattice rearrangement, add copper and titanium to the lattice of nickel manganese oxide, and obtain a precursor of lithium nickel manganese oxide doped with copper and titanium. Here, the sintering process may be a high-temperature sintering process in the range of 400 °C to 1000 °C, but the present invention is not limited thereto. Also, in the case of calcination, the sintering time may be in the range of 6 hours to 24 hours, and the sintering atmosphere is air or an oxygen atmosphere (oxygen is oxygen with a purity of 99.99%, and air is a general atmospheric environment).

[0035] Note that by controlling the coprecipitant, the coprecipitation reaction temperature and time, the sintering treatment temperature, etc., the particle size of the powder precursor can be in the range of 0.5 μm to 20 μm. Furthermore, since the lithium nickel manganese oxide powder is doped with copper and titanium, due to the interaction between the inert element in the electron configuration of titanium and the manganese metal ion (Mn 4+ , Ti 4+ ), the structural stability during cycling can be effectively provided. Also, due to the interaction between the nickel metal ion (Ni 2+ ) and the copper metal ion (Cu 2+ ), a high potential capacity can be effectively provided during cycling. Therefore, the doping of copper and titanium in the present invention can further improve the performance of the lithium battery in terms of structure and capacity.

[0036] The precursor of lithium nickel manganese oxide doped with copper and titanium is mixed with a carbon source and coated with a nitrogen source by a supercritical fluid extraction method to obtain lithium nickel manganese oxide doped with copper, titanium, nitrogen and carbon.

[0037] First, a carbon source and a precursor of lithium nickel manganese oxide doped with copper and titanium are dry-mixed in a three-dimensional mixer (model POETWQM10), and then secondarily fired in a tubular furnace to coat the surface of the lithium nickel manganese oxide with the carbon source, thereby improving the specific discharge capacity of the powder. Here, the carbon source includes graphene, glucose, or a combination thereof.

[0038] Next, a nitrogen source is applied by the supercritical fluid extraction method to dope and modify nitrogen in the lithium nickel manganese oxide doped with copper and titanium and having a surface coated with a carbon material. For example, the nitrogen source is coated by the supercritical fluid extraction method, and a precursor of lithium nickel manganese oxide doped with dopamine, copper, and titanium is added to a high-pressure reactor. The reaction temperature is 40°C to 100°C, and the pressure is increased to 50 atmospheres to 100 atmospheres using carbon dioxide and reacted for 8 hours to dope and modify nitrogen in the lithium nickel manganese oxide doped with copper and titanium and having a surface coated with a carbon material, and a nitrogen / carbon doped layer is formed on the surface of the lithium nickel manganese oxide, thereby further improving the conductivity and specific discharge capacity of the material. Also, when a carbon material doped with nitrogen is formed on the surface of the lithium nickel manganese oxide doped with copper and titanium, the number of active sites on the surface of the material increases, and the energy barrier encountered during the intrusion of ions decreases, thereby significantly promoting the movement of lithium ions and improving the effect of the cycle test. Here, the nitrogen source includes dopamine, p-phenylenediamine, or a combination thereof.

[0039] Furthermore, since the size of nitrogen is close to that of carbon, nitrogen can replace a part of carbon and be filled on the surface of the lithium nickel manganese oxide, and the specific discharge capacity can be further increased, but the present invention is not limited thereto.

[0040] In addition, nitrogen doping is a modification technology for carbon materials. Its principle is a chemical functionalization method that uses nitrogen to replace some of the carbon atoms in fullerenes, carbon nanotubes, graphene, etc. Since nitrogen atoms are similar in size to carbon, they have high compatibility, and nitrogen is easily doped into the crystal lattice of carbon materials. In the N-C bond formed after doping, the N atom attracts the electrons on the adjacent C atom, inducing electron defects and promoting the conduction of electrons in the material. Therefore, doping nitrogen atoms on the surface of carbon materials can effectively improve their conductivity and catalytic properties.

[0041] Note that supercritical fluid extraction (SFE) is a technology for separating and extracting compounds. Generally, supercritical fluids are used as extractants. Supercritical fluids are in a state between gas and liquid and have special physical and chemical properties that make them effective extractants under specific circumstances. For example, in the normal state, supercritical fluids can reach the supercritical state by adjusting pressure and temperature. In such a state, supercritical fluids can have the following properties: High diffusivity: Supercritical fluids have diffusion properties similar to liquids, enabling them to effectively penetrate and interact with compounds in solid samples, allowing the liquid to mix uniformly with the solid sample. Adjustable: The density and solubility of supercritical fluids can be controlled by adjusting pressure and temperature, thereby adjusting the selectivity and efficiency of the extraction process. Low surface tension: Supercritical fluids have lower surface tension than liquids, promoting penetration into solid samples. Reversibility: Since the state of supercritical fluids changes rapidly when pressure and temperature change, the extracted compounds can be easily separated from the supercritical fluids. The supercritical fluid extraction method can be widely used in various fields including food, pharmaceuticals, cosmetics, and environmental analysis. Since the supercritical fluid extraction process eliminates the need for organic solvents, reducing the environmental impact and residues, it can also be used for the extraction of natural products, removal of impurities, separation of compounds, and other applications.

[0042] Hereinafter, examples will be given to describe in detail the lithium nickel manganese oxide doped with copper, titanium, nitrogen, and carbon according to the present invention. However, the following examples do not limit the present invention. Here, other unspecified components and specifications of the lithium battery can be obtained by those skilled in the art based on any content included in the spirit and scope of the claims.

[0043] Positive electrode material of Example 1 (lithium nickel manganese oxide doped with copper and titanium and modified with nitrogen-doped carbon material)

[0044] 41.83 g (0.168 mol) of nickel acetate (Ni(CH3COO)2·4H2O) and 10.38 g (0.06 mol) of manganese acetate (Mn(CH3COO)2) were dissolved in 228 ml of ethylenediamine according to a molar ratio of elements of 1:2.8. The total concentration of metal ions was 1.0 M. 27.5 g (0.458 mol) of urea was added according to a molar ratio of urea:metal ions of 2:1 and magnetically stirred for 30 minutes. After magnetically stirring this mixed solution for 2 hours, it was transferred to a high-pressure reactor, sealed, and reacted at 80°C to 170°C for 10 hours, and then naturally cooled to room temperature. The obtained solution was centrifugally precipitated (the rotation speed in the centrifuge was 10,000 RPM), and the upper clear washing liquid was removed. The solution was alkaline. The precipitate was washed with water and dried in an oven at 120°C. After drying, Ni 0.25 Mn 0.75 CO3 precursor was obtained.

[0045] Next, the obtained Ni 0.25 Mn 0.75 CO3 precursor was calcined at 400°C to 700°C for 3 hours and mechanically mixed with LiOH·H2O according to Li:(Ni+Mn)=1.05:2 (molar ratio). After uniformly mixing, the obtained mixture was fired in air at 800°C for 12 hours, and then sintered at 800°C to 1000°C for 10 hours. After natural cooling and pulverization, LiNi 0.5 Mn 1.5 O4 positive electrode material was obtained.

[0046] Next, copper acetate (7.2 grams) and titanium nitrate (8.4 grams) were added to the above lithium nickel manganese oxide powder and uniformly mixed with a three-dimensional mixer. Next, the above materials were mixed with a solvent (water) to prepare a 2M metal solution, and stirred to suspend the corresponding materials. Next, based on the property that the LiNi 0.5 Mn 1.5 O4 precursor and the dopant are insoluble in the solvent (IPA, MEK, methanol, toluene), a solvent was added to the above materials at a ratio of 1:1 to precipitate the materials. Here, the coprecipitation reaction temperature in the coprecipitation method was room temperature to 100 °C, and the coprecipitation reaction time in the coprecipitation method was 30 minutes.

[0047] Next, a filtration process was performed to remove the solvent (for example, water) of the precursor of the copper- and titanium-doped lithium nickel manganese oxide, and the solid part was taken out. A sintering process was performed to complete the lattice rearrangement, add copper and titanium to the lattice of the nickel manganese oxide, and obtain a precursor of the copper- and titanium-doped lithium nickel manganese oxide. Here, the sintering temperature was 400 °C to 1000 °C, and the sintering time was 10 hours.

[0048] Next, the obtained product and the water-soluble carbon-containing organic compound were uniformly mixed at a ratio of 100:10 to 20, and fired at 600 °C for 2 to 3 hours under an inert gas atmosphere to obtain carbon-coated lithium nickel manganese oxide. Next, a nitrogen source was coated by the supercritical fluid extraction method, and dopamine and the precursor of the lithium nickel manganese oxide were added to a high-pressure reactor. The reaction was carried out at a reaction temperature of 40 °C to 100 °C and a pressure of 50 atmospheres to 100 atmospheres for 8 hours to dope nitrogen into the copper- and titanium-doped lithium nickel manganese oxide coated with a carbon material on the surface, and a nitrogen / carbon doped layer was formed on the surface of the above lithium nickel manganese oxide.

[0049] The cathode material of Comparative Example 1 (lithium nickel manganese oxide material)

[0050] 41.83 g (0.168 mol) of nickel acetate (Ni(CH3COO)2·4H2O) and 10.38 g (0.06 mol) of manganese acetate (Mn(CH3COO)2) were dissolved in 228 ml of ethylenediamine according to a molar ratio of elements of 1:2.8. The total concentration of metal ions was 1.0 M. 27.5 g (0.458 mol) of urea was added according to a molar ratio of urea:metal ions of 2:1 and mixed with a three-dimensional mixer for 30 minutes. After this mixed solution was magnetically stirred for 2 hours, it was transferred to a high-pressure reactor, sealed and reacted at 80 °C to 170 °C for 10 hours, and then naturally cooled to room temperature. The obtained solution was centrifugally precipitated (the rotation speed in the centrifuge was 10,000 RPM) and the upper clear washing liquid was removed. The solution was alkaline. The precipitate was washed with water and dried in an oven at 120 °C. After drying, Ni 0.25 Mn 0.75 CO3 precursor was obtained.

[0051] The obtained Ni 0.25 Mn 0.75 CO3 precursor was calcined at 400 °C to 700 °C for 3 hours and mechanically mixed with LiOH·H2O by a three-dimensional mixer according to Li:(Ni + Mn)=1.05:2 (molar ratio). After uniformly mixing, the obtained mixture was fired in air at 800 °C for 12 hours, and then sintered at 800 °C to 1000 °C for 10 hours. After natural cooling and pulverization, LiNi 0.5 Mn 1.5 O4 cathode material was obtained.

[0052] The cathode material of Comparative Example 2 (lithium nickel manganese oxide doped with copper and titanium)

[0053] 41.83 g (0.168 mol) of nickel acetate (Ni(CH3COO)2·4H2O) and 10.38 g (0.06 mol) of manganese acetate (Mn(CH3COO)2) were dissolved in 228 ml of ethylenediamine according to a molar ratio of 1:2.8 of the elements. The total concentration of metal ions was 1.0 M. 27.5 g (0.458 mol) of urea was added according to a molar ratio of urea:metal ions of 2:1. After magnetic stirring of this mixed solution for 2 hours, it was transferred to a high-pressure reactor, sealed and reacted at 80 °C to 170 °C for 10 hours, and then naturally cooled to room temperature. The resulting solution was centrifuged and precipitated (the rotation speed in the centrifuge was 10,000 RPM), and the upper clear washing liquid was removed. The solution was alkaline. The precipitate was washed with water and dried in an oven at 120 °C. After drying, Ni 0.25 Mn 0.75 CO3 precursor was obtained.

[0054] The obtained Ni 0.25 Mn 0.75 CO3 precursor was calcined at 400 °C to 700 °C for 3 hours and mechanically mixed with LiOH·H2O according to Li:(Ni + Mn)=1.05:2 (molar ratio). After uniform mixing, the obtained mixture was calcined in air at 800 °C for 12 hours and then sintered at 800 °C to 1000 °C for 10 hours. After natural cooling and pulverization, LiNi 0.5 Mn 1.5 O4 cathode material was obtained.

[0055] 7.2 grams of copper acetate and 8.4 grams of titanium nitrate were added to the above lithium nickel manganese oxide powder and uniformly mixed with a three-dimensional mixer. Next, the above materials were mixed with a solvent (water) to prepare a 2M metal solution, and stirred to suspend the corresponding materials. Next, based on the property that the LiNi 0.5 Mn 1.5 O4 precursor and the dopant are insoluble in the solvent (IPA, MEK, methanol, toluene), a solvent was added to the above materials at a ratio of 1:1 to precipitate the materials. Here, the coprecipitation reaction temperature in the coprecipitation method was room temperature to 100 °C, and the coprecipitation reaction time in the coprecipitation method was 30 minutes.

[0056] Next, a filtration process was carried out to remove the solvent (e.g., water) of the precursor of lithium nickel manganese oxide doped with copper and titanium, and the solid part was taken out. A sintering process was carried out to complete the lattice rearrangement, and copper and titanium were added to the lattice of nickel manganese oxide to obtain a precursor of lithium nickel manganese oxide doped with copper and titanium. Here, the sintering temperature was 400°C to 1000°C, and the sintering time was 10 hours.

[0057] The cathode material of Comparative Example 3 (lithium nickel manganese oxide material modified by carbon doping)

[0058] 41.83 g (0.168 mol) of nickel acetate (Ni(CH3COO)2·4H2O) and 10.38 g (0.06 mol) of manganese acetate (Mn(CH3COO)2) were dissolved in 228 ml of ethylenediamine according to a molar ratio of 1:2.8 of the elements. The total concentration of metal ions was 1.0 M. 27.5 g (0.458 mol) of urea was added according to a molar ratio of urea:metal ions of 2:1. After this mixed solution was magnetically stirred for 2 hours, it was transferred to a high-pressure reactor, sealed and reacted at 80°C to 170°C for 10 hours, and then naturally cooled to room temperature. The obtained solution was centrifuged and precipitated (the rotation speed in the centrifuge was 10,000 RPM), and the upper clear washing solution was removed. The solution was alkaline. The precipitate was washed with water and dried in an oven at 120°C. After drying, Ni 0.25 Mn 0.75 CO3 precursor was obtained.

[0059] The obtained Ni 0.25 Mn 0.75 CO3 precursor was calcined at 400°C to 700°C for 3 hours and mechanically mixed with LiOH·H2O according to Li:(Ni+Mn)=1.05:2 (molar ratio). After uniformly mixing, the obtained mixture was calcined in air at 800°C for 12 hours, and then sintered at 800°C to 1000°C for 10 hours. After natural cooling and grinding, LiNi 0.5 Mn 1.5 O4 cathode material was obtained.

[0060] 7.2 grams of copper acetate and 8.4 grams of titanium nitrate were added to the above lithium nickel manganese oxide powder and uniformly mixed with a three-dimensional mixer. Next, the above materials were mixed with a solvent (water) to prepare a 2M metal solution, and the mixture was stirred to suspend the corresponding materials. Next, based on the property that the LiNi 0.5 Mn 1.5 O4 precursor and the dopant are insoluble in the solvent (IPA, MEK, methanol, toluene), a solvent was added to the above materials at a ratio of 1:1 to precipitate the materials. Here, the coprecipitation reaction temperature in the coprecipitation method was room temperature to 100 °C, and the coprecipitation reaction time in the coprecipitation method was 30 minutes.

[0061] Next, a filtration process was performed to remove the solvent (for example, water) of the precursor of the lithium nickel manganese oxide doped with copper and titanium, and the solid part was taken out. A sintering process was performed to complete the lattice rearrangement, add copper and titanium to the lattice of the nickel manganese oxide, and obtain a precursor of the lithium nickel manganese oxide doped with copper and titanium. Here, the sintering temperature was 400 °C to 1000 °C, and the sintering time was 10 hours. Next, the obtained product and the water-soluble carbon-containing organic compound were uniformly mixed at a weight ratio of 100:1 to 20 (preferably 7 to 12), and fired at 600 °C for 2 to 3 hours in an inert gas atmosphere to obtain a carbon-coated lithium nickel manganese oxide.

[0062] The positive electrode material of Comparative Example 4 (lithium nickel manganese oxide material modified with a nitrogen-doped carbon material)

[0063] 41.83 g (0.168 mol) of nickel acetate (Ni(CH3COO)2·4H2O) and 10.38 g (0.06 mol) of manganese acetate (Mn(CH3COO)2) were dissolved in 228 ml of ethylenediamine according to a molar ratio of 1:2.8 of the elements. The total concentration of metal ions was 1.0 M. 27.5 g (0.458 mol) of urea was added according to a molar ratio of urea:metal ions of 2:1. After the mixed solution was magnetically stirred for 2 hours, it was transferred to a high-pressure reactor, sealed and reacted at 80 °C to 170 °C for 10 hours, and then naturally cooled to room temperature. The obtained solution was centrifuged and precipitated (the rotation speed in the centrifuge was 10,000 RPM), and the upper clear washing solution was removed. The solution was alkaline. The precipitate was washed with water and dried in an oven at 120 °C. After drying, Ni 0.25 Mn 0.75 CO3 precursor was obtained.

[0064] The obtained Ni 0.25 Mn 0.75 CO3 precursor was calcined at 400 °C to 700 °C for 3 hours and mechanically mixed with LiOH·H2O according to Li:(Ni + Mn)=1.05:2 (molar ratio). After uniformly mixing, the obtained mixture was calcined in air at 800 °C for 12 hours, and then sintered at 800 °C to 1000 °C for 10 hours. After natural cooling and grinding, LiNi 0.5 Mn 1.5 O4 cathode material was obtained.

[0065] The obtained product and the water-soluble carbon-containing organic compound were uniformly mixed at a weight ratio of 100:10 to 20, and calcined at 600 °C for 2 to 3 hours in an inert gas atmosphere to obtain lithium nickel manganese oxide coated with carbon. Next, the nitrogen source was coated by the supercritical fluid extraction method, and dopamine and the precursor of lithium nickel manganese oxide were added to a high-pressure reactor. The reaction temperature was 40 °C to 100 °C, the pressure was adjusted to 50 atmospheres to 100 atmospheres using carbon dioxide, and the reaction was carried out for 8 hours to dope and modify the lithium nickel manganese oxide with nitrogen whose surface was coated with a carbon material, and a nitrogen / carbon doped layer was formed on the surface of the above lithium nickel manganese oxide.

[0066] Manufacture of lithium battery

[0067] First, the cathode material of the example and conductive carbon black (Super P) were placed in an oven at 120°C for 1 hour to remove moisture. Next, 80 parts by weight of the cathode material of the example, 10 parts by weight of conductive carbon black (Super P), and 10 parts by weight of an adhesive (PVDF (HSV-900)) were uniformly mixed in a solvent (NMP) to prepare a uniform cathode slurry. Next, this cathode slurry was applied onto an aluminum foil using a scraper. The wet film thickness was 200 μm and the coating speed was 2 mm / second. The aluminum foil was transferred to an oven and dried at 60°C to 120°C, and then calendered to a thickness of 0.038 mm. The calendered cathode sheet was cut into circular electrode sheets with a diameter of 13 mm.

[0068] Thereafter, a CR2032 button battery pack was prepared. First, the lower cover of the negative electrode (metallic lithium sheet) was placed flat on an insulating table, and a metallic lithium sheet with a diameter of 15.8 mm was placed at the center of the lower cover of the negative electrode, and the lithium sheet was flattened using a tableting machine. Next, an appropriate amount of electrolyte (1 M LiPF6 in EC:DEC 1:1 v / v%) was dropped onto a commercially available insulating film with a diameter of 18 mm (product name: Celgard 2400). Next, the insulating film was placed on the lithium sheet, and the cathode, spacer, lead, and upper cover of the cathode manufactured according to the above method were sequentially added. Next, the button-type lithium battery was placed in a battery press with the negative electrode facing up using insulating tweezers and pressed at a pressure of 800 Pa to mount the battery.

[0069] Comparative Example

[0070] A button-type lithium battery was manufactured in the same manner as in the example, except that the cathode material of the comparative example manufactured as described above was used instead of the cathode material of the example.

[0071] Analysis of Electrochemical Characteristics:

[0072] Initial discharge capacity and capacity decay rate

[0073] Table 1 shows the discharge specific capacities at 25°C at 0.5C of the button-type lithium batteries of Example 1 and Comparative Examples 1 to 4. The calculation formula for the charge-discharge capacity for each cathode material is as follows. Specific discharge capacity (mAh / g) = (current (mA) × time (h)) / (mass (g) of the active material (cathode material of the example or comparative example)).

[0074]

Table 1

[0075] In summary, at least one embodiment of the present invention uses copper / titanium-nitrogen / carbon doping technology to improve the energy density of the lithium nickel manganate material and solve the problem of low specific discharge capacity. Therefore, the cathode material of the lithium battery of the present invention can effectively increase the specific discharge capacity, thereby reducing costs.

Industrial Applicability

[0076] The lithium battery cathode material and its manufacturing method according to the present invention can be applied in the field of lithium batteries.

[0077] As described above, the present invention has been disclosed with reference to the embodiments, but these embodiments do not limit the present invention. Any person skilled in the art can make changes and modifications without departing from the spirit and scope of the present invention. Therefore, the protection scope of the present invention shall be defined by the following claims.

Claims

1. A lithium battery cathode material comprising lithium nickel manganese oxide doped with copper, titanium, nitrogen, and carbon, wherein in the lithium nickel manganese oxide doped with copper, titanium, nitrogen, and carbon, the weight ratio [(lithium nickel manganese oxide):(copper + titanium):(nitrogen + carbon)] of the weight of the lithium nickel manganese oxide, the total weight of copper and titanium, and the total weight of nitrogen and carbon is 1:0.4:0.1 to 1:0.1:0.

1.

2. The lithium battery cathode material according to claim 1, wherein the average particle size of the lithium nickel manganese oxide doped with copper, titanium, nitrogen, and carbon is in the range of 0.5 micron to 20 microns.

3. Using a copper source, a titanium source, and lithium nickel manganese oxide powder, performing a coprecipitation process, a filtration process, and a sintering process to form a precursor of lithium nickel manganese oxide doped with copper and titanium, mixing the precursor of the lithium nickel manganese oxide doped with copper and titanium with a carbon source and coating the nitrogen source by a supercritical fluid extraction method to obtain the lithium nickel manganese oxide doped with copper, titanium, nitrogen, and carbon, which is a method for manufacturing a lithium battery cathode material.

4. The method for manufacturing a lithium battery cathode material according to claim 3, wherein the copper source includes copper chloride, copper sulfate, copper sulfite, copper nitrate, copper acetate, or a combination thereof.

5. The method for manufacturing a lithium battery cathode material according to claim 3, wherein the titanium source includes titanium chloride, titanium sulfate, titanium nitrate, or a combination thereof.

6. The method for manufacturing a lithium battery cathode material according to claim 3, wherein the nitrogen source includes dopamine, p-phenylenediamine, or a combination thereof.

7. The method for manufacturing a lithium battery cathode material according to claim 3, wherein the carbon source includes graphene, glucose, or a combination thereof.

8. The coprecipitant used in the coprecipitation method includes water, ethanol, isopropyl alcohol, acetone, methyl ethyl ketone, ammonia, sodium hydroxide, sodium carbonate, or a combination thereof, the coprecipitation reaction temperature in the coprecipitation method is in the range of 25°C to 100°C, and the coprecipitation reaction time in the coprecipitation method is in the range of 1 minute to 30 minutes, which is the method for manufacturing a lithium battery cathode material according to claim 3.

9. The temperature of the sintering process is in the range of 400°C to 1000°C, and the method for manufacturing a lithium battery cathode material according to claim 3.

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