Cathode material and method of manufacturing the same

Abstract

To provide a cathode material and a method of manufacturing the same.SOLUTION: A cathode material comprises a core made of a first material and a coating made of a second material and wrapping the core. The first material is a composition that is represented by the formula: LiNi0.5Mn1.5O4-δ (δ>0). The second material is a ternary halide containing lithium.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a cathode material and a method for producing the same, in particular a cathode material having a core made of lithium nickel manganese oxide material and a coating made of lithium-containing ternary halide. [Background technology]

[0002] Lithium batteries have the advantage of high energy density and are currently the mainstream energy storage components for portable electronic products. Through appropriate material selection and modification, the working voltage and specific capacitance of the battery can be increased, further increasing the energy density of lithium batteries and making them effectively applicable in the fields of energy storage and mobile power carriers.

[0003] The cathode material accounts for 40% of the total cost of a lithium battery, and is a determining factor in the price of the battery, as well as an important indicator that determines the performance of the battery, such as its energy density, safety, and cycle life.

[0004] However, lithium nickel manganese oxide (LNMO) is used as a cathode material for lithium batteries because of the Mn 3+ However, this can induce a disproportionation reaction that leads to the dissolution of manganese, resulting in a change in the structure of the spinel and a decrease in the electrical capacity. Summary of the Invention

[0005] The chemical formula for ideal lithium nickel manganese oxide is LiNi 0.5 Mn 1.5 O4, and Mn 4+ The oxidation valence is maintained, and the structure is stable without being involved in the reaction. It is mainly a spinel structure of space group P4332. 3+ It is well known that the presence of LiNi is caused by the manufacturing conditions. In order to maintain the electroneutrality, "oxygen loss" occurs in the material, and LiNi 0.5 Mn 1.5 O 4-δThe space group changes to Fd-3m, which is not favorable for structural stability, but can provide better discharge rate performance.

[0006] As mentioned above, Mn in LNMO materials 3+ The influence of the halide on the electrochemical performance of the material has both advantages and limitations. 0.5 Mn 1.5 O 4-δ By covering the LiNi 0.5 Mn 1.5 O 4-δ We have devised a new material that prevents contact between the electrolyte and the electrode, and that combines good ionic conductivity with cycle stability.

[0007] Therefore, the object of the present invention is to provide a cathode material and a manufacturing method thereof to solve the problems of the prior art.

[0008] In order to solve the problems of the prior art, the present invention provides a cathode material including a core made of a first material and a coating made of a second material and surrounding the core, wherein the first material is LiNi 0.5 Mn 1.5 O 4-δ and δ>0, and the second material is a lithium-containing ternary halide.

[0009] In one embodiment of the present invention, the second material is Li a MX b wherein M is a non-lithium metal, X is a halogen, and a and b are positive integers.

[0010] In one embodiment of the present invention, there is provided a cathode material, wherein the second material is lithium indium halide (LiInCl6).

[0011] In one embodiment of the present invention, there is provided a cathode material, wherein the coating has a thickness of 5 to 60 nm.

[0012] In one embodiment of the present invention, there is provided a method for producing a cathode material, the method including: a co-precipitation step in which a nickel-manganese metal solution, a sodium hydroxide solution, and an ammonia solution are mixed in a container to obtain a precipitate, and the precipitate is dried and sieved to obtain a nickel-manganese precursor; a sintering step in which a lithium salt is added to the nickel-manganese precursor and the resulting mixture is sintered in a low-oxygen environment to obtain the first material; and a coating step in which a halogen is added to the first material to obtain a coating mixture, and the coating mixture is dried and sintered in a vacuum environment to obtain the cathode material, wherein the molar ratio of nickel to manganese in the nickel-manganese metal solution is 1:3.

[0013] In one embodiment of the present invention, there is provided a method for producing a cathode material, wherein the sintering step is performed in a nitrogen atmosphere.

[0014] In one embodiment of the present invention, there is provided a method for producing a cathode material, wherein the sintering step is performed at 500° C. to 1000° C. for 1 to 13 hours.

[0015] The present invention relates to a cathode material, particularly a cathode material having a core made of lithium nickel manganese oxide material and a coating made of a lithium-containing ternary halide. The present invention also relates to a method for producing a cathode material, particularly a method for coating a lithium nickel manganese oxide material with a lithium-containing ternary halide material. The method comprises preparing a nickel manganese precursor by coprecipitation and sintering it to LiNi 0.5 Mn 1.5 O 4-δ The material is obtained and finally coated with Li3InCl6 by sol-gel method. 0.5 Mn 1.5 O 4-δTo obtain the material, i.e., the cathode material of the present invention, herein LIC@LiNi 0.5 Mn 1.5 O 4-δ Also called. [Effects of the Invention]

[0016] LiNi in Li3InCl6 0.5 Mn 1.5 O 4-δ By covering the material with the electrolyte, the material is prevented from coming into contact with the electrolyte, and good ionic conductivity and cycle stability can be achieved. [Brief explanation of the drawings]

[0017] [Figure 1] 1 is a diagram showing the structure of a cathode material in an embodiment of the present invention. FIG. [Figure 2] FIG. 2 is a diagram showing the analysis results of Fourier transform infrared spectroscopy (FT-IR) of a cathode material according to an embodiment of the present invention. [Figure 3] FIG. 2 is a diagram showing the results of Raman spectrum analysis of a cathode material according to an embodiment of the present invention. [Figure 4] FIG. 10 is a diagram showing the results of a cycle test of a cathode material according to an embodiment of the present invention. [Figure 5] FIG. 10 is a diagram showing the results of a cycle test of a cathode material according to an embodiment of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0018] Hereinafter, an embodiment of the present invention will be described with reference to Figures 1 to 5. The description is merely an example of an embodiment of the present invention, and is not intended to limit the embodiment of the present invention.

[0019] The cathode material according to an embodiment of the present invention includes a core 1 made of a first material and a coating 2 made of a second material and surrounding the core.

[0020] According to the cathode material of the embodiment of the present invention, the first material is LiNi 0.5 Mn1.5 O 4-δ and δ>0, the second material is a lithium-containing ternary halide.

[0021] According to the cathode material of the present invention, the second material is Li a MX b wherein M is a non-lithium metal, X is a halogen, and a and b are positive integers.

[0022] The second material Li a MX b The composition represented by the formula (I) is preferably lithium indium halide (LiInCl6).

[0023] According to the cathode material of the embodiment of the present invention, the coating has a thickness of 5 to 60 nm.

[0024] When the cathode material having the above technical features is used as an electrode of a lithium battery, it can effectively improve the discharge rate performance and cycle life.

[0025] The method includes a co-precipitation step in which a nickel-manganese metal solution, a sodium hydroxide solution, and an ammonia solution are mixed in a container to obtain a precipitate, which is dried and sieved to obtain a nickel-manganese precursor; a sintering step in which a lithium salt is added to the nickel-manganese precursor and sintered in a low-oxygen environment to obtain the first material; and a coating step in which a halogen is added to the first material to obtain a coating mixture, which is dried and sintered in a vacuum environment to obtain the cathode material.

[0026] In the nickel manganese metal solution, the molar ratio of nickel to manganese is 1:3.

[0027] According to the method for producing a cathode material of the embodiment of the present invention, the sintering step is performed in a nitrogen atmosphere.

[0028] According to the method for producing a cathode material of the embodiment of the present invention, the sintering step is performed at 500° C. to 1000° C. for 1 to 13 hours.

[0029] According to the method for producing a cathode material of the embodiment of the present invention, in the coating step, the weight of the halogen accounts for 1 to 10% of the total weight of the coating mixture.

[0030] According to the method for producing a cathode material of the embodiment of the present invention, in the coating step, sintering is performed at 150°C to 250°C for 4 to 6 hours.

[0031] The method for producing the cathode material of the present invention will be described below based on a production example, but the present invention is not limited thereto.

[0032] (Production Example 1) Low-oxygen lithium nickel manganese oxide material (LiNi 0.5 Mn 1.5 O 4-δThe coprecipitation step was first performed: nickel sulfate (NiSO4·6H2O), manganese sulfate (MnSO4·H2O), and ammonium sulfate ((NH4OH)SO4) were mixed in a 1:3:1 molar ratio as the feed metal solution, 18% aqueous ammonia solution was used as the chelating agent, and 1.2 M sodium hydroxide solution was used as the precipitant. A 2 L glass reactor was used as the coprecipitation reaction vessel, and diluted aqueous ammonia solution was used as the starting solution. The feed metal solution and chelating agent were injected into the glass reactor using a peristaltic pump, and the coprecipitation step was performed at feed rates of 40 ml / h and 20 ml / h, respectively. During this time, the pH was set to 10.2 ± 0.1 using a pH controller, and precipitant was added using a dosing pump to maintain the reaction environment if the pH deviated from the set value. The reactor temperature was set to 40 °C, the agitator speed was set to 2000 rpm, and nitrogen gas was used as a protective atmosphere. When the solution in the reactor reached the overflow port, the co-precipitation product was collected in the overflow tank via a plastic tube. Finally, the co-precipitation product was centrifugally washed with pure water, dried in an oven at 80 °C, and sieved to obtain the nickel-manganese reaction precursor. The nickel-manganese reaction precursor was sieved and mixed with an appropriate molar ratio of lithium carbonate (or lithium hydroxide) and two zirconium balls (1 cm diameter) in a 3D mixer for 16 hours. The mixed powder was then sintered in a tubular furnace. In a nitrogen atmosphere, the mixture was heated from room temperature to 910 °C at a rate of 1 °C / min, maintained for 12 hours, then cooled to 600 °C, maintained for 12 hours, cooled to room temperature, and sieved to obtain LiNi 0.5 Mn 1.5 O 4-δ The prototype material was obtained.

[0033] Next, the oxygen-deficient structure is verified by FT-IR and Raman spectroscopy. The results of FT-IR and Raman spectroscopy are shown in Figures 2 and 3. 0.5 Mn 1.5 O 4-δ It was shown that the absorption peaks of Ni-O in the

[0034] (Example) Next, a cathode material is produced by the production method of the present invention: First, lithium chloride (LiCl) and indium chloride (InCl) in a molar ratio of 3:1 are dissolved in deionized water, and the LiNi 0.5 Mn 1.5 O 4-δ The material was added to the aqueous solution at a ratio of 95 wt%, and the material was mixed uniformly by ultrasonic treatment. The solution was then dried at 100 °C for two days to obtain powder, and finally sintered at 200 °C for 5 h to obtain 5% LIC@LiNi. 0.5 Mn 1.5 O 4-δ The material was obtained.

[0035] (Electrical Test) In order to understand the effect on the charge-discharge performance of a battery when the cathode material of the present invention is applied to the battery, a battery was manufactured by the following method and a charge-discharge test was carried out.

[0036] The conductivity test was divided into a manufacturing example group and an example group. First, 1.5 g of polyvinylidene fluoride was added to 24.75 g of N-methylpyrrolidone (NMP) and mixed. After the polyvinylidene fluoride was completely dissolved, the material of the manufacturing example (LiNi 0.5 Mn 1.5 O 4-δ Material) 12g, or the material of the example (LIC@LiNi 0.5 Mn 1.5 O 4-δAfter adding 1.5 g of conductive carbon material and mixing thoroughly, the resulting paste was applied to an 18 μm-thick aluminum foil using a 120 μm scraper and baked in an oven at 120 °C to complete the battery electrode plate. In this case, the weight ratio of active material:conductive carbon material:adhesive was 80:10:10. Before assembling the battery, the electrode plate was baked in a vacuum environment at 120 °C for 12 hours. The electrode plate was then placed in a glove box and used a lithium metal counter electrode. The electrolyte was a 1 M LiPF6 solution mixed with ethylene carbonate (EC) and diethyl carbonate (DEC) in a 1:1 volume ratio. A button-type half cell was assembled using the lithium metal, separator, electrolyte, and electrode plate, and then subjected to electrical conductivity testing. The results are shown in Figures 4 and 5.

[0037] Figure 4 shows LiNi 0.5 Mn 1.5 O 4-δ Electrode plate batteries and LIC@LiNi made using the materials 0.5 Mn 1.5 O 4-δ The graph shows the results of measuring the discharge capacity after discharging a battery with electrode plates made using the material at discharge rates of 0.2C, 0.5C, 1C, 2C, 4C, 6C, 8C, and 10C.

[0038] As shown in Figure 4, even after discharge at each rate, the LIC@LiNi 0.5 Mn 1.5 O 4-δ The capacity retention rate of the battery electrode plate made using the material is 0.5 Mn 1.5 O 4-δ This is higher than batteries made with electrode plates made using this material.

[0039] Figure 5 shows LiNi 0.5 Mn 1.5 O 4-δ Electrode plate batteries and LIC@LiNi made using the materials 0.5 Mn 1.5 O 4-δThe graph shows the results of 200 discharge cycles of a battery with electrode plates made using the material, and measuring the discharge capacity at each cycle.

[0040] As shown in Figure 5, even after 200 discharge cycles, the LIC@LiNi 0.5 Mn 1.5 O 4-δ The capacity retention rate of the battery electrode plate made using the material is 0.5 Mn 1.5 O 4-δ This is higher than batteries made with electrode plates made using this material.

[0041] That is, LIC@LiNi 0.5 Mn 1.5 O 4-δ When the material is used as a cathode material in lithium batteries, LiNi 0.5 Mn 1.5 O 4-δ The core provides magnification performance, and the LIC coating is LiNi 0.5 Mn 1.5 O 4-δ This prevents the problems of manganese coming into contact with the electrolyte and dissolving, providing stable cycle performance.

[0042] Although the preferred embodiments of the present invention have been disclosed above, they are not intended to limit the present invention in any way. Various changes and modifications can be made without departing from the spirit and scope of the present invention. Therefore, the claims of the present invention should be interpreted to include such changes and modifications. [Explanation of symbols]

[0043] 1 core 2. Coating

Claims

1. A cathode material comprising a core made of a first material and a coating made of a second material surrounding the core, The first material is LiNi ０．５ Mn １．５ O ４－δ and δ>0, and the second material is a lithium-containing ternary halide. A cathode material characterized by:

2. The second material is Li ａ MX ｂ wherein M is a non-lithium metal, X is a halogen, and a and b are positive integers. The cathode material of claim 1 .

3. The second material is lithium indium halide (LiInCl ６ ) The cathode material of claim 1 .

4. The thickness of the coating is 5 to 60 nm. The cathode material of claim 1 .

5. a co-precipitation step in which a nickel manganese metal solution, a sodium hydroxide solution, and an ammonia solution are mixed in a vessel to obtain a precipitate, which is dried and sieved to obtain a nickel manganese precursor; adding a lithium salt to the nickel manganese precursor and sintering the resulting mixture in a low-oxygen environment to obtain the first material; and A method for producing a cathode material, comprising: a coating step in which the first material is added to a halogen to obtain a coating mixture; the coating mixture is dried and sintered in a vacuum environment to obtain the cathode material; In the nickel-manganese metal solution, the molar ratio of nickel to manganese is 1:

3. A method for producing a cathode material comprising the steps of:

6. In the sintering step, sintering is carried out in a nitrogen atmosphere. The method for producing the cathode material according to claim 5 .

7. In the sintering step, sintering is performed at 500°C to 1000°C for 1 to 13 hours. The method for producing the cathode material according to claim 5 .

8. In the coating step, the weight of the halogen accounts for 1 to 10% of the total weight of the coating mixture. The method for producing the cathode material according to claim 5 .

9. The coating step is sintered at 150°C to 250°C for 4 to 6 hours. The method for producing the cathode material according to claim 5 .

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